Mating scenarios to reduce the effects of recessive disorders affecting abortion in dairy cattle breeding programs

In this research, two mating schemes for the management of recessive genetic disorders affecting abortion in a dairy cattle population were simulated. The first mating scheme was performed under three different scenarios: 1. The mating of a pair of two carriers of the same lethal haplotype was avoided. 2. It was avoided matings in which the service sires and cow's sire carried the same lethal haplotypes. 3. It was avoided matings in which the service sires and cow's sire or maternal grandsire carried the same lethal haplotypes. In the second mating scheme, matings were done randomly. The mating schemes were developed for 20-year time horizon. Similar genetic trend was observed for lifetime net merit in the three scenarios and the second mating scheme over time. The highest and the lowest cost belonged to the first and third scenario, respectively. In the second mating scheme, on average 22 cases of abortion due to the lethal haplotypes were occurred for an average 2290 matings per year. In the first scenario, no case of abortion resulting from the lethal haplotypes was observed. In the second and third scenario the approximate number of abortions for an average 2290 matings per year was 10 and 4 cases, respectively. The results of this study showed that in the current situation the third scenario with the lowest cost and less animal losses is suitable option for management of recessive disorders affecting abortion in dairy cattle population.