WHEN it comes to managing rations for dairy cows, it is always better to make decisions proactively versus reactively, according to Dr. Dwight Roseler, a dairy nutritionist with Purina Animal Nutrition in Ohio.
Roseler noted that evaluating feedstuffs with proper methods and having a ration model that predicts performance accurately are critical when looking into the crystal ball for future herd performance.
"You want to be prepared and know what to expect from the forages and total ration that is going to be fed," Roseler said. "Being proactive and looking ahead allows the opportunity to make better decisions about ration costs and income over feed cost."
For example, if an operation is targeting a certain level of milk production for the herd and it knows, through proper testing, that the forages on hand are not adequate to maintain or achieve that production level, then a decision must be made to determine the best-cost ration to achieve the most profit for the operation. In some cases, forages or byproducts can be purchased that complement the existing inventory to achieve the best profit, he said.
Beyond overall animal health and milk production potential, evaluating feeds ahead of time can also help with budgeting and inventories.
"Running the correct feed analysis at harvest can help decide how current inventories will be best used. Then, running 'best-profit' rations into future months will determine strategies for optimal cash flow and profit," Roseler added.
With a multitude of tests available to assist in evaluating forages and byproducts, it can be a challenge to determine which tests to run to make the best decisions. Roseler offered a look at some of the nutrients for which to test and what they may mean when formulating rations and projecting budgets:
* Rumen degradable starch measures how much starch is actually available to rumen microbes when the feed is fed. Rumen degradable starch tests give producers an idea of how their animals are digesting starch and what impact that might have on performance.
* Neutral detergent fiber (NDF) digestibility determines how digestible the fiber in an ingredient will be and, as a result, how much rumen fill there will be. Rumen fill has a direct effect on dry matter intake (DMI), diet digestibility and feed efficiency.
* Volatile fatty acid analysis and ammonia give producers an idea of what fermentation has occurred in the silo, in terms of proper fermentation levels, and is useful in predicting the performance in terms of rumen microbial performance and milk protein production. Excess ammonia from forages can be wasted if not properly balanced across all diets in a herd.
* Amino acid balance takes precedence over balancing metabolizable protein or crude protein. Accurate amino acid profiles of proteins and byproducts provide knowledge to properly balance low-protein (14-15%) diets with milk urea nitrogen tank levels below 10. This improves protein purchases and reduces nitrogen losses.
* Fatty acids provide a more accurate measure of true digestible energy coming from the fat of forages and ingredients. The fatty acid profile improves the ability to balance the polyunsaturated fatty acid (PUFA) load, which has a bearing on reproductive performance and milk fat yield.
"Evaluating feedstuffs prior to feeding will help optimize rations for optimal health, milk components, income over feed cost and overall profit potential," Roseler said.
Several abstracts presented at the recent midwestern section meetings of the American Dairy Science Assn. and American Society of Animal Science in Des Moines, Iowa, highlighted specific feed ingredients in diets for high-producing dairy cows.
In abstract 214, P. Piantoni, A.L. Lock and M.S. Allen of Michigan State University explained that long-chain saturated fatty acid (LCSFA) supplements are used to increase energy density of diets and milk fat yield or energy balance in dairy cows. However, production responses to LCSFA vary greatly, which could be due to differences in fat type, diets and the physiological state of the cows.
LCSFA supplements are comprised primarily of stearic and/or palmitic acids, they said.
For cows past peak lactation, palmitic acid (99% purity), compared to a control diet with no supplemental fat, increased yields of milk to 46.0 kg from 44.9 kg per day (P = 0.04), milk fat to 1.53 g from 1.45 g per day (P < 0.01) and 3.5% fat-corrected milk (3.5% FCM) to 44.6 kg from 42.9 kg per day (P < 0.01), with a similar response for cows across a wide range of milk yields, Piantoni et al. reported.
In a similar experiment, they noted that stearic acid (98% purity) increased DMI to 26.1 kg from 25.2 kg per day (P = 0.01), yields of milk to 40.2 kg from 38.5 kg per day (P = 0.02), milk fat to 1.42 g from 1.35 g per day (P < 0.01) and 3.5% FCM to 40.5 kg from 38.6 kg per day (P < 0.01), with a greater response for high-yielding cows (linear interaction [P < 0.10]).
However, the recovery of additional fatty acids consumed as additional yield of milk fatty acids was only 11.7% for palmitic acid and 13.3% for stearic acid supplementation, Piantoni et al. said.
Supplementation of LCSFA (greater than 85% saturated, 46% stearic acid and 37% palmitic acid) increased DMI to 23.6 kg from 22.2 kg per day (P = 0.04) and tended to decrease milk yield to 46.6 kg from 49.7 kg per day (P = 0.10), improving energy balance (P = 0.01) and body condition scores (P = 0.02) when fed during the first four weeks postpartum in diets containing 20% and 26% forage NDF.
However, postpartum supplementation of LCSFA interacted (P < 0.10) with forage NDF concentration for 3.5% FCM yield when cows were fed a common diet from five to 10 weeks postpartum: LCSFA decreased 3.5% FCM yield to 51.1 kg from 58.7 kg per day in the 20% forage NDF diet, but not in the 26% forage NDF diet, which was 58.5 kg versus 58.0 kg per day.
According to Piantoni et al., LCSFA supplementation might benefit lactating dairy cows in some cases, but the results are dependent on fat supplements fed, diet, stage of lactation and milk yield of cows.
In abstract 215, A. Pineda and P. Cardoso from the University of Illinois at Urbana-Champaign described the effects of rumen-protected choline (RPC) on plasma, milk yield and composition of Holstein cows in middle and late lactation.
Pineda and Cardoso randomly assigned 50 lactating, multiparous Holstein cows that were more than 100 days in milk to one of two treatments: (1) a control diet that was not supplemented with RPC or (2) a diet supplemented with 115 g of RPC per cow per day. The control and supplemented diets were fed ad libitum once daily.
Bodyweight and body condition scores were measured weekly. Milk production and DMI were recorded daily. Milk samples were collected twice weekly on weeks 3, 6 and 9 and were analyzed for fat, protein, lactose, milk urea nitrogen, somatic cell count, fatty acid composition and choline concentration. Plasma from blood samples was obtained on weeks 1, 3, 4, 6, 7 and 9 and analyzed for non-esterified fatty acids and choline concentrations. Cows remained in the experiment for nine weeks.
According to Pineda and Cardoso, DMI, bodyweight and body condition scores were not affected (P > 0.05) by RPC supplementation. Cows supplemented with RPC did not have greater milk yield, 3.5% FCM, energy-corrected milk or milk components than control cows (P > 0.05).
While the concentrations of de novo and mixed (16:0 + cis-9 16:1) fatty acids were greater in control cows, preformed fatty acids had greater concentration in supplemented cows (P < 0.05), the researchers reported. The total saturated fatty acid concentration was higher (P < 0.001) in control cows than supplemented cows. Total monounsaturated fatty acid and cis-PUFA concentrations were greater in supplemented cows (P < 0.05) than the control.
A higher choline concentration in plasma (P < 0.05) indicated RPC intake and absorption by supplemented cows, Pineda and Cardoso said. Supplemented cows had their milk fat composition enriched by long-chain PUFAs either in middle or late lactation.
A new biological treatment could help dairy cattle stave off uterine diseases and eventually may help improve food safety for humans, according to a University of Florida study.
Kwang Cheol Jeong, an assistant professor in animal sciences and with the University of Florida Emerging Pathogens Institute, examined cattle uterine illnesses because they can make cows infertile, lower milk production and are often linked to bacteria, he said.
Jeong and his research team infused chitosan microparticles — antimicrobial material derived from dissolved shrimp shells — into diseased cow uteri.
The study's findings suggest that chitosan microparticles kill bacteria in the uteri. Jeong said it may one day be possible for chitosan microparticles to be used to help people who have become ill from consuming Escherichia coli-contaminated food, but more research is needed.
Scientists can use the chitosan study's findings to begin to develop better drugs that target bad pathogens but leave beneficial bacteria, Jeong said.
E. coli are everywhere, including the human gut, but they can contaminate beef, unpasteurized milk, soft cheeses made from raw milk and raw fruits and vegetables that haven't been washed properly.
Jeong's latest study was published online March 21 by the journal PLoS ONE.