Study On The Relationship Between Birth Weight,Weaning Weight And Cashmere Production Performance,Hair Follicle Population And Reproductive Performance In Cashmere Goats

Cashmere is an unmyelinated hair fiber formed by secondary hair follicles of the skin on the cashmere goat.And the number of secondary hair follicles is an important factor affecting the quality and economic value of cashmere.Therefore,the number of secondary skin follicles is often used as an important reference indicator for breed selection.However,determining the number of secondary hair follicles is time-consuming and laborious,which limits its application as a selection indicator.Studies have shown that the level of nutrition during fetal and lactation periods is an important factor affecting the number of secondary hair follicles in the skin of cashmere goats.The first birth weight and weaning weight partially reflect the nutritional level during fetal and lactation periods.Whether the first birth weight and weaning weight can be used as an indirect indicator of the number of secondary hair follicles in the skin of cashmere goats needs further study.Therefore,we systematically investigated the relationship between birth weight and weaning weight with cashmere production performance and skin follicle number in cashmere goats to provide a theoretical basis for incorporating birth weight and weaning weight into the selection index of breeding goats.Experiment 1 was conducted to investigate the relationship between birth weight and cashmere production performance and the number of skin follicles in cashmere goats.At the time of lambing in April 2019,thirty-five single kids and forty double kids(female)were randomly selected,and the weight of each kid was recorded and numbered,and the single kids and double kids were grouped according to their birth weight: 2.0 ~ 2.5 kg,2.6 ~ 3.0 kg,and 3.1 ~ 3.5 kg,respectively.Skin samples were collected in January 2020 for measuring the number of skin follicles.And cashmere samples were collected for measuring cashmere length and cashmere fineness.The cashmere yield was recorded in May 2020.(1)The results showed that for single lambs: birth weight had a significant effect(P < 0.05)on cashmere yield,with a cashmere yield of870.72 ± 41.46 g in the 2.6 ~ 3.0 kg weight group,which significantly higher than the 2.0 ~ 2.5 kg and 3.1 ~ 3.5 kg weight groups.There was no significant effect of birth weight on cashmere length and cashmere fineness(P > 0.05).Birth weight had significant effects(P < 0.05)on secondary follicle density index,number of secondary follicles and S:P in cashmere goats,with significantly higher secondary follicle density index and the number of secondary follicles in 2.6 ~ 3.0 kg and3.1 ~ 3.5 kg groups than in 2.0 ~ 2.5 kg groups,and significantly higher S:P in 2.6 ~ 3.0 kg groups than in 2.0 ~ 2.5 kg group.S:P was significantly higher in the 2.6 ~ 3.0 kg group than in the 2.0 ~2.5 kg group;Birth weight was moderately positively correlated with S:P in cashmere goats(P <0.05).(2)For double kids: there was no significant effect of birth weight on cashmere production,cashmere length and fineness of cashmere goats(P > 0.05);there was no significant effect of birth weight on secondary follicle density,skin secondary follicle density index,number of secondary follicles and S:P of Cashmere goats(P > 0.05).In conclusion,for single lambs,the birth weight reflects the yearling fleece production performance and the number of secondary skin hair follicles.And individuals with a birth weight of 3.0 kg or more can be preferred for breeding purposes.For double kids,the birth weight did not fully reflect the cashmere production performance and the number of skin follicles of cashmere goats.Experiment 2 was conducted to investigate the relationship between weaning weight and cashmere production performance and the number of skin follicles in cashmere goats.At the time of weaning in June 2019,weaning weights of test kids in experiment 1 were measured,and single and double lambs were grouped according to weaning weights: 10.0 ~ 20.0 kg and 20.0 ~ 30.0 kg,respectively.The results showed that for single kids,weaning weight had no significant effect on the cashmere production performance of cashmere goats;there were significant effects(P < 0.05)on the secondary follicle density index,secondary follicle number and S:P of cashmere goats,and the secondary follicle density index,secondary follicle number and S:P of cashmere goats increased significantly with increasing weaning weight;weaning weight and secondary follicle density index of cashmere goats were moderately correlated with the S:P of cashmere goats.Weaning weight was moderately positively correlated with the secondary follicle density index of cashmere goats(P < 0.05).For double lambs: weaning weight had no significant effect(P > 0.05)on the cashmere production,cashmere length and fineness of cashmere goats;and no significant effect(P > 0.05)on secondary follicle density,skin secondary follicle density index,number of secondary follicles and S:P of cashmere goats.In conclusion,for singlekids,weaning weight reflects the cashmere performance and the number of secondary skin hair follicles of the cashmere goats,and individuals with weaning weight above 20.0 kg can be preferred for breeding.For double kids,the weaning weight did not fully reflect the cashmere production performance and the number of skin follicles of cashmere goats,which might be influenced by other factors and need further study.