AVERAGE DAILY GAINS OF BRAHMAN-CROSSBRED AND ENGLISH X EXOTIC FEEDER HEIFERS DURING LONG-TERM EXPOSURE TO STABLE FLIES (DIPTERA, MUSCIDAE)

Long-term exposure of Brahman-crossbred and English x Exotic heifers t o a medium (approximate to 14 stable flies per foreleg per minute at 1 600 hours) stable fly, Stomoxys calcitrans (L.), population level caus ed a continuous decline in average daily gains of both breeds from day 1 to day 84 of exposure (that is, from 12 to 14 mo of age). Neither b reed was affected by stable fly feeding from 85 d until 112 d exposure , when heifers were greater than or equal to 15 mo in age. At that age , heifers compensated for weight loss during the previous 84-d exposur e to stable fly feeding. Overall reduction in average daily gain was a pproximate to 0.15 kg/d or 9% for both breeds, indicating that Brahman -crossbred heifers were as susceptible to long-term exposure to a medi um stable fly poulation as were English x Exotic heifers.