Estrus Response of Boran and Boran-Holstein Crossed Cattle to Pgf2α and Pregnancy Rates to Sexed and Conventional Semen, Holeta, Ethiopia

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The study was conducted majorly to evaluate pregnancy rate to sex sorted semen and high grade non sex sorted imported semen in a 2X2 factorial design in Boran and Boran X Holstein cross cows and heifers. The effect of some animal related factors which may affect pregnancy rate and heat characteristics of different breeds and party were evaluated. A total of 71cows/heifers consisting of 36 Boran and 35 Boran x Holstein of which 49 were cows and 22 heifers were purposively selected and synchronized using PGF2, twenty five Boran (69.4%) and twenty seven Boran x Holstein cross (77.1) were responded to PGF2 and exhibited estrus. When response to PGF2 was compared by parity, 65.3% cows (n=32) and 90.9% heifers (n=20) exhibited estrus. Parity has statistically significant (P<0.05) effect on estrus response in which heifers showed higher response rate than cows whereas, breeds, body condition score and treatment (response at single or double PGF2) did not show significant effects on estrus response (P>0.05). Average duration of estrus was significantly longer in Boran x Holstein cross breed than Boran breed. However, average interval to onset of estrus and duration of standing estrus were not significant differ (P>0.05) by both breed and parity. A multivariable logistic regression model including the breed, parity, body condition score, treatment, semen type and their interactions was evaluated. Parity and semen type showed significant variation (P<0.05) on the pregnancy rate. On pregnancy detection, 54.1% Boran and 57.6% cross breed cattle were found pregnant of which 46.8% were cows and 72.2% were heifers to both types of semen. The pregnancy rate was 66.6% to conventional semen and 46.1% to sexed semen. It could be concluded that sexed semen could be a better option to improve number of replacement heifers. Similarly, high grade imported semen may help speeding up genetic improvement when used on Boran heifers. However, data from large number of animals should better be generated. Heifers were well responded to than cows; duration of estrus was longer in Boran breeds than crossbred and heifers was higher conception rates than cows.



Boran, Cross breed, Estrus response, Ethiopia, Pregnancy rate, PGF2, sexed semen