Responses to Post-ruminal Infusion of Casein and Glucose in Lactating Goats

Lactating goats fed a basal ration containing 11% crude protein, were infused intra-abomasally with 45g/d of either casein or glucose, in an attempt to determine whether milk production responsesto casein infusions could be attributed to gluconeogenesis from the casein. Infusions of casein increased the production of milk and milk constituents whereas the-production during glucose infusions was similar to that on the basal ration. Milk fat content was depressed by the glucose infusion. The output of nitrogen in milk and urine was increased during the casein infusion. Consideration of the data from this and other similar experiments leads us to conclude that the production response to casein infusion post ruminally, cannot be attributed to an increased availability of glucose precursors.