A single drench of virginiamycin to increase safety of feeding grain to sheep

Abstract

Two experiments tested the efficacy of a single drench of virginiamycin for protecting sheep against grain poisoning (lactic acidosis). In Expt 1, 80 penned sheep (30±0·4 kg) were drenched with 0, 40, 80, or 160 mg of virginiamycin in 10 mL of water, then fed wheat ad libitum. Eleven sheep that received no virginiamycin and one receiving 40 mg virginiamycin were withdrawn from the trial due to inappetence after eating wheat. Sheep drenched with 80 or 60 mg virginiamycin were heavier (P < 0·05) than control sheep at 20 days after drenching, and none was withdrawn. Rumen pH was higher (P < 0·05) in sheep drenched with virginiamycin than in control sheep.

In Expt 2, 100 sheep (62±0·7 kg) were either gradually introduced to a standing wheat crop by restricting the length of time they had access to the crop, or drenched with 160 mg of virginiamycin then given unlimited access to the crop. Sheep receiving virginiamycin lost more weight in the first week of the experiment, but thereafter gained weight faster than the sheep gradually introduced to wheat. There was no difference between groups in wool strength.

These trials indicate that a single drench of virginiamycin can effectively prevent lactic acidosis in sheep.