The effect of deworming with ivermectin of cows before calving and of suckling calves on fecal egg counts (EPG) and productive performance of two beef cattle herds in Central Brazil was studied. Four groups of pregnant cows received the following treatments: T1- cows and calves not treated, T2- only calves treated, T3- only cows treated, and T4- cows and calves treated. The calves of T2 and T4 were distributed in the following treatments: A- calves treated at 3 to 5 months of age with long action ivermectin, B- treated with ivermectin, and C- control. For the cows, the deworming did not diminish the EPG during lactation and also did not have significant effect on the conception rate, live weight gain and the body weight of their calves at 3 to 5 months of age. The calves of treatment A gained, from the time of treatment to weaning (84 to 108 days), an average of 4.2kg (P=0.0003) and 7.1kg (P<0.0001) more than those of treatment B and C, respectively. The average difference in live weight gain of 2.9kg between the animals of treatment B and C was not significant. The EPG before treatment was not significantly different from the treatments (P=0.8665); but at weaning, the average EPG of the calves from treatment A was lower than for treatment B (P=0.0004) and C (P<0.0001). There was no significant difference in the mean EPG for the calves from treatment B and C.
Beef cattle; cows; suckling calves; nematodes; treatment; Brazilian savannas