THE use of soybean meal in diets fed to weanling pigs must be limited due to the presence of anti-nutritional factors that young pigs can't tolerate. Therefore, other sources of protein, such as fish meal and plasma, are used in nursery pig diets.
However, there are other ingredients available to producers as well. Researchers at the University of Illinois have determined the nutritional value of three new protein products that have recently become available to use as feed ingredients for pigs.
University of Illinois professor of animal sciences Hans H. Stein and his team measured the amino acid content and digestibility, the digestible and metabolizable energy concentration and the phosphorus content and digestibility of dried fermentation biomass (DFB), PEP50 and PEP2+ (both byproducts of heparin production) fed to weanling pigs.
DFB consists of the material left over when lysine has been extracted from fermentation tanks containing lysine-producing bacteria, Stein explained, while PEP50 and PEP2+ consist of porcine intestinal mucosa that have been hydrolyzed with enzymes, ground and combined with soybean meal in the case of PEP50 and a mixture of DFB and enzyme-treated soybean meal in the case of PEP2+.
DFB contained 77% crude protein, PEP50 contained 53% crude protein and PEP2+ contained 59%. "All of these ingredients are relatively high in crude protein, and there's a lot of lysine in (DFB) because extracting lysine from the biomass is not a 100% efficient process," Stein said.
The digestibility of amino acids in DFB and PEP50 was generally at least as high as in fish meal and sometimes greater than in fish meal, while the digestibility of most amino acids in PEP2+ was about the same as in fish meal or slightly less, Stein noted. However, the lower protein content in PEP50 and PEP2+ means that the concentration of digestible amino acids in these ingredients was less than in fish meal, he said.
Results from the study also showed that the concentration of metabolizable energy in DFB was 5,236 kcal/kg, followed by 4,617 kcal/kg in PEP2+, 4,512 kcal/kg in PEP50, 3,960 kcal/kg in fish meal and 3,846 kcal/kg in corn.
The standardized total tract digestibility of phosphorus was greatest in DFB at 96.9% and PEP2+ at 97.6%, followed by PEP50 at 76.2% and fish meal at 68.5%.
"However, fish meal contains approximately three times as much phosphorus as DFB, PEP50 and PEP2+, so the concentration of digestible phosphorus in these ingredients is still less than in fish meal. Producers who substitute these ingredients for fish meal would need to supplement the diets with additional phosphorus," Stein explained.
Stein said growth performance studies would be the next step.
"We need to do some performance experiments to confirm that we can use 5%, 6% or 7% of each of these ingredients in the diets and take out fish meal and maybe even some plasma as well."
The study, "Nutritional Value of Dried Fermentation Biomass, Hydrolyzed Porcine Intestinal Mucosa Products & Fish Meal Fed to Weanling Pigs," was recently published in the Journal of Animal Science.
In other recent research, Stein and his team determined the true ileal and total tract digestibility of fat in four corn co-products as well as in full-fat soybeans and corn oil.
Pork producers need accurate information on the energy value of fat in feed ingredients to ensure that diets are formulated economically and in a way that maximizes pork fat quality, an announcement said.
Stein's team looked at four corn co-products: dried distillers grains with solubles (DDGS), high-protein dried distillers grains (HP-DDG), corn germ and a high-oil corn that contained about 7% lipids.
Three diets were formulated containing each source of oil as well as a basal diet that contained no added fat. These diets were fed to cannulated pigs. The apparent ileal and total tract digestibility of lipids in each diet was calculated, and a regression procedure was used to estimate endogenous losses and to calculate the true ileal digestibility and true total tract digestibility of lipids, Stein explained.
"We observed that the digestibility of oil in soybeans is much greater than in the corn co-products. It appears that pigs can utilize that oil much more easily," Stein said.
He attributed this to differences in the way fat is stored in the ingredients.
"In soybeans, you have almost 20% fat, and therefore, a lot of that fat is just stored as regular triglycerides and (is) relatively easy to get to. In the other ingredients, in particular the corn germ and DDGS, some of the fat is encapsulated by fiber, which makes it more difficult for the enzymes to digest," he said.
According to study results, the true ileal digestibility of corn oil was greatest at 95.4%. Among intact sources of fat, the fat in full-fat soybeans (85.2%) and HP-DDG (76.5%) was the most digestible. Digestibility of fat was lowest in DDGS (62.1%), high-oil corn (53.0%) and corn germ (50.1%).
Corn oil also had the greatest true total tract digestibility at 94.3%. Full-fat soybeans had the next greatest digestibility at 79.7%, followed by HP-DDG at 70.2%. DDGS, corn germ and high-oil corn had the lowest true total tract digestibility at 51.9%, 43.9% and 41.4%, respectively.
Stein said the results of the research were in agreement with several previous experiments indicating that the energy value of some ingredients was less than expected based on their lipid content.
"Now, we have an explanation because we realize that pigs don't digest those lipids very well, so it doesn't necessarily help that these products have higher concentrations of oil," he said. "From a nutritional point of view, there would be a clear advantage if we could first extract the fat and then add it to the diet as corn oil rather than leave it in the ingredients. Whether such an approach would be economical would depend on the cost of extracting the oil from corn germ and other ingredients."
The study was published in the Journal of Animal Science.
The energy content of DDGS is a concern as more oil content is being extracted during the ethanol production process, Kansas State University researchers said in an abstract presented at the recent joint annual meeting of the American Society of Animal Science and American Dairy Science Assn.
In abstract 701, S. Nitikanchana, A.B. Graham, R.D. Goodband, M.D. Tokach, S.S. Dritz and J.M. DeRouchey of Kansas State described a study that determined the digestible energy (DE) and net energy (NE) values of DDGS sources that varied in oil content.
To determine the DE of DDGS, Nitikanchana et al. fed 12 pigs in metabolism cages a corn-based diet or corn/50% DDGS diets from five sources of DDGS that had various oil contents (5.35%, 7.63%, 9.38%, 9.57% and 12.10% on an as-fed basis).
The same five sources of DDGS were also used in three growth studies to determine the NE of the DDGS sources from the gain:feed responses, the researchers said, noting that four of the DDGS sources were tested at 20% and 40% of the diet and the fifth source was tested at 15%, 30% and 45%.
The NE efficiency — calories of NE intake (kcal) per kilogram of gain — of pigs fed the respective DDGS diets in each study was calculated to equal the NE efficiency of pigs fed the corn/soybean meal diet in the same study by adjusting the dietary NE of the DDGS diet, Nitikanchana et al. said.
Corn and soybean meal were assumed to have an NE content of 2,672 and 2,087 kcal/kg, respectively. The dietary NE content that resulted in equal NE efficiency was then used to calculate the NE of DDGS according to the percentage of DDGS in that diet, the researchers explained.
From this method, the NE of the five DDGS sources was determined. Then, DE from the digestibility study and NE from the growth studies for the five DDGS sources were used in a stepwise regression to establish the DE and NE prediction equations, they said.
The linear and quadratic terms of oil (ether extract), crude protein, crude fiber, acid detergent fiber, neutral detergent fiber, particle size and bulk density, including the interaction terms, were the variables included in the regression analysis, but of these measures, only the oil content was a significant variable, the researchers noted.
According to Nitikanchana et al., the equations to predict DE and NE as a function of oil content were: [DE (kcal/kg) = 62.347 x oil (%) + 3,058.13 (adjusted R-square = 0.41); NE (kcal/kg) = 115.011 x oil (%) + 1,501.01 (adjusted R-square = 0.86)].
These equations indicate that changing the oil content 1% in DDGS will change the DE by 62 kcal/kg and the NE by 115 kcal/kg, the researchers concluded.