Periódicos Brasileiros em Medicina Veterinária e Zootecnia

p. 32-39

A comparison of fertility with a Cosynch protocol versus a modified Ovsynch protocol which included estradiol in lactating dairy cows during the summer season in Jordan

Alnimer, M AAlfataftah, A AAbabneh, M M

A total of 332 postpartum (pp) lactating Friesia n cows allocated in two treatment groups at a commercial dairy farm were used to study the effect of a modified Ovsynch protocol supplemented with exogenous estradiol (E2) on fertility in lactating dairy cows during the summer season. All cows were injecte d with gonadotrophin releasing hormone (GnRH), followed 7 d ays later by an injection of prostaglandin (PGF 2 α ). Then cows were randomly assigned to receive GnRH and TAI 72 h after PGF 2 α ( CO - 72; control group) or E2 , GnRH and TAI at 48, 56 and 72 h , respecti vely after PGF2 α (OV - 56+ E2). Estrus response for cows in the OV - 56+E2 ( 59.8 %) group was higher (P < 0.0 5 ) than for cows in the CO - 72 ( 40.2 %) group. Pregnancy per insemination ( P/AI ) at two diagnoses ( days 30 to 35 and confirmed at days 45 to 50 after AI ) w ere similar between the two treatment group s , but were higher ( P < 0.05) for cows that showed estrus (59.8 and 41.2% , respectively ) than for cows that did not show estrus (45.5 and 7.9% , respectively ) . Moreover, P /AI at the two diagnoses were higher (P < 0 .05) for cows with a body condition score (BCS ) >2.5 (60.1 and 36.4 %, respectively) compared to those with BCS < 2.5 (44.3 and 16.5%, respectively). Pregnancy losses were higher (P < 0.05) for cows that did not show estrus (82.6%) or with BCS < 2.5 (62.8%) t han for cows that showed estrus (31.0%) or with a BCS >2.5 (39.5%). No differences were observed in P/AI or pregnancy losses between primiparous and multiparous cows . Results indicate that the OV - 56+ E2 synchronization protocol resulted in a higher expressi on of estrus than the CO - 72 without improving fertility as measured by P /AI and pregnancy losses. However , cows with high BCS had higher estrus expression, pregnancy rates, and lower pregnancy losses than cows with low BCS during the summer season.(AU)

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