JDS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Journal of Dairy Science Vol. 71 No. 1 99-108
© 1988 by American Dairy Science Association ®
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Enright, W. J.
Right arrow Articles by Tucker, H. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Enright, W. J.
Right arrow Articles by Tucker, H. A.

Effects of Infusions of Various Doses of Bovine Growth Hormone-Releasing Factor on Growth Hormone and Lactation in Holstein Cows1

W. J. Enright2,3, L. T. Chapin2, W. M. Moseley4 and H. Allen Tucker2

Department of Animal Science, Animal Reproduction Laboratory, Michigan State University, East Lansing 48824
The Upjohn Company 7921-25-4, Reproduction and Growth Physiology Research, Kalamazoo, MI 49001

ABSTRACT

In a first experiment growth hormone was determined in serum of lactating cows infused intravenously with bovine growth hormone-releasing factor for 24 h. Concentrations of growth hormone increased 5 times above placebo after 3.125, 6.25, 12.5, 25.0, or 50.0 mg releasing factor/cow per 24 h. Releasing factor increased the pulsatile nature of growth hormone release. In a second experiment we determined effects of intravenous infusions of releasing factor for 20 d on growth hormone and lactation in primiparous cows (n = 5/treatment; 144 · 7 d after parturition). Milk yield of placebo-infused cows averaged 26.5 · 1.7 kg/d during d 6 to 20 of infusion. Infusions of 1 and 3 mg releasing factor/cow per 24 h increased milk yield 11 and 23%, respectively. Releasing factor had only small effects on milk composition, net energy intake, and BW. Releasing factor did not affect energy efficiency of milk production (energy output in milk per unit of net energy intake) when corrected for BW changes. Average growth hormone across d 1, 10, and 19 of infusion was 2.1, 4.1, and 6.8 ng/ml serum for placebo, 1, and 3 mg releasing factor, respectively. Infusions of bovine growth hormone-releasing factor: 1) increased mean and pulsatile release of growth hormone during 24 h and 20 d, 2) increased milk yield in a dose-dependent manner, and 3) did not affect BW-corrected energy efficiency of milk production.

FOOTNOTES

1 Michigan Agricultural Experiment Station Journal Article Number 12297.

2 Department of Animal Science.

3 Present address: The Agricultural Institute, Grange/Dunsinea Research Center, Grange, Dunsany, Co. Meath, Ireland.

4 The Upjohn Company.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1988 by the American Dairy Science Association ®.