Evaluation of inbreeding trend in dairy cattle with respect to mating system, selection intensity and embryo transfer using stochastic simulation

The effects of mating system, selection intensity and embryo transfer on inbreeding in dairy cattle were studied using stochastic simulation. Two mating systems (random and minimum consistory), two levels of selection intensity (high and low) for four selection paths (young bull, active sire, sire of dam, dam of dam) with or without embryo transfer for bull dams were combined together to make eight scenarios. 5000 cows distributed among 50 herds of size 100 and recorded for 6 traits (milk, fat, and protein production, age at first calving, calving interval, and somatic cell score) for 30 years were simulated. The results showed that minimum coancestry mating and low selection intensity had 60.43 % and 57 % annual changes of inbreeding lower than random mating and high selection intensity, respectively. Annual changes of inbreeding were 21.98 % higher when embryo transfer was used compared with not using it. Minimum and maximum annual change of inbreeding was estimated for eighth scenario (minimum consistory mating- low selection intensity- using embryo transfer) and third scenario (random mating- high selection intensity- no embryo transfer), respectively. The results suggest that high intensity of selection with minimum coancestry mating and embryo transfer can lead to genetic gain with minimum increase in inbreeding.