Abstract

The objective of this study was to measure the relative influence of the animal’s age, body condition score (BCS), glycemia at day of insemination (D₀) and the livestock management system on the probability of conception and occurrence of embryonic mortalities. In this study, 81 inseminated cows both of the Gobra Zebu breed and crossbred were sampled. Blood samples were collected the day of insemination (D₀) and twenty-one (D₂₁) and thirty-five (D₃₅) days after AI. The BCS, the age and the livestock management system were recorded for all animals before the artificial insemination (AI). The glycemia was measured on D₀. Pregnancy diagnosis was performed by progesterone and pregnancy associated glycoprotein assays and transrectal palpation. A multinomial logistic model was used to analyze the effect of the selection criteria for cows on the success rate of AI.

The pregnancy diagnosis makes possible to detect 47% of pregnant cows and 26% of late embryonic mortality (LEM) at D₆₀ post AI. The maximum likelihood test carried out on the model permits to reject the null hypothesis (p < 0.0001) according to which all animals have the same chance of being pregnant (47%). The variables thus provide a significant amount of information to explain the variability in the success rate of AI. The most significant factor was age (p < 0.0001), followed by the BCS, then glycemia and finally the livestock management system (p = 0.047). The BCS is the factor that most explains the variability in pregnant cows. For the group of LEM, age of the animal accounts for variability.

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