Genetic variation in the feeding value of alfalfa genotypes evaluated from experiments with dairy cows.

摘要

Experimental lucerne (Medicago sativa) line 6328P with improved digestibility, and control variety Europe, were fed to cows in order to determine the effects of nutritive value on milk yield. Three trials lasting 20, 9 and 16 days were conducted on2 groups of 10 cows (Prim'Holstein [French Holstein]) each during 1990-91. Eight lucerne quality parameters, milk yield and milk fat and protein contents were recorded. 6328P had a higher leaf:stem ratio and crude protein content than Europe. In vitro and in vivo digestibilities increased by 1-9% in samples of 6328P. Intake of 6328P increased by 12% whilst milk yield increased by an average of 7%, compared with Europe. This overall increase in milk yield was responsible for increased milk fat and protein yields despite a lower fat content and only a slightly higher protein content in milk produced by cows fed 6328P.