Wynn P C, Wallace A L, Kirby A C, Annison E F
Department of Animal Husbandry, Sydney University, Camden, N.S.W.
Aust J Biol Sci. 1988;41(2):177-87. doi: 10.1071/bi9880177.
The effects of daily administration of 10 mg of highly purified ovine growth hormone (GH) for a period of 4 weeks on wool growth have been measured in 12 Merino ewes fed either a calculated maintenance energy intake or 1.6 times this amount (six on each ration). Concentrations of hormones, glucose, urea, alpha-amino N and amino acids in the blood were monitored and faeces and urine collected for measurement of nitrogen balance. Wool growth rate decreased by 20% during the 4 weeks of GH treatment in sheep fed the high energy diet, largely because of reduced wool fibre diameter. This was followed by restoration of normal growth and then an increase of up to 20% above control levels, a response which persisted for 12 weeks following cessation of GH administration, and which was due to increases in both fibre length and diameter. GH administration caused marked increases in plasma concentrations of GH, insulin and somatomedin C, glucose and free fatty acids, all of which returned to basal levels following cessation of GH administration. No consistent changes in plasma concentration of T3, T4, cortisol, prolactin or alpha amino N were detected. Plasma urea and methionine levels decreased during GH treatment and returned to, or were raised above, basal levels after the GH treatment period. GH injection also resulted in a net retention of N during treatment, followed by a transient period of net N loss. The GH-induced changes in wool growth may be caused by a change in the partitioning of amino acids between the muscle mass and the skin. No other contributing factor(s) were identified.
在12只美利奴母羊中测量了每日注射10毫克高纯度绵羊生长激素（GH），持续4周对羊毛生长的影响。这些母羊分别饲喂计算得出的维持能量摄入量或该量的1.6倍（每种日粮各6只）。监测血液中激素、葡萄糖、尿素、α-氨基氮和氨基酸的浓度，并收集粪便和尿液以测量氮平衡。在接受高能量日粮的绵羊中，GH治疗的4周内羊毛生长速度下降了20%，主要是因为羊毛纤维直径减小。随后恢复正常生长，然后比对照水平高出20%，这种反应在停止注射GH后持续12周，这是由于纤维长度和直径均增加所致。注射GH导致血浆中GH、胰岛素和生长调节素C、葡萄糖和游离脂肪酸的浓度显著增加，停止注射GH后所有这些均恢复到基础水平。未检测到血浆中T3、T4、皮质醇、催乳素或α-氨基氮的浓度有一致变化。GH治疗期间血浆尿素和蛋氨酸水平下降，GH治疗期后恢复到基础水平或高于基础水平。注射GH在治疗期间也导致氮的净保留，随后是短暂的氮净损失期。GH诱导的羊毛生长变化可能是由于氨基酸在肌肉和皮肤之间分配的改变所致。未发现其他促成因素。
