Utilisation des protéines par le veau préruminant à l'engrais. VII. — Influence du remplacement des protéines du lait par celles du soja ou de la fèverole sur l'évacuation gastrique

Abstract

The effects of replacing skim milk protein with soybean or field bean protein concentrates on gastric emptying of the preruminant calf was studied. The 1st concentrate was a soy bean oil meal treated by moist heating and cleared of its sucrose and .alpha. galactosides by ethanol extraction. The 2nd was prepared from dehulled field bean seeds by aqueous extraction at pH 8. Preruminant calves (7) were fitted with a duodenal reentrant cannula. During 7 h after the morning feed, abomasal digesta was collected. The data were treated by correspondance analysis. When using the 2 milk substitutes containing plant proteins, the abomasal emptying of total N, protein N and lipids was accelerated and protein was less hydrolyzed, mainly with field bean. The output of total N and protein N was respectively multiplied by 1.2 and 1.7 (soybean) and 1.6 and 2.3 (field bean). The speed of non protein N output relative to protein N suggested that casein must be partly hydrolyzed before leaving the abomasum; this was not necessary for the plant proteins which did not coagulate. The pH of the abomasal outflow was higher with the field bean diet. For each milk substitute, individual variations with the day of measure were large but were independant of the calf used. Digestion in the abomasum seems to be affected by the origin of the dietary protein. The changes observed when replacing milk protein by soybean or field bean proteins may possibly account for the lower digestibility of the latter.