Efficiency of two timed artificial insemination protocols in Murrah buffaloes managed under a semi-intensive system in the tropics

Oropeza, Armando José, Rojas, Angel F., Velazquez, Miguel A., Muro, Juan D., Márquez, Ysabel C. and Vilanova, Lourdes T. (2010) Efficiency of two timed artificial insemination protocols in Murrah buffaloes managed under a semi-intensive system in the tropics. Tropical Animal Health and Production, 42 (6), 1149-1154. (doi:10.1007/s11250-010-9539-9). (PMID:20358403)

Abstract

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 PGF?? 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 PGF?? injections 14 days apart, with the second injection administered 14 days before starting the OV protocol. Progesterone (P(4)) was measured at the time of PGF?? 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 P(4) 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 P(4) at AI seem to be detrimental for the establishment of pregnancy in lactating buffalo cows.

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