HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sechen, S. J. Articles by Reynolds, P. J. Search for Related Content PubMed PubMed Citation Articles by Sechen, S. J. Articles by Reynolds, P. J.

Effect of Somatotropin on Kinetics of Nonesterified Fatty Acids and Partition of Energy, Carbon, and Nitrogen in Lactating Dairy Cows^1,2,

Department of Animal Science, Cornell University, Ithaca, NY 14853-4801

Henry F. Tyrrell and Paul J. Reynolds⁵

Ruminant Nutrition Laboratory, ARS, USDA, Beltsville, MD 20705

⁴ Reprint requests.

ABSTRACT

The utilization of energy, carbon, and nitrogen, and irreversible loss rates of nonesterified fatty acids were examined in lactating cows during treatment with bovine somatotropin. Six multiparous Holstein cows at approximately 62 d postpartum received daily intramuscular injections of somatotropin (29.4 mg/d) or excipient during two 21-d treatment periods in a crossover experimental design. Milk yield was increased 11% (37.1 versus 41.3 kg/d), whereas intake and digestibility of DM, energy, nitrogen, and carbon were not affected. Cows remained near zero net energy balance during both treatments (1.31 versus –1.52 Mcal/d for control and somatotropin, respectively). The major effect of somatotropin was to partition net energy into milk while tissue energy accretion was reduced. Postabsorptive use of nitrogen and carbon was altered by somatotropin as reflected by greater secretion in milk. Urinary losses of nitrogen and tissue use of carbon were reduced. Plasma concentrations and irreversible loss rates of nonesterified fatty acids did not differ between treatments. Somatotropin treatment of lactating cows results in partitioning of nutrients away from tissue deposition toward milk synthesis. The extent to which different metabolic processes are altered depends upon the energy balance of the somatotropin-treated animal.

¹ Supported in part by Cornell University Agricultural Experiment Station and USDA Biotechnology Program (GAM-8502654).

² Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by USDA and does not imply its approval to the exclusion of other products that may also be suitable.

³ Present address: HFV-126, Food and Drug Administration, 5600 Fishers Lane, Rockville, MD 20857.

⁵ Deceased.

This article has been cited by other articles:

				J. C. Velez and S. S. Donkin Bovine Somatotropin Increases Hepatic Phosphoenolpyruvate Carboxykinase mRNA in Lactating Dairy Cows J Dairy Sci, May 1, 2004; 87(5): 1325 - 1335. [Abstract] [Full Text] [PDF]