Body weight, condition score, deuteriated water dilution space, estimated body lipids and proteins, and calculated energy and protein balances were determined in 24 multiparous Holstein cows at wk 1, 7, 20, and 39 after parturition. Cows received two levels of energy concentrate (high and low groups) from wk 3. The objective was to estimate changes in body composition as affected by stage of lactation, concentrate level, and bST administration or placebo from wk 9 in a 2 x 2 factorial design. Cows from high and low energy groups lost 25 and 35 kg of body lipids and 3.3 and .5 kg of body proteins, respectively, during the first 7 wk of lactation. During the end of the winter period (wk 8 to 20), control and bST-injected cows lost 8.5 and 21.1 kg of body lipids, respectively. During the grazing period (wk 20 to 39), bST-injected cows gained more BW (34 kg), water (36 kg), and estimated proteins (5.8 kg) and lost more condition score (-.2 units) and estimated lipids (-11.5 kg) than controls. Using data from control periods, it was calculated that 1 unit change in body condition score corresponded to changes of 35 to 44 kg in BW (corrected for estimated gut content variation), 21 to 29 kg in body lipids, and 200 to 300 Mcal in body energy. One kilogram of corrected BW change corresponded to a change of 4.3 or 5.5 to 5.9 Mcal in body energy when calculated from cumulative energy balances or body components, respectively.
Summary — In two trials each using 3 cows fitted with, rument cannulas, the effects of different lipid supplements on digestibility and ruminal digestion were analyzed. In trial 1, a control diet based on maize silage (Ci ) was compared to the same diet with a supplement of crude (untreated)
A la mise à l'herbe et au cours des six premières semaines d'exploitation du premier cycle de la plante, nous avons observé les variations de la composition en acides gras majeurs des matières grasses du lait de vache et de la quantité de ces acides gras sécrétée par jour. Seize
Summary. Effects of ruminal infusion of volatile fatty acids and duodenal infusion of caseinate on digestion and metabolism in the dairy cow. l. -Production and digestion.The effects on the metabolism of dairy cows of two energy levels (85 and 110 p. 100 of requirements) in factorial combination with two nitrogen levels (70 and 100 p. 100 of requirements) were studied in a 4 x 4 latin square by the responses of milk constituent secretion and mammary nutrient uptake.
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