Haldar A, Prakash B S
Reproductive Physiology Laboratory, Dairy Cattle Physiology Division, National Dairy Research Institute Karnal, Haryana, India.
Endocr Res. 2005;31(4):295-306. doi: 10.1080/07435800500422608.
Buffalo, the premier dairy animal in India, suffers from slow growth rate, delayed puberty, and silent heat. It is not known whether the delay in puberty in such animals is due to the delay in expression of hypothalamus-pituitary-gonadal functions. To determine the changes in growth hormone (GH), luteinizing hormone (LH), and progesterone before, at, and after puberty of Murrah buffalo heifers, six Murrah buffalo heifers (21.92 +/- 1.09 months of age, 269.67 +/- 7.97 kg body weight) were assigned to well-ventilated individual pens and fed a roughage-concentrate diet to provide weight gain of 0.4 kg/day. Blood samples were collected at 3-day intervals during a period of 12 months, and plasma harvested from blood samples was assayed for progesterone, LH, and GH. The day that plasma progesterone was greater than 1 ng/mL for three consecutive sampling days was defined as the day of puberty. Heifers attained puberty at an average age of 31.53 +/- 0.88 months with a body weight of 380.67 +/- 6.42 kg. Progesterone levels were very low (0.20 to 0.30 ng/mL) during the pre-pubertal period. There were two distinct elevations before the day of puberty onset. Plasma LH and GH concentrations increased (P < 0.05) during the months preceding puberty and were highest during the month before puberty. GH and LH were positively correlated (P < 0.05) prior to (r = +0.59) as well as after puberty (r = +0.42). A positive correlation (P < 0.05)between LH and body weight during the pre-pubertal period (r = +0.61) and thereafter, negative correlation (P < 0.05) during post-pubertal period (r = -0.64) was noted. GH and body weight showed positive correlation both before puberty (r = +0.92, P < 0.01) and after puberty (r = +0.32, P < 0.05). Results suggest that both GH and LH are equally important and vital cues in inducing onset of ovarian functions in buffalo heifers.
水牛是印度主要的奶牛品种，但生长速度缓慢、青春期延迟且发情不明显。目前尚不清楚此类动物青春期延迟是否归因于下丘脑 - 垂体 - 性腺功能表达的延迟。为了确定穆拉水牛小母牛在青春期前、青春期时和青春期后的生长激素（GH）、促黄体生成素（LH）和孕酮的变化，将六头穆拉水牛小母牛（年龄21.92±1.09个月，体重269.67±7.97千克）分配到通风良好的单独围栏中，并饲喂粗饲料 - 精饲料日粮，以使体重每天增加0.4千克。在12个月期间，每隔3天采集一次血样，并对从血样中提取的血浆进行孕酮、LH和GH检测。连续三个采样日血浆孕酮大于1 ng/mL的那天被定义为青春期日。小母牛平均在31.53±0.88个月龄、体重380.67±6.42千克时达到青春期。青春期前孕酮水平非常低（0.20至0.30 ng/mL）。在青春期开始前有两个明显的升高。在青春期前的几个月中，血浆LH和GH浓度升高（P < 0.05），并在青春期前一个月达到最高。青春期前（r = +0.59）和青春期后（r = +0.42），GH和LH呈正相关（P < 0.05）。青春期前LH与体重呈正相关（r = +0.61，P < 0.05），之后在青春期后呈负相关（r = -0.64，P < 0.05）。GH与体重在青春期前（r = +0.92，P < 0.01）和青春期后（r = +0.32，P < 0.05）均呈正相关。结果表明，GH和LH在诱导水牛小母牛卵巢功能开始方面同样重要且至关重要。
