Comparative Study on the Growth and Development Trait of Poll Dorset and Smalltail Han Sheep Improved with Borderdale

[Objective] The optimum crossing parent of sheep was experimented for elite sheep breeding.[Method] The hybrid offspring(F1,F2 and F3) from the combination between the Poll Dorset sheep introduced,Borderdale and the local Tan sheep and Small-tail Han sheep,respectively,being taken as experimental material,the growth and development index such as the body weigh and length at different ages of the sheep hybrids in the partial population of bred mutton sheep in northwestern China was measured with the random sampling method.[Results] The results showed that the growth and development of F3 were faster than these of F2 and the growth and development of F2 were superior to these of F1.The improvement effect from the combination among DBH was superior to DH,the combination between DH was superior to DTH and the improvement of Small-tail Han sheep from three combinations was good,especially for higher economic benefit from significant high generation or three-crossbreed.[Conclusion] Therefore,it was feasible to breed the population of mutton sheep through the fixed crossing between ideal F2 and F3 hybrids.