2001, Number 2
Vet Mex 2001; 32 (2)
Influence of body condition and biostimulation on the reproductive efficiency in Simmental beef cows grazing
Madrigal AMA, Colín NJ, Hallford DM
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ABSTRACTThis experiment was conducted to evaluate the effect of body condition (BC) and biostimulation with bulls over the reproductive efficiency through the anoestrus postpartum interval, and rate of pregnancy due to matting at synchronised oestrus with progestogens (SMB). Seventy-three Simmental uni or pluriparous grazing beef cows were randomly assigned to treatments. Factorial arrangement 2 ´ 2 with covariate was applied. Factors included were high or low body condition (HBC or LBC), and with or without bull (B or O) biostimulation. Treatments (t) were: t1, HBC-B; t2, HBC-O; t3, LBC-B, and t4, LBC-O. Progesterone (P4) in blood serum samples was analysed by RIA to detect ovarian cyclical activity. On the other hand, ovaries were palpated to detect postpartum first corpus luteum (CL). Ovarian cyclical activity started on weeks 6, 8, 11 and 15 postpartum (P ‹ 0.01), respectively for t1 to t4. Rates of pregnancy with AI were 46% and 24% (P ‹ 0.05) for cows HBC and LBC, respectively, and 46% and 25% (P ‹ 0.05) for cows B and O, respectively. Rates of pregnancy due to AI service were 63%, 30%, 28 and 19% (P ‹ 0.05) for t1 to t4, respectively. Pregnancy at the end the mating season were 84%, 70%, 61% and 44% (P ‹ 0.05) for t1 to t4, respectively. In conclusion, anoestrus postpartum interval could be reduced in cows with BC ‹ 5.5, and biostimulated pursuing “bull effect” immediately after parturition. Rate of pregnancy could be improved through the body condition and/or bull stimulation, and oestrus synchronisation in an AI program.