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Layer Performance and Phytase Retention as Influenced by Copper Sulfate Pentahydrate and Tribasic Copper Chloride

Department of Poultry Science, Auburn University, Auburn, Alabama 36849

Correspondence: D. A. Roland, E-mail: roland1{at}auburn.edu

An experiment was conducted to study copper sulfate pentahydrate (CSPH, CuSO₄·5H₂O) and tribasic copper chloride (TBCC, Cu₂(OH)₃Cl) as sources of supplemental Cu for layers. A total of 1,560 W-36 first cycle (Phase I) hens were randomly divided into 13 groups and fed a basal corn-soybean diet or a basal diet supplemented with 65, 130, 195, 260, 325, or 390 ppm of Cu from either CSPH or TBCC for 16 wk. The common intercept multiple linear regression over 4 Cu levels (65, 130, 195, and 260 ppm) indicated the bioavailability of TBCC relative to CSPH was 134%, and the optimal supplemental Cu level was 195 ppm for TBCC and 260 ppm for CSPH based on egg weight. There were no supplemental Cu level effects (P > 0.05) over the 4 Cu levels (65, 130, 195, and 260 ppm) based on feed intake, egg production, egg mass, feed conversion, and BW over 16 wk. Feed intake during the last 4 experimental weeks was lower (P < 0.01) for birds fed CSPH than for birds fed TBCC and basal diets, indicating that CSPH, but not TBCC, began depressing bird performance after being fed for 12 wk. Feed samples for both CSPH and TBCC at concentrations of 0, 195, and 390 ppm of Cu were taken from the diets and were stored at 40°C for up to 21 d. Samples were removed at 1-wk intervals for analysis of phytase retention. Phytase retention in diets with added TBCC was higher (P < 0.05) than in control diets or in diets with added CSPH. The results from this experiment suggest that the bioavailability of Cu in TBCC is greater than in CSPH, and TBCC is more effective than CSPH at reducing the oxidation of phytase during feed storage.

Key Words: bioavailability • copper • layer • phytase