| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061
2 Department of Animal Nutrition and Physiology, Danish Institute of Agricultural Sciences, Foulum, DK-8830 Tjele, Denmark
Our objective was to investigate the mammary expression of insulin-like growth factor-I (IGF-I) and IGF-binding proteins in prepubertal heifers and regulation of IGF-I by bovine somatotropin (bST) and feeding level. Twenty-four prepubertal Friesian heifers were divided into six blocks according to genotype and starting date for the experiments. Within blocks, heifers were assigned to daily bST treatment (0 or 15 mg/d) at low or high feeding level (0.55 kg/d or 1.1 kg/d average daily gain, respectively) for 5 wk so that the mean body weight and standard error was approximately equal for all four treatment groups. At high feeding level, content of IGF-I protein in mammary tissue extracts was increased 46% by somatotropin compared with placebo. Somatotropin tended to increase abundance of IGF-binding protein-3 (40 to 43 kD) in mammary extracts. High feeding level increased abundance of a 24-kD binding protein and reduced abundance of IGF-binding protein-2 (32 kD) in mammary extracts. High feeding level reduced abundance of IGF-binding protein-1 mRNA in mammary tissue, but there was no significant effect of feeding level or somatotropin on mRNA levels of other IGF-binding proteins. These results suggest that effects of somatotropin treatment and feeding level on the prepubertal mammary gland are mediated in part by alterations in local synthesis of IGF-I and IGF-binding proteins.
Key Words: insulin-like growth factor-I • binding proteins • mammary • somatotropin
Submitted on March 5, 1999
Accepted on August 20, 1999
This article has been cited by other articles:
|
|
 |
|
  M J Meyer, R P Rhoads, A V Capuco, E E Connor, A Hummel, Y R Boisclair, and M E Van Amburgh Ontogenic and nutritional regulation of steroid receptor and IGF-I transcript abundance in the prepubertal heifer mammary gland J. Endocrinol., October 1, 2007; 195(1): 59 - 66. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Miller, L. Delbecchi, D. Petitclerc, G. F. Wagner, B. G. Talbot, and P. Lacasse Effect of Stage of Lactation and Parity on Mammary Gland Cell Renewal J Dairy Sci, December 1, 2006; 89(12): 4669 - 4677. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. R. Thorn, S. Purup, W. S. Cohick, M. Vestergaard, K. Sejrsen, and Y. R. Boisclair Leptin Does Not Act Directly on Mammary Epithelial Cells in Prepubertal Dairy Heifers J Dairy Sci, May 1, 2006; 89(5): 1467 - 1477. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. M. Akers Major advances associated with hormone and growth factor regulation of mammary growth and lactation in dairy cows. J Dairy Sci, April 1, 2006; 89(4): 1222 - 1234. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. L. Annen, R. J. Collier, M. A. McGuire, and J. L. Vicini Effects of Dry Period Length on Milk Yield and Mammary Epithelial Cells J Dairy Sci, July 1, 2004; 87(13_suppl): E66 - 76. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Vestergaard, S. Purup, J. Frystyk, P. Lovendahl, M. T. Sorensen, P. M. Riis, D. J. Flint, and K. Sejrsen Effects of growth hormone and feeding level on endocrine measurements, hormone receptors, muscle growth and performance of prepubertal heifers J Anim Sci, September 1, 2003; 81(9): 2189 - 2198. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. D. K. Berry, P. M. Jobst, S. E. Ellis, R. D. Howard, A. V. Capuco, and R. M. Akers Mammary Epithelial Proliferation and Estrogen Receptor {alpha} Expression in Prepubertal Heifers: Effects of Ovariectomy and Growth Hormone J Dairy Sci, June 1, 2003; 86(6): 2098 - 2105. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
