Feed deprivation of mares: plasma metabolite and hormonal concentrations and responses to exercise.
Twelve light horse mares were fed a control diet that provided 100% of their maintenance protein and energy requirements for 7 d and were then either continued on the control diet or totally deprived of feed (with access to water) for 3 d . Plasma samples were drawn twice daily throughout the experiment, at 15-min intervals for 9 h beginning 45 h after feed removal, and at 10-min intervals around an exercise bout beginning 73 h after feed removal. Feed deprivation increased (P < or = .06) whole blood beta-hydroxybutyrate and plasma NEFA, urea N, L-lactate, and glucagon concentrations, decreased (P = .02) IGF-I concentrations, and did not change (P > .1) plasma glucose insulin, prolactin, triiodothyronine, and thyroxine concentrations. Exercise increased (P < .05) plasma NEFA, prolactin, and growth hormone (GH) concentrations in all mares. Plasma NEFA concentrations increased (P < .001) after exercise and remained increased in fed mares, but rapidly decreased in deprived mares (time x diet interaction, P = .006). Plasma glucose concentrations following exercise increased in deprived mares but decreased in fed mares (time x diet interaction, P = .07). The plasma prolactin response after exercise also differed between groups (P = .09). Feed-deprived mares had greater (P = .02) plasma GH concentrations before exercise (73 h after feed withdrawal) and had a greater (P < .001) GH peak at 10 min after initiation of exercise. The increase in secretion rate o GH due to feed deprivation in these mares was similar to that reported for other domestic species but was not nearly as great in magnitude.
Publication Source (Journal or Book title)
Journal of animal science
Sticker, L., Thompson, D., Bunting, L., Fernandez, J., DePew, C., & Nadal, M. (1995). Feed deprivation of mares: plasma metabolite and hormonal concentrations and responses to exercise.. Journal of animal science, 73 (12), 3696-3704. https://doi.org/10.2527/1995.73123696x