NON-GENETIC FACTORS AFFECTING FERTILITY TRAITS IN SOUTH AFRICAN HOLSTEIN COWS

Discipline: reproduction;

Profitable milk production and genetic improvement in dairy herds depend largely on fertile cows calving annually to initiate a new lactation period. Over the last 30 years, several studies have indicated a decline in the reproductive performance of dairy cows. From the perspectives of many farmers and veterinarians, the reproductive performance of cows is related to the calving interval and services per conception. Using these traits as cow fertility indicators is problematic as calving interval is dependent on subsequent calving dates, while services per conception is strongly linked to inseminator proficiency.

Cow fertility refers to the ability of cows to come into oestrus soon after calving, to conceive from a minimum number of services, and to stay pregnant until the next calving. In this paper, non-genetic factors affecting fertility traits other than calving interval in Holstein cows are discussed. Some 69 200 service records and pregnancy check results of 9 050 cows in 14 commercial herds were available for analysis. The fertility traits studied were: calving to first insemination, interval from calving to conception (days open), services per conception, proportion of first service occurring within 80 days after calving, and the proportion of cows being confirmed pregnant within 100 days or 200 days respectively. The means (± standard deviation) for the interval traits, namely calving to first insemination and the interval from calving to conception were 77 ± 30 and 134 ± 74 days respectively, whereas the number of services per conception was 2.55 ± 1.79. The proportion of first services occurring within 80 days after calving and the proportion of cows being confirmed pregnant within 100 days and 200 days after calving were 0.64 ± 0.48, 0.36 ± 0.48 and 0.71 ± 0.45 respectively. Whereas lactation number, calving year and calving season affected reproduction traits significantly, herds (management) had the largest effect; which points to the efficacy of the farmer or manager to manage the herd.

Reference:

Muller, C.J.C., Potgieter, J.P., Cloete, S.W.P. & Dzama, K., 2014. Non-genetic factors affecting fertility traits in South African Holstein cows. S. Afr. J. Anim. Sci. 44, 54-63.