You don't want to overfeed crude protein for a couple of reasons:
- The high cost of feedstuffs
- The environmental ramifications of excreted nitrogen.
But you don't want to scrimp too much and hurt animal performance.
An article in the April edition of the Journal of Dairy Science suggests that supplementation with methionine can help in this regard. Over a 12-week feeding study, supplementation of lactating cows with either absorbable methionine as isopropyl-2-hydroxy-4-(methylthio)-butanoic acid or else a commercially available rumen-protected methionine product improved milk production and nitrogen utilization. When either source of methionine was added to a 15.6 percent crude protein diet, performance was equal or better than that of cows fed a 16.8 percent crude protein diet.