Effects of melatonin implantation on cashmere yield, fibre characteristics, duration of cashmere growth as well as growth and reproductive performance of Inner Mongolian cashmere goats

Melatonin's effect on hair follicles in a goat (Capra hircus) animal model

Introduction

Melatonin can treat androgenetic alopecia in males. Goats can be used as animal models to study melatonin treatment for human alopecia. In this study, a meta-analysis of melatonin's effects on goat hair follicles was pursued.

Methods

Literature from the last 20 years was searched in Scopus, Science Direct, Web of Science and PubMed. Melatonin's effect on goat hair follicles and litter size were performed through a traditional meta-analysis and trial sequential analysis. A network meta-analysis used data from oocyte development to blastocyst. The hair follicle genes regulated by melatonin performed KEGG and PPI. We hypothesized that there are differences in melatonin receptors between different goats, and therefore completed melatonin receptor 1A homology modelling and molecular docking.

Results

The results showed that melatonin did not affect goat primary follicle or litter size. However, there was a positive correlation with secondary follicle growth. The goat melatonin receptor 1A SNPs influence melatonin's functioning. The wild type gene defect MR1 is a very valuable animal model.

Discussion

Future studies should focus on the relationship between goat SNPs and the effect of embedded melatonin. This study will provide theoretical guidance for the cashmere industry and will be informative for human alopecia research.

Effects of Dietary Selenium Yeast Supplementation in Pregnant Cashmere Goats on the Development of Offspring Hair Follicles

The objective of this study was to investigate the effects of maternal dietary selenium yeast (SY) supplementation during pregnancy on the hair follicle development of kids. Sixty pregnant Hanshan white cashmere goats were randomly divided into the con group (fed with a basal diet) and the SY group (fed with a basal diet with 0.4 mg/kg SY). SY was supplemented during the pregnancy until the birth of the kids. The growth performance, cashmere performance, hair follicle characteristics, and serum antioxidant capacity of the kids were periodically determined. The results showed that the birth weight of the kids in the SY group was significantly higher than that in the con group (p < 0.05), and the average weight at 15 days, 1 month, 3 months, and 5 months of age increased by 13.60%, 8.77%, 8.86%, and 3.90%, respectively (p > 0.05). The cashmere fineness at early birth was dramatically reduced with SY supplementation (p < 0.001), whereas cashmere length and production were significantly increased at 5 months of age (p < 0.05). Histology assays indicated that the primary hair follicles were fully developed at birth, and there was no significant difference in the number of primary hair follicles between the two groups (p > 0.05). The number of secondary hair follicles and the number and density of active secondary hair follicles in the SY group at 15 days were significantly higher than those in the con group (p < 0.05) and were increased by 11.18%, 6.18%, and 22.55% at 5 months of age, respectively (p > 0.05). The serum antioxidant capacity analysis revealed that the SY group had higher levels of T-AOC, SOD, CAT, and GSH-Px activities and lower levels of MDA (p > 0.05). These results reveal that the maternal dietary supplementation of SY in gestation can promote the morphogenesis and maturation of secondary hair follicles and increase the number and density of secondary hair follicles by enhancing the body's antioxidant capacity, contributing to the improvement of cashmere quality and yield.

Hair Follicle Development and Cashmere Traits in Albas Goat Kids

The objectives of this trial were to study the growth and development of hair follicles and cashmere traits in cashmere goats and to provide a theoretical basis for the regulation of secondary hair follicle development and the scientific breeding selection of cashmere goats. Twelve single-fetal female kids were selected as research objects. A long-term tracking plan was created to regularly determine their growth performance, cashmere performance, and hair follicle traits. The results showed no significant difference in live weight after the first and second combing. The cashmere yield and unit yield of the first combing were significantly higher than those of the second combing (p < 0.05). Sections of hair follicles showed that the primary hair follicles are almost fully developed by 1 month, and the secondary hair follicles are fully developed by 5-6 months after birth. The primary hair follicle density (PFD) and secondary hair follicle density (SFD) were highest at birth and decreased within 1 month; and SFD was stable at 5-6 months of age. The change of MSFD took a maximum time of 2 to 3 months. The S:P increase reached its peak at 6 months. BMP4 expression increased with time. FGF2, FGF21 and BMP7 were higher at 3 months old than at the other two-time points. In conclusion, this study determined the total development time of primary and secondary hair follicles from morphology and speculated that FGF2, FGF21, and BMP7 may play a regulatory role in developing secondary hair follicles. Therefore, the period from birth to 6 months of age was the best time to regulate secondary hair follicle development in cashmere goats kids. The traits of the hair follicle and cashmere at 6 months of age could be breeding selection indicators for cashmere goats.

Melatonin Promotes the Development of Secondary Hair Follicles in Adult Cashmere Goats by Activating the Keap1-Nrf2 Signaling Pathway and Inhibiting the Inflammatory Transcription Factors NFκB and AP-1

Exogenous melatonin (MT) has been used to promote the growth of secondary hair follicles and improve cashmere fiber quality, but the specific cellular-level mechanisms involved are unclear. This study was carried out to investigate the effect of MT on the development of secondary hair follicles and on cashmere fiber quality in cashmere goats. The results showed that MT improved secondary follicle numbers and function as well as enhanced cashmere fiber quality and yield. The MT-treated goat groups had high secondary-to-primary ratios (S:P) for hair follicles, greater in the elderly group (p < 0.05). Antioxidant capacities of secondary hair follicles improved fiber quality and yield in comparison with control groups (p < 0.05/0.01). Levels of reactive oxygen and nitrogen species (ROS, RNS) and malondialdehyde (MDA) were lowered (p < 0.05/0.01) by MT. There was significant upregulation of antioxidant genes (for SOD-3; GPX-1; NFE2L2) and the protein of nuclear factor (Nrf2), and downregulation of the Keap1 protein. There were significant differences in the expression of genes for secretory senescence-associated phenotype (SASP) cytokines (IL-1β, IL-6, MMP-9, MMP-27, CCL-21, CXCL-12, CXCL-14, TIMP-1,2,3) plus their protein of key transcription factors, nuclear factor kappa B (NFκB) and activator protein-1 (AP-1), in comparison with the controls. We concluded that MT could enhance antioxidant capacity and reduce ROS and RNS levels of secondary hair follicles through the Keap1-Nrf2 pathway in adult cashmere goats. Furthermore, MT reduced the expression of the SASP cytokines genes by inhibiting the protein of NFκB and AP-1 in the secondary hair follicles in older cashmere goats, thus delaying skin aging, improving follicle survival, and increasing the number of secondary hair follicles. Collectively, these effects of exogenous MT enhanced the quality and yield of cashmere fibers, especially at 5-7 years old.

Identification of key pathways and genes that regulate cashmere development in cashmere goats mediated by exogenous melatonin

The growth of secondary hair follicles in cashmere goats follows a seasonal cycle. Melatonin can regulate the cycle of cashmere growth. In this study, melatonin was implanted into live cashmere goats. After skin samples were collected, transcriptome sequencing and histological section observation were performed, and weighted gene co-expression network analysis (WGCNA) was used to identify key genes and establish an interaction network. A total of 14 co-expression modules were defined by WGCNA, and combined with previous analysis results, it was found that the blue module was related to the cycle of cashmere growth after melatonin implantation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that the first initiation of exogenous melatonin-mediated cashmere development was related mainly to the signaling pathway regulating stem cell pluripotency and to the Hippo, TGF-beta and MAPK signaling pathways. Via combined differential gene expression analyses, 6 hub genes were identified: PDGFRA, WNT5A, PPP2R1A, BMPR2, BMPR1A, and SMAD1. This study provides a foundation for further research on the mechanism by which melatonin regulates cashmere growth.

Time-course RNA-seq analysis reveals stage-specific and melatonin-triggered gene expression patterns during the hair follicle growth cycle in Capra hircus

Background

Cashmere goat is famous for its high-quality fibers. The growth of cashmere in secondary hair follicles exhibits a seasonal pattern arising from circannual changes in the natural photoperiod. Although several studies have compared and analyzed the differences in gene expression between different hair follicle growth stages, the selection of samples in these studies relies on research experience or morphological evidence. Distinguishing hair follicle growth cycle according to gene expression patterns may help to explore the regulation mechanisms related to cashmere growth and the effect of melatonin from a molecular level more accurately.

Results

In this study, we applied RNA-sequencing to the hair follicles of three normal and three melatonin-treated Inner Mongolian cashmere goats sampled every month during a whole hair follicle growth cycle. A total of 3559 and 988 genes were subjected as seasonal changing genes (SCGs) in the control and treated groups, respectively. The SCGs in the normal group were divided into three clusters, and their specific expression patterns help to group the hair follicle growth cycle into anagen, catagen and telogen stages. Some canonical pathways such as Wnt, TGF-beta and Hippo signaling pathways were detected as promoting the hair follicle growth, while Cell adhesion molecules (CAMs), Cytokine-cytokine receptor interaction, Jak-STAT, Fc epsilon RI, NOD-like receptor, Rap1, PI3K-Akt, cAMP, NF-kappa B and many immune-related pathways were detected in the catagen and telogen stages. The PI3K-Akt signaling, ECM-receptor interaction and Focal adhesion were found in the transition stage between telogen to anagen, which may serve as candidate biomarkers for telogen-anagen regeneration. A total of 16 signaling pathways, 145 pathway mRNAs, and 93 lncRNAs were enrolled to construct the pathway-mRNA-lncRNA network, which indicated the function of lncRNAs through interacting with their co-expressed mRNAs. Pairwise comparisons between the control and melatonin-treated groups also indicated 941 monthly differentially expressed genes (monthly DEGs). These monthly DEGs were mainly distributed from April and September, which revealed a potential signal pathway map regulating the anagen stage triggered by melatonin. Enrichment analysis showed that Wnt, Hedgehog, ECM, Chemokines and NF-kappa B signaling pathways may be involved in the regulation of non-quiescence and secondary shedding under the influence of melatonin.

Conclusions

Our study decoded the key regulators of the whole hair follicle growth cycle, laying the foundation for the control of hair follicle growth and improvement of cashmere yield.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08331-z.

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.

Roles of Melatonin in Goat Hair Follicle Stem Cell Proliferation and Pluripotency Through Regulating the Wnt Signaling Pathway

Emerging studies show that melatonin promotes cashmere development through hypodermic implantation. However, the impact and underlying mechanisms are currently unknown. In vitro study has previously demonstrated that melatonin induces cashmere growth by regulating the proliferation of goat secondary hair follicle stem cells (gsHFSCs), but there is limited information concerning the effects of melatonin on cell pluripotency. It is also known that Wnt signaling may actively participate in regulating cell proliferation and stem cell pluripotency. Therefore, in the current investigation, goat hair follicle stem cells were exposed to multiple concentrations of melatonin and different culture times to reveal the relationship between melatonin and the activation of Wnt signaling. A proportionally high Catenin beta-1 (CTNNB1) response was induced by 500 ng/L of melatonin, but it was then suppressed with the dosages over 1,000 ng/L. Greater amounts of CTNNB1 entered the cell nuclei by extending the exposure time to 72 h, which activated transcription factor 4/lymphoid enhancer-binding factor 1 and promoted the expression of the proliferation-related genes C-MYC, C-JUN, and CYCLIND1. Moreover, nuclear receptor ROR-alpha (RORα) and bone morphogenetic protein 4 (BMP4) were employed to analyze the underlying mechanism. RORα presented a sluggish concentration/time-dependent rise, but BMP4 was increased dramatically by melatonin exposure, which revealed that melatonin might participate in regulating the pluripotency of hair follicle stem cells. Interestingly, NOGGIN, which is a BMP antagonist and highly relevant to cell stemness, was also stimulated by melatonin. These findings demonstrated that melatonin exposure and/or NOGGIN overexpression in hair follicle stem cells might promote the expression of pluripotency markers Homeobox protein NANOG, Organic cation/carnitine transporter 4, and Hematopoietic progenitor cell antigen CD34. Our findings here provided a comprehensive view of Wnt signaling in melatonin stimulated cells and melatonin mediated stemness of gsHFSCs by regulating NOGGIN, which demonstrates a regulatory mechanism of melatonin enhancement on the growth of cashmere.

Inhibition of prolactin promotes secondary skin follicle activation in cashmere goats

The aim of this study was to investigate the involvement of prolactin (PRL) on development of secondary skin follicles in cashmere goats. Goats were randomly assigned to either a bromocriptine treatment or control group. Samples of cashmere fiber, blood, and skin were collected from all goats after 1 mo. The results indicated that the length, growth rate, and diameter of fibers were not influenced (P > 0.05) by the inhibition of PRL resulting from the treatment with bromocriptine. There was a tendency for increases in total follicle number, primary and secondary follicle numbers, and in the ratio of secondary to primary follicles following treatment with bromocriptine, but these differences were not significant (P > 0.05). The percentage of active secondary follicles in anagen was increased (P < 0.05) in the bromocriptine-treated goats, but there was no effect of treatment on the percentage of active primary follicles. Bromocriptine decreased (P < 0.05) circulating concentrations of PRL and Insulin-like growth factor 1 (IGF1) and increased (P < 0.05) those of melatonin (MT), but there was no effect of this treatment on the serum concentrations of cortisol, growth hormone, tetraiodothyronine, and triiodothyronine. In bromocriptine-treated goats, mRNA expressions of PRL and MT membrane receptor 1a (MTNR1a) were decreased (P < 0.05) and mRNA expression of MT nuclear receptor (RORα) was increased (P < 0.05), but there was no effect of the treatment on expression of long PRL receptor, short PRL receptor, MT membrane receptor 1b and IGF1. It is concluded that inhibition of PRL promotes secondary hair follicle development in the anagen phase, possibly by downregulating MTNR1a and up-regulating RORα gene expression in the skin.

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.

Genetic Signatures of Selection for Cashmere Traits in Chinese Goats

Simple Summary

Cashmere goats are a unique husbandry resource in China. These goats are well known for producing the highest cashmere yield and best fiber quality in the world. Although cashmere is highly valued and also known as “fiber gem” and “soft gold”, few studies have examined the genetic basis of cashmere traits in cashmere goats. Here, we identified selection signals by comparing Fst and XP-EHH (the cross population extend haplotype homozygosity test) of a non-cashmere breed (Huanghuai goat) with those of two cashmere breeds (Inner Mongolia and Liaoning cashmere goats). Two genes (WNT10A and CSN3) were potentially associated with cashmere traits. This information may be valuable for studying the genetic uniqueness of cashmere goats and elucidating the mechanisms underlying cashmere traits in cashmere goats.

Abstract

Inner Mongolia and Liaoning cashmere goats in China are well-known for their cashmere quality and yield. Thus, they are great models for identifying genomic regions associated with cashmere traits. Herein, 53 Inner Mongolia cashmere goats, Liaoning cashmere goats and Huanghuai goats were genotyped, and 53,347 single-nucleotide polymorphisms (SNPs) were produced using the Illumina Caprine 50K SNP chip. Additionally, we identified some positively selected SNPs by analyzing Fst and XP-EHH. The top 5% of SNPs had selection signatures. After gene annotation, 222 and 173 candidate genes were identified in Inner Mongolia and Liaoning cashmere goats, respectively. Several genes were related to hair follicle development, such as TRPS1, WDR74, LRRC14, SPTLC3, IGF1R, PADI2, FOXP1, WNT10A and CSN3. Gene enrichment analysis of these cashmere trait-associated genes related 67 enriched signaling pathways that mainly participate in hair follicle development and stem cell pluripotency regulation. Furthermore, we identified 20 overlapping genes that were selected in both cashmere goat breeds. Among these overlapping genes, WNT10A and CSN3, which are associated with hair follicle development, are potentially involved in cashmere production. These findings may improve molecular breeding of cashmere goats in the future.

A blood metabolomics study of metabolic variations in Inner Mongolia white cashmere goats under shortened and natural photoperiod conditions

This study investigated metabolic variations by using gas chromatography – mass spectrometry (GC–MS)-based metabolomics in the blood of Inner Mongolia white cashmere goats under shortened and natural photoperiod conditions. Twenty-four female (non-pregnant) Inner Mongolia white cashmere goats aged 1–1.5 yr with similar live weights (mean, 20.36 ± 2.63 kg) were randomly allocated into two groups: a natural daily photoperiod group (NDPP group: 10–16 h light, n = 12) and a short daily photoperiod group (SDPP group: 7 h light:17 h dark, n = 12). In this study, we found that a SDPP promoted the blood metabolic perturbations based on the GC–MS-based metabolomics investigation, and nine metabolites were related to a SDPP. Compared with the NDPP group, the contents of serine, oxaloacetic acid, xylose, l-3,4-dihydroxyphenylalanine, and xanthosine significantly were up-regulated, whereas the contents of carnitine, 1,3-diaminopropane, indole-3-acetic acid, and l-kynurenine were significantly down-regulated in the SDPP group. The different metabolites could contribute to the regulation mechanisms of promoting cashmere growth of goats in the SDPP group.

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.

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.

Effects of photoperiod on nutrient digestibility, hair follicle activity and cashmere quality in Inner Mongolia white cashmere goats

OBJECTIVE

This study investigated the effects of photoperiod on nutrient digestibility, hair follicle (HF) activity and cashmere quality in Inner Mongolia white cashmere goats.

METHODS

Twenty-four female (non-pregnant) Inner Mongolia white cashmere goats aged 1 to 1.5 years old with similar live weights (mean, 20.36±2.63 kg) were randomly allocated into two groups: a natural daily photoperiod group (NDPP group:10 to 16 h light, n = 12) and a short daily photoperiod group (SDPP group: 7 h light:17 h dark, n = 12). All the goats were housed in individual pens and fed the same diets from May 15 to October 15, 2015. The digestibility of crude protein (CP), dry matter (DM), and neutral detergent fiber (NDF) were measured in different months, along with secondary hair follicle (SHF) activity, concentration of melatonin (MEL), and cashmere quality.

RESULTS

Although there was no significant difference in the live weights of goats between the SDPP and NDPP groups (p>0.05), the CP digestibility of goats in the SDPP group was significantly increased compared to the NDPP group in July, September, and October (p<0.05). For the DM and NDF digestibility of goats, a significant increase (p<0.05) was found during in September in the SDPP group. Furthermore, compared to the NDPP group, the SHF activity in July, the MEL concentration in July, and the cashmere fiber length and fiber weight in October were significantly increased in the SDPP group (p<0.05).

CONCLUSION

The cashmere production of Inner Mongolia white cashmere goats was increased without obvious deleterious effects on the cashmere fibers in the SDPP group (metabolizable energy, 8.34 MJ/kg; CP, 11.16%; short daily photoperiod, 7 h light:17 h dark).

Cashmere growth control in Liaoning cashmere goat by ovarian carcinoma immunoreactive antigen-like protein 2 and decorin genes

Objective

The study investigated the biological functions and mechanisms for controlling cashmere growth of Liaoning cashmere goat by ovarian carcinoma immunoreactive antigen-like protein 2 (OCIAD2) and decorin (DCN) genes.

Methods

cDNA library of Liaoning cashmere goat was constructed in early stages. OCIAD2 and DCN genes related to cashmere growth were identified by homology analysis comparison. The expression location of OCIAD2 and DCN genes in primary and secondary hair follicles (SF) was performed using in situ hybridization. The expression of OCIAD2 and DCN genes in primary and SF was performed using real-time polymerase chain reaction (PCR).

Results

In situ hybridization revealed that OCIAD2 and DCN were expressed in the inner root sheath of Liaoning cashmere goat hair follicles. Real-time quantitative PCR showed that these genes were highly expressed in SF during anagen, while these genes were highly expressed in primary hair follicle in catagen phase. Melatonin (MT) inhibited the expression of OCIAD2 and promoted the expression of DCN. Insulin-like growth factors-1 (IGF-1) inhibited the expression of OCIAD2 and DCN, while fibroblast growth factors 5 (FGF5) promoted the expression of these genes. MT and IGF-1 promoted OCIAD2 synergistically, while MT and FGF5 inhibited the genes simultaneously. MT+IGF-1/MT+FGF5 inhibited DCN gene. RNAi technology showed that OCIAD2 expression was promoted, while that of DCN was inhibited.

Conclusion

Activation of bone morphogenetic protein (BMP) signaling pathway up-regulated OCIAD2 expression and stimulated SF to control cell proliferation. DCN gene affected hair follicle morphogenesis and periodic changes by promoting transforming growth factor-β (TGF-β) and BMP signaling pathways. OCIAD2 and DCN genes have opposite effects on TGF-β signaling pathway and inhibit each other to affect the hair growth.

Identification of selection signals by large-scale whole-genome resequencing of cashmere goats

Inner Mongolia and Liaoning cashmere goats are two outstanding Chinese multipurpose breeds that adapt well to the semi-arid temperate grassland. These two breeds are characterized by their soft cashmere fibers, thus making them great models to identify genomic regions that are associated with cashmere fiber traits. Whole-genome sequencing of 70 cashmere goats produced more than 5.52 million single-nucleotide polymorphisms and 710,600 short insertions and deletions. Further analysis of these genetic variants showed some population-specific molecular markers for the two cashmere goat breeds that are otherwise phenotypically similar. By analyzing F_ST and θ_π outlier values, we identified 135 genomic regions that were associated with cashmere fiber traits within the cashmere goat populations. These selected genomic regions contained genes, which are potential involved in the production of cashmere fiber, such as FGF5, SGK3, IGFBP7, OXTR, and ROCK1. Gene ontology enrichment analysis of identified short insertions and deletions also showed enrichment in keratinocyte differentiation and epidermal cell differentiation. These findings demonstrate that this genomic resource will facilitate the breeding of cashmere goat and other Capra species in future.

Effects of melatonin implantation on cashmere growth, hormone concentrations and cashmere yield in cashmere-perennial-type Liaoning cashmere goats

The aim of the present study was to investigate the effects of melatonin implants on cashmere growth, the concentrations of plasma melatonin and prolactin and the total cashmere yield in cashmere-perennial-type Liaoning cashmere goats. Twenty female goats were assigned to two treatments (n = 10) including a control and a treatment in which melatonin (2 mg/kg bodyweight) was implanted in March and May, respectively. The experiment lasted for 153 days. Fibre samples were collected in July, August and April the following year (before cashmere harvest). Blood samples were taken monthly from March to August. Cashmere yield was recorded after harvest. In melatonin-treated goats, cashmere length and cashmere growth rate from April to July were significantly increased (P < 0.05), but no influence was observed (P > 0.05) in August. Implantation of melatonin significantly increased plasma melatonin concentrations (P < 0.05) and decreased prolactin concentrations from April to July compared with the control group (P < 0.05), but no difference was observed in August (P > 0.05). Administration of melatonin increased the cashmere yield by 6.2% and the maximum cashmere length by 8.4%, but the differences were not significant (P > 0.05). Moreover, the cashmere fibre diameter was not influenced by melatonin implantation (P > 0.05). The results also indicated that plasma melatonin concentrations were correlated with plasma prolactin in the regulation of cashmere growth. Implantation of melatonin was an effective way to promote cashmere growth, and administration during the cashmere slow-growing period improved cashmere production without changing cashmere fibre diameter in cashmere-perennial-type Liaoning cashmere goats.