Toxicological evaluation of endophyte-infected perennial ryegrass straw to Japanese Black steers

Abstract

Experimental feeds containing 0, 500, 1000, 1500 or 2000 ppb of lolitrem B derived from perennial ryegrass straw were fed to 9 month-old Japanese Black steers (average liveweight 180 kg) to determine their threshold level of lolitrem B. Steers received feeds containing 1000, 1500 and 2000 ppb of lolitrem B showed signs of ryegrass staggers after 2 to 7 weeks of feeding. The lowest observed adverse effect level (LOAEL) of lolitrem B was approximately 24 μg/kg body weight per day. Only small amounts of lolitrem B residue were detected in muscle, liver, kidney and cerebrum. In contrast, approximately 100 ng/g of lolitrem B was detected in perirenal fat of steers with ryegrass staggers. Keywords: Lolitrem B, Japanese Black cattle, ryegrass staggers, muscle, fat