A comparison of 1- and 2-cell ova production by F2 50% Meishan versus F1 White line gilts
1993
Martin, M.J. | Merriman, C. | Freeman, B. | Merriman, J. | Keirns, J. | Pumfrey, R.A.
The objective of this study was to compare recovery of pronuclear and 2-cell ova from F2 50% Meishan (MX) gilts versus F1 White line (L42) gilts. Sexually mature MX and L42 gilts were allocated across 2 treatments: Super (MX:n = 9; L42:n = 10) and Control (MX:n = 6; L42:n = s) in a 2 X 2 factorial experiment. Allyl trenbolone (AT) was used to synchronize estrus in all gilts. Super gilts were given pregnant mare serum gonadotropin (PMSG: 1250 IU) at 24 h after AT withdrawal. Eighty-five hours after PMSG administration, all Super gilts received 750 IU of human chorionic gonadotropin (hCG). Super gilts which exhibited estrus within 24 h of hCG administration MX-Super: n = 6; L42-Super: n = 5) and all Control gilts were bred naturally to Line 3 boars at 12 and 24 hours after the onset of estrus. Ova were recovered from Super gifts between 60 and 64 h after hCG and Control gilts at 48 h after the onset of estrus. All 1- and 2-cell ova were centrifuged at 15000 X g and observed using differential interference contrast microscopy. The mean ovulation rate was greater (P < 0.05) for both MX-Super and L42-Super gilts in comparison to their respective Control groups. No differences were detected in the mean ovulation rate (P > 0.38) or the mean number of 1 - and 2-cell ova recovered (P > O.50) between MX-Super and L42-Super gilts. The proportion of 1 - and 2-cell ova which exhibited visible pronuclei or nuclei was also similar among MX-SUPER and L42-SUPER gilts. This study demonstrates that MX gilts respond/perform comparably to L42 gilts with respect to estrus synchronization, superovulation, ova yield, and the ease of visibility of pronuclei or nuclei in the ova.
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