Economic and production performance of crossbred F1 Nellore and Angus calves infested with Cochliomyia hominivorax larvae in Amazonic region, Brazil

The aim of this study was to evaluate the economic and production performance of crossbred F1 Nellore and Angus calves infested with Cochliomyia hominivorax larvae in the state of Rondônia, Brazil, and the factors that contributed for the infestation. A total of 134 calves from F1 Nellore-Angus crossings were evaluated; and they were divided into two groups, with and without infestation with C. hominivorax larvae. The variables assessed included body weight at birth and at weaning and factors that contributed to infestations, with results compared based on birth season and intervals between birth and umbilical healing treatment. No significant difference in economic and production losses was found between the groups. Negative economic and production impacts were identified in calves with low body weight at weaning. The birth season significantly affected infestation occurrence, with higher frequency in rainy periods, and increased the incidence of myiases in the umbilicus of calves with longer intervals between birth and umbilicus treatment. Thus, calves infested with C. hominivorax larvae and raised in rural property under extensive system in the state of Rondônia had higher predisposition to reach body weights below the herd average and generate negative economic impacts. The birth season with higher probability of C. hominivorax larvae infestations in calves in the state of Rondônia was between October and April, with a trend of increasing C. hominivorax larvae infestation incidence in the umbilicus of calves with longer interval between birth and umbilicus treatment.