The effect of experimental variation in the quantity of pancreatic secretion on the digestion and utilization of milk-substitute diets by the calf.

Abstract

1. Apparent digestibility, apparent absorption and nutrient-balance studies were made with two Ayrshire and three Friesian calves given milk-substitute diets. Cannulas were inserted into the duodenum of the calves at about 21 d old, so that the quantity of pancreatic secretion entering the duodenum could be varied.2. After cannulation, there was a significant reduction in the apparent digestibility of the dry matter, organic matter, crude protein and fat, and in the apparent absorption of calcium and phosphorus from a milk-substitute diet containing ‘mildly’ pre-heated, spray-dried skim-milk powder. The amounts of nitrogen and P retained by the calves were also significantly reduced.3. Collection and removal of the pancreatic secretion for a period of 12 h/d resulted in a further significant reduction in the apparent digestibility of the dry matter, organic matter and crude protein of the milk-substitute diet.4. At 77 d of age, there was no significant effect on the nutrient balance or on the digestibility of a diet containing a ‘severely’ pre-heated, spray-dried skim-milk powder when the normal secretion of the pancreas was supplemented for 12 h/d with additional pancreatic secretion collected from the same calf.5. Friesian calves, in comparison with Ayrshires, tended to have a higher digestibility of dry matter, organic matter and fat, apparent absorption of Ca and P and retention of N, Ca and P. These differences were apparent both before and after the calves were cannulated.