Pregnancy Rates in Horro and Holstein-Horro Cross-Breed Cattle Breeds Following AI With Sexed Semen Under the Smallholder Farming System in Central Ethiopia.

Abstract

This study aimed to evaluate the pregnancy rate achieved with sexed semen (SS) in Horro and Holstein-Horro cross-breed cattle under a smallholder farming system in Central Ethiopia. 120 cows and heifers (60 Horro and 60 Holstein-Horro cross-breed) were enrolled in the study. Selection criteria included parity, body condition score (BCS), and pregnancy status of the animals. To synchronize estrus, all selected animals received a single injection of prostaglandin (PGF2α). Estrus signs were monitored to assess heat response and the time to estrus induction in the treated animals. The responded animals were then randomly inseminated with either SS or conventional semen (CS). The conception rate was calculated based on the number of animals that exhibited estrus, were inseminated, and subsequently conceived. Data analysis was conducted using SAS (Version 9.4). Estrus response and conception rate data were analyzed using logistic regression while the interval to estrus was analyzed using a general linear model. Out of the 120 synchronized animals, 44 Horro and 52 Holstein-Horro cross-breed cows and heifers responded to PGF2α, resulting in an estrus response rate of 80%. Body condition and parity significantly influenced estrus response (p < 0.05). The breed had a significant effect (p < 0.05) on the interval from PGF2α injection to the onset of estrus, while parity and BCS did not show significant effects. Upon pregnancy detection, 56.8% of Horro and 63.5% of Holstein-Horro cross-breed cows and heifers were found to be pregnant; among these, 65.1% were cows and 56.6% were heifers across both semen types. The type of semen used had a significant impact on the pregnancy rate (p < 0.05), with a pregnancy rate of 72.9% for CS compared to 47.9% for SS. Overall, the pregnancy rate of 47.9% achieved with SS is promising and exceeds the national pregnancy rate for first inseminations using CS, which ranges from 7.14% to 40.23%.