Effect of Mixing Uniformity on Broiler Chick Performance

Two experiments were conducted to determine the effects of diet nonuniformity, caused by inadequate mixing, on performance of day-old broiler chicks. In both experiments, a common diet was mixed for different times to represent poor, intermediate, and adequate uniformity. Methods of uniformity analysis had quadratic responses (P < .001), with diet variability decreasing as mixing treatment was increased from poor to intermediate, and negligible reductions as mixing treatment was increased from intermediate to adequate. In Experiment 1 (a 24-d growth assay), average daily gain, average daily feed intake, bone strength and ash, and carcass CP, fat, and ash were not different among treatments (P > .12). However, a 3.3% increase (linear trend, P < .09) occurred in gain:feed ratio as mixing treatment was increased from poor to adequate. In Experiment 2 (a 28-d growth assay), quadratic responses were observed for average daily gain (P < .04), average daily feed intake (P < .10), and gain:feed ratio (P < .07), with improvements as mixing treatment was increased from poor to intermediate, but no further improvements as mixing treatment was increased from intermediate to adequate. Mortality was not affected by treatment (P > .21), although the only deaths occurred in birds fed the most nonuniform treatment. Beginning on Day 28, all birds were fed a common finishing diet for 14 d to determine whether compensatory growth occurred. The difference in average BW between the poor and adequate uniformity treatments decreased from 116 to 57 g per bird, with increased (P < .007) gain:feed ratio for birds that were lighter at the end of the grower phase (i.e., those fed nonuniform diets). These experiments indicate that diet uniformity affects broiler chick performance.