Efficiency of two timed artificial insemination protocols in Murrah buffaloes managed under a semi-intensive system in the tropics
2010
Oropeza, Armando José | Rojas, Angel F. | Velazquez, Miguel A | Muro, Juan D | Márquez, Ysabel C | Vilanova, Lourdes T
The objective of the study was to determine the efficiency of ovsynch (OV) versus presynch-ovsynch (P-OV) protocol for synchronization of ovulation and timed artificial insemination (TAI) in female buffaloes. The OV group (n = 40) received gonadotrophin-releasing hormone (GnRH) on day 0 (random day of the estrous cycle), prostaglandin [graphic removed] on day 7 and a second GnRH administration on day 9 followed by a single artificial insemination (AI) 16-20 h later. The P-OV group (n = 40) received two [graphic removed] injections 14 days apart, with the second injection administered 14 days before starting the OV protocol. Progesterone (P₄) was measured at the time of [graphic removed] administration (within the OV protocol) and AI. Neither ovulation rate ((24 h after TAI) OV 90%-36/40 vs. P-OV 85%-34/40) nor pregnancy rates ((day 60 after TAI) OV 35%-14/40 vs. P-OV 45%-18/40) differed between the two protocols. Pregnant buffaloes had lower concentrations of P₄ at AI compared with non-pregnant animals in the OV group (0.7 ± 0.1 vs. 1.1 ± 0.1 ng/ml); but in the P-OV group, differences did not reach statistical significance (0.8 ± 0.1 vs. 1.0 ± 0.1 ng/ml). This apparent trend reached statistical significance when the analysis was carried out in animals from both protocols (0.7 ± 0.1 (pregnant) vs. 1.1 ± 0.1 (non-pregnant) ng/ml). In conclusion, both protocols synchronize ovulation effectively with no significant differences in conception rates. High concentrations of P₄ at AI seem to be detrimental for the establishment of pregnancy in lactating buffalo cows.
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