Studies Of Adjustment Factors For Standardizing Milking Records And Genetic Evaluation Using Animal Model BLUP In Xinjiang Brown Cattle

According to 17962 test-day records of 751 Xinjiang Brown Catties in 4014 location periods from Urumqi between July,1985 and Aug,2008,location curves were fitted to five models(Wood's incomplete gamma function,inverse polynomial model,polynomial regression models(sextic),Schaeffer model and Wilmink model),Parameters of the five mathematics model were estimated by the nonlinear(NLIN) procedure,SAS software.The fittest model was selected by the following three criteria:the highest of R~2,the least of residual sum of squares(RSS) and the least of standardized estimated error(SEE),then cumulative 305-day milk yield were eatimated with the fittest model,and we had formulated adjustment factor of standardizing 305-day milk yield for different parities.Furthermore,we calculated also corrected all milking record those DIM were higher than 90 days to 305-day.Besides correction milk yield,this paper had also analyzed five non-genetic factors(year,season,parity,first calving age and calving interval) react on milk production by use of variance analysis procedure of disequilibrium design in SAS software,and divided the fixed effect according to each factor's difference of significant.Variance composition,heritability, repeatability of 305-day milk yield and calving interval were estimated using animal model of single trait repeated observations,and fixed effect sizes,inbreeding coefficient,and breeding value(305-day milk yield,fat percentage,protein ratio and type score) were estimated using BLUP animal model by the MTDFREML program.We have also calculated the total performance index of Xinjiang brown cattle according to the breeding value of each trait,and constructed a nucleus herd with cow in herd.The results obtained are summarized as follows:The degree of fitting R2 in five models was in range of 0.8340-0.9214,Difference was in five models with different parities.The most combination is Model(2)>Model(4)>Model(1)>Model(5)>Model(3).Inverse polynomial model is sure to the best fitting model of milking curves in this study,and lactation curves with different parity were draw up.Cumulated milking yield was estimated and correction index of DIM with different parities were adjusted according to the inverse polynomial model,we had calculated the corrected milking yield of all the individuals between 90 and 305 days.The results suggested that year,calving season,parity,calving interval and first calving age were dissimilar influence factors for 305-day milk yield,and year,parity,calving interval had highly significant(P<0.01) for milk production.With the growth of parity,milk production was increased continuously,and peaking production was appeared in the fifth parity,and then gradually declined.There has a minimum milk yield when calving interval was under 330-day,and milk production increased with the extended of calving interval,production was peaking when days in milk is 360-420.Winter was Favorite for improving milk production,and cows in summer had lower production.Milking production was better than other months when first calving age was 24-33.Heritability of 305-day milk yield and calving interval were 0.35,0.02,respectively,and repeatability were 0.36,0.06, respectively,inbreeding coefficient of herd is 0.006819,The first five bulls arrayed by TPI were 120,435,232,274,867,TPI was 2227.0,1821.8,1564.2,1238.9,1001.6,respectively,The cow arrayed first ten were 20028126,20058010,20058182, 20048202,20048139,20028039,20048183,20038138,20038048,20048201,and their TPI was 2699.6,2411.1,1956.4, 1953.4,1764.9,1763.5,1755.3,1706.6,1703.6,1698.9,respectively.75 dairy(TPI >550,and 305-day milk yield >4500kg) were selected to set up nucleus herd.The means of milk yield,fat percentage,protein ratio and type score,and TPI were 344.5,0.1935,0.1043,0.045,1082,respectively.