THE INFLUENCE OF EGG WEIGHT LOSS DURING AND IMMEDIATELY FOLLOWING INCUBATION, AND DIETARY INTAKE OF ENERGY AND PROTEIN ON GROWTH AND FEED EFFICIENCY IN BROILER CHICKENS

One thousand two hundred and seven eggs were obtained from a flock of 34-wk-old broiler breeders (Indian River strain). Prior to setting, eggs were weighed and sorted into groups of a common weight. Following hatching, the weight of the pooled hatch debris from each weight group was recorded. The percent weight loss (PWL) during incubation for each egg was calculated as follows:[Formula: see text]Chicks were sorted into two groups of 416 chicks each, based on PWL (high: 29.57% ± 0.31 and low: 24.32% ± 0.28). Chicks from each PWL group were fed one of four starter diets to 3 wk of age: (1) 26% crude protein (CP), 3200 kcal ME kg−1; (2) 23% CP, 2830 kcal ME kg−1; (3) 23% CP, 3200 kcal ME kg−1; and (4) 26% CP, 2830 kcal ME kg−1. From 3–6 wk of age all chicks were fed a 20% CP 3200 kcal ME kg−1 grower diet. Chicks in the low PWL treatments exhibited significantly higher body weights than high PWL chicks up to 5 wk of age. During the period from 1 to 3 wk, chicks fed the low-energy diet were heavier than chicks fed the high-energy diet. During the period from 1 to 6 wk, chicks fed the low-protein diet were significantly heavier than chicks fed the high-protein diet. The effects of energy and protein on body weight are attributed to significantly higher feed intake in the low-energy and low protein-fed birds. Key words: Broiler chicken, dietary energy, dietary protein, egg weight loss, incubation