Relative bioavailability of copper from sulfate, oxide and chloride salts in broiler chickens

A feeding trial was conducted to evaluate the relative bioavailability of copper (Cu) from the sulphate (CuSO₄.5H₂O), oxide (CuO) and carbonate (CuCO₃) salts in broiler chicks (315). Each of the salts was tested at three levels (100, 200 or 400 ppm) in a 3 × 3 factorial pattern. The chicks were distributed into 9 treatment groups with 7 replicates of 5 chicks each and reared in stainless steel cages. The basal diet (maize and soybean meal) was offered to all chicks up to 5 days of age for depleting the Cu reserves following which the test diets were fed ad libitum up to 4 weeks of age. Results indicated that broiler chicks elicited higher growth response to CuO than CuSO and CuCO salts while CuSOexhibited better feed efficiency than CuCO Copper supplementation to diets up to 200 ppm level had no negative influence on growth and feed intake. The interaction between Cu salts and their levels had no influence on body weight gain, except for growth depression with CuCO₃ at 400 ppm level. Birds raised on CuO supplementation had significantly (P<0.05) higher bone weight followed by CuSO₄ and CuCO₃. Retention of Cu in tibia was significantly higher with carbonate salt, but it depressed Mn and Zn uptake more than CuSO₄ or CuO depressed the uptake of Mn and Zn compared to CuO and CuSO₄ salts. The mineral uptake by hepatic tissue also followed the same trend. However, the retention of Cu in kidney was higher with sulphate salt. The concentration of Mn and Zn increased in renal tissue with the levels of Cu in diet, reflecting higher excretion leading to lower retention in liver and bone tissues. It can be inferred from these results that CuCO₃ produced higher Cu retention in tissues, but with negative effect on growth, feed intake, bone weight and retention of Mn and Zn in tissues compared to CuO and CuSO_4. Among the salts, CuO followed by CuSOmaintained lower tissue retention with beneficial effects on performance. ⁴