Lupinosis of ewes around the time of mating reduces reproductive performance

Abstract

Lupinosis was induced in Merino ewes by subcutaneous injections of phomopsin toxins, given for 2 weeks before and up to 2 weeks after the start of joining, and the reproductive performance of the injected ewes was compared with untreated control ewes. Two experiments were conducted in consecutive years, with similar results. The liver damage and impairment of liver function due to lupinosis were measured by increases in plasma activities of glutamate dehydrogenase and gamma glutamyl transferase, plasma concentration of bilirubin, and plasma clearance of bromosulfthalein. Ovulation rate was depressed by phomopsin administration (1.11 v. 1.33 for the combined phomopsin-treated and control ewes, P < 0.001), and fewer phomopsin-treated ewes were pregnant (70.4% for the combined phomopsin-treated ewes v. 93.8% for the combined control ewes, P < 0.01). Thus, fewer lambs were born to the phomopsin-treated ewes compared with the control ewes (66.0 v. 109.3% for the combined years, P < 0.01). These results indicate that there may be severe detrimental effects of phomopsin intoxication on reproductive performance of ewes.