de Boer G, Trenkle A, Young J W
J Dairy Sci. 1985 Feb;68(2):326-37. doi: 10.3168/jds.S0022-0302(85)80829-8.
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 postpartum. The onset of lactation caused concentrations of growth hormone, glucagon, acetoacetate, beta-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 ketosis results from more than severe energy deficit.
对6头荷斯坦奶牛进行了24小时的每小时一次采样，以测定血浆中激素和代谢物的浓度。在产前约2周、产后3周、通过将采食量限制为自由采食量的54%诱导酮血症期间以及恢复期后对奶牛进行采样。产后给它们喂长苜蓿干草。泌乳开始导致血浆中生长激素、胰高血糖素、乙酰乙酸、β-羟基丁酸和总氨基酸的浓度升高，而葡萄糖和胰岛素的浓度降低。采食量限制加剧了产后3周时的变化，但总氨基酸和胰高血糖素除外，这两者均降至产前浓度。恢复自由采食使大多数激素和代谢物恢复到产前浓度。对于生长激素、游离脂肪酸和总氨基酸，每日两次采食引起的昼夜变化最为明显。产后3周和酮血症期对采食的反应最大。产后3周时胰岛素与胰高血糖素以及胰岛素与生长激素的摩尔比趋于降低，在酮血症时进一步降低，表明泌乳期间激素对能量摄入减少的适应性变化。泌乳期酮病不仅仅是由严重的能量缺乏引起的。
