Effects of rumen bypass processed feed on milk yield and growth hormone secretion in lactating cow

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 13460116
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Zootechnical science/Grassland science
• Research Institution: Obihiro university of agriculture and veterinary medicine
• Principal Investigator: HIDARI Hisashi Obihiro university, professor, 畜産学部, 教授 (80003119)
• Co-Investigator(Kenkyū-buntansha): ODA Shinichi Iwate university, Asistant professor, 農学部, 助教授 (60211827) ; HAGINO Akihiko Tohoku university, Asistant professor, 大学院・農学研究科, 助手 (80156249) ; OHTANI Masayuki Obihiro university, Lecturer, 畜産学部, 講師 (80250538)
• Project Period (FY): 2001 – 2003
• Keywords: lactating cow / rumen bypass / starch / growth hormone / milk yield / milk constituents / rumen digesta / milk fatty acids composition

Research Abstract

Feeding rumen bypass processed (RBP) starch for daily cow is expected to increase milk yield effectively because the energy supply from RBP starch does not accompany any increment of volatile fatty acids(VFAs) production in rumen and with prevention of plasma GH decline after feeding due to the increment of rumen VFAs.
Four experiments were carried out to investigate the effects of rumen bypass processed (RBP) starch on milk yield and growth hormone secretion in lactating cows.
1)Supplementation of more than 1.0kg starch to lactating cows increase ruminal propionate and decrease rumen pH, milk yield. Less than 1.0kg RBP starch supplementation seems to be proper for the following experimental cows.
2)RBP starch supplementation does not more increase milk yield than in accordance with 4,000kcal increment of ingested energy content from the supplementation of RBP palmitic acid, Sodium linoleate and RBP starch to early lactating cows.
3)The daily supplementation of 1.0kg RBP starch for 180 days to mid lactating cows enhanced milk yield during the first 100 days of experiment. Mean plasma IGF-1 concentration of the cows supplemented RBP starch are higher than in control. Plasma glucose levels of the RBP starch supplemented cows were maintained at the normal level before and during the experiment Plasma NEFA levels of them decreased until 60 days from the initiation of the experiment then keep their normal level.
4)Mean plasma GH concentration, pulse height and number of GH pulse in the mid lactating cows supplemented 1.0kg RBP starch for 60 days are higher than those of control without any changes in rumen pH and volatile fatty acids concentration.
These results suggested that daily supplementation of 1.0kg rumen bypass starch to mid lactating cow stimulates plasma growth hormone levels and enhance persistency of lactation.