تاثیر جنس گوساله روی صفات تولیدی و عملکردی گاوهای هلشتاین در استان اصفهان

The economic benefit of dairy cattle breeding units is a function of milk production volume, reproductive efficiency and herd health that various environmental and physiological factors such as nutrition, parity and offspring sex can play a role in the incidence of these traits. the main aim of this study was to investigate the effect of calf sex on production, reproductive and udder health traits in Isfahan Holstein cows. The data included 37,038 Holstein cows from the first to fifth lactation period from 13 industrial herds during the years 2005 to 2017. To investigate the effect of calf sex on the production and health traits, the mixed linear model procedure and on the reproduction traits, GLIMMIX procedure of SAS9.4 software were used. The results showed that cows with female calf had higher 305-days of milk (90.7 kg) in compared to cows with male calf (P<0.01). For percentage of 305-d fat and protein and the number of days from calving to first service, the effect of calf sex different was low but significant (P<0.05). However, no significant difference was observed between male and female calves for other traits. According to the results, it seems necessary to consider the effect of calf sex in the genetic evaluation of Isfahan Holstein cows and also cost-benefit analysis of the use of sexed semen in herds. [ABSTRACT FROM AUTHOR]