The objective of the study was to determine the long-term effects of melatonin treatment on cashmere production and hair follicle populations in cashmere goats and their activity in two consecutive cashmere growth cycles. Twenty-four female Inner Mongolian Cashmere goats were randomly allocated to two groups (n = 12), one of which received melatonin implants, the other being an untreated control group. Melatonin implants were subcutaneously inserted behind the ear at a dose of 2 mg/kg live weight on two occasions –April 30 and June 30, 2016. Hair samples were collected by combing in April of 2017 and 2018, and the weight, staple length, and diameter of the cashmere fibers were measured. Blood and skin samples were collected monthly between April and September 2016, and in April and September in 2017 for the analysis of melatonin concentration and the characteristics of secondary hair follicle populations, respectively. The results indicated that serum melatonin concentration in the treated goats was elevated (P < 0.05) relative to that of the control group, but only during the first growth cycle. Melatonin treatment of cashmere goats in one cashmere growth cycle increased the weight, staple length, and density (all P < 0.05) of the cashmere fibers and decreased fiber diameter (P < 0.01), but did not affect the characteristics of cashmere production in the subsequent annual cycle. Melatonin treatment had no effect on the population of skin secondary hair follicles for two consecutive cycles. However, in the first growth cycle after treatment, it advanced the onset of activity of skin secondary hair follicles by 2 mo (P < 0.05), and it increased the number of follicles that were active (P < 0.05). In summary, the melatonin treatment of cashmere goats in one cashmere growth cycle improved cashmere production for that cycle only, with no residual effects on the subsequent cycle, a technique acceptable to the cashmere goat industry. The enhancement of cashmere production after the treatment of goats with melatonin appears to involve the acceleration of the annual regeneration of skin secondary hair follicles and increased population of active secondary hair follicles in the skin of cashmere goats.

该研究的目的是确定褪黑激素处理对羊绒山羊的羊绒产量和毛囊数量的长期影响及其在两个连续的羊绒生长周期中的活性。24 只雌性内蒙古绒山羊被随机分为两组（n = 12），其中一组接受了褪黑激素植入，另一组是未处理的对照组。2016 年 4 月 30 日和 6 月 30 日，分别以 2 mg/kg 活重的剂量将褪黑激素植入物皮下植入耳后。 2017 年 4 月和 2018 年 4 月通过梳理收集毛发样本，并测定重量、短纤维长度、并测量了羊绒纤维的直径。2016 年 4 月至 9 月期间每月收集血液和皮肤样本，2017 年 4 月和 9 月分别用于分析褪黑激素浓度和次级毛囊种群特征。结果表明，处理后山羊的血清褪黑激素浓度升高（P < 0.05) 相对于对照组，但仅限于第一个生长周期。在一个羊绒生长周期中，褪黑素处理使羊绒纤维的重量、短纤维长度和密度增加（均P < 0.05），纤维直径减小（P < 0.01），但不影响羊绒生产特性随后的年度周期。褪黑激素治疗连续两个周期对皮肤次级毛囊的数量没有影响。然而，在治疗后的第一个生长周期中，它使皮肤次级毛囊的活动开始提前了2个月（P < 0.05），并增加了活动的毛囊数量（P< 0.05)。总之，在一个羊绒生长周期中对羊绒山羊进行褪黑激素处理，仅提高了该周期的羊绒产量，对后续周期没有任何残留影响，这是一种羊绒山羊行业可以接受的技术。用褪黑激素处理山羊后羊绒产量的增加似乎涉及加速皮肤次级毛囊的年度再生和羊绒山羊皮肤中活跃的次级毛囊数量的增加。