LOW-LEVEL FEEDING OF TROLENE FOR CONTROL OF THE CATTLE GRUBS HYPODERMA LINEATUM (DE VILL.) AND H. BOVIS (L.)

Abstract

Calves were fed individually for 18 days on a ration of crushed oats treated with Trolene to give a daily dosage of 10 mg./kg. This treatment produced 94 per cent mortality of pre-hypodermal cattle grubs. This was not significantly different from 97 per cent mortality obtained with a single treatment by boluses at 100 mg./kg. The low-level treatment had no effect on the mortality of the pre-hypodermal grubs during the first week of treatment but reached its full effect before the beginning of the third week. Of the hypodermal grubs present at the time of treatment, 94 per cent died and the remainder pupated. The only symptom of toxicity observed was mild diarrhoea in the low-level-treated calves.In a field experiment, two groups of calves that had consumed treated range blocks daily at averages of 7.7 and 4.2 mg. Trolene/kg. for 93 and 64 days showed 95 and 88 per cent mortality, respectively, of the pre-hypodermal grubs. By comparison, another group of calves, treated with boluses at 110 mg. Trolene/kg., showed 80 per cent mortality. The average number of grubs surviving the three treatments were significantly different from each other and from the untreated controls (P <.01). All treatments were begun before hypodermal grubs had appeared. No symptoms of toxicity were seen in the calves of the two low-level-treated groups; ataxia of the hindquarters was observed in the bolus-treated calves on the day following treatment, but these symptoms disappeared on the same day without the use of an antidote.

Free-Choice Feeding of Trolene for Reduction of Cattle Warble Infestations (Oestridae: Diptera)

“…De Foliart et al (l) fed 55 milligrams per kilogram daily for 2 days to 160 calves and reported reductions of from 6l to 82 per cent in grub numbers. Weintraub et al, (9) fed 10 milligrams per kilogram daily for 18 days to 30 calves and reported that the reduction of 94 per cenr in grub members was statistically comparable to the reduction produced in a similar group by treatment with Trolene boluses ar ll0 milligrams per kilogram. French et al (2) fed 35 milligrams per kilogram daily for 6 days to 28 steers and reported a reduction of 97.8 in grub numbers.…”