The aim of this study was to evaluate temporal variations in circulating levels of selected hormones and metabolites in commercial dairy goats during the transition period. Blood samples from 940 goats were collected weekly, from -3 to 3 wk relative to delivery, to measure the effects of level of milk production, parity number, and litter size on concentrations of glucose, β-hydroxybutyrate (BHB), fatty acids, and plasma urea nitrogen (PUN). A subset of 80 goats [40 low-yielding (LY, < 1.8 L/d) and 40 high-yielding goats (HY, > 3.7 L/d)] were selected from the study population to measure the effects of level of milk production on plasma concentration of insulin, prolactin, and growth hormone. Average (±SD) milk yield (from 3 to 30 d in milk), body weight, and body condition score for the study population were 2.4 ± 0.78 L/d, 70 ± 16.0 kg, and 2.5 ± 0.28 units, respectively. Milk yield was moderately correlated with parity number (r = 0.49) but had weak correlation with litter size (r = 0.14). In multiparous but not in primiparous goats, antepartum concentrations of fatty acids and BHB increased with increasing litter size. Concentrations of fatty acids, BHB, and PUN were consistently lower in primiparous goats compared with those in second or greater parity. Postpartum, HY goats had higher ratios of glucose, fatty acids, and BHB to insulin than did LY goats, which might explain the greater mobilization of body tissues and enhanced milk production observed in this group. Collectively, our results indicate that increased milk yield has the most significant influence on the magnitude of body tissue mobilization. Our results also show that goats of higher parity display higher levels of lipid mobilization, and that both pregnancy and lactation are less able to elicit lipomobilization in primiparous compared with multiparous goats.

中文翻译：

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过渡期内商品奶山羊的内分泌和代谢状况。

这项研究的目的是评估过渡时期商业奶山羊中所选激素和代谢产物循环水平的时间变化。每周从-3到3 wk相对于分娩每周采集940只山羊的血样，以测量产奶量，胎次数和产仔量对葡萄糖，β-羟基丁酸（BHB），脂肪酸，和血浆尿素氮（PUN）。从研究人群中选择了80只山羊的子集[40只低产山羊（LY，<1.8 L / d）和40只高产山羊（HY，> 3.7 L / d）]以测量产奶量的影响血浆中胰岛素，催乳素和生长激素的浓度。研究人群的平均（±SD）产奶量（牛奶中3到30 d），体重和身体状况评分分别为2.4±0.78 L / d，70±16.0 kg，和2.5±0.28单位。产奶量与胎次数适度相关（r = 0.49），但与产仔数相关性较弱（r = 0.14）。在多胎山羊而非初产山羊中，产前脂肪酸和BHB的浓度随产仔数的增加而增加。初产山羊的脂肪酸，BHB和PUN的浓度始终低于第二胎或更大胎的山羊。产后HY山羊的葡萄糖，脂肪酸和BHB与胰岛素的比例高于LY山羊，这可能解释了该组中观察到的更大的身体组织动员和增加的产奶量。总的来说，我们的结果表明增加的牛奶产量对身体组织动员的程度具有最显着的影响。