Effect of chronic T-2 toxin exposure in rabbit bucks, determination of the No Observed Adverse Effect Level (NOAEL)

Abstract

T-2 toxin (T-2) was administered to adult Pannon White (n = 10/group) male rabbits for 65 days, first in a suspension by gavage (0.05, 0.1 or 0.2 mg/animal/day), and secondly mixed into the feed (0.33 and 0.66 mg/kg feed). In the first experiment 0.1 mg T-2 exposure resulted in temporary decrease in feed intake, slower increase in the gonadotropin-releasing hormone (GnRH) induced testosterone synthesis, slight centrolobular infiltration in the liver and a slight hyperplasia of the Leydig cells. In addition to the temporary feed refusal effect, 0.2 mg T-2 caused a temporary decrease in plasma albumin and urea concentrations, lesser glutathione peroxidase (GPx) activity in the seminal plasma, a greater (by 320%) ratio of spermatozoa with cytoplasmic droplets, slower increase in the GnRH-induced testosterone synthesis, centrolobular infiltration in the liver, slightly hyperaemic testes and increased proliferative activity of the Leydig cells. The two smaller doses applied in feed (0.33 and 0.66 mg/kg) did not cause any significant adverse effect, and no feed refusal was observed. According to these results the No Observed Adverse Effect Level (NOAEL) of T-2 for adult rabbit males was found to be <0.1 mg/animal/day (<0.02 mg/kg b.w./day).