Measurement And Analysis Of Milk Yield Of Imported Holstein Cows In Wuhan

In this study,we observed and analyzed the milk yields and its effect factors that affect on milk production of 230 Holstein cows importeded from Australian,Shanghai and Zhejiang province by measuring dairy herd improvement,evaluating their linear type traits and their heredities.1) The resμLts showed,After recording and analyzing the annual milk yields (305days),that the milk yields of cow from different area were significantly different (P＜0.01).Holstein cows from Australia had the highest milk yield,and then from Shanghai,the cows from Zhejiang provided the lowest milk yields,the season had an significant effects on the annual yields(P＜0.01).The cows had the highest annual yield in autumn,then in spring,summer and winter.The difference of milk yield between different seasons was dominant significant(P＜0.01) with no difference between spring and summer,summer and winter.We also found the cows from Shanghai and Zhejiang provided the similar annual milk yields of the first and the second parity.2) According to the average evaluated score of each segment by computer,it had a low score in height and anguLarity(they were 66.95 and 67.74,respectively) and a higher score in other segments which were from 74 to 79.Among these five segments, there was a higher score of 81.05 in hooves and an inferior score of other segment.The overall grade of these segments was fine which had a mean score of 78.35.The breed of Holstein had a tuff hoof,but with the height and the anguLarity that were not optimal. The relationship between all the characters and the milk yields illuminanted were negative,incμLding the rump width,the depth of udder and the milk yield.Thus,it was important to select the rump width and the depth of udder in cow selecting and breeding.3) PCR - RFLP method was used for genotyping of genes.We found three genotypes AA,AB and BB in PIT-1 gene,with the frequencies of genotypes 6.2%,31.6%and 62.2%respectively,the associations between polymorphisms of the PIT-1 gene and milk yield of Holstein cows were carried out,and the resμLts showed that there was significant difference of milk yield in the three genotypes(P＜0.01),the milk yield of cow with AB genotype was higher than that of AA and BB,while genotype BB had a lowest milk yield.