Estimation Genetic Trend For Reproductive Traits in Holstein Heifers Inseminated With Sex-Sorted Semen

Background and aim: nowadays, the use of sex-sorted semen is more commonplace in industrial dairy farms. the objective of this study was to estimate the genetic trends as well as the heritability open days, days from calving to first insemination, and conception rate. data were included the reproductive performance of 64070 heifers collected during 2007-2017 from 10 industrial farms with various sizes. evaluated reproductive traits were conception rate, days open, and days from calving to the first service (dfs) in heifers inseminated with various semen types. quality control and calculation of descriptive statistics for all traits were performed using foxpro 9.1 software and sas program. animal breeding values were predicted through a single-trait animal model by dmu software. the genetic and phenotypic trends were estimated using the regression procedure (proc reg) in the sas package. the genetic trend was plotted using excel software. the estimated heritability of open days, dfs, and conception rate were 0.051, 0.03, and 0.028 in conventional semen and 0.063, 0.03, and 0.028 for sex-sorted semen respectively. estimated genetic trend for days open, dfs, and conception rate traits were desirable and significant (p<0.05).methods: all procedures were carried out by the science and research branch, islamic azad university, tehran, iran guidelines for animal handling, and the project was approved by the ethics committee of science and research branch, islamic azad university, tehran, iran. data were collected from a record registration unit in herds from january 2008 to december 2017 on 64070 heifers record reared in ten commercial farms in isfahan province (32.6539° n, 51.6660°). quality control and calculation of descriptive statistics for all traits were performed using foxpro 9.1 software and sas program. animal breeding values were predicted through a single-trait animal model by dmu software. the genetic and phenotypic trends were estimated using the regression procedure (proc reg) in the sas package. the genetic trend was plotted using excel software.results: the result illustrated that using sex-sorted semen dramatically improved the open days and dfs. although the trend of open days and dfs decreased from 2008 to 2017 in sex-sorted semen was better than conventional semen. ebv for sex-sorted semen in 2007 was 6.9 and 2017 has been 2.9. the estimated heritability of open days, dfs, and conception rate were 0.051, 0.03, and 0.028 in conventional semen and 0.063, 0.03, and 0.028 for sex-sorted semen respectively. the genetic trend for days open, dfs, and conception rate were 5.4.3.17 and 0.003 in conventional semen and for sex-sorted semen were 4.81, 2.65, and 0.056 respectively.conclusion: the result of the study revealed that utilizing sex-sorted semen can drastically decline reproductive disorders. however, conventional semen, as expected, showed a higher conception rate compared to the sexed semen. indeed, by facilitating reproductive management and using qualified and efficient insemination inspectors we can enhance the conception rate of sex sorted semen. the result showed that genetic trend of reproductive traits in both semen types has improved for example, conception rate in sex-sorted semen is better than past in sex-sorted semen. investigating the genetic trend chart of reproductive trend showed that breeding programs has been effective. however more studies need to be performed to prove this hypothesis.