Lactational responses to postruminal infusions of amino acids in dairy cows fed maize silage, hay or grass silage.

نویسندگان

  • L Le Henaff
  • H Rulquin
  • R Vérité
چکیده

Duodenal infusions of methionine and ly-sine have been shown to increase milk protein yield in dairy cows given a dehydrated maize diet (Rulquin, 1987). As du-odenal amino acids (AA) profiles vary according to diet (Le Henaff, unpublished), a trial was undertaken to test the lactational responses of dairy cows to methionine and lysine infusions with 3 other diets based on either maize silage (M), perennial rye-grass hay (H) or silage (S). Each diet was given to a different group of 6 fistulated Holstein cows in early lacta-tion that received duodenal infusions of either 11 g of methionine and 24 g of lysine (ML) or 90 g of glutamic acid (control) in a double reversal design over 2 wk periods. Diets were calculated to be isoenergetic either with 'fibrous' concentrate (26% of the diet M) or a 'starchy' concentrate (43.6% of the diet H and 28% of the diet S) and to supply in theory the same level of intestinal digestible proteins in order to meet 90% of the protein requirement. The ML infusion significantly increased milk yield only with diet M (+ 3.9%) and protein yield with diets M (+ 8.8%) and S (+ 3.7%) (table I). The protein content was significantly increased by ML with diets M (+ 4.8%) and H (+ 2%) and casein content with diet M. The ML infusion decreased the fat content with diet M. These results, consistent with those of Schwab ot al (1976) and of Rulquin (1987), indicate that methionine and lysine are not as clearly limiting factors with hay and grass silage as with maize silage diets.

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عنوان ژورنال:
  • Reproduction, nutrition, development

دوره Suppl 2  شماره 

صفحات  -

تاریخ انتشار 1990