Influence of age and sex on footpad quality and yield in broiler chickens reared on low and high density diets

The effect of age and sex on live performance, processing yields, and footpad quality of broiler chickens was evaluated by rearing 2 commercial strain-crosses (SC) to 56 d of age on 2 diets varying in nutrient density. Each strain cross was placed in 10 replicate pens of 50 birds (25 males and 25 females per pen). Equally distributed among the replicate pens were high- and low-density starter (0 to 21 d) and grower (22 to 42 d) diets with a common finisher fed from 43 to 56 d to all birds. Body weights, adjusted feed conversion, and mortality were determined at 21, 42, and 56 d of age. Processing yields, foot weights, and yields, and the incidence and severity of footpad dermatitis were evaluated on d 35, 42, 49, and 56. No differences (P > 0.05) were seen in mortality between the SC and diet density treatments throughout the course of the study. Strain-cross had a significant effect on body weights at d 21 and feed conversion at d 42, but no differences remained at d 56. Significant SC effects were present for carcass without giblets at d 35, 42, and 56. Diet density effects were limited to carcass without giblets at d 35 and abdominal fat content at d 56. As expected, females had higher abdominal fat yields than males at all ages examined. Foot weight and yields were significantly affected (P < 0.05) by SC and sex at d 42, 49, and 56. As expected, foot weights increased with age. The proportion of birds with footpad dermatitis tended to increase until 49 d of age after which they started to decline. Male broilers had significantly higher incidence of footpad dermatitis than female broilers at d 49 and 56. Footpad dermatitis response to diet density and pigmentation of the feet was dependent on SC.