VIRGINIAMYCIN TO PROTECT SHEEP FED WHEAT, BARLEY OR OATS FROM GRAIN POISONING UNDER SIMULATED DROUGHT FEEDING CONDITIONS

Lactic acidosis can occur when cereal grains are fed to sheep in large quantities without an adequate introduction. Virginiamycin has been s hown to reduce lactic acid accumulation in vitro and in the rumen of s heep following ingestion of readily fermentable carbohydrates. The aim of this experiment was to determine if virginiamycin would prevent ac idosis in hungry sheep fed wheat, barley or oat grain without any intr oductory period. Merino wethers were penned individually and fed wheat en chaff (300 g/day for 9 days) before being offered 2.1 kg of wheat, barley or oat grain, with or without virginiamycin (n = 20, N = 120). Rumen fluid was collected prior to grain feeding and at 6 and 24 h fol lowing grain feeding. Blood samples were obtained prior to feeding and at 24 and 48 h following grain feeding. Twenty-four hours following a ccess to grain, the rumen pH was lower (P < 0.001) and the rumen L-lac tate was higher (P < 0.05) in sheep fed wheat without virginiamycin co mpared to sheep fed wheat plus virginiamycin. D- and L-lactate were pr oduced in equal proportions in sheep fed grain plus virginiamycin, whi le sheep fed grain without virginiamycin produced more of the L-isomer at 24 h following grain feeding. There was no effect (P > 0.05) of vi rginiamycin on grain intake, although intake of sheep fed oat grain wa s lower (P < 0.01) than intake of sheep fed wheat or barley. The numbe r of sheep withdrawn from the experiment following grain feeding was l ower (P < 0.05) when wheat was fed to sheep with virginiamycin compare d to untreated wheat grain. Inclusion of virginiamycin with grain did not reduce grain intake, but did reduce the severity of acidosis in sh eep fed wheat grain.