Haldar A, Prakash B S
Reproductive Physiology Laboratory, Dairy Cattle Physiology Division, National Dairy Research Institute, Karnal, Haryana, India.
J Anim Physiol Anim Nutr (Berl). 2007 Aug;91(7-8):326-32. doi: 10.1111/j.1439-0396.2006.00658.x.
Previous studies have suggested that growth-hormone-releasing factor (GRF) enhanced growth and advanced puberty onset along with hormonal changes in buffalo heifers (Bubalus bubalis). However, it is not known to what extent exogenous GRF could influence blood metabolites and minerals to bring about puberty in buffalo heifers. Therefore, we planned to investigate the effect of exogenous bovine GRF (bGRF) on blood metabolites and minerals in buffalo heifers during a 3-month pre-treatment period, 9-month treatment period and 1-month post-treatment period. Six buffalo heifers were treated intravenously with bGRF (10 mug per 100 kg body weight) at 15-day interval for 9 months. Another six buffalo heifers of weight- and age-matched received requisite amount of vehicle (0.9% NaCl solution) during the same period. Exogenous bGRF enhanced (p < 0.01) plasma non-esterified fatty acids (NEFA) concentrations in treatment group when compared with control group during the treatment and post-treatment period, while plasma alpha-amino nitrogen (AAN) concentrations showed a decreasing trend (p < 0.05) in the treatment group when compared with the control group during the treatment and post-treatment periods. The plasma inorganic phosphorus (Pi) was found to be higher (p < 0.05) in the treatment group animals in comparison with the levels recorded in the control group animals during the treatment as well as post-treatment periods. However, there was no change (p > 0.05) in plasma glucose and calcium concentrations between the two groups. Plasma NEFA was found to be positively correlated with plasma growth hormone (GH); however, it was only significant for the treatment group (r = + 0.76; p < 0.05). Plasma AAN in the treatment group exhibited negative correlation with plasma GH (r = 0.72; p < 0.05), while plasma AAN and GH were recorded to be positively correlated in the control group (r = 0.47; p < 0.05). The present findings suggest that exogenous bGRF induces GH release that increases plasma NEFA and Pi and decreases AAN concentrations, which probably help to reach a certain physiological state that initiates events necessary for bringing about puberty in buffalo heifers.
以往的研究表明，生长激素释放因子（GRF）可促进水牛犊牛（Bubalus bubalis）生长并使青春期提前开始，同时伴有激素变化。然而，外源性GRF在多大程度上能够影响血液代谢物和矿物质从而促使水牛犊牛进入青春期尚不清楚。因此，我们计划研究外源性牛GRF（bGRF）在为期3个月的预处理期、9个月的治疗期和1个月的治疗后期对水牛犊牛血液代谢物和矿物质的影响。六头水牛犊牛每隔15天静脉注射bGRF（每100千克体重10微克），持续9个月。另外六头体重和年龄匹配的水牛犊牛在同一时期接受等量的赋形剂（0.9%氯化钠溶液）。与对照组相比，治疗组在治疗期和治疗后期外源性bGRF提高了（p < 0.01）血浆非酯化脂肪酸（NEFA）浓度，而治疗组在治疗期和治疗后期与对照组相比，血浆α-氨基氮（AAN）浓度呈下降趋势（p < 0.05）。在治疗期和治疗后期，治疗组动物的血浆无机磷（Pi）高于对照组动物记录的水平（p < 0.05）。然而，两组之间血浆葡萄糖和钙浓度没有变化（p > 0.05）。发现血浆NEFA与血浆生长激素（GH）呈正相关；然而，仅在治疗组显著相关（r = + 0.76；p < 0.05）。治疗组血浆AAN与血浆GH呈负相关（r = 0.72；p < 0.05），而对照组血浆AAN与GH呈正相关（r = 0.47；p < 0.05）。目前的研究结果表明，外源性bGRF诱导GH释放，从而增加血浆NEFA和Pi并降低AAN浓度，这可能有助于达到某种生理状态，引发水牛犊牛进入青春期所需的一系列事件。
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