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 Google Scholar Google Scholar Articles by de Boer, G. Articles by Young, J. W. Search for Related Content PubMed PubMed Citation Articles by de Boer, G. Articles by Young, J. W.

Glucagon, Insulin, Growth Hormone, and Some Blood Metabolites During Energy Restriction Ketonemia of Lactating Cows¹

Nutritional Physiology Group, Department of Animal Science, Iowa State University, Ames 50011

ABSTRACT

Six Holstein cows were sampled hourly for 24 h for plasma concentrations of hormones and metabolites. Cows were sampled at about 2 wk prepartum, at 3 wk postpartum, during a ketonemia induced by feed restriction to 54% of ad libitum intake, and after a recovery period. They were fed long alfalfa hay prepartum and a complete mixed diet postpartum. The onset of lactation caused concentrations of growth hormone, glucagon, acetoacetate, ß-hydroxybutyrate, and total amino acids of plasma to increase and those of glucose and insulin to decrease. Feed restriction exacerbated changes at 3 wk postpartum except for total amino acids and glucagon, which both decreased to prepartal concentrations. Resumption of ad libitum feeding caused most hormones and metabolites to return to prepartum concentrations. Diurnal variations in response to feeding twice daily were most evident for growth hormone, free fatty acids, and total amino acids. The 3-wk postpartum and ketonemic periods gave the greatest responses to feeding. Molar ratios of insulin to glucagon and insulin to growth hormone tended to decrease at 3 wk postpartum and decreased further in ketonemia, demonstrating hormonal adaptations to decreased energy intake during lactation. Lactation ketonis results from more than severe energy deficit.

¹ Journal Paper No. J-11418 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Projects No. 2578 and 2603. Data were taken from a dissertation presented to Iowa State University by G. de Boer to fulfill partly requirements for the Ph.D. degree. Papers were presented at the 1983 Annual Meeting of the American Dairy Science Association, Madison, Wl [J. Dairy Sci. 66(Suppl.);232 (Abstr.)] and at the 1983 Meeting of the Canadian Society of Animal Science, Truro, Novia Scotia, Canada [Can. J. Anim. Sci. 63:1020 (Abstr.)] .

² Ruminant Nutrition Group.