Low expression of CCKBR in the acinar cells is associated with insufficient starch hydrolysis in ruminants

Unlike monogastric animals, ruminants exhibit significantly lower starch digestibility in the small intestine. A better understanding of the physiological mechanisms that regulate digestion patterns in ruminants could lead to an increased use of starch concentrates. Here we show more robust pancreatic exocrine function in adult goats (AG) than in neonatal goats (NG) by combining scRNA-seq and proteomic analysis. Our findings suggest that inadequate amylase activity could be a limiting factor in starch digestion in ruminants. In addition, we show that insufficient starch hydrolysis in adult goats might be associated with low expression of a CCKBR receptor in the acinar cells. On top of that, the low expression of CCKBR in adult goats, in conjunction with a low distribution of the CCK-I cells in the duodenum, may jointly lead to a slow response of the intestinal-pancreatic reflex and induce an asynchronous process of food entering the small intestine and releasing of digestive enzymes, which ultimately limits the starch digestibility. Overall, the present findings generate a resource that can provide better insight into the mammalian pancreas.