Dietary Calcium and Phosphorus Requirements for Bobwhite Chicks

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Two experiments were conducted with bobwhites (Colinus virginianus) to determine the optimum calcium and phosphorus levels to be used in a corn-soy diet fed to birds from 1 day to 6 weeks of age. Five levels of phosphorus, 0.354, 0.450, 0.550, 0.60, and 0.750 percent, were fed with calcium levels of 0.25 to 0.95 percent. The data indicated that levels of 0.65 percent calcium and 0.650 percent phosphorus gave maximum body weight, bone ash, and viability of chicks. Nestler et al. (1948) reported that maximum growth of bobwhite chicks was obtained with 0.75 percent phosphorus and 1.00 percent calcium in the diet. A lower phosphorus requirement ( 0.6 percent ) was reported by Scott et al. (1958); however, this phosphorus requirement was determined in conjunction with a stable test level of 1.65 percent calcium. IXe National Research Council (1971) has not established a recommendation of calcium or phosphorus levels for bobwhite chicks. The following experiments, using cornsoy diets, were conducted to obtain information on the calcium and phosphorus requirements of bobwhite chicks. METHODS AND MATERIALS Bobwhite chicks were confined between the ages of 1 day and 6 weeks, in battery brooders with raised wire floors. During this time they were fed the experimental diets. A total of 48 pens were used in each experiment, with three replicate pens assigned to each of 16 treatments. Eight birds per pen and 15 birds per pen were started in Experiments 1 and 2, respectively. The number of birds was increased in Experiment 2 in order to obtain a better measure of viability. The 16 treatments consisted of 1 Florida Agr. Expt. Sta. Journal Series No. 4229. dietary phosphorus levels ranging from 0.354 to 0.750 percent in combination with calcium levels ranging from 0.25 to 0.95 percent on a calculated basis. Analyses of the diets indicated the values to be correct except for the 0.750 percent phosphorus and 0.75 percent calcium diet in Experiment 1. The basal diet ( Table 1 ) contained 28.0 percent protein, 2,037 keal of productive energy per kg, 0.354 percent phosphorus, and 0.154 percent calcium. Sodium acid phosphate, calcium carbonate, and sand were added to the basal diet to obtain the desired calcium:phosphorus ratios (Table 2). Body weight was measured at 3 and 6 weeks of age, and mortality was recorded throughout the experiments. At the end of each experiment, four birds per pen were sacrificed and the right tibiae removed for analysis of bone ash (Horowitz 1965). Data were analyzed by the analysis of variance with significant treatment differences determined by Duncan's ( 1955 ) multiple range test. RESULTS AND DISCUSSION Maximum body weight of bobwhite chicks at 6 weeks of age was obtained with dietary phosphorus levels of 0.650 percent (Table 2). A level of 0.550 percent phosphorus appeared to be marginal in Experiment 1 since a numerically higher body