Performance Improves with a Diet Rich in Metabolizable Protein and Balanced in Amino Acids
After calving, cows need to quickly increase their dry matter intake to meet nutrient demands and support the increase in milk production.
In the first weeks of lactation, intake does not always meet this demand, and consequently, cows must mobilize fat reserves and body proteins to sustain productive performance.
Recent research indicates that increasing the intake of metabolizable protein (MP) and balancing the amino acid profile of the fresh cow’s diet can increase voluntary intake, milk production, and help minimize weight loss during the first weeks of lactation.
Researchers at Ohio State University evaluated 4 dietary strategies to identify the best way to increase metabolizable protein and balance amino acids (AA) in the fresh cow’s diet. Both immediate results and carryover effects during the first 90 days of lactation were assessed.
The Study
The experiment included: 40 primiparous and 40 multiparous cows, all of which received the same Close-Up diet. After calving, cows were randomly assigned to one of 4 diets and fed until 25 days in milk (DIM). From 26 to 90 DIM, they were fed the same lactation diet with 17% crude protein.
During the 3-week treatment period, the 4 diets administered were as follows:
– MP-deficient diet: 20% less than the requirements;
– Adequate MP diet: meets MP requirements, main protein source: soybean meal;
– Mixed diet: Meets MP requirements, mix of soybean, canola, corn gluten, plus protected AA;
– Mixed diet: Meets MP requirements but with less NDF from forages (fNDF).
The mixed diet was formulated to ensure adequate levels of undegradable protein (RUP) and an AA profile similar to that of casein essential amino acids.
Bill Weiss, Professor of Dairy Nutrition at Ohio State University, explains that previous research (Schei et al., 2005) has shown that cows have a greater ability to mobilize body fat reserves to produce energy compared to mobilizing body proteins. However, during the early phase of lactation, proteins are the primary limiting factor, not energy. Much of recent research has focused on answering questions about how much MP fresh cows need, how to meet those needs while maintaining amino acid balance, and how to increase dry matter intake for optimal results.
This experiment was designed specifically to help answer these questions and identify the nutritional strategy that works best for fresh cows.
Results
For some of the measured parameters, the results for both multiparous and primiparous cows were the same. During the first 25 days of lactation, dry matter intake increased by about 1.10 kg/head/day for all cows fed mixed diets compared to cows fed a diet with adequate MP from a single protein source. Additionally, all cows fed diets with higher MP levels increased milk production, energy-corrected milk (ECM), and milk components by 6-7% regardless of parity.
When the level of NDF from forages in the diet was reduced but MP remained high, multiparous and primiparous cows responded differently. Multiparous cows reduced dry matter intake and produced less milk, while primiparous cows increased both intake and milk production when fed the mixed diet with less NDF from forages.
This indicates that multiparous cows may require more fNDF than primiparous cows in the early stage of lactation. During the subsequent period, from 26 to 50 DIM, differences between multiparous and primiparous cows reemerged.
Multiparous cows had greater intake and produced more milk when they received the mixed diet at the start of lactation. Conversely, primiparous cows showed higher dry matter intake and better production performance when fed the mixed diet with lower NDF from forages during the fresh cow phase.
When researchers assessed cumulative milk production at 92 DIM, the difference in intake and production between multiparous and primiparous cows in relation to NDF from forages in the diet persisted.
The subsequent period, from 26 to 92 DIM, provides further evidence that multiparous cows have a greater fNDF requirement compared to primiparous cows when fed high MP rations at the start of lactation.
Nutrient Partitioning in Fresh Cow Nutrition
In another article, also in the Journal of Dairy Science from May 2021, researchers examined whether the nutritional strategies evaluated affected the mobilization of protein or fat reserves, body composition, or nutrient partitioning during early lactation. Using “empty body composition,” researchers observed various interactions between treatments and parity.
Overall, feeding fresh cows a diet rich in MP with a balanced AA profile increases dry matter intake and reduces tissue mobilization.
However, the additional energy from increased DMI was partitioned differently based on parity. Primiparous cows used the increased intake to minimize fat mobilization. Multiparous cows used the increased intake to boost milk production.
It is interesting to note that when the NDF from forages was reduced while maintaining high MP, tissue mobilization tended to increase. Again, there was a difference between primiparous and multiparous cows. Primiparous cows mobilized more reserve fat, while multiparous cows used more body proteins.
Overall, the results suggest that parity, AA profile, and the concentration of NDF from forages in the diet given to fresh cows can affect immediate and long-term nutrient partitioning in tissues and milk production.
In primiparous cows fed a mixed diet (soybean, canola, corn gluten meal, and protected AA) or a mixed diet with lower NDF from forages, the intake of metabolizable protein was 1,800-1,850 grams/day. In multiparous cows fed the mixed diet, the intake of metabolizable protein was 2,500 grams/day.
This information is very useful and allows for adjustments in fresh cow diets to provide the nutrients needed to maximize production performance.
Energytech
Energytech is a blend of energy feeds with various digestibility modes supported by specific supplementation for better utilization by the animal.
- Flaxseed: very interesting lipids due to their energy value and omega-3 fatty acids content.
- Fractionated Palmitic Acid that provides fat without interfering with fiber digestibility and supports the lipid content of milk.
- Whole roasted soy provides bypass proteins and ruminally available oil.
- Carob is rich in sugars for better ruminal microbiota function.
- Dextrose, an essential element in the energy cycle.
- Vitamin E, a fundamental ally against fat oxidation.
- B vitamins, Choline, Niacinamide, and Methionine that assist the liver in energy metabolism processes.
- Highly bioavailable trace elements as catalysts in caloric utilization reactions.
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Bibliography “Fresh Cow Nutrition”:
- Tebbe & Weiss, 2021a. J. Dairy Sci. 104:5583-5600
- Tebbe & Weiss, 2021b. J. Dairy Sci. 104:5601-5616
