Alterations in the performance, haematology and clinical biochemistry of growing lambs fed with aflatoxin in the diet.
Twenty-three male lambs were fed 2.5 ppm of aflatoxin for 21 days. Thirteen lambs constituted the control group. Twelve lambs given toxin and six from the control group were killed at 21 days. The remaining animals were killed 8 days later. To determine haematological and biochemical parameters, samples of blood were obtained at 0, 7, 14 and 21 days of exposure and at 1, 2, 4 and 8 days after exposure. The most sensitive indicator of intoxication was the reduction in body weight (17 +/- 2.2 kg-1 body wt. in intoxicated lambs and 19.2 +/- 1.8 kg-1 body wt. in the control group: P >> 0.01) and in the average daily weight gain (133 +/- 79 g day-1 in the intoxicated group and 254 +/- 105 g day-1 in the control group; P >> 0.001) from the 14th day onwards. Lambs fed with aflatoxins had relatively smaller liver weights and higher kidney and spleen weights than lambs from the control group. Feeding aflatoxins increased the erythrocyte count and the mean corpuscular haemoglobin concentration and decreased the mean corpuscular volume and mean corpuscular haemoglobin values. An elevation of the levels of globulins with an increase of the beta and gamma fractions and no variation in total protein and albumin was observed in lambs fed on aflatoxins. Urea levels and the alkaline phosphatase and glutamate dehydrogenase enzymatic activities decreased as a consequence of intoxication, whereas gamma-glutamyl transferase was increased. During the clearance period, haematological values regressed towards basal values, but biochemical parameters remained unchanged. These results suggest that lambs are sensitive to the toxic effects of the aflatoxins and that the determination of zootechnical parameters is a better aid to the diagnosis of intoxication than haematological or biochemical analyses.