Effects on milk yield and composition of infusions of different levels and natures of energy into the digestive tract of dairy cows

C. Hurtaud, H. Rulquin, R. Vérité
1992 Annales de Zootechnie  
The positive effect of concentrates on milk production and especially on protein content (Remond, 1985) has been classically imputed to an increased production of propionic acid. However, propionic infusion did not always lead to an increase in protein content (Hurtaud et al, 1992). Other factors such as an increase in energy level or in intestinal glucose supply might explain this effect. A rumen infusion of propionic acid (13.41 mol/d) was compared with water as a negative control (90% of
more » ... control (90% of energy needs) and 2 positive isoenergetic controls (100% of energy needs) consisting of intra-ruminal infusion of 17 mol/d of a normal VFA mixture (64% acetic, 21 % propionic and 15% butyric acids) or intra-duodenal infusion of glucose (1295 g/d). Four ruminally and duodenally-fistulated Holstein cows were used 2 months post partum in a 4 x 4 Latin square (2 weeks/period). The diet consisted of 60% maize silage, 10% hay, 17.5% energy concentrate and 12.5% soya bean meal and covered 90% of energy requirements. Increasing energy input without change in VFA profile improved milk yield (+ 0.9 kg; P < 0.05), but did not change protein and fat content whereas lactose content tended to increase. At a similar
doi:10.1051/animres:19920158 fatcat:cddinbbtenetpcemblttu6wkom