| In this study,the body measurement data and semen production data of the Holstein bulls of the Shandong OX Animals Co.,Ltd.were used to analyze the environmental factors affecting the semen production traits of the bulls,and estimate the genetic parameters of body size and semen production of various bulls.It provides certain theoretical guidance for breeding excellent breed bulls and improvement of the semen production in production practice.1.Using the 27888 semen production data of 297 Holstein bulls in 2009-2017,the four factors(year,season,age and the semen collection interval)that may affect the quality of the bull semen were analyzed by SAS software GLM program.The results showed that year,age,and the interval of semen collection were significantly related to ejaculation,semen concentration,sperm motility,post-freezing motility,percentage of abnormal sperm,total number of sperm per and total number of live sperm per ejaculation(P<0.01).The season had significant effects on four semen traits except for ejaculation,percentage of abnormal sperm and post-freezing motility(P<0.01).2.Using the 3026 body measurement data of 300 Holstein bulls in 2009-2017,the variance analysis was carried out,and the growth curves were drawn to reveal the growth and development rules.The study found that body weight,armor height,body length,chest circumference,abdominal circumference,tube circumference,iliac width,cross height and scrotal circumference reached their peak of growth at 40,22,24,30,20,25,20,25 and 20 months of age respectively,and later became flat.3.Using the body measurement data and semen production data of 270 Holstein bulls,the genetic parameters of growth traits and semen production traits were estimated using DMU software and animal model BLUP method.The results showed that the heritability of body weight,armor height,body length,chest circumference,abdominal circumference,tube circumference,iliac width,hip height and scrotal circumference were 0.76,0.80,0.41,0.43,0.61,0.48,0.29,0.71 and 0.60,respectively,belonging to medium to height heritability.The heritability of ejaculation volume,concentration,motility,post-freezing motility,deformity rate,total sperm count and total live sperm count per ejaculation were 0.63,0.55,0.36,0.24,0.33,0.49 and 0.51,respectively,belonging to medium to height heritability.The genetic correlation between growth traits and semen production traits was from-0.19 to 0.40,and the phenotype correlation was from-0.09 to 0.25.The genetic correlation of armor height,body length,scrotal circumference with total number of sperm per ejaculation were 0.21,0.35,and 0.41,respectively;with total number of live sperm per ejaculation were 0.22,0.35,and 0.40,respectively,which were highly genetically related.In summary,we should pay attention to the impact of the age of the bull and the interval of semen collection on the quality of semen,in the actual production.In the appropriate age of the bull and control the interval of semen collection,high semen production can be obtained.The heritability of growth traits and semen production traits in Holstein bull were medium to high,and some growth traits such as scrotal circumference are highly genetically related to semen production traits,it was feasible to genetically select high-sperm production of bulls in theory. |
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