Effect of dietary organic arsenicals and cupric sulfate on copper toxicity, liver accumulation and residue in eggs and excreta of laying hens

Abstract

A trial was conducted to examine the effects of the interaction of an organic arsenical compound (roxarsone): 3-nitro-4-hydroxy-phenylarsonic acid and copper sulfate on the egg production, liver function, and the copper content of the liver, eggs and excreta of laying hens. The experiment was a 2×3 factorial design with three replications. Ninety 38-weeks-old layer hens were selected from a commercial flock, and placed into six dietary treatments, i.e. two levels of roxarsone (0, 50 mg kg −1) and three levels of supplementary copper (400, 500, 600 mg kg −1), with five layer hens in each cage. Feeding was undertaken for four weeks. The interaction between copper and roxarsone in the diet significantly influenced the feed intake, egg production, and copper content in the liver and excreta ( P<0.05). Increasing the supplementation of copper from 400 to 600 mg kg −1 significantly depressed feed intake and egg production in both groups receiving diets with or without added roxarsone ( P<0.05). Increasing the supplement of copper from 400 to 500 mg kg −1 significantly depressed feed intake and egg production only in the diet including roxarsone. Adding roxarsone to the low copper supplemented diet (400 mg kg −1) significantly depressed egg production ( P<0.05). The copper content in liver significantly increased with an increasing level of copper supplement ( P<0.05) in the diet without roxarsone inclusion. With the addition of roxarsone, the level of copper supplement did not significantly influence the copper concentration in the liver ( P>0.05). With all supplement levels of copper, the copper concentration in both the liver and egg were significantly depressed by adding roxarsone to the diet. Without the roxarsone supplement, increased levels of copper supplements also significantly depressed the copper content in the eggs ( P<0.05). In all diets, both with and without roxarsone, the copper content in excreta of layers significantly increased as the level of supplemental copper increased ( P<0.05). The rate of copper excretion increased significantly more with the diet containing added roxarsone as supplemental copper increased from 400 to 500 mg kg −1. The response of serum aspartate aminotransferase (AST) and creatine kinase (CK) to the dietary supplement of copper and roxarsone was inconsistent. However, lactate dehydrogenase (LDH) activity increased significantly ( P<0.05). High dietary copper (500 or 600 mg kg −1) diets increased the serum LDH activity significantly ( P<0.05) with the roxarsone inclusion in the diet at the end of the first week of feeding. With the dietary inclusion of roxarsone, the LDH enzyme activity also significantly ( P<0.05) raised in the high copper diet of 500 mg kg −1 on the third week, and in all levels of copper on the forth week. Liver damage was also observed with the bile duct proliferation and hepatocyte degeneration.