Abstract
A dependence between dietary protein and starch levels flowing to the duodenum has been characterized in monogastric animals for optimal enzymatic secretions of the pancreas, but those in ruminants remain unclarified. The present experiment was conveyed to assess the pancreas growth and mRNA expression of the small intestine enzymes in growing goats fed a low-protein diet. Twenty-four Liuyang goats (19.55 ± 3.55 of body weight (BW)) and aged approximately 8 months were randomly assigned to either a control protein diet (NP: 10.77% CP) or a low-protein diet (LP: 5.52% CP) for 70 days. The results show that no statistical differences (p > 0.05) were observed in the pancreas growth indices between the groups. Pancreas and small intestine α-amylase and lipase activities were unaffected (p > 0.05) by the LP diet, while activities of trypsin and chymotrypsin were decreased (p < 0.05). The LP diet reduced (p < 0.05) the mRNA expressions of trypsin and chymotrypsin in the duodenum and jejunum, and had no effects (p > 0.05) on the mRNA expressions of α-amylase and lipase. Goats fed with the LP diet had higher (p < 0.05) concentrations of cholecystokinin and insulin than those fed with the NP diet. In conclusion, feeding an LP diet (5.52% CP) had no profound influence on pancreas growth and digestive enzyme synthesis in goats.
Highlights
Feed supplied was adjusted for each group in the morning according to previous day dry matter intake (DMI) at least 5% refusals
LP diet tended to have lower total pancreas DNA content (mg/kg of body weight (BW); p = 0.072) than those fed with control protein (NP) diet
Goats fed with an LP diet decreased proteolytic enzymes synthesis without significant changes in pancreas weight, DNA, and protein concentrations
Summary
The combined need to reduce feed costs and nitrogen (N) losses to the environment and to improve the efficiency of feed has resulted in transformed interest to reduce protein levels in the diets of ruminants [1]. Several studies have recently adopted dietary nutrition strategies to probe the effects of feeding decreased dietary protein levels on performance and metabolism in ruminants. Cortese et al [2] have noticed that reducing dietary protein levels from 15% to 13.5% of DM does not affect the feed efficiency and growth performance of growing bulls during growing and finishing phases. Decreasing dietary protein levels by 2.8% than that of the NRC recommendations seems to affect the growth performance but improved feed efficiency in goat kids [3]. Huhtanen and Hristov [4]
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