期刊
JOURNAL OF DAIRY SCIENCE
卷 98, 期 4, 页码 2576-2582出版社
ELSEVIER SCIENCE INC
DOI: 10.3168/jds.2014-8404
关键词
amino acid; duodenal infusion; digestive enzyme; insulin; cow
资金
- National Funds for Natural Science of P. R. China [31472122]
- National Key Technologies R&D Program of China [2012BAD12B02]
- Program of International S&T Cooperation of China [2010DFB34230]
Four Holstein heifers (215 + 7 kg; means + SD), fitted with one pancreatic pouch, duodenal re-entrant cannulas, and duodenal infusion catheters, were used in this experiment. In phase 1, the 24-h profile of pancreatic fluid was determined. Pancreatic fluid flow peaked 1 h after feeding, but peaks of similar magnitude also occurred before the morning feed, necessitating 24-h collection of pancreatic fluid to estimate daily excretion. In phase 2, the effects of duodenal infusions of 0, 10, 20, or 30 g of leucine on pancreatic fluid flow were determined in a 4 x 4 Latin square design. The leucine was infused for 12 h in 2,500 mL of the infusate, and samples of pancreatic fluid and jugular blood were collected in 1-h intervals from the beginning of the infusion for 36 h. The results showed that the secretion rate of pancreatic fluid (mL/h) was significantly higher in 10-g leucine group than the other groups (mL/h). Protein concentration (mg/mL) in pancreatic fluid was elevated proportional to the amount of leucine infused. Leucine infusions increased both the concentration (U/mL) and secretion rate (U/h) of alpha-amylase. Infusion of 10 g of leucine also increased the secretion rates (U/h) of trypsin, chymotrypsin, and lipase, but did not change their concentrations. No significant effects of leucine infusions on plasma glucose and insulin concentrations were found. The results indicate that leucine could act as a nutrient signal to stimulate alpha-amylase production and pancreatic exocrine function in dairy heifers.
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