Blast of hot air reduces bacteria in poultry cages

Blast of hot air reduces bacteria in poultry cages

POULTRY producers can reduce bacterial cross-contamination in poultry cages by treating the cages with forced air that has been heated to 122 degrees F, according to a study by scientists with the U.S. Department of Agriculture's Agricultural Research Service (ARS).

While being transported in coops on trucks, poultry that have bacteria such as campylobacter can contaminate, through their feces, other poultry that are free of pathogens, ARS reported. Those disease-causing bacteria can then be passed on to the next group of birds during the next trip, and so forth, unless the cycle is broken.

Campylobacter is a foodborne pathogen that can be present in raw or undercooked poultry. Since the bacteria are commonly found in the digestive tracts of poultry, they're readily deposited onto coops and trucks when contaminated animals are transported to processing plants, ARS said.

In the study, ARS microbiologists Mark Berrang and Richard Meinersmann collaborated with researcher Charles Hofacre of the University of Georgia at Athens. Berrang and Meinersmann work in the ARS Bacterial Epidemiology & Antimicrobial Resistance Research Unit in Athens, Ga.

The researchers tested the use of hot flowing air to speed the process of drying soiled or washed cages to lower or eliminate detectable campylobacter on cage flooring.

When the hot flowing air was applied to transport cage flooring samples soiled with fecal matter for 15 minutes after a water-spray wash treatment, campylobacter levels declined to an undetectable level, ARS reported. Static heat at similar temperatures was not nearly as effective, and unheated flowing air was moderately effective, but less so than hot flowing air.

The study's results were published in the Journal of Applied Poultry Research.

Volume:85 Issue:05

Barriers to science communication

Barriers to science communication

RESEARCHERS today, more than ever, focus their work on real-world problems, oftentimes making their research relevant to the public locally, regionally and sometimes nationally.

However, engaging the public in their research can be a daunting task for researchers both professionally and personally.

Leah Gerber, an associate professor in the Arizona State University School of Life Sciences, has identified impediments to productive science communication. She presented her findings at the recent annual meeting of the American Association for the Advancement of Science (AAAS) in Boston, Mass.

As a researcher, Gerber and her group at Arizona State develop mathematical approaches that bring together the best available scientific information to make rational, efficient conservation decisions about endangered species and ecosystem management. Getting that information to the public is a key component of her work.

Gerber said barriers to communicating science include a lack of reward for engaging the public and decision-makers on science, limited communications training and the time pressure faculty members face while trying to obtain tenure.

She said other barriers for researchers include prioritizing their commitments, understanding the value of communicating their work to the public and needing to push their comfort zone, such as standing in front of a camera.

While the culture is slowly changing within academic institutions, success in higher education still is largely measured by publications and grants, which demand large amounts of time, Gerber said.

"We must find a way to make engagement rise to the top of the pile," Gerber said, noting that new institutional incentives need to be developed and implemented.

Gerber said some other institutional changes need to be made as well. For example, she said new accounting measures need to be developed for faculty who engage the public, and their outreach work needs to be part of their evaluations.

In addition to the standard grants and publications measures, communications training should become part of leadership programs for scientists, and professors should be given time to develop relationships with the media, Gerber added.

 

'Wild West' of blogs

In a separate AAAS presentation, University of Wisconsin-Madison science communication researcher Dominique Brossard reported the results of a study showing that the tone of blog comments alone can influence the perception of risk posed by nanotechnology, the science of manipulating materials at the smallest scales.

The study, now in press at the Journal of Computer Mediated Communication, was supported by the National Science Foundation. It sampled a representative cross-section of 2,338 Americans in an online experiment in which the civility of blog comments was manipulated.

For example, the study showed that introducing name calling into commentary tacked onto an otherwise balanced newspaper blog post could elicit either lower or higher perceptions of risk, depending on one's predisposition to the science of nanotechnology.

"It seems we don't really have a clear social norm about what is expected online," Brossard said, contrasting online forums with public meetings, where prescribed decorum helps keep discussion civil. "In the case of blog postings, it's the Wild West."

For rapidly developing nanotechnology, which is already built into more than 1,300 consumer products, exposure to uncivil online comments is one of several variables that can directly influence the perception of risk associated with the technology.

"When people encounter an unfamiliar issue like nanotechnology, they often rely on an existing value such as religiosity or deference to science to form a judgment," explained Ashley Anderson, a postdoctoral fellow in the Center for Climate Change Communication at George Mason University and the lead author of the upcoming journal article.

The study revealed that highly religious readers were more likely to see nanotechnology as risky when exposed to rude comments compared to less-religious readers, Brossard noted.

"Blogs have been a part of the new media landscape for quite some time now, but our study is the first to look at the potential effects blog comments have on public perceptions of science," Brossard said.

While the tone of blog comments can have an impact, simple disagreement in posts can also sway perception: "Overt disagreement adds another layer. It influences the conversation," she explained.

University of Wiscosin-Madison life sciences communication professor Dietram Scheufele, another of the study's co-authors, noted that the internet is a primary destination for people who are looking for detailed information and discussion on aspects of science and technology.

Because of that trend, "studies of online media are becoming increasingly important, but understanding the online information environment is particularly important for issues of science and technology," he said.

 

 

Volume:85 Issue:08

Past, future advances in equine nutrition

Past, future advances in equine nutrition

*Dr. Joe D. Pagan is president and founder of Kentucky Equine Research Inc., which, through consultation and research, aims to bridge the gap that may exist between basic research and horse production.

IN 2013, Kentucky Equine Research (KER) will celebrate its 25th anniversary as an equine nutrition research and consultation company.

During the past quarter-century, several advances have been made in the field of equine nutrition and feed manufacturing.

To kick off this important milestone year, I would like to review what I feel are five of the most important advancements that have been made in the field of equine nutrition and predict what's ahead for the industry.

 

Trace minerals

In the mid-1980s, a landmark study was published by researchers at The Ohio State University in which a correlation was found between the level of copper in a breeding farm's ration and the incidence of metabolic bone disease in the farm's foals.

Metabolic bone disease (later renamed developmental orthopedic disease) is a major problem for many horse breeders that causes huge economic losses due to lameness in performance horses.

Following this study, researchers around the world concentrated on finding the link between trace minerals -- particularly copper and zinc -- and bone development.

One important study from New Zealand demonstrated that trace mineral nutrition of the pregnant mare also affected subsequent bone health in her foal.

Since then, the feed industry has universally embraced the importance of trace mineral fortification for broodmare and foal feeds, and high levels of copper and zinc have become standard.

 

Carbohydrate nutrition

Although carbohydrates make up the majority of most horse feeds, historically little was known about their chemical composition or metabolic effects in horses.

For more than 100 years, the feed industry depended on the proximate, or Weende, system of feed analysis to estimate the carbohydrate content in horse feed. This system did a poor job of measuring the types and amounts of sugar and starch present.

Along with advancements in carbohydrate chemistry came a huge amount of research that studied the effect of starch type and processing effects on the digestibility and utilization of starches and sugars from different sources. This research proved that starch from various cereals was very different and that grain processing greatly affected starch digestibility.

In addition, it was discovered that the glycemic nature of a feed had profound effects on bone metabolism, behavior and exercise performance.

The time of feeding in relation to exercise was also determined to be important. Today, the glycemic index of various feedstuffs is known, and this information is used in feed formulation.

 

Alternative energy sources

The last 25 years have seen a large shift away from starch and sugar as the only energy sources in horse feeds.

Adding fat to horse feeds became popular in the 1980s, and there have been dozens of studies since then that have focused on feeding fat to performance horses. Several of these studies showed that horse muscle can be trained to burn fat instead of carbohydrates, resulting in a glycogen sparing effect and improved endurance capacity.

The early work with fat supplementation used a variety of different vegetable oils and animal fat without paying much attention to the fatty acid composition of the fat source.

This has changed recently with the recognition of the importance of omega-3 polyunsaturated fatty acids (PUFAs) in horse diets. Optimal levels of omega-3 PUFAs have been shown to reduce inflammatory responses, support immune function and enhance fertility.

Continuing research is revealing more information about the benefits of supplementing horses with omega-3 fatty acids to achieve a more nutritionally sound balance.

In addition to fat, fermentable fiber has become an important component of performance horse feeds. Fermentable fiber includes galactans, fructans, gums, mucilages and pectin. They are not degraded by digestive enzymes but are rapidly and completely fermented by gastrointestinal microflora, yielding volatile fatty acids, which are versatile energy substrates for performance horses.

The most common sources of fermentable fiber are sugar beet pulp and soy hulls. These raw materials are now common ingredients in most performance horse feeds.

 

Nutrition and disease

Several metabolic disorders have become common in modern breeds of horses. Recent research has demonstrated that many of these disorders -- such as equine Cushing's disease, equine metabolic syndrome, osteochondritis dissecans, recurrent equine rhabdomyolysis (RER) and polysaccharide storage myopathy -- can be managed nutritionally by careful regulation of caloric intake while paying particular attention to the source of energy provided.

Although these disorders have very different etiologies, they are all either triggered or aggravated by excessive starch and sugar intake.

RER is a specific form of tying-up seen in Thoroughbreds, Standardbreds and Arabians. It is an inherited trait caused by abnormal intracellular calcium regulation during muscle contraction. Excitement and stress seem to be triggers.

Studies conducted at the University of Minnesota in conjunction with KER showed that replacing much of the grain in the diet with a low-starch, high-fat feed will significantly decrease the amount of muscle damage in RER horses. This research lead to the development of Re-Leve, the first commercial horse feed produced to manage a specific metabolic disorder. Since then, a number of reduced-carbohydrate feeds have been developed for a variety of special needs.

 

Balanced rations

The past quarter-century has seen a great increase in demand for well-fortified horse feeds in both the performance and breeding sectors of the horse industry. Much of this increase has resulted from technological advances that have allowed feed manufacturers to illustrate the importance of including fortified feeds in a horse's ration.

Rather than relying on feed tags or brochures with limited nutrition information, horse feed companies now have access to sophisticated software that graphically illustrates how each feedstuff in a ration meets a specific horse's nutrition requirements.

KER released the first version of its computer-based equine nutrition evaluation software called MicroSteed in the early 1990s. Since then, MicroSteed has migrated onto the internet, where horse managers can use their smartphones to evaluate their horses' rations and receive detailed technical support without leaving the barn aisle.

 

The future

What does the future hold for the equine nutrition field?

Certainly at the top of the list is nutrigenomics, the study of the effects of feeds and feed constituents on gene expression. By understanding how nutrients interact with the genome, better dietary regimens may be designed, or novel treatment of important diseases may be addressed.

The emergence and development of nutrigenomics have been possible due to powerful developments in genetic research. These tools are already being used in horses, and they will certainly become a major tool for equine nutrition research in the future.

Finally, I believe that there will be a great demand for alternative ingredients for horse feeds in the future. As human population growth continues to increase, demand for cereal grains and oilseeds for human consumption will place added pressure on the livestock industry to look at alternative feedstuffs. Co-products from human food production will become attractive future ingredients for horse feed. 

Volume:84 Issue:54

Brewers yeast, byproducts may have role in pet foods

Brewers yeast, byproducts may have role in pet foods

The authors are with the department of animal sciences at the University of Illinois.

Industrial strains of Saccharomyces cerevisiae are heterogeneous and used in several industries including baking, brewing, distilling and wine production (Sumner and Avery, 2002). Although these strains share common features such as efficient sugar utilization, high ethanol tolerance and production, high yield and fermentation rate and genetic stability, they also possess properties specific to each group (Trivedi et al., 1986; Benítez et al., 1996).

Eight official and one "tentative" yeast products are currently defined by the Association of American Feed Control Officials (AAFCO; 2002) and are differentiated by source of yeast and characteristics such as moisture and crude protein concentrations and fermentative activity. By definition, "brewers dried yeast" is the dried, non-fermentative, non-extracted yeast of the botanical classification Saccharomyces resulting as a byproduct from the brewing of beer and ale. It must contain not less than 35% crude protein and be labeled according to its crude protein content (AAFCO, 2002).

As defined, brewers dried yeast must originate from a brewery and the brewing of beverages -- beer or ale -- for human consumption and should not be confused with corn wet milling yeast that is used in industrial ethanol production.

As Table 1 illustrates, the chemical compositions of brewers dried yeast and corn wet milling yeast are different. Chemical and organoleptic differences likely are due to differences in the fermentation processes and in the substrates used. In the brewing industry, wort derived mostly from malted barley is fermented slowly at temperatures of 10-20 degrees C using a batch fermentation process that yields a beer with an alcohol content of approximately 6%.

In contrast, during wet milling ethanol fermentation, distillers commonly grind and cook corn using enzymes to convert starch to sugar. A rapid, continuous fermentation process at temperatures between 35 and 38 degrees C is then employed to maximize substrate utilization and ethanol production, yielding 9-12% alcohol.

Although not fully researched, many of the differences in brewers dried yeast and yeast from corn wet milling ethanol production (e.g., fat content, hops products [caryophyllene, humulene] and sugar profiles) are likely factors that affect palatability.

Composition of brewers yeast

Commercially available brewers yeast is typically dried from a yeast slurry to a dry powder of less than 10% moisture to facilitate handling, storage and transport. Brewers yeast is relatively high in crude protein and carbohydrate concentrations, while the concentrations of fat and ash are relatively low. This is not surprising because yeast synthesizes protein and vitamins while absorbing minerals from the beer wort during the fermentation process.

The relatively low fat content of brewers yeast compared to yeast from commercial wet milling ethanol fermentation likely is due to substrate differences (the low fat concentration of barley compared to corn) and differences in the fermentation processes.

Various methods are used to determine fiber concentration of ingredients, including brewers yeast. As Table 2 illustrates, the concentration of fiber present in yeast depends greatly on method used. Although the method of measuring crude fiber (AOAC, 1980) is used for regulatory purposes, results are misleading as several fibrous compounds are solubilized with this procedure, resulting in a large underestimation of fiber content.

The neutral detergent fiber (NDF) method of Robertson and Van Soest (1977) results in solubilization of viscous fiber components and recovery of cell wall constituents. Because brewers yeast contains a considerable amount of protein that becomes viscous when partially hydrolyzed during the NDF procedure, filtration problems and inflated recoveries result in overestimated fiber concentrations (Merchen et al., 1990). The best method for proteinaceous feeds such as brewers yeast is that of Prosky et al. (1992) used to measure total dietary fiber (TDF; Merchen et al., 1990).

The cell wall of S. cerevisiae constitutes approximately 15-30% of the dry weight of the cell and consists primarily of mannosylated proteins, beta-glucans and chitin (N-acetylglucosamine), which are covalently linked with one another. The glucan portion consists of beta-(1,3)- and beta-(1,6)-chains. The major structural components of the cell wall are the beta-(1,3)-glucans, which form the internal skeletal framework of the cell and are largely responsible for its mechanical strength. This form of glucan is highly branched and possesses multiple non-reducing ends that function as attachment sites for other components of the cell wall (Kollár et al., 1997). Beta-(1,6)-glucans are found primarily outside the skeletal framework and often are linked to cell wall proteins (CWP).

Mannose polysaccharides are linked to proteins to form a mannoprotein layer localized at the external surface of the yeast cell wall. Two classes of covalently linked CWP have been identified. The first class consists of glycosyl phosphatidylinositol (GPI) proteins, which form a GPI-CWP ® beta-(1,6)-glucan ® beta-(1,3)-glucan complex (Kollár et al., 1997).

The second class of CWP, the protein with internal repeats (Pir), are linked directly to beta-(1,3)-glucans. Mannoproteins are strictly regulated in response to changes in external conditions (e.g., heat shock, hypo-osmotic shock, carbon source) and internal changes during the cell division cycle (Horie and Isono, 2001).

While glucans and mannoproteins are main components of the cell wall and found in approximately equal amounts, chitin constitutes only about 1-3% of the cell wall. Although present in minute quantities, it is a major component of the primary septum and is involved in the separation of mother and daughter cells, making it essential for cell division (Shaw et al., 1991). The remaining components of yeast, excluding the cell wall, are collectively referred to as yeast cell extract and contain numerous nucleotides, enzymes, vitamins and minerals.

Use of yeast in pet foods

Brewers yeast is used in companion animal foods because it is a high quality protein source rich in B vitamins, amino acids and minerals. Inclusion of brewers yeast in companion animal diets has been shown to increase (P < 0.05) palatability in both dogs (Figure 1; Kennelwood Inc., unpublished data; Ontario Nutri Lab Inc., unpublished data) and cats (Figure 2; Kennelwood Inc., unpublished data) compared to diets containing wet milling yeast, with consumption ratios ranging from 1.9:1 to 2.1:1 in these experiments.

In these experiments, either brewers yeast or wet milling yeast was included in the diet at a 1% inclusion level. In each experiment, a panel of 20 dogs or cats was used to test food preference with a standard four-day palatability test. Each day on test, both diets were offered simultaneously for a period of one hour. To account for right-left bias, the placement of diets was alternated each day. After the one-hour feeding period, both diets were removed simultaneously and weighed to calculate intake. To our knowledge, more detailed nutritional studies with dogs and cats have not been conducted.

Use of yeast byproducts

In recent years, human food ingredients have been evaluated not only for their nutritional contribution but for their non-nutritional properties as well. "Functional foods," "nutraceuticals" and "phytochemicals" are terms commonly used to refer to foods or compounds in foods that possess properties that may benefit the human in ways other than providing nutritive value. Although use of functional foods began in the human food industry, the pet food industry, too, has recognized their potential benefits.

Many functional ingredients are thought to decrease the incidence of certain disease states or extend the lifespan of pets by possessing antioxidant activity, antimicrobial action or immuno-enhancing properties. Several components present in yeast may be classified as being "functional," including glucomannans, mannans, mannoproteins, beta-glucans and nucleotides.

Glucomannans.

Sharma and Márquez (2001) tested 12 pet foods commercially available in Mexico for frequency and concentration of aflatoxins. In that experiment, seven aflatoxins and aflatoxicol were detected in most samples, with aflatoxin B1 being present in the highest frequency and concentration. In all contaminated samples, maize was the main ingredient.

Research is needed to measure incidence and concentration of mycotoxins in pet foods commercially available in the U.S. and to determine whether these concentrations are cause for concern. If that is the case, inclusion of glucomannans in pet foods, especially those containing high concentrations of grain, may be prudent.

Due to the antimutagenic and antioxidative activity of glucomannans, they also could play a role in colon cancer prevention (Chorvatovicová et al., 1999; Križková et al., 2001).

Mannans.

Mannans have been studied for their ability to agglutinate and interfere with intestinal binding and colonization of harmful microbial species. Numerous Escherichia coli and Salmonella strains possess mannose-specific fimbriae, agglutinate mannans in vitro and colonize in lower concentrations in animals supplemented with mannans. Fimbrial adhesins specific for mannan residues are referred to as "Type-1" adhesins.

Mannans aid in the resistance of pathogenic colonization by acting as receptor analogues for Type-1 fimbriae and decrease the number of available binding sites (Oyofo et al., 1989).

Mannans are capable of modulating the immune system and influencing microbial populations in the gut. Mannans have been reported to increase (P = 0.14) serum immunoglobulin A (IgA) concentrations in dogs (2.33 versus 1.93 g/L; Swanson et al., 2002a). In adult dogs, MOS beneficially altered microbial ecology by increasing (P = 0.13) lactobacilli populations (9.16 versus 8.48 log10 colony-forming units [cfu]/g fecal dry matter) and decreasing (P = 0.05) total aerobe populations (7.68 versus 8.67 log10 cfu/g fecal dry matter; Swanson et al., 2002a).

Mannoproteins.

Beta-glucans.

An experiment using free-living, obese, hypercholesterolemic men demonstrated that yeast-derived beta-glucans were well tolerated and decreased (P < 0.05) blood total cholesterol concentrations similar to the effect of oat products (Nicolosi et al., 1999). In that experiment, beta-glucan supplementation decreased blood total cholesterol after seven (8% reduction) and eight (6% reduction) weeks of supplementation.

Yeast-derived beta-glucans also appear to possess antimicrobial and antitumor properties by enhancing immune function. The binding of beta-glucan to its receptor present on macrophages results in phagocytosis, respiratory bursts and secretion of tumor necrosis factor-alpha (TNF-alpha; Chen and Hasumi, 1993; Lee et al., 2001).

Finally, beta-glucans are readily fermented in the large bowel and serve as a fuel source for microbial populations.

Nucleotides.

In addition to stimulating the development of the small intestine (Bueno et al., 1994) and liver (Sánchez-Pozo et al., 1998), exogenous nucleotides have been shown to enhance immune function by increasing production of immunoglobulins, improving response to vaccines and increasing tolerance to dietary antigens (Maldonado et al., 2001).

Because of its importance in neonatal nutrition, the inclusion of nucleotides in human infant formulas is under investigation (Cordle et al., 2002; Ostrom et al., 2002).

In vitro research on yeast byproducts.

When using canine fecal inoculum to determine the fermentability characteristics of MOS, Vickers et al. (2001) observed the production of moderate concentrations of total short-chain fatty acids after 6 (0.49 mmol/g of organic matter), 12 (1.45 mmol) and 24 hours (2.40 mmol) of in vitro fermentation. Very low concentrations of lactate were produced as a result of MOS fermentation. The microbial species responsible for MOS breakdown were not determined in this experiment.

Hussein and Healy (2001) also performed an in vitro experiment using canine and feline fecal inoculum to determine fermentability of MOS. Differences were not observed in fermentability between dog and cat fecal inoculum. By examining dry matter and organic matter disappearance, it appeared that MOS was highly fermented. Dry matter disappearance after 6, 12, 18 and 24 hours of in vitro fermentation was 54.3, 57.9, 60.7 and 61.3%, respectively. Organic matter disappearance was similar to that of dry matter (56.8, 60.7, 63.7 and 64.1% after 6, 12, 18 and 24 hours of fermentation).

Dry matter and organic matter disappearance do not always reflect microbial fermentation due to the disappearance of soluble carbohydrates present in the substrates that are not retained during filtering. Although soluble carbohydrates are available for fermentation, gravimetric methods cannot determine the proportion used by the microbes as an energy source. Therefore, the measurement of dry matter and organic matter disappearance is not as accurate as the measurement of the fermentation end products (i.e., short-chain fatty acids and gas), which is a direct measurement of fermentation.

Concentrations of total short-chain fatty acids, acetate and propionate increased linearly over time. Moderate concentrations of total short-chain fatty acids (10.1, 26.8, 36.7 and 49.7 mM) were produced after 6, 12, 18 and 24 hours. In comparison to total short-chain fatty acids, lactate concentrations were fairly high (7.7, 8.7, 7.6 and 5.9 mM), suggesting fermentation by a lactate-producing species (e.g., lactobacilli, bifidobacteria).

In agreement with the work of Vickers et al. (2001), these data suggest that MOS is moderately fermentable by canine and feline microflora. The lactate produced during fermentation suggests that lactate-producing species are able to utilize MOS, possibly by acting as a prebiotic for these species.

In vitro

In agreement with short-chain fatty acid data, gas was produced in relatively high amounts (corrected gas values were 17.4, 58.3 and 100.9 ml/g organic matter after 4, 12 and 24 hours of fermentation).

Canine research on yeast byproducts.

In the second experiment, Border collie pups were fed diets containing 0 or 2 g MOS/kg. After a seven-day adaptation period, a vaccination protocol was initiated. All dogs were vaccinated against parvovirus, leptospirosis, adenovirus and distemper. Vaccine boosters were applied on day 21 for leptospirosis and on day 35 for parvovirus. Blood characteristics were measured over a nine-week period.

No changes were observed in weight gain, lysozyme activity, plasma protein concentration or plasma IgG concentration. Neutrophil activity was numerically increased in pups fed the diet containing MOS after vaccination (approximately 18 versus 14 Nitroblue tetrazolium [NBT]+ cells per slide]. However, due to low animal numbers (n = three per group), statistical significance was not reached.

Using adult ileal cannulated dogs, Strickling et al. (2000) compared a control diet to those containing 5 g oligosaccharide/kg diet, one of which was MOS. Researchers measured ileal and total tract nutrient digestibilities, microbial populations, ileal pH, ammonia and short-chain fatty acid concentrations, blood glucose and fecal consistency. Besides minor changes in short-chain fatty acid concentrations, the only relevant finding was a decrease (P = 0.07) in Clostridium perfringens populations in dogs fed MOS (4.48 log10 cfu/g) versus dogs fed xylooligosaccharides (5.16 log10 cfu/g) or oligofructose (4.74 log10 cfu/g).

Because clostridia species do not possess mannose-specific fimbriae, another mechanism is likely occurring. The lack of any significant findings may be due to the low dose of prebiotics consumed (only about 1.3 g per day) or to the use of soybean meal in the control diet, which supplied an estimated 10 g/kg of naturally occurring oligosaccharides, mainly galactooligosaccharides. Any beneficial effects resulting from MOS consumption may have been masked by the presence of these naturally occurring oligosaccharides.

Zentek et al. (2002) used four dogs in a 4 x 4 Latin square design to determine the effects of MOS, transgalactosylated oligosaccharides, lactose and lactulose on fecal characteristics, total tract digestibility and concentrations of microbial end products in feces and urine. Carbohydrate supplements were administered at a rate of 1 g/kg bodyweight per day. MOS supplementation decreased (P < 0.05) fecal pH (6.6 versus 6.9), fecal ammonia excretion (78.4 versus 116 ;Jmol/g feces) and apparent dry matter (81.9 versus 85.0%), crude protein (79.8 versus 82.5%) and nitrogen-free extract (83.1 versus 94.8%) digestibilities.

By decreasing fecal pH and ammonia, MOS supplementation appeared to improve indices of colonic health. However, the decreases observed in apparent nutrient digestibilities resulting from MOS supplementation would increase fecal quantity and the cost of feeding the animal. The dose of carbohydrate supplements fed in this experiment (1 g/kg bodyweight per day) was very high. Smaller doses of MOS may not have such negative effects on nutrient digestibility.

Using ileal cannulated adult dogs, Swanson et al. (2002a) examined the effects of supplemental MOS and/or fructooligosaccharides (FOS) on colonic microbial populations, local and systemic immune function, fecal protein catabolite concentrations and ileal and total tract nutrient digestibilities. A 4 x 4 Latin square design with 14-day periods was used. Twice daily, dogs were offered 200 g of a dry, extruded kibble diet and given the following treatments orally via gelatin capsules: (1) control (no supplemental MOS or FOS), (2) 1 g FOS, (3) 1 g MOS or (4) 1 g FOS and 1 g MOS.

MOS supplementation beneficially influenced microbial populations, decreasing (P = 0.05) total aerobe (7.68 versus 8.67 log10 cfu/g fecal dry matter) and tending to increase (P = 0.13) lactobacillus populations (9.16 versus 8.48 log10 cfu/g fecal dry matter). MOS also increased serum IgA concentrations (2.33 versus 1.93 g/l, P = 0.14) and lymphocyte numbers (20.4 versus 15.6% of total white blood cells, P < 0.05). A tendency for decreased ileal dry matter (55.0 versus 67.7 %, P = 0.15) and organic matter (63.6 versus 74.1%, P = 0.15) digestibility also was observed from MOS supplementation.

The combination of FOS and MOS supplementation enhanced immune characteristics, increasing ileal IgA concentrations on a dry matter basis (4.90 versus 3.40 mg/g ileal dry matter, P = 0.06) and crude protein basis (12.22 versus 8.22 mg/g ileal crude protein, P = 0.05). Supplementation of FOS plus MOS also decreased (P < 0.05) total fecal indole and phenol concentrations (1.54 versus 3.03 ;Jmol/g fecal dry matter), compounds partially responsible for fecal odor and detrimental to intestinal health.

This experiment was performed using healthy adult dogs, which would not be at the highest risk for intestinal irregularities. It is likely that the health benefits of feeding MOS alone, or in combination with FOS, would be more beneficial to populations of elderly dogs, young weanling puppies or stressed animals.

In a follow-up study, Swanson et al. (2002b) supplemented ileal cannulated dogs with either 1 g sucrose (placebo) or 2 g FOS plus 1 g MOS. Fecal, ileal and blood samples were collected at the end of each 14-day period to measure microbial populations and immune characteristics. Supplementation of FOS plus MOS increased (P < 0.05) fecal bifidobacteria (10.04 versus 9.42 log10 cfu/g fecal dry matter) and lactobacilli concentrations in feces (9.75 versus 8.24 log10 cfu/g fecal dry matter) and ileal effluent (8.66 versus 7.55 log10 cfu/g ileal dry matter).

Dogs fed FOS plus MOS also tended to have lower (P = 0.08) blood neutrophils (62.99 versus 66.13% of total white blood cells; 6.40 versus 7.22 x 103 cells/;Jl) and greater (P = 0.06) blood lymphocytes (19.95 versus 17.29% of total white blood cells) compared to placebo. Serum, fecal and ileal immunoglobulin concentrations were unchanged (P >0.05) by treatment. Supplementation of FOS plus MOS beneficially influenced indices of gut health by improving ileal and fecal microbial ecology and altered immune function by causing a shift in blood immune cells.

Active components in yeast byproducts?

Source B was unique in that it contained a considerable amount of galactose in addition to glucose and mannose. The presence of galactose in that source may suggest that guar gum or locust bean gum, which contain galactomannans, are also present in this source of MOS. Although marketed as a source of MOS, these products are very complex and also contain glucans, mannoproteins, phosphate and several other compounds that apparently are not excluded in the crude extraction process.

Because the composition of MOS is complex, the components that result in beneficial effects are not known. Although the mannan portion of MOS is generally thought to be responsible for the pathogenic resistance effect by acting as a receptor analog for Type-1 fimbrial adhesions present on species such as E. coli and salmonella, it is possible that a different fraction present in MOS is responsible for its effects on immune function.

For example, mannoproteins and beta-glucans taken from yeast cell walls have been reported to enhance immunity. Therefore, more research is needed in order to determine whether bioactive peptides, beta-glucans, mannans or unknown factors present in MOS are responsible for the immune responses observed as a result of their supplementation.

Conclusions

Relatively little research has been performed with companion animal species, but the limited data suggest that inclusion of brewers yeast or yeast byproducts in pet foods may support gut health. Although brewers yeast often is included for palatability enhancement, its functional properties may be an even more important reason for its inclusion in pet foods.

From the limited number of experiments testing MOS, it appears that it has beneficial effects on indices associated with gut health. MOS supplementation has resulted in improved ileal and fecal microbial ecology and enhanced immune status. Because glucomannans are able to bind mycotoxins, their presence in pet foods also may be beneficial. Finally, yeast-derived beta-glucans, mannoproteins and nucleotides require further testing to determine their role, if any, in companion animal nutrition and health.

REFERENCES

AAFCO. 2002 Official Publication. AAFCO, West Lafayette, Ind.

AOAC. 1980. Official Methods of Analysis, 13th edition. Association of Official Analytical Chemists, Washington, D.C.

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Volume:75 Issue:40

Diet may affect nutrition, immune system of pets

Diet may affect nutrition, immune system of pets

Dr. C.M. Grieshop is with the department of animal sciences at the University of Illinois, Urbana-Champaign. She presented this paper at Alltech's 19th annual international symposium held May 12-14 in Lexington, Ky.

One goal of companion animal nutrition is optimization of the immune system. For many years, researchers have been aware of the interaction between nutrition and health status. Much of the early work in this area focused on the effects of nutrient deficiencies on the immune system, but more recent work has shifted toward enhancement of immune status, particularly at times in the animal's life when it is susceptible to an immune challenge.

Before any discussion can be made on the effects of nutrition on the immune system, a basic understanding of the physiology of the system is needed.

The immune system is a complex array of cells, tissues and signaling agents that work toward the common goal of protecting the body against foreign substances. An animal's immune system can be divided into two interactive components -- innate immunity and adaptive immunity.

Innate (also called native or natural) immunity includes physical barriers (skin and gastrointestinal tract), nonspecific phagocytic cells (neutrophils and macrophages), natural killer cells, blood proteins (complement system and inflammation mediators) and regulatory cytokines (Abbas, 2000). Components of innate immunity are present prior to exposure to the antigen and are capable of rapidly reacting to general structures that are common to groups of microbes.

In contrast to innate immunity, adaptive (also called acquired or specific) immunity is highly specific and increases in magnitude and defense capabilities with successive exposures to a particular macromolecule (Abbas, 2000). The adaptive immune response can be divided into humoral and cell-mediated immunity, which act differently to eliminate different types of microbial challenges from the body.

Humoral immunity is mediated by specific antibodies produced by B-lymphocytes in response to specific antigens. Humoral immunity is the primary defense against extracellular microbes and their toxins (Abbas, 2000). In contrast, cell-mediated immunity is mediated by T-lymphocytes, which act upon intracellular microbes inaccessible to circulating antibodies (Abbas, 2000).

Adaptive immunity is capable of distinguishing and reacting to subtle differences among antigens. After an initial exposure, adaptive immunity memory will result in a response to subsequent exposures to the same antigen that not only is more rapid, but is also of increased magnitude (Kuby, 1994). Innate and adaptive immunity do not act discretely; rather both are a part of a complex system and must act cooperatively for optimal protection from foreign invaders.

Interactions between the various cells of the immune system are mediated by cytokines, which are proteins secreted during an immune response. Cytokines are secreted either locally or systemically in response to an antigenic stimulus. Cytokines can act on different cells, tissues or organs in an endocrine, paracrine or autocrine fashion (Hall, 1998).

The gut-associated lymphoid tissue (GALT) is composed of cells residing in the lamina propria region of the gut, interspaced between epithelial cells (intraepithelial lymphocytes), and in organized lymphatic tissue (Peyer's patches and mesenteric lymph nodes). Since the GALT spans the entire intestine, it is the largest immune organ of the body (Jalkanen, 1990).

The mucosal epithelium is a barrier between the internal and external environments and, therefore, is a first line of defense against antigenic invaders. The mucosal immune system is specialized to produce large quantities of immunoglobulin A (IgA). This is the only class of antibody that is efficiently secreted through the epithelial cells into the lumen of the gastrointestinal tract (Abbas, 2000).

There are certain times in an animal's life that it is particularly susceptible to an immune challenge. Two of these critical times are immediately postweaning and late in life. Environmental inadequacies, dietary changes and numerous age-associated changes in the immune system all make these time periods particularly challenging to the animal.

In general, normal immune responses increase during fetal and early neonatal periods, reach their maximum after puberty and then decrease markedly with age (Schultz, l984). Both puppies and kittens are able to mount an immune response at birth although their immune systems are not fully mature (Felsburg, l998a; Levy and Tompkins, 1998). Unfortunately, only a small amount of immunoglobulin G (IgG; 5-10%) is transferred from dam to offspring in utero in dogs and cats (Tizard, 1987). It is, therefore, critical that these animals receive adequate amounts of colostrum and milk. Both canine and feline colostrum are rich in IgG (500-2,200 mg/dl and 4,400 mg/dl, respectively) and also contain IgA (canine, 150-340 mg/dl; feline, 340 mg/dl) and immunoglobulin M (IgM) (canine, 70-370 mg/dl; feline, 58 mg/dl) (Felsburg, 1998b; Pu and Yamamoto, 1998).

As the maternal supply of immunoglobulins declines, neonatal levels increase. In puppies, serum IgM and IgG concentrations reach adult levels by 4-8 and 16 weeks of age, respectively. As with other species, serum IgA does not reach adult levels until approximately one year of age (Felsburg, 1998a). In kittens at 90 days of age, serum immunoglobulin values are 80% (IgG), 7% (IgA) and 100% (IgM) those of adult cats (Yamada et al., l991).

Animals are particularly susceptible to an immune challenge during their senior years as well. As companion animal diets improve and advances are made in veterinary health care, life expectancy is increased. Although determining the specific chronological age at which a dog or cat can be considered physiologically "old" is difficult, the following ages have been established based on the age at which the animal exhibits diseases associated with aging: small dogs, 11.5 years; medium dogs, 11.0 years; large dogs, 9.0 years; giant dogs, 7.5 years, and cats, 12 years (Hayek, l998).

Unfortunately, the geriatric pet population tends to have multiple health problems, such as a less desirable intestinal microbial balance and diminished immune capacity (Kearns et al., 1998; Shultz, 1984). Numerous physiological changes occur with increasing age that reduce the immune capacity of the animal. The lymph nodes, Peyer's patches, tonsils and thymus all involute with age. Phagocytosis and chemotaxis are less efficient and, in general, there is a reduction in the animal's immunological competence, in spite of a normal number of cells (Mosier, 1989).

The bone marrow and spleen also show physiological changes with age. Old animals may require twice as long to restore red blood cells after bleeding compared to young or mature animals. The leukocyte response is reduced, and most dogs over nine years of age have a lower number of antibody-forming cells and specific IgG antibodies compared to young dogs (Mosier, l989).

A recent longitudinal study with German Shepherds reported numerous changes in immunological parameters with age. Absolute numbers of white blood cells (10.68 ;R 2.34 x 109 cells/L versus 8.63 ;R 2.65 x 109 cells) and peripheral blood lymphocytes (2.97 ;R 0.94 x 109 cells/L versus 2.08 ;R 0.75 x 109 cells) both were higher in young (2-4 years) versus old (8-13 years) dogs (Strasser et al., 1999).

One of the most dramatic changes that occur with age in the dog is a decrease in lymphoproliferative response. Lymphoproliferative responses of both young (mean 2.4 years) and middle-aged (mean 5.8 years) Labrador Retrievers to concanavalin A, phytohemagglutinin, pokeweed mitogen and staphylococcal enterotoxin B are higher than those of old dogs (mean 9.1 years; Greeley et al., 1996). In addition, an age-related decline in absolute numbers of lymphocytes, T-cells, CD4-cells and CD8-cells is observed, and the distribution of lymphocyte subsets shifts with age such that the percentages of B-cells decline while those of T-cells increase (Greeley et al., 2001).

Hayek (1998) observed similar age-associated declines in the ability of lymphocytes from young and old Fox Terriers and Labrador Retrievers to respond to different mitogens. In this research, the age-associated decreases in lymphocyte response to concanavalin A, phytohemagglutinin and pokeweed mitogen ranged from -216 to -292% in Fox Terriers and -102 to -114% in Labrador Retrievers. From the information presented, it is evident that there is an age-related decline in immunity of companion animals. This decline could increase the susceptibility to, and severity of, an antigen challenge in senior pets.

Nutrition x immunity

Many nutrients have been implicated in either enhancement or suppression of the immune system. Early studies on the interaction of nutrition and immunity focused on the effects of protein-energy deprivation. Adequate supply of these nutrients continues to be of critical importance for maintenance of a healthy immune system throughout the life of companion animals.

Many additional nutrients, such as vitamins, minerals and fatty acids, also have been implicated in maintenance of optimal immune capacity, but due to space limitations, this paper will focus on energy, protein and oligosaccharides only.

Effects of energy

Given the typical energy content of commercial companion animal diets, energy deficiencies are uncommon in healthy adult animals. On the contrary, up to 40% of the dogs and cats seen by veterinarians are overweight (Sunvold and Bouchard, 1998). It is commonly assumed that most senior dogs are overweight. In reality, a greater proportion of older dogs and cats are underweight than any other age group (Laflamme, 1997), possibly resulting from decreased feed intake.

Energy requirement is known to change over the life of an animal. One of the most intriguing areas being addressed in companion animal research today is the relationship between age and maintenance energy requirements. Unfortunately, many of the studies that evaluate the effect of aging on maintenance energy requirement only utilize food intake as an indicator of energy requirement, rather than monitoring changes in bodyweight and/or composition.

Kienzle and Rainbird (1991) observed a 22 and 16% reduction, respectively, in maintenance energy requirements of young (1-2 years) versus old (more than seven years) Labradors and Beagles. Similarly, reductions in senior dog energy requirements were observed by Finke (1994) and Burger (1994). Laflamme et al. (2000) also demonstrated a reduction of 25% in maintenance energy requirement of old dogs (10.9 ;R 0.7 years) compared to young dogs (2.5 ;R 0.5 years) but found that the ability to digest nutrients was unaffected by age.

Few studies have evaluated the energy requirements of aged cats. Daily energy required for cats to maintain bodyweight over a four-week period was estimated to be 20% lower in cats more than seven years of age (Perez-Camargo and Rudnick, 2002). However, a possibly confounding factor in this research was that cats more than 12 years old demonstrated a slow and progressive loss of bodyweight starting at least two years prior to death. These data suggest that assessment of energy requirement over a four-week maintenance period may not be suitable in old cats (Perez-Camargo and Rudnick, 2002).

In contrast, neither Harper (1998) nor Taylor et al. (l995) reported a significant age effect on energy intake in cats. There is no obvious reason that dogs demonstrate such a dramatic decrease in energy intake with age while cats do not experience this phenomenon, although it is thought to be related to physical activity. In contrast to dogs that experience an age-related reduction in activity, cats are relatively inactive throughout their life (Harper, l998).

Dietary energy concentration is of particular importance to an optimal immune response. In mice, natural killer cell activity, which is thought to aid in defense against tumor growth, is reduced with age (Weindruch et al., 1983). Aged mice (30-33 months) fed restricted diets (50 kcal per week) possess natural killer cell activity similar to those of young (2-3 months) mice fed either restricted or control diets (85 kcal per week). Energy restriction in mice also increases survival time 10-20% and tends to inhibit spontaneous lymphoma (Weindruch and Walford, l982).

Research also has demonstrated a benefit of caloric restriction in maintaining optimal immune responses in the senior dog. Newberne et al. (1966) evaluated the effect of overnutrition on resistance of dogs to distemper virus. Purebred Beagles (5-7 months) were fed a balanced diet containing 90-100 (high), 70-75 (moderate) or 40-45 (low) kcal/kg bodyweight per day. High caloric intake resulted in obesity in 5-6 weeks. All dogs were exposed to distemper virus after a six-week dietary adaptation period. Mortality rate of dogs fed the high-calorie diet was 87% compared to 74 and 31% for the moderate- and low-calorie groups, respectively.

Average survival time also was reduced by overfeeding (8, 10 and 14 days for dogs fed the high-, moderate- and low-energy diets, respectively). Clinical responses to the virus were most severe in the high-calorie group, and the majority of these animals developed paralytic encephalitis in 8-10 days (Newberne, 1966).

In a longitudinal study that monitored Labrador Retrievers from eight weeks of age to death, diet-restricted (75% of total food consumption of pair-fed controls) dogs exhibited a slower rate of age-related decline in lymphoproliferative responses to concanavalin A, phytohemagglutinin and pokeweed mitogens. Restricted-fed dogs had lower numbers of B-cells than pair-mates, and dietary restriction slowed the rate of decline for CD4, CD8 and total T-cell numbers (Greeley et al., 2002). The authors reported that immune predictors of increased survival (high lymphoproliferative responses, high percentage and number of CD8 cells and high numbers of T-cells) were positively affected by diet restriction (Greeley et al., 2002).

Effects of protein

Dispute also exists over the changes in protein requirement that occur with aging in companion animals. Wannemacher and McCoy (1966) demonstrated that the dietary protein needed to maintain nitrogen balance and maximize the liver protein-to-DNA ratio was up to 50% higher in old beagles (12-13 years old) compared to young Beagles (1-2 years old). This contradicts the currently held belief that protein requirement decreases with age. Since many products of the immune system are proteins, such as immunoglobulins, lymphokines and bacteriocidal enzymes, it is not surprising that a protein-deficient diet impairs the immune response (Burkholder and Swecker, 1990).

The detrimental effect of severe protein depletion on the immune response is well documented in numerous species. Infant mice subjected to severe protein deprivation (28 versus 6% casein diets) at weaning (20 days of age) exhibited persistent decreases in thymus-derived lymphoid cells and diminished specific antibody responses (Jose et al., 1973).

The ability to mount a specific mucosal IgA response also is impaired by protein deficiency. This is demonstrated by rats fed a low-protein diet (3.2% casein), which subsequently had markedly impaired mucosal immune response to cholera toxoid/toxin compared to rats fed a control diet (24% protein). This impairment was rapidly reversed by refeeding with the high-protein diet (Barry and Pierce, 1979).

Protein deficiencies also influence antibody production. Rats and mice fed protein-deficient versus control diets (3 versus 16% casein in rat diets; 1 versus 16% casein in mouse diets) showed a marked reduction in the number of antibody-producing cells in response to a sheep red blood cell challenge (Mathur et al., l972).

Most commercial pet foods are formulated to provide more than the required protein levels, making severe protein deficiencies unlikely in most companion animals. Certain life stages do exist, such as the neonatal and senior periods, where food intake is decreased and mild protein deficiencies are possible.

In addition, deficiencies of specific essential amino acids also have been shown to affect the immune system of animals. Mice fed synthetic diets limited in a single essential amino acid (leucine, isoleucine, valine or lysine) for three weeks after weaning had significantly increased susceptibility to Salmonella typhimurium infection, as indicated by a higher mortality rate and spread of the bacterial cells compared to control mice (Petro and Bhattacharjee, l981).

Cats have a particularly high dietary requirement for the amino acid taurine. This is partly due to the low hepatic activity of cysteinesulfinic acid decarboxylase, which limits the synthesis of taurine from ethionine and cysteine (Schuller-Levis, l990). Healthy adult cats typically do not experience taurine deficiencies since their natural diet of meat and fish contains a high concentration of taurine (Hayes and Trautwein, 1989).

Problems may arise, though, when cats are fed commercially formulated diets based on cereals and grains or diets that are arbitrarily restricted by owners, such as vegetarian diets (Hayes and Traitwein, l989). Additional factors that may affect a cat's taurine requirement include the type of diet fed (i.e., expanded dry diets versus canned cat foods) and level of sulfur amino acids in the diet (Case et al., 2000).

Severe deficiency of dietary taurine can result in abnormalities in the immune system. Domestic female cats fed taurine-deficient diets for at least one year have significantly lower total white blood cell counts than taurine-supplemented cats. Feeding a taurine-deficient diet also results in significant leukopenia, a shift in the percentage of polymorphonuclear and mononuclear leukocytes. Polymorphonuclear cell functionality and histologic characteristics of the lymph nodes and spleen also are altered by taurine deficiencies in these cats (Schuller-Levis, 1990).

These results clearly demonstrate significant immunological consequences to prolonged taurine deficiency in cats. Taurine is important not only for prevention of deficiency in the adult animal, but also for maintenance of the immune system in a senior animal. Taurine is capable of augmenting the proliferative responses of T-cells from both young and old mice, although the augmentation is more marked in old T-cells (Negoro and Hara, 1992).

Functional food ingredients

Recent research not only has focused on the suppression of the immune system by nutritional deficiencies but also on enhancement via nutrient supplementation. Dietary ingredients can elicit an effect on the immune system via: a localized effect on the GALT, alteration in microbial population (prebiotic effect) or a systemic effect on the immune system.

In reality, these mechanisms do not act exclusively but rather interact to cause an overall effect. Non-digestible oligosaccharides, such as fructoologosaccharides (FOS) and mannan oligosaccharides (MOS), are examples of compounds that elicit an effect on the gastrointestinal ecology and immune system when supplemented to companion animal diets.

Non-digestible oligosaccharides can affect gastrointestinal health by promoting beneficial bacterial populations (prebiotic effect) and/or directly enhancing the immune system. Fructans (including oligofructose (OF), inulin and short-chain FOS) are prebiotic oligosaccharides that aid in host resistance to pathogenic bacteria by promoting growth of beneficial bacteria.

These beneficial bacteria compete with less desirable bacteria for nutrients and binding sites and produce antimicrobial compounds against pathogenic strains of bacteria. Alterations in microbial populations, or the short-chain fatty acids that are produced as a result of oligosaccharide fermentation, can influence the immune system by inhibiting growth of harmful bacteria, restoring normal intestinal flora and acting as immunomodulators (Meyer et al., 2000).

Some oligosaccharides, such as inulin, a storage carbohydrate found in many plants and vegetables, are specifically fermented in the colon by the beneficial bacteria bifidobacterium and lactobacillus (Meyer et al., 2000). Ingestion of only 5 g per day of OF, a hydrolyzed product of inulin, by humans increased the fecal concentration of bifidobacteria after only 11 days (Rao, 2001). Feeding adult cats FOS (0.75% diet) for 12 weeks had no effect on anaerobic or aerobic duodenal fluid bacteria concentrations (Sparks et al., 1998a).

In contrast, the same feeding regimen reduced fecal concentrations of Escherichia coli (6.3 versus 7.5 log10 CFU/g) and increased fecal concentrations of bacteroides (9.5 versus 8.0 log10 CFU/g) and the beneficial lactobacilli (7.9 versus 5.7 log10 CFU/g) compared to the basal diet. FOS supplementation also tended to reduce fecal concentrations of the potentially negative bacteria Clostridium perfringens (4.9 versus 6.6 log10 CFU/g; Sparks et al., l998b). This study indicates that low levels of OF supplementation can elicit changes in the colonic microbial population in cats.

Short-chain FOS are synthesized from sucrose by bacteria. Willard et al. (1994) supplemented diets of German Shepherds affected with small intestinal bacterial overgrowth, a condition that results in increased diarrhea and weight loss, with 1% FOS. Results indicated decreased aerobes and facultative anaerobes in duodenal fluid and in the duodenal mucosa. These results signify a positive health response and support a role for FOS in the maintenance of gut health.

Swanson et al. (2002a) also reported that supplementation of adult dogs with 4 g per day FOS positively influenced indices of gut health, including increased concentrations of the beneficial bacteria bifidobacteria and lactobacilli, and decreased concentration of the potentially negative bacteria C. perfringens. Supplementation of FOS also increased fecal butyrate and lactate concentrations.

This is of particular interest since short-chain fatty acids, particularly butyrate, are the main energy source for colonocytes. FOS supplementation also decreased the fecal concentration of several putrefactive compounds (e.g., branched-chain fatty acids, phenols, indoles).

MOS are oligosaccharides derived from the cell wall of Saccharomyces cerevisiae. In vitro data indicate that MOS is highly fermentable by canine fecal inoculum (Swanson, unpublished data). MOS can affect the immune system by a number of mechanisms including bacterial exclusion (Spring et al., 2000), neutralization of mycotoxins (Devegowda et al., 1994) and immunostimulation. MOS exclude many pathogenic bacteria by inhibiting intestinal binding via bacterial fimbriae.

Many harmful bacterial species, such as salmonellae, possess the mannose-sensitive type 1 fimbriae that undergo agglutination by MOS in vitro (Oyofo et al., 1989a; Finucane et al., 1999) and colonize in lower concentrations in animals supplemented with MOS (Spring et al., 2000, and Oyofo et al., 1989b).

MOS also can protect the animal by neutralizing mycotoxins (Devegowda et al., l994), systemically increasing IgG (Savage et al., 1996) and increasing neutrophil activity (O'Carra, 1998). Supplementation of aflatoxin-infected broilers with S. cerevisiae culture results in alleviation of toxic effects (Devegowda et al., l994). It has also been shown that immunostimulation by MOS results in systemic increases in IgG concentrations in turkeys (Savage et al., 1996).

Swanson et al. (2002b) supplemented dogs with 2 g MOS, 2 g FOS or 2 g MOS plus 2 g FOS per day for 14 days. Dogs supplemented with MOS had an enhanced systemic immune status as evidenced by a significant increase in percent serum lymphocytes and a tendency for increased serum IgA concentrations compared to control dogs. In addition, dogs supplemented with 2 g FOS plus 2 g MOS per day had significantly greater ileal IgA concentrations than control dogs, indicating enhanced local immunity also. MOS-fed dogs had lower total fecal aerobic bacteria and tended to have greater fecal concentrations of lactobacilli.

In this study, MOS supplementation tended to decrease dry matter and organic matter digestibilities compared to control dogs. In a subsequent study, dogs supplemented with 4 g FOS plus 2 g MOS per day exhibited increased fecal bifidobacteria and fecal and ileal lactobacilli concentrations, but serum, fecal and ileal immunoglobulin concentrations were unchanged. Dogs supplemented with FOS plus MOS tended to have lower concentration of blood neutrophils and greater concentration of blood lymphocytes than unsupplemented dogs (Swanson et al., 2002c).

Zentek et al. (2002) also demonstrated that dogs supplemented with 1 g MOS/kg bodyweight had reduced apparent total tract digestibility of dry matter (82 versus 90%), crude protein (80 versus 91%) and nitrogen-free extract (83 versus 93%) and had lower fecal dry matter (32 versus 37%) compared to unsupplemented dogs. Alteration in the solubility of nutrients in the intestinal chyme and activity of the intestinal microflora were offered by the author as possible mechanisms for the reductions in nutrient digestibilities observed (Zentek et al., 2002).

O'Carra (1998) evaluated the effects of supplemental MOS on the immune system of both rats and dogs. Rats fed 2-4 g MOS/kg feed exhibited a linear increase in intestinal IgA concentrations on days 12-32. In contrast, rats fed 8-10 g MOS/kg feed had a maximum intestinal IgA concentration on day 18. For all MOS supplementation levels, pooled treatment means were significantly higher than rats fed a control diet (0% MOS).

Feeding dogs 2 g MOS/kg feed resulted in a numerical increase in number of circulating neutrophils in response to a vaccine, beginning seven days post-vaccination and continuing over the 63-day trial. In this case, neutrophil activity was used as an indicator of enhanced protection against pathogenic infection.

Summary

Individual nutrients can have profound effects on the immune systems of companion animals. This paper has reviewed only a few of the many well-established interactions that exist. Although historical research has focused on immunological defects caused by nutrient deficiencies, current research is exploring the potential for enhancement of the immune response through nutrient supplementation.

As demonstrated in this paper, there are certain times in an animal's life, such as immediately postweaning and late in life, when it is particularly susceptible to an immune challenge. A great potential for enhancement of the immune system exists during these times.

Future research will focus on elucidating the role of specific nutrients on the immune system and their potential to improve the health of companion animals throughout their life.

Volume:75 Issue:26

Stabenow's deal called lopsided

Stabenow&#039;s deal called lopsided

WITH automatic budget cuts, i.e., sequestration, looming, Senate Agriculture Committee chair Debbie Stabenow (D., Mich.) thought she helped broker the right deal -- one that would eliminate direct payments in the farm bill to contribute the needed non-defense spending cuts -- but her counterpart in the House as well as many farm groups remain opposed to her tactic.

In a letter to Senate majority leader Harry Reid (D., Nev.), 14 national farm groups called the approach lopsided because it takes all of the cuts entirely from the commodity title of the farm bill.

The groups added that, within the context of the farm bill, the suggested cuts were spread out among the entire farm bill, and savings from the elimination of direct payments could be reinvested into other risk management tools.

"Your proposed legislation seriously undermines efforts to advance much-needed reforms to meet the long-term risk management needs of America's family farms," the groups wrote. "The prospect of multiyear crop disasters coupled with projections of sharp declines in commodity prices over the next few years are widely acknowledged as serious threats to the stability of farm income.

"With an appropriate level of resources, more efficient and market-oriented risk management tools can better address the gaps in protection not covered by crop insurance. Conversely, inadequate funding to restructure the farm bill commodity title will almost certainly eliminate options to reform the farm safety net in a long-term, fiscally responsible manner," the farm groups added.

House Agriculture Committee chairman Frank Lucas (R., Okla.) said the elimination of direct payments is the "resource base" that will be used to craft the next farm bill in 2013.

"Literally, if the Senate gets their way, I don't know what we have left to write a farm bill with this summer," he said.

The groups noted that the agriculture industry has been willing to accept its fair share of cuts to help reduce the nation's unsustainable deficits, citing last year's House and Senate farm bill proposals that provided $23 billion to $35 billion in savings.

"While the $27 billion in reductions in your bill are in the same ballpark as the cuts achieved by both of those bills, both farm bill proposals spread the pain among various titles rather than requiring all of it to be shouldered by just one title of the respective bills," the groups wrote to Reid.

There is also a concern that if the proposal is adopted, it would simply delay sequestration until January 2014 in hopes that a larger long-term deal could be reached. The action has the groups "very concerned that agriculture is the only non-defense budget sector being cut while other sectors are not touched."

 

Sequester impacts

The U.S. Department of Agriculture continues to claim that food safety officials will have to be furloughed if sequestration does go into effect March 1. Reports indicate that if the government is forced to absorb the $85 billion in spending cuts, federal workers will begin to take unpaid leave by late March or early April since they must be given an official 30-day notice.

The American Meat Institute had asked Secretary of Agriculture Tom Vilsack to find a way to avoid furloughing meat inspectors, which would account for $51 million in cuts to USDA's food safety branch.

In a response letter, Vilsack said furloughing meat inspectors would be the "last option" but, ultimately, an unavoidable one if a deal isn't struck.

In a letter to customers Feb. 21, CME Group explained that the possible mandatory spending cuts could have an impact on the physical delivery and cash settlement mechanisms of certain CME livestock and dairy products.

In addition, the budget cuts could result in the disruption of USDA reports that are used in the daily calculation of the CME Feeder Cattle Index and CME Lean Hog Index and the monthly calculations used to determine settlement prices for CME dairy futures products, CME said.

Since the CME live cattle contract utilizes USDA grading/inspection in the delivery process, a furlough of USDA staff may require the exchange to modify, in accordance with exchange rules, the current operational process surrounding the delivery/settlement of these products, CME said.

In addition, CME's cash-settled livestock and dairy products could be affected in the event that the data used to compile these indexes are unavailable.

Finally, CME's spot call dairy markets could be affected if USDA grading/inspection staff are unavailable starting March 1.

According to CME, the list of CME livestock and dairy contracts that may be affected include: the February 2013 live cattle futures contract; April 2013 and subsequent lean hog futures and options contracts; March 2013 and subsequent feeder cattle futures contracts; March 2013 and subsequent contracts for milk (Class III and IV), butter, cheese, nonfat dry milk and whey, and spot call for butter, cheese and nonfat dry milk on March 1 and subsequent trading days.

Volume:85 Issue:08

Colorado House rejects GMO labeling law

A committee in the Colorado House of Representatives has rejected a proposal that would have required food made with genetically modified organisms (GMOs) to be labeled, siding with farmers and food manufacturers over the objections of GMO labeling advocates, including a number of mothers who had brought their children to a hearing.

The farmers and food producers argued that a label requirement is not necessary as the Food & Drug Administration has found no health or safety differences between conventionally produced and GMO foods and said a label would increase food prices.

The advocates argued that consumers have a right to know if their food contains genetically modified ingredients.

The committee voted 7-2 against the proposal on Feb. 21. The vote effectively kills the proposal in the current legislative session.

Meanwhile, U.S. Reps. Peter DeFazio (D., Ore.) and Jared Polis (D., Colo.) announced on Feb. 21 that they will co-sponsor a bill in Congress that would make GMO labels a federal law.

Arkansas, Oklahoma AGs agree to watershed plan

The attorneys general of Arkansas and Oklahoma have negotiated a plan to conduct a comprehensive, three-year study to assess the phosphorus levels of the Illinois River that flows through northwestern Arkansas and northeastern Oklahoma. 

The plan was announced Feb. 21 by Arkansas Attorney General Dustin McDaniel and Oklahoma Attorney General Scott Pruitt and follows a lawsuit that then Oklahoma Attorney General Drew Edmondson brought against a number of Arkansas-based poultry companies in 2005 that alleged the companies' contract growers had debilitated the Illinois River Watershed with runoff from litter applied on their farms' fields (Feedstuffs, June 20, 2005).

Edmondson said the companies were responsible for the actions of their growers.

The case eventually was heard in late 2009 and early 2010 by Judge Gregory K. Frizzell in the U.S. District Court for the Northern District of Oklahoma (Feedstuffs, Jan. 25, 2010). Frizzell has never ruled on the matter.

The findings from the new study will guide farmers, businesses and municipalities in future planning to improve the water quality in the watershed, the attorneys general said.

The study will determine the amount of phosphorus that the watershed can contain without a negative impact on water quality, according to the announcement. It will be overseen by a six-member committee and will use U.S. Environmental Protection Agency-approved methods that ensure scientifically reliable data collection and analysis.

Officials in both states have agreed to comply with the results.

EPA is conducting its own study to establish permit levels for all discharges into the watershed.

Ethanol adds $43b to GDP

Ethanol adds $43b to GDP

WHILE ethanol production is no less controversial today -- still plagued by the phrase "food versus fuel" -- industry leaders contend that the aggregate benefits of producing renewable fuels in the U.S. include the creation of hundreds of thousands of jobs and billions of dollars in gross domestic product (GDP).

A recent study commissioned by the Renewable Fuels Assn. (RFA) showed that, for states with local ethanol plants in operation, the economic benefits are significant.

At the end of 2012, RFA said 211 ethanol plants in 28 states were producing ethanol at an annualized rate of 13.1 billion gal. -- well off the 14.7 billion gal. those plants are capable of producing. With high corn and oil prices pressuring plants' margins, production fell nearly 5% last year to an estimated 13.3 billion gal.

With the past year's economic challenges plus ongoing legal opposition from the petroleum and food marketing sectors, RFA said the report on the study, released earlier this month by analyst John Urbanchuk at Cardo ENTRIX, points out the important contributions the renewable fuel industry makes to the U.S. economy.

Urbanchuk found that ethanol production supported more than 383,000 direct and indirect jobs across all sectors of employment last year and contributed $43.3 billion to GDP.

"We are successfully creating job and economic opportunities in a tough economy," RFA president Bob Dinneen said. "Not only are we helping revitalize rural communities across this country, (but) we are positively impacting states outside of the Corn Belt."

According to the state-by-state analysis, the non-Corn Belt states receiving the most significant benefits were Texas, Colorado and Tennessee, each with less than 400 million gal. of ethanol production capacity but enjoying economic benefits from supporting more than 4,000 jobs.

Coming as no surprise, Corn Belt states with heavy concentrations of ethanol production capacity saw the most economic benefit from the industry. Iowa easily was the biggest beneficiary since its production of 3.8 billion gal. supported more than 63,500 jobs. Nebraska, Illinois, Indiana, Minnesota and South Dakota are all home to more than 1 billion gal. of production capacity, which supported more than 22,000 jobs in each state in 2012.

Nebraska and Indiana felt the greatest pains from drought-inflicted high corn prices last year and, as a result, idled 314 million and 322 million gal. of production, respectively. Minnesota and Kansas also had significant differences in their productive capacity and actual output last year, each sidelining more than 100 million gal. of capacity.

In calculating the ethanol industry's contribution to the U.S. economy in 2012, Urbanchuck analyzed employment, income and GDP supported by the industry by examining both forward and backward linkages to the various sectors of the economy touched by the renewable fuel business. The major component industry benefiting from ethanol production was agriculture, reflecting "the importance of ethanol demand to total corn utilization, the aggregate value of crop production and crop receipts and farm income."

Agricultural production accounted for $32.4 billion of the total economic benefits and 267,605 jobs quantified in the study. The report notes that ethanol production is a capital-intensive, rather than labor-intensive, industry, and as such, the direct number of jobs supported by the industry is relatively small and concentrated primarily in the manufacturing and agriculture sectors (Figure).

Looking at ethanol industry expenditures in 2012, the study found that producers spent nearly $40 billion on raw materials, inputs, goods and services to produce ethanol last year. Of that total, more than $33 billion was spent on corn and other feedstocks, with natural gas and electricity comprising more than $2.1 billion of total industry spending.

 

Volume:85 Issue:08

Food price inflation picks up

Food price inflation picks up

DROUGHT finally started to make its effects felt at the grocery store in the final quarter of 2012.

In the latest update of the consumer price index (CPI), U.S. Department of Agriculture economists noted that in the final three months of 2012, higher corn prices trickled down into a host of food items on supermarket shelves.

According to the Economic Research Service (ERS), from October to December, prices rose for most foods that heavily rely on corn-based animal feeds: beef, poultry, other meats, eggs and dairy products (Figure). Milk prices rose nearly 3% during the quarter, egg prices increased 1.7% and prices for beef, poultry and other meats rose roughly 0.5%.

Of interest, pork prices bucked the trend as rising inventories and slower exports pressured retail prices down from the historically high levels seen early in 2012. For the quarter, pork prices fell slightly more than 3%.

ERS economists said last year's drought was unlikely to affect food prices much in 2012; rather, the overall impact of the harsh growing season will truly be felt this year.

USDA's current projection is for food price inflation of roughly 3-4%.

According to ERS economist Ricky Volpe, the inflation forecast represents an annual increase that is above the historical average, with inflation expected to be most pronounced for animal-based food products in the first half of the year. Higher feed prices are cited as the biggest culprit in driving consumer food costs higher.

Looking at December's food price data, the CPI for all food increased only 0.2% from November to December and was roughly 1.8% higher than the December 2011 index. Beef prices may be where consumers notice the largest increase, with December's beef index 4.6% above December 2011, but poultry prices actually increased more year over year, at 5.7% above 2011.

The price trend for pork, however, is the first evidence that meat supplies may actually be keeping a lid on meat prices, at least for now.

Economists Steve Meyer and Len Steiner, in their "Daily Livestock Report," pointed out last week that while much of the current market talk has focused on "weak demand," beef and pork supplies appear to be a much bigger issue.

"We are trying to get U.S. consumers to purchase more beef, pork and poultry meat than they did last year while, at the same time, charging them more money for it," they wrote. "You can do that if demand for your product has gone up, but that is a difficult proposition as the economy is stuck in low gear and consumers face higher energy costs and higher real taxes."

Market analysts generally assumed, at the start of 2013, that tighter meat supplies would force prices higher, and while prices may have trended higher as retail and foodservice customers tried to book their needs in anticipation of prices going higher, beef and broiler production has been running higher than last year during the past six weeks. In fact, output has tallied 2% and 6% above the previous year for beef and broilers, respectively, while pork output has held steady.

Meyer and Steiner noted that packers might finally be responding to the disparity in supply and demand by throttling back production in the most recent few weeks. If supplies, indeed, begin to shrink as expected, food price inflation in the first quarter of the year could look much different than it did in the final quarter of 2012.

Volume:85 Issue:08