[Effects of the addition of iso-acids to feed on ruminal fermentation, in sacco degradation of dry matter and the concentration of several blood parameters in cows]. / Effets de l'addition d'iso-acides à la ration sur la fermentation ruminale, la dégradation in sacco de la matière sèche et la concentration de quelques paramètres sanguins chez la vache.

Three rumen-fistulated cows fed maize silage and concentrates were supplemented with either soybean oil meal or urea, associated or not with isoacids. The isoacids increased the volatile fatty acid concentration, lowered the ruminal ammonia concentration and in sacco dry matter disappearance and did not influence blood parameters.

Feeding strategies for dairy cattle. Comparison of flat rate feeding and standard feeding during early lactation.

In a 14-week experiment beginning at week 4 postpartum, with 40 individually housed autumn calving cows a system of flat rate feeding (F) was compared with standard feeding (N). The basal ration consisted of a restricted amount of maize silage and ad libitum grass silage. Average daily concentrate DM consumed was 6.3 and 6.5 kg for treatment F and N respectively. Treatment F resulted in a non-significant higher forage DM intake. Covariant adjusted yields of milk (27.8 and 27.9 kg/d) and 4% fat corrected milk (28.3 and 28.3 kg/d) were not decreased by treatment F. The system of concentrate allocation had no effect on either milk composition or body weight changes. The results are discussed in relation to other data.