Study On The Growth And Development Patterns Of Kazak Sheep And Their Hybrid Offspring

Kazakh sheep are widely distributed in Xinjiang,and they are characterized by large individuals,large amounts of meat fat,and strong limbs.Because of its high carcass fat content,it is mostly used for genetic improvement of varieties.The F1 and F2 generations produced by crossing Texel rams with Kazakh ewes inherited the characteristics of Texel sheep’s daily weight gain,high pupae weight,and strong resistance and adaptability of Kazakh sheep.At the same time,hybrid sheep can significantly improve the shortcomings of Kazakh sheep with large tails and fat accumulation.This study analyzed the non-genetic factors of the birth weight of 2804 Kazak sheep F1 hybrids from February 2016 to May 2019,the growth regularity of Kazakh sheep and their F1 and F2 hybrids in 2016 to 2019 and the eye muscle test results of F1 and F2 generations in 2019 in the horse farm and stud farm of Zhaosu County,Yili Prefecture.(1)The influence of birth type,gender,year of birth and field of non genetic factors on the birth weight of Kazak crossbred F1 hybrids have reached a extremely significant level(P<0.01).The influence of birth type*year of birth,birth type*field,year of birth*field on the birth weight was extremely significant(P<0.01).The interaction effects of birth type*birth gender,birth gender*year of birth,birth gender*field have no significant effect on the birth weight(P>0.05).(2)From birth to weaning identification,the relative growth and absolute growth of Kazak sheep and their F1 and F2 hybrids were relatively higher,and then decreased in varying degrees.The F1 group was significantly higher than the Kazakh sheep among the growth indexes of birth weight,weaning weight,6-month-old weight,9-month-old weight and body steep length,which showed obvious heterosis.The chest width and cross width of Kazak sheep and F1 generation were significantly higher than those of F2 generation.(3)The dorsal fat thickness of F1 generation male and female lambs was higher than that of F2 generation.The coefficients of variation of the eye muscle area in the F1 and F2 generations were higher than the eye muscle depth.The analysis of the non-genetic factors of the birth weight of Kazak sheep F1 hybrids and the growth regularity of Kazakh sheep and their F1 and F2 hybrids provided scientific theoretical basis for genetic improvement of Kazakh sheep.The analysis of in vivo measurement results of eye muscle area and dorsal fat thickness of 6-month-old Kazak sheepx Texel sheep crossbred F1 and F2 generations provided theoretical basis for the selection of excellent individuals and breeding.