A Comparative Study on the Usage of USA and CHN Holstein Bulls in Tianjin
This study investigated the usage of USA and CHN Holstein Bulls based on the 2022 DHI data of Tianjin,and compared the production performance of descendants of USA and CHN Holstein bulls.The relationship between Total Performance Index/General Lifetime Profit Index(TPI/GTPI)and offspring performance of Bulls was analyzed by one-way Anova.The results showed that USA and CHN were the main sources of frozen bull essence in Tianjin area.There were 455 bulls from USA and 444 bulls from CHN,there were 1543 heirs and 11019 daughters of USA bulls,however,1335 heirs and 16910 daughters of CHN bulls.The production performance measurement data of USA descendants show that the average daily milk yield of USA descendant was 0.78%higher than that of CHN descendant,the milk fat rate was 0.81%lower than that of CHN descendant(P<0.05),the somatic cell number was 0.86%higher than that of CHN descendant,the 305d milk yield of USA descendant was 0.21%higher than that of CHN descendant,the 305d milk fat amount and 305 milk protein amount were 0.55%,1.03%higher than those of CHN descendants,respectively.The TPI/GTPI of USA breeding bulls was graded and compared with the production performance of the progeny.The results showed that the production performance indexes of bull offspring in grade 3 TPI level were higher than those in grade 2,and there were significant differences in daily milk,305 milk,305 milk fat and 305 milk protein(P<0.05).The daily milk and 305 milk of the offspring of the 3rd grade GTPI horizontal species were higher than those of the 1st grade,and the 1st grade was higher than that of the 2nd grade,and the difference between the 3rd grade and the 2nd grade was significant(P<0.05),and the milk fat and protein of 305 milk decreased from the 3rd grade to the 2nd grade,and the difference was not significant(P>0.05).Conclusion:USA and CHN Holstein bulls are the most used breeding bulls in Tianjin pasture.The number of offspring of CHN Bulls is lower than that of USA bulls,and the number of daughters is higher than that of USA Bulls.The production performance of offspring of CHN and USA bulls was similar.Various indicators of descent were not positively correlated with TPI/GTPI levels of bulls.Through the above analysis,it is suggested that dairy farms should pay more attention to domestic breeds of bull frozen essence in the future and avoid choosing imported bulls with high TPI/GTPI blindly.
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