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Changes in glutamine metabolism indicate a mild catabolic state in the transition mare

H. C. Manso Filho^*,, K. H. McKeever^*, M. E. Gordon^*, H. E. C. Costa^,, W. S. Lagakos and M. Watford

^* Department of Animal Sciences, Rutgers University, New Brunswick, NJ 08901 , Department of Animal Sciences, Federal Rural University of Pernambuco, Brazil Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901

Watford{at}aesop.rutgers.edu

Abstract

Glutamine is the most abundant free -amino acid in the mammalian body and large amounts of glutamine are extracted by both the fetus during pregnancy and the mammary gland during lactation. The work presented here addressed the hypothesis that there would be major changes in glutamine metabolism in the mare during the transition period, that time between late gestation, parturition and early lactation. Eight foals were born to Standardbred mares provided with energy and protein at 10% above NRC recommendations and foals remained with mares for 6 mo. During lactation, lean body mass decreased by 1.5% (P < 0.05) while fat mass was unchanged throughout gestation and lactation. There was a sharp rise in the concentration of most plasma metabolites and hormones after birth that was, in part, due to hemoconcentration due to fluid shifts at parturition. Plasma glutamine concentration, however, was maintained at greater concentrations for up to 2 wk post-partum, but then began to decrease reaching a nadir at around 6 wk of lactation. Skeletal muscle glutamine content did not change, but glutamine synthetase expression was decreased at the end of lactation (P < 0.05). Free glutamine was highly abundant in milk early in lactation, but the concentration decreased by more than 50% by 3 mo of lactation and paralleled the decrease in plasma glutamine concentration. Thus, lactation represents a mild catabolic state for the mare where decreased glutamine concentrations may compromise glutamine availability to other tissues such as the intestine and the immune system.

Key Words: body composition • equine • glutamine • glutamine synthetase • lactation • pregnancy

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				H. C. Manso Filho, K. H. McKeever, M. E. Gordon, H. E. Manso, W. S. Lagakos, G. Wu, and M. Watford Developmental changes in the concentrations of glutamine and other amino acids in plasma and skeletal muscle of the Standardbred foal J Anim Sci, August 1, 2009; 87(8): 2528 - 2535. [Abstract] [Full Text] [PDF]