Practical formulation of dairy cow diets with digestible amino acids to improve nitrogen efficiency and the bottom line.

Sloan, B.K., Garthwaite, B.D., Schwab, C.G. 1998

In Focus : 1998 Provision of vitamins and amino acids for ruminants. Cornell Nutrition Conference for Feed Manufacturers. New York, October 20-22, 1998.

Formulating for digestible Lys and Met can improve dairy herd performance.
1. Milk protein yield increases of 60 to 100 g/ day over a complete lactation are attainable.
2. Milk protein content can be increased immediately in cows at any stage of lactation, by 0.1 to 0.2%.
3. Milk yield can be improved by up to 2.5 kg/day in early lactation.
4. Reduction in metabolic problems such as fatty liver and ketosis.
5. Feed N utilization can be improved by up to 10%. Further research is needed to optimize this further.
To maximize the economic return to balancing rations for digestible Lys and Met, practical Lys and Met formulation constraints of either 6.9 and 2.1 % of PDI or 6.82 and 2.19 of MP as calculated in the present version of the CPM model are recommended as guidelines. In situations where it is infeasible to meet the minimum digestible Lys level, a ratio of digestible Lys to Met of 3.1:1 (CPM model) should be respected. The AA balance concept will only give consistent results and profitable returns if raw materials are well characterized in terms of the contributions they can make to digestible Lys and Met supplies. Likewise for rumen protected Met sources, it is not the price per kg of product which should be the deciding factor but the price per g of digestible Met that product can deliver.