Genetic analysis of reproductive traits of Tianmu multiparous sheep
Reproductive traits are one of the important economic traits in the sheep industry. The purpose of this study was to explore the non-genetic factors affecting the reproductive traits of Tianmu multiparous sheep and their genetic parameters. In this study,the reproductive performance records of 5335 Tianmu multiparous sheep from 2014 to 2022 were collected from Zhejiang Sino Ecological Agriculture Co.,Ltd.,including litter size at birth (LSB),litter mean weight per lamb born (LMWLB),total litter weight at birth (TLWB) and litter survival lamb numbers (LSLN). SAS 8.1 and DMU softwares were used to analyze the effects of non-genetic factors on reproductive traits,estimate genetic parameters and breeding values,and further analyze genetic trends and phenotypic trends. The results showed that birth parity,year of lambing and type of lambing had extremely significant effects on all traits (P<0.01). The direct heritability estimates of LSB,LMWLB,TLWB and LSLN were 0.016,0.063,0.049 and 0.034,respectively,indicating that these were low heritability traits. The LSB was negatively correlated with LMWLB both genetically and phenotypically. The genetic correlation between LMWLB and LSLN was positive,but their phenotypic correlation was negative. The genetic and phenotypic correlations of the remaining traits were both positive. The average breeding value of LSB first increased and then decreased,and the average phenotypic value showed an overall upward trend. The average breeding values of LMWLB and TLWB first decreased and then increased,and the average phenotypic value first increased and then decreased. The average breeding value and average phenotypic value of LSLN first increased and then decreased. This study has laid a foundation for the genetic improvement of reproductive traits of Tianmu multiparous sheep,and also provided guidance for breeding work.
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