The effect of T-2 mycotoxin on adult bobwhite quail : (Colineus virginianus)

Four experiments were conducted to assess mortality rate, hematopoietic, and histological changes associated with exposure to T-2 mycotoxin. In Experiment 1, adult bobwhite quail were orally dosed with T-2 toxin to determine the acute lethal dose that resulted in 50% mortality of the affected population. The acute one time lethal dosage of T-2 toxin that resulted in 50% mortality was determined to be 14.7 milligrams of T-2 toxin per kilogram of body weight (BW).

A second experiment was performed to compare the effects of intermittent vs. chronic exposure to T-2 toxin on peripheral blood leukocyte populations. Intermittent exposure to T-2 toxin results in highly significant (P≤.01) increases in absolute number of heterophils among LD₄₀ (40% of the acute 100% lethal dose) and LD₆₀ (60% of the acute 100% lethal dose) birds as compared to control birds. In contrast, absolute number of monocytes and leukocytes were significantly (P≤.01) decreased among LD₄₀ and/or LD₆₀ birds as compared to controls. Chronic exposure to T-2 toxin resulted in a highly significant (P≤.01) increase in absolute number of heterophils as a result of any T-2 toxin treatment. In contrast, absolute number of monocytes and lymphocytes were less (P≤.01) among hens receiving 16 or 20 mg toxin/kg feed as compared to hens receiving the control diet. Results indicate that T-2 toxin is a potent immunosuppressor of peripheral lymphocyte populations.

In a third study, the effects of 12-18 mg/kg BW T-2 toxin on blood chemistry and liver enzyme profiles was determined. Posttreatment plasma glucose, total protein, calcium, cholesterol and triglyceride levels numerically decreased as compared to pretreatment values. In contrast, post treatment potassium, uric acid, aspartate aminotransferase, lactic dehydrogenase, creatinine phosphokinase and gamma glutamyl transferase increased as compared to pretreatment values, which is indicative of liver damage.

Histological analyses of spleen, liver, small intestine, kidney, and heart tissues were conducted on birds dosed in Experiment 3 and on birds fed T-2 toxin for 4 weeks in a 4th experiment. Marked lymphocyte necrosis and depletion throughout the spleen, thymus, bursa and gut associated lymphoid tissue in the small intestine was observed in birds dosed with 15 and 18 mg/kg BW T-2 toxin. Necrosis of liver and lipid accumulation as a result of malfunctioning hepatocytes was also observed. The most prevalent lesion in chronically fed birds was pronounced depletion of splenic lymphocytes. Heart and liver tissue of chronically treated birds showed little or no morphological changes.

The LD₅₀ for adult bobwhite quail as found in this study is 2-3 times higher than that reported for other species of commercial poultry. Results from these data confirm previously reported studies on the immunosuppressive and cytotoxic effects of T-2 toxin in other mammalian and avian species. T-2 toxin may have a negative impact on the viability of wild quail populations.