shimon carmi
Milk yield was 41 kg/d with 3.5% fat and 3% true protein.

well done

In a follow up experiment with the same team at USDA Wisconsin, a Negative Control treatment was also included to allow a better assessment of what part of the improvements in N-efficiency were simply due to reducing N intake and what part were due to an improvement in performance through amino acid balancing.

Effect of feeding different sources of rumen-protected methionine on milk production and N-utilization in lactating cows : Chen et al J. Dairy Sci. 94 : 1978-1988

Lowering CP content in the ration from 16.8% to 15.6% without any attempt to amino acid balance, did not reduce milk protein but did reduce milk fat. N-efficiency (Milk N/N intake %) was improved from 30.2 to 32.4 (+7.3%). When Smartamine M was added to the 15.6% ration to respect a metabolizable LYS to MET ratio according to NRC 2001 of 3 to 1, daily milk fat yield was improved by 200 grams and milk protein by 90 grams, pushing the N-efficiency up to 34.2 (+13.2% vs the 16.9% CP ration)

Judicious use of Amino acid balancing to lower ration CP levels can improve performance and improve efficiency of N use essential in our goals of sustainable production.

The objective should be to reach at least 40% of intake N being converted into productive N