Assessing the effects of house fly (Diptera: Muscidae) nuisance activities on cattle feeding behavior by use of a custom feeding box

To date, the economic impact of adult house fly activity on cattle production is limited largely to costs associated with managing house fly populations and treating diseases associated with pathogens they are known to transmit. However, anecdotal evidence suggests that house flies present in and around feed bunks may disrupt normal cattle feeding behavior. Eight angus heifers (∼385 kg) were used in a crossover experimental design to determine the potential effect that adult house fly activity has on cattle feeding behavior. Heifers were acclimated to voluntarily using a custom, standalone box into which their head was enclosed while feeding. The acclimation period was followed by 2 4-d observation periods, during which heifers were offered feeding boxes that were either infested with ∼1,000 adult house flies or were uninfested. During each observation period, heifer behavioral responses were recorded, including tail tosses, skin twitches, foot-stomping, feeding hesitation, as well as the weight of any remaining feed not consumed (grain refusal). Although no significant differences in leg stomping or resultant grain refusal occurred between treatment groups, the frequency of tail tosses, skin twitches, and feeding hesitation was significantly higher when flies were present in feeding boxes than when feeding from uninfested boxes. These findings suggest that house fly activity at the feed bunk causes a level of discomfort among heifers that results in feeding disruption and therefore may account for a previously unrecognized source of economic loss for cattle producers.