The Effects of Environmental and Management Factors on the Quality of the Corpus Luteum and Subsequent Conception Rates of Beef and Dairy Cows in South Africa.

The corpus luteum (CL) controls the success of pregnancy. The current study investigated the effects of some environmental and management factors on the development of the CL and the subsequent impact on conception rates of beef and dairy cows in South Africa. Cows (Jersey, Holstein, Nguni, Bonsmara, Tuli, Ankole, Charolais and Angus crosses) receiving an embryo were synchronized based on the breed type and status. Standing estrus was observed from day 9 to day 12 after synchronization. Embryo transfer occurred on day 18. CLs were graded based on size and consistency of each CL by an experienced veterinarian. Production type (beef versus dairy types) was marginally associated with conception after the first synchronization cycle (p = 0.065). Cows were moved between groups, and this influenced the CL (p = 0.08). Climatological factors, maximum THI (p = 0.017) and precipitation (p = 0.061) influenced the quality of the CL in dairy cows. By contrast, precipitation (p = 0.067) influenced the quality of CLs in beef cows. More attention needs to be paid to the management of maximum THI and shelter from precipitation in dairy production systems, while precipitation alone was more important in beef cows. Climate affects the corpus luteum quality of cows of different production types differently.