Facteurs de variation des performances de la reproduction chez la vache laitière.

Abstract

Our work was carried out at the level of 12 farms located in 3 willayas of eastern Algeria (Bejaïa, Constantine, Sétif). The study was carried out over 10 campaigns from 2005 to 2015 and focused on a workforce of 493 cows. The aim is to quantify reproductive performance and to study the effect of certain variation factors on the fertility and fecundity of cows. The results of the reproduction results obtained vary from year to year and from one farm to another. Fertility was optimal in eight out of ten farms with an IFT varying between 1.30 and 1.80 and a first serving success rate between 43 and 79%. The infertility observed during our study resulted in calving-first service intervals exceeding standards, in fact the average calving-first service interval ranges from 50 to 164 days. The same is true for the calving-fertilization interval, the average varies from 78 to 144 days. Mean values of 367 and 456 days were noted for the calving interval. The results of the analysis of the effect of influencing factors showed that, breed had a significant effect on cow performance. Indeed, the local breed had better fertility performance compared to the Montbéliard, the calving interval is respectively (374 ± 47 days vs 454 ± 87 days). While other variables such as, age, lactation rank of cows showed no significant effect. The effect of the policy of the first insemination is marked by a maximum fertility of the cows in spring, expressed by an excellent success rate (TR1 = 72% ± 20), while it is low in winter (37% ± 23 ). Likewise, the success rate was better with matings performed between 70 and 90 days postpartum (TR1 = 67% ± 23), a strong correlation between the calving-first service interval and the success rate has been proven (r = 0.74).