Articles | Volume 59, issue 2
Original study
19 May 2016
Original study |  | 19 May 2016

Genetic parameters of reproductive traits in Tunisian Holsteins

Hafedh Ben Zaabza, Abderrahmen Ben Gara, Hedi Hammami, Borni Jemmali, Mohamed Amine Ferchichi, and Boulbaba Rekik

Abstract. Multi-trait Bayesian procedure was used to estimate genetic parameters for reproductive traits in Tunisian Holstein cows. A total of 31 348 lactations of the calving years 2005 to 2012 were analyzed. Fertility traits were the calving interval (CI), days open (DO), days to first insemination (DFI), days from first insemination to conception (FIC), and number of inseminations per conception (NI). Posterior means of heritabilities of CI, DO, DFI, FIC, and NI were 0.047, 0.03, 0.025, 0.024, and 0.069, respectively. Posterior means of repeatabilities of the same respective traits were 0.106, 0.094, 0.051, 0.036, and 0.17. Genetic correlations among female fertility traits were also computed. Calving interval and DO had the highest genetic correlation estimate (0.85) because they have overlapping genetic meanings. The lowest genetic correlation estimate (−0.25) was found between DFI and NI. Genetic parameter estimates are low and are even lower than those reported in most literature, implying that more focus should be put upon improving the management of reproduction in dairy cattle herds in Tunisia.

Short summary
Genetic parameters for 11 456 Tunisian Holstein cows were estimated for the following five reproductive traits: calving interval (CI), calving to first service interval, calving to conception interval (CCI), first service to conception interval and number of services per conception. Low heritabilities were estimated for these traits, and genetic correlation estimates between them were moderately high. The CCI–CI genetic correlation was 0.85, indicating that they are the same trait genetically.