RESUMO
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)
Assuntos
Animais , Bovinos , Estradiol/análise , Fertilidade/fisiologia , Estro/metabolismo , Bovinos/metabolismo , Inseminação Artificial/veterináriaRESUMO
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 2.5 (60.1 and 36.4 %, respectively) compared to those with 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.
Assuntos
Animais , Bovinos , Estradiol/análise , Estro/metabolismo , Fertilidade/fisiologia , Bovinos/metabolismo , Inseminação Artificial/veterináriaRESUMO
A total of 586 Awassi ewes of varying ages were mated to 11 Jordanian and 11 Syrian Awassi rams either naturally or artificially during the normal breeding season to evaluate reproductive performance of Awassi sheep and compare the local Awassi rams toSyrian rams. The length of the estrous cycle was longer (P < 0.01) during June to July (28.6 + 0.9 d) than August to September (17.8 + 0.7 d). Syrian-sired matings resulted in a greater lambing rate to the first mating within breeding season than Jordanian-sired matings (P < 0.05), but not for the second, third, or fourth mating. The cumulative lambing rate after the fourth mating tended to be greater (P < 0.1) using Jordanian compared to Syrian sires. The number of single lambs per ewe lambing was significantly (P < 0.001) greater than multiple births. Birth, weaning, and marketing weights and average daily gain before weaning were significantly greater in single (P < 0.001) and male-lamb (P < 0.05) pregnancies than in twins and females. An increase (P < 0.01) in the average daily gain during the lambing season was observed in November and December compared to January, February, or March. The overall mortality rate was 21%, and there was a decrease (P < 0.001) from 1 to 3 yr of age and an increase (P < 0.01) from November to March. Jordanian and Syrian rams yielded similar reproductive characteristics except for the lambing rate of first mating. Lambs born early in the season had better (P < 0.01) average daily gain and lower (P < 0.001) mortality than those born later.(AU)
Assuntos
Animais , Reprodução , Caracteres Sexuais , Inseminação Artificial/métodos , Ovinos/classificaçãoRESUMO
A total of 586 Awassi ewes of varying ages were mated to 11 Jordanian and 11 Syrian Awassi rams either naturally or artificially during the normal breeding season to evaluate reproductive performance of Awassi sheep and compare the local Awassi rams toSyrian rams. The length of the estrous cycle was longer (P < 0.01) during June to July (28.6 + 0.9 d) than August to September (17.8 + 0.7 d). Syrian-sired matings resulted in a greater lambing rate to the first mating within breeding season than Jordanian-sired matings (P < 0.05), but not for the second, third, or fourth mating. The cumulative lambing rate after the fourth mating tended to be greater (P < 0.1) using Jordanian compared to Syrian sires. The number of single lambs per ewe lambing was significantly (P < 0.001) greater than multiple births. Birth, weaning, and marketing weights and average daily gain before weaning were significantly greater in single (P < 0.001) and male-lamb (P < 0.05) pregnancies than in twins and females. An increase (P < 0.01) in the average daily gain during the lambing season was observed in November and December compared to January, February, or March. The overall mortality rate was 21%, and there was a decrease (P < 0.001) from 1 to 3 yr of age and an increase (P < 0.01) from November to March. Jordanian and Syrian rams yielded similar reproductive characteristics except for the lambing rate of first mating. Lambs born early in the season had better (P < 0.01) average daily gain and lower (P < 0.001) mortality than those born later.