Studies on the inhibitory effect of increased VFA concentrations in the rumen after feeding on GH secretion in sheep

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 10460120
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Applied animal science
• Research Institution: TOHOKU UNIVERSITY
• Principal Investigator: HAGINO Akihiko Department of Agriculture, Tohoku University, Research Associate, 大学院・農学研究科, 助手 (80156249)
• Co-Investigator(Kenkyū-buntansha): SASAKI Yasuyuki Obihiro University of Agriculture and veterinary Science, President, 学長 (90005637) ; KATOH Kazuo Department of Agriculture, Tohoku University, Associate Professor, 大学院・農学研究科, 助教授 (60091831) ; OBARA Yoshiaki Department of Agriculture, Tohoku Univekatorsity, Professor, 大学院・農学研究科, 教授 (50302196)
• Project Period (FY): 1998 – 1999
• Keywords: GROWTH HORMONE / IGF-I / INSULIN / VFA / FOOD INTAKE / SHEEP

Research Abstract

(1) Effects of dietary concentrate content (0%, 40% and 80%) on GH, IGF-I and insulin secretion were investigated in six adult, crossbred sheep. Significant decreases of plasma GH concentrations were observed after feeding in all dietary treatments and these decreases were continued for 8 hours (0%) and 12 hours (40%, 80%), respectively. Mean 24-hour concentrations of GH were 10.4, 7.9 and 5.6 ng/ml for 0%, 40% and 80% concentrated diet treatments, respectively. These were significantly different from each other. Marked increases in plasma insulin concentrations after feeding were observed when animals were fed the 40% and 80% concentrate diets, whereas only slight increase was detected when animals were fed 0% concentrate diet. Plasma IGF-I concentrations were not changed after feeding in contrast to GH and insulin.
(2) Effects of intra-ruminal and intra-duodenal infusion of casein and starch on GH, IGF-I and insulin secretion were tested in sheep. Animals were fed orchard grass hay once daily with food available for 4 hours (1400-1800). Casein and starch were infused during the 4 hours. Both of intra-ruminal and intra-duodenal infusion of casein caused prolonged decreases in plasma GH concentrations after feeding compared with control. Intra-ruminal infusion of starch also caused prolonged decrease in GH, but intra-duodenal infusion of starch did not affect the GH decrease after feeding.
(3) It is concluded that increased VFA concentrations after feeding may play an important role in the decrease of GH secretion after feeding in sheep.