Effect of Fasted Live-Weight Gain during the Cashmere Non-Growing Period on Cashmere Production Performance and Secondary Hair Follicle Activity of Cashmere Goats

The objective of this study was to investigate the effects of fasted live-weight gain during the cashmere non-growing period on cashmere production performance and secondary hair follicle activity, to provide a theoretical basis for appropriate supplementary feeding of cashmere goats. Fifty Inner Mongolian cashmere goats aged 2-4 years old were randomly selected and weighed in May and September 2019, respectively. Based on fasted live-weight gain between the two weights, the experimental ewe goats were divided into two groups: 0-5.0 kg group (n = 30) and 5.0-10.0 kg group (n = 20). Skin samples and cashmere samples were collected. Results of a Pearson correlation analysis showed that fasted live-weight gain during the cashmere non-growing period had a moderate and strong positive correlation with cashmere yield (p = 0.021) and cashmere staple length (p = 0.002), respectively, but did not correlate with cashmere diameter (p = 0.254). Compared with cashmere goats with a fasted live-weight gain of 0-5.0 kg, cashmere goats with a fasted live-weight gain of 5.0-10.0 kg had a 17.10% increase in cashmere yield (p = 0.037) and an 8.09% increase in cashmere staple length (p = 0.045), but had no significant difference in cashmere diameter (p = 0.324). Results of a Pearson correlation analysis showed that there was a strong positive correlation between fasted live-weight gain and the population of active secondary hair follicles in the skin of cashmere goats (p < 0.01). Compared with cashmere goats with a fasted live-weight gain of 0-5.0 kg, cashmere goats with a fasted live-weight gain of 5.0-10.0 kg had an increase in the population of active secondary hair follicles (p < 0.05). In conclusion, the fasted live-weight gain during the cashmere non-growing period had a significant effect on secondary hair follicle activity and cashmere production performance in cashmere goats. Since fasted live-weight gain reflects nutritional level to a certain extent, this study suggests that nutritional manipulations such as supplementary feeding during cashmere non-growing periods can increase cashmere production performance. However, specific nutritional manipulations during the cashmere non-growing period need further research to increase cashmere production performance.

Melatonin promotes the development of the secondary hair follicles by regulating circMPP5

BACKGROUND

The quality and yield of cashmere fibre are closely related to the differentiation and development of secondary hair follicles in the skin of cashmere goats. The higher the density of secondary hair follicles, the higher the quality and yield of cashmere from the fleece. Development of secondary hair follicles commences in the embryonic stage of life and is completed 6 months after birth. Preliminary experimental results from our laboratory showed that melatonin (MT) treatment of goat kids after their birth could increase the density of secondary hair follicles and, thus, improve the subsequent yield and quality of cashmere. These changes in the secondary hair follicles resulted from increases in levels of antioxidant and expression of anti-apoptotic protein, and from a reduction in apoptosis. The present study was conducted to explore the molecular mechanism of MT-induced secondary hair follicle differentiation and development by using whole-genome analysis.

RESULTS

MT had no adverse effect on the growth performance of cashmere kids but significantly improved the character of the secondary hair follicles and the quality of cashmere, and this dominant effect continued to the second year. Melatonin promotes the proliferation of secondary hair follicle cells at an early age. The formation of secondary hair follicles in the MT group was earlier than that in the control group in the second year. The genome-wide data results involved KEGG analysis of 1044 DEmRNAs, 91 DElncRNAs, 1054 DEcircRNAs, and 61 DEmiRNAs which revealed that the mitogen-activated protein kinase (MAPK) signaling pathway is involved in the development of secondary hair follicles, with key genes (FGF2, FGF21, FGFR3, MAPK3 (ERK1)) being up-regulated and expressed. We also found that the circMPP5 could sponged miR-211 and regulate the expression of MAPK3.

CONCLUSIONS

We conclude that MT achieves its effects by regulating the MAPK pathway through the circMPP5 sponged the miR-211, regulating the expression of MAPK3, to induce the differentiation and proliferation of secondary hair follicle cells. In addition there is up-regulation of expression of the anti-apoptotic protein causing reduced apoptosis of hair follicle cells. Collectively, these events increase the numbers of secondary hair follicles, thus improving the production of cashmere from these goats.

Melatonin Regulates the Periodic Growth of Cashmere by Upregulating the Expression of Wnt10b and β-catenin in Inner Mongolia Cashmere Goats

Secondary hair follicle growth in cashmere goats has seasonal cycle changes, and melatonin (MT) has a regulatory effect on the cashmere growth cycle. In this study, the growth length of cashmere was measured by implanting MT in live cashmere goats. The results indicated that the continuous implantation of MT promoted cashmere to enter the anagen 2 months earlier and induce secondary hair follicle development. HE staining of skin tissues showed that the number of secondary hair follicles in the MT-implanted goats was significantly higher than that in the control goats (P < 0.05). Transcriptome sequencing of the skin tissue of cashmere goats was used to identify differentially expressed genes: 532 in February, 641 in October, and 305 in December. Fluorescence quantitative PCR and Western blotting results showed that MT had a significant effect on the expression of Wnt10b, β-catenin, and proteins in the skin tissue of Inner Mongolia cashmere goats. This finding suggested that MT alters the cycle of secondary hair follicle development by changing the expression of related genes. This research lays the foundation for further study on the mechanism by which MT regulates cashmere growth.

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.

Effect of melatonin administration to lactating cashmere goats on milk production of dams and on hair follicle development in their offspring

Melatonin treatment in adult cashmere goats can increase cashmere yield and improve cashmere fibre quality by inducing cashmere growth during cashmere non-growth period, of which time cashmere goats are in the mid and late stages of lactation. However, whether melatonin treatment in adult cashmere goats affects their offspring's growth performance remains unknown. Therefore, the objectives of the current study were to determine the effects of melatonin treatment in adult cashmere goats on cashmere and milk production performance in dams and on hair follicle development and subsequent cashmere production in their offspring. Twenty-four lactating Inner Mongolian Cashmere goat dams (50 ± 2 days in milk, mean ± SD) and their single-born female offspring (50 ± 2 days old, mean ± SD) were randomly assigned to one of two groups supplemented with melatonin implants (MEL; n = 12) or without (CON; n = 12). The melatonin implants were subcutaneously implanted behind the ear at a dose of 2 mg/kg live weight on two occasions - 30 April and 30 June 2016. The results demonstrated that melatonin treatment in adult cashmere goats increased cashmere production and improved cashmere fibre quality as indicated by greater cashmere yield, longer cashmere fibre staple length, finer cashmere fibre diameter and thicker cashmere fibre density. The milk fat content was higher in MEL compared with CON cashmere goats. The daily yields of milk production, milk protein and milk lactose were lower in MEL compared with CON cashmere goats. Serum melatonin concentrations were greater, serum prolactin concentrations were lower and milk melatonin concentrations and yields were greater in MEL compared with CON cashmere goats. With regard to offspring, there were no differences in cashmere yield, fibre staple length, fibre diameter and fibre density at yearling combing, and the primary and secondary hair follicles population and maturation between treatments. In conclusion, melatonin treatment in adult cashmere goats during cashmere non-growth period is a practical and an effective way in cashmere industry as indicated by not only increasing cashmere yield and improving cashmere fibre quality in adult cashmere goat dams but also having no impairment in hair follicle development and the subsequent cashmere production in their single-born offspring.

Effects of melatonin implantation on carcass characteristics, meat quality and tissue levels of melatonin and prolactin in Inner Mongolian cashmere goats

Background

Implantation of goats with melatonin can induce cashmere growth and significantly increase cashmere production performance. However, the impact of melatonin implantation on the carcass characteristics, meat quality and related hormone levels in muscle and viscera of cashmere goats has not been studied. This experiment was conducted to determine the effects of melatonin implantation of cashmere goats during the non-growing period on meat quality and related hormone levels in the tissues. It aimed to provide a theoretical basis for the practical application of melatonin in cashmere goat production systems.

Results

Melatonin implantation (2 mg/kg live weight) had no influence (P > 0.05) on daily weight gain, carcass weight, dressing percentage, loin muscle area, or the pH, moisture level, crude fat (except for Gluteus muscle) and amino acid content of muscles of cashmere goats. After implantation for 1 month, shear force of Longissimus dorsi and water loss rate of Longissimus dorsi and Biceps femoris of cashmere goats were increased (P < 0.05), whereas the cooking yield of Gluteus muscle was reduced (P < 0.05). The melatonin treatment decreased (P < 0.05) muscle crude protein, Gluteus muscle crude fat and ∑n-3PUFA content and decreased (P < 0.05) ∑n-6PUFA content. However, after 2 months of implantation most of these effects had resolved. Melatonin implantation had no effect (P > 0.05) on the melatonin or prolactin contents of kidney, heart, spleen, liver, Longissimus dorsi, Biceps femoris and Gluteus muscles. Melatonin content of lung tissue was lowered (P < 0.05) and that of prolactin was elevated (P < 0.05) by the melatonin implantation.

Conclusion

This study has shown little impact of melatonin implantation of cashmere goats on carcass quality. A few meat quality indices i.e., shear force, water loss rate, ∑n-3PUFA, ∑n-6PUFA, and crude protein content of Longissimus dorsi; water loss rate, cooking yield and crude protein content of Biceps femoris; ether extract, crude protein content of Gluteus; were affected briefly (at 1 month of implantation) but these effects were not evident after 2 months of implantation. There was little effect of the melatonin treatments on tissue levels of melatonin or prolactin except in lung.