Toxicological evaluation and bioaccumulation potential of lolitrem B, endophyte mycotoxin in Japanese black steers

Abstract

Lolitrem B, a causative toxin for ryegrass staggers, is produced by Neotyphodium lolii infecting perennial ryegrass (Lolium perenne). Japanese black cattle have been suspected to be more sensitive to lolitrem B than to other strains, and there has been a concern about the public health hazard of eating beef contaminated with lolitrem B. We carried out a feeding experiment to examine the sensitivity of Japanese black cattle to lolitrem B and the residual level of lolitrem B in several animal tissues. Japanese black steers were fed a 0, 500, 750, 1000, 1500 or 2000 µg kg−1 diet of lolitrem B provided by endophyte-infected perennial ryegrass straw for 12 weeks. All six animals in the 2000 µg kg−1 diet group exhibited ryegrass staggers symptoms. Furthermore, two out of three animals in the 1500 µg kg−1 diet group, three out of six animals in the 1000 µg kg−1 diet group and one out of three animals in the 750 µg kg−1 diet group presented clinical signs of ryegrass staggers. These results suggest that a daily intake of 18 µg kg−1 body weight of lolitrem B can produce ryegrass staggers in Japanese black steers. Perirenal fat tissues of the steers from those groups having one or more animals exhibiting ryegrass staggers symptoms contained approximately 150 ng g−1 of lolitrem B, while only small amounts of lolitrem B were detected in muscle, liver and kidney. Because the residual amount of lolitrem B in tissues of Japanese black cattle is small, the exposure to lolitrem B in consumers of the beef is likely to be low.