Forsyth I A, Lee P D
Department of Cell Biology, AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
J Dairy Res. 1993 Aug;60(3):307-17. doi: 10.1017/s0022029900027655.
British Saanen dairy goats (n = 10) were treated with bromocriptine or vehicle from day 147 of pregnancy to day 4 post partum, a treatment duration of 8.8 +/- 1.7 d (mean +/- SEM). The periparturient prolactin surge was abolished by this treatment, but there were no significant effects on plasma growth hormone or insulin concentrations. Lactogenesis was delayed in the bromocriptine-treated goats, milk yields being significantly depressed (P < 0.01) for the first week of lactation. Yields had recovered to control values by day 10 when prolactin concentrations were still significantly depressed. Mammary gland biopsies were taken on day 4 post partum from five animals in each group. Using this tissue, no significant differences could be shown in mammary morphology or DNA synthesis, but the RNA:DNA ratio was significantly reduced (P < 0.05). After week 1, there were no significant differences between bromocriptine-treated and control goats in milk yield, milk composition, udder volume, time of peak yield or persistence. The goats given short-term bromocriptine treatment at parturition showed prolonged effects on prolactin secretion, their seasonal prolactin rise being severely blunted (P < 0.001). A normal lactation is therefore not prevented in goats by a delay in lactogenesis, suppression of prolactin at parturition or the resulting prolonged depression of circulating prolactin. Goats in established lactation given bromocriptine for 8 d showed, by contrast, a rapid recovery of plasma prolactin concentrations within 5 d post treatment. Milk yield declined significantly (P < 0.03) compared with pretreatment values during and for 1 week after bromocriptine but then began to recover, with no significant change in vehicle-treated goats.
从妊娠第147天至产后第4天，对10只英国萨能奶山羊进行溴隐亭或赋形剂处理，处理持续时间为8.8±1.7天（平均值±标准误）。这种处理消除了围产期催乳素激增，但对血浆生长激素或胰岛素浓度没有显著影响。溴隐亭处理的山羊泌乳发生延迟，泌乳第一周的产奶量显著降低（P<0.01）。到第10天，产奶量已恢复到对照值，此时催乳素浓度仍显著降低。每组五只动物在产后第4天进行乳腺活检。利用该组织，在乳腺形态或DNA合成方面未显示出显著差异，但RNA:DNA比值显著降低（P<0.05）。第1周后，溴隐亭处理组和对照组山羊在产奶量、乳成分、乳房体积、产奶高峰时间或持续性方面没有显著差异。分娩时接受短期溴隐亭处理的山羊对催乳素分泌有延长的影响，其季节性催乳素升高严重减弱（P<0.001）。因此，泌乳发生延迟、分娩时催乳素抑制或循环催乳素由此导致的长期降低并不会阻止山羊正常泌乳。相比之下，处于泌乳期的山羊给予溴隐亭8天，在处理后5天内血浆催乳素浓度迅速恢复。与溴隐亭处理期间及处理后1周的预处理值相比，产奶量显著下降（P<0.03），但随后开始恢复，而赋形剂处理的山羊没有显著变化。
