Beneficial effects of dietary ascorbic acid supplement on hens subjected to ochratoxin A toxicosis under normal and high ambient temperatures

Three experiments were conducted to study ochratoxin A (OA) toxicity and the effect of supplemental ascorbic acid (AA) in laying hens housed under two environmental temperatures. In exp. 1, 18 hens were divided into three groups of six hens and fed diets containing either 0, 1.7, or 3.1 ppm OA for 14 d. In exps. 2 and 3, 24 hens were randomly assigned to four dietary treatments in six replications. Treatments consisted of a control and three diets containing either 300 ppm AA, 3 ppm OA, or 300 ppm AA plus 3 ppm OA. Treatment diets were fed for 14 d following the feeding of the basal diet for 14 d. The test-period temperature was 25 °C in exp. 1 and 2 and 33 °C in exp. 3. In exp. 1, feeding OA at 1.7 ppm significantly (P ≤ 0.05) decreased feed intake and increased liver weights and eggshell elasticity. At 3 ppm, OA significantly (P ≤ 0.05) reduced feed intake, body-weight change and egg production, and increased shell elasticity. Similar trends were also observed in exps. 2 and 3 when laying hens were fed 3 ppm OA compared with those fed the control diet. An analysis of plasma constituents showed that OA also increased Cl − concentration and aspartate transaminase activity and decreased plasma Ca ++ concentrations. Exposing hens to 33 °C (compared with 25 °C) appeared to aggravate the negative effects of OA. All the negative effects of OA, apart from body-weight changes, reductions in feed intake, and increases in eggshell elasticity at 33 °C, were either moderated or significantly (P ≤ 0.05) reversed by dietary AA supplementation. The results suggest that some of the detrimental effects of OA in the diet of the laying hen can be counteracted by dietary supplementation of AA. Key words: Ochratoxin A, toxicity, ascorbic acid, hen, temperature