Changes in skin and fleece characteristics of Scottish cashmere goats following selection for increased annual production and decreased fibre diameter

Effects of melatonin administration to cashmere goats on cashmere production and hair follicle characteristics in two consecutive cashmere growth cycles

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.

Melatonin supplement induced the hair follicle development in offspring rex rabbits

Previous studies have shown that the administration of melatonin (MT) to early post-natal fur-bearing animals increases the numbers of hair follicles (HFs). In this study, the effect of maternal MT supplementation on the HF development in offspring was investigated. To explore the potential underlying mechanisms, the expression of the melatonin receptor 1A (MTNR1A) gene was determined in the offspring. The Rex rabbit was the animal model, and 79 same-day-pregnancy females were randomly assigned to either a control (n = 39) or MT treatment (n = 40) group, and 10 mg MT microcapsules was implanted at the base of the neck of rabbits in the treatment group. Skin, lung, liver, muscle, kidney, heart and duodenum samples were collected from the newborn rabbits. The results showed that MT improved fur quality in the offspring rabbits by reducing the diameter of primary and secondary HFs, and increasing the HF population. MT did not affect the reproductive performance of female rabbits, and it did affect the blood levels of thyroid-stimulating hormone, prolactin and MT. In the offspring rabbits, MT significantly stimulated MTNR1A gene expression in the skin and heart (p < .01), whereas MTNR1A gene expression was significantly suppressed in the liver and kidney (p < .05). These results revealed that maternal MT supplementation increased HF density, reduced hairiness and improved the fur quality in Rex rabbit offspring. Maternal MT supply may modulate the responses of HFs in the offspring by upregulating the expression of MTNR1A in the skin. In this study, implantation of low-dose MT did not affect the reproductive performance of female rabbits or on the growth of their offspring.

Melatonin promotes secondary hair follicle development of early postnatal cashmere goat and improves cashmere quantity and quality by enhancing antioxidant capacity and suppressing apoptosis

Development of secondary hair follicles in early postnatal cashmere goats may be adversely affected by reactive oxygen species which cause oxidative stress. Because melatonin is a potent antioxidant and scavenger of free radicals, this study explored the effects of melatonin on secondary hair follicle development and subsequent cashmere production. It was found that the initiation of new secondary follicles in early postnatal Inner Mongolian cashmere goats of both melatonin-treated and control goats occurred in the first 10 weeks of age. Melatonin promoted the initiation and maturation of secondary follicles and increased their population. Importantly, the beneficial effect of melatonin on secondary follicle population remained throughout life. As a result, melatonin increased cashmere production and improved its quality in terms of reduced fiber diameter. The mechanisms underlying the role of melatonin on secondary follicle development included the enhancement of activities of antioxidant enzymes, for example, superoxide dismutase and glutathione peroxidase (GSH-Px), elevated total antioxidant capacity, and upregulated anti-apoptotic Bcl-2 expression and downregulated expression of the pro-apoptotic proteins, Bax and caspase-3. These results reveal that melatonin serves to promote secondary hair follicle development in early postnatal cashmere goats and expands our understanding of melatonin application in cashmere production. Melatonin treatment led to an increase in both the quantity and quality of cashmere fiber. This increased the textile value of the fibers and provided economic benefit.