Effects Of Duodenal Infusion Of Leucine On Pancreatic Exocrine Secretion In Diary Goats

Starch is the main energy source for high producing ruminants. Starch digestion in the small intestine is theoretically more energetically efficient than ruminal fermentation, while small intestinal starch assimilation is limited in the ruminants for the low activity of pancreaticα-amylase. The effects of protein on the secretion of pancreaticα-amylase are different between ruminants and single-stomache animals. Leucine (Leu) stimulates the secretion of pancreaticα-amylase in single-stomache animals, while the effects of Leu on secretion of pancreaticα-amylase are rarely reported in ruminants.After comparing the anatomical structure of gallbladder and pancreas in goats with sheep, three surgeries were taken to collect pancreatic juice or the mixture of pancreatic juice and bile juice, and the best surgical passway was determined. Then the further experiment was taken to evaluate the effects of duodenal infusion of Leu on pancreatic exocrine secretion, blood parameters, and the digestibility of dietary components in diary goats.Experiment 1 The methods of collecting pancreatic juiceSix goats and three sheep (from 1 to 1.5 years old) were whole-body anesthetic to com- pare the anatomical structure. The results showed that the anatomical structure was basically consistent between goats and sheep.Twelve guanzhong dairy goats (from 1 to 1.5 years old) were used to collect pancreatic juice or the mixture of pancreatic juice and bile juice by three surgeries: (1) Ligating the bile duct and fixing a bile duct bridge and a common bile duct reentrant; (2) Fixing a steel fistula; (3) Only fixing a common bile duct reentrant. Pancreatic juice can be independently collectted by the first surgical method, and the mixture of pancreatic juice and bile juice can be collected by others.The results showed that the third surgery to collect the mixture was best and easist for the further experiment, with all diary goats healthy. The second surgery was unfeasible duing to the texture of steel fistula. Diary goats (35-45 kg) secreted about 500 to 900 mL mixture of pancreatic juice and bile every day. In the first method, there goats (35-40 kg ) were alive with the secretion rate of pancreatic juice is about 200 to 300 mL/d.Experiment 2 The effects of Leu on pancreatic exocrine secretion in diary goatsFour goats (30.1±1.3 kg) with duodenal catheters and common bile duct reentrants were used in a 4×4 Latin square. Each goat received infusion of 0, 3, 6 or 9 gd-1Leu into duodenum respectively.The results showed that Leu didn't affect the digestibility of dietary components, plasma glucose, total juice secretion, total protein in juice, the secretion of trypsin, chymotrypsin and lipase, and the secretion concentration (U/L and U/g protein) of pancreaticα-amylase. Leu didn't change the plasma insulin(P>0.05) , while the secretion rate of pancreaticα-amylase was increased when the level of Leu was 3 and 9 g.d-1 (P<0.05). The results indicated that Leu can effect on the total secretion of pancreaticα-amylase independent on insulin.