was offered successively another normal diet containing 6 5 p. 100 skim milk powder and two experimental diets obtained by addition of sodium citrate or hydrochloric acid to the normal diet. In vitro, the normal diets gave quickly a firm curd with rennet. The « citrate diets )) ( 13 , 3 g sodium citrate/kg dry matter) gave no curd with rennet but could clot with hydrochloric acid. The « acid diets » ( 39 g pure HCl/kg dry matter -pH 4 , 25 ) were submitted to a strong agitation and did not clot

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... with rennet nor hydrochloric acid. During consecutive hours after the morning feeding, gastric .effluents were completely collected ; they were simultaneously re-introduced into the duodenum after representative samples were taken for analysis. In calf A, 1 , 3 et 4 collecting days took place respectively with the normal, citrate, acid and yeast diets. Abomasal emptying of fluid and dry matter was a little quicker with the experimental diets during the first hour after the feeding (table i). The outflow of all the dry matter constituents was also slightly greater, except for reducing substances with the acid diet : 17 , 25 , 27 and 24 p. 100 respectively of the ingested nitrogen left the abomasum. Over the total of hours of measurements, the cumulative outputs of nitrogen reached 68, !4, 8 9 and 6 5 p. 100 of the ingested amounts. In calf B, 3 , 4 and 4 collecting days took place respectively with the normal, citrate and acid diets. Abomasal emptying of fluid and dry matter was a little quicker with citrate diet during the first hour after the feeding (table i). The outflow of nitrogen, fat and minerals was also greater with the citrate diet, the outflow of nitrogen and fat was greater and that of minerals lower with the acid diet, but all these differences were not very important : 10 , 17 and 14 p. 100 respectively of the ingested nitrogen left the abomasum. Over the total of hours of measurements, the cumulative outputs of nitrogen reached 66, 66 and 70 p. 100 of the ingested amounts. Therefore, the alteration or suppression of the clotting ability of milk proteins, and their replacement by those of alkanes grown yeasts ( 70 p. 100 ) and of whey ( 30 p. 100 ) increasethe rate of abomasal emptying of nitrogen and fat ; however, this acceleration is relatively restricted and stays less important than that observed with milk replacers containing only whey proteins as source of nitrogen. It appears that abomasal emptying is influenced at least as much by the source of proteins and the technology of their preparation as by the clotting in the abomasum. Des études antérieures nous ont montré que le comportement physiologique du porc était fortement perturbé après l'ingestion d'un repas d'une richesse azotée inhabituelle : en particulier, nous avions, sur deux animaux, noté un ralentissement de l'activité électrique très nette dans la région du pylore, moins marqué dans la zone duodénale. Pour vérifier si de telles variations étaient