Effect of once-daily suckling on postpartum reproduction in zebu-cross cows in the tropics

A trial was conducted in the tropical area of Mexico. Eighty-nine multiparous zebu-cross lactating cows were assigned by calving date and body condition to either of the following treatments: (1) no suckling manipulation (control; n = 44); (2) once-daily suckling (n = 45). The suckling manipulation period began at 30 days post calving and lasted 30 days; thereafter, calves continued to nurse their dams until weaning (8 months old) without any supplemental creep feed. Both groups were maintained on pasture for a 90 day breeding period (May–July) with semen-tested bulls. The data were analyzed using a linear model procedure. The average calving-conception interval was not affected by treatment (83 ± 8 vs. 78 ± 8 days for control and treated groups respectively); however, the pregnancy rate at 60 days and 90 days of the breeding period was significantly greater (P < 0.05) for the treated group than for the control group (81% and 90% vs. 59% and 72%, respectively). The average daily gain for calves and also the weaning weights were not affected by treatment (P > 0.05). It was concluded that once-daily suckling did increase the pregnancy rates of zebu-cross cows without depressing the growth performance of the calf.