Abstract
In buffalo industry artificial insemination is being used in breeding programs of our country . It has limitations such us seasonality, difficult estrus detection and low pregnancy rates when compared with cattle. IATF programs using a single insemination show results from 10 to 50% pregnancy rate, little information is available about minimum requirements of spermatozoa for IA. The aim of this paper is to compare the pregnancy rates after using narual mating or frozen semen in a sincronization of ovulation program. This work were conducted in Pueblo Nuevo Cordoba Colombia in August during the breeding season of 2005-6. 99 multiparous crossbred females were used with 50 to 150 postpartum days. Body score condition of 3,5 to 4. All animals were palpated to exclude anatomical alterations. Ovsynch protocol for IATF reported by Baruselli (2000), they were allocated in two groups: Buffalo group, after the last GnRH analog injection 17 females were allocated with 5 bulls, and IATF Group 82 females were inseminated 16 hours later. The semen of 7 different buffalo bulls were used and evaluated and qualified as normal. Inseminations were performed by 3 different technicians. A blood sample was obtained 20 days after IA to determine pregnancy by determinations of P4 levels using chemiluminiscence, ≥1ng/ml were used as cut off value to determine pregnancy. Data were compared using Chi square test. 70% (12/17) females of the bull group and 29% (24/82) of IATF group were diagnosed us pregnant using P4, this difference were statistically significant (P≤0.001). Buffalo bulls mount all females. No statistical differences were found in pregnancy rates of the bulls used for IATF, from 12% to 37 %, one exceptional bull obtain 71%. As expected bulls have higher pregnancy rates than artificial insemination, the results obtained here allow researchers to evaluated semen quality, specially density to improve results IATF in buffaloes.
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