Abstract: The aim of this study was determined the effect of suckling of the calf restricted to once a day per 30 min plus a combined hormonal treatment on the postpartum anestrous period and fertility in beef cows after 120 days postpartum. About 67 Bos taurus x Bos indicus crossbred multiparous pregnant cows were used and randomly distributed to five treatments: traditional suckling (TS; n = 15), calf stayed all day with the dam; restricted suckling (RS; n = 14), calf sucked the cow once a day per 30 min beginning day 7 postpartum; TS plus a combined hormonal treatment (TSH; n = 15), applied at day 50 postpartum, consisting in GnRH+Norgestomet for 7 days+PGF2α (day 0)+GnRH (day 2); RS plus hormonal treatment (RSH; n = 16) as described in group 3 and without suckling (WS; n = 7) which included cows with death calves before day 7 postpartum. There was an increase (p≥0.001) in the ovarian activity of cows in the RS and RSH treatment compared to TS and TSH group cows (78.6 and 87.5 vs. 26.7 and 46.7%, respectively). Calving-first ovulation interval for WS cows was shorter (p≤0.001) than intervals for RSH, RS, TSH and TS cows (22.3 vs. 49.3, 68.8, 63.5 and 86.3 days, respectively). Likewise, the calving-first ovulation interval was shorter for RSH (p≤0.01) vs. TSH and TS. Cows in RS and RSH treatments were more fertile (p≤0.001) than those from TS and TSH groups (42.3 and 56.3 vs. 20.0 and 6.6%, respectively). The WS cows (71.4%) had higher fertility (p≤0.001) than cows from all other combined treatments (31.6%). No differences were found between treatments (p>0.05) regarding the incidence of corpora lutea of short half-life. In conclusion, suckling restricted to 30 min reduced the resumption period of ovarian activity in beef cows in the tropics of Mexico. Double dose of GnRH plus Norgestomet and PGF2α induced fertile ovulations after 50 days postpartum in restricted suckling cows.
F. Escobedo-Amezcua, J. Herrera-Camacho, M.G.J. Nuncio-Ochoa, J.C. Segura-Correa, J. Gallegos-Sanchez and M.A. Marin-Aguilar, 2011. Restricted Suckling and Hormonal Treatment on the Postpartum Ovarian Activity Resumption of Beef Cows in the Tropics of Mexico. Journal of Animal and Veterinary Advances, 10: 195-199.