Litter quality and incidence and severity of footpad dermatitis in heat stressed broiler chickens fed supplemental zinc

Abstract

In this study, we evaluated the effect of dietary Zn supplementation on growth performance, serum Zn concentration, litter quality attributes, and occurrence of footpad dermatitis in broiler chickens subjected to chronic heat stress. The study was conducted using a 2 × 2 factorial arrangement of dietary Zn oxide supplementation (0 and 70 mg/kg) and temperature (thermoneutral and chronic heat stress) in a completely randomized design. Five hundred forty-four 1-d-old male broiler chickens were randomly assigned to 4 experimental treatments with 8 replicate pens per treatment having 17 chickens in each replicate pen. Broiler chickens were fed corn-soybean meal-based basal diets for starter (0 to 10 d), grower (10 to 24 d), and finisher (24 to 42 d) growth periods with or without 70 mg/kg supplemental Zn oxide. Growth performance was recorded in terms of body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR). Serum Zn concentration and occurrence of footpad dermatitis were evaluated at d 14, d 28, and d 42 of experiment. Litter quality attributes were measured at d 1 and d 42 of the experiment except ammonia volatilization that was measured at d 28 and d 42 of the experiment. There was no interaction between dietary Zn and temperature for growth performance, serum Zn concentration, litter quality, and occurrence of FPD. Dietary Zn supplementation had no effect on overall growth performance, serum Zn, and litter quality of broiler chickens. However, supplemental Zn reduced the occurrence of footpad dermatitis in broiler chickens at the end of experiment (P < 0.05). Broiler chickens subjected to heat stress had lower overall BWG (P = 0.002) and FI (P = 0.001). Serum Zn concentrations were similar regardless of the temperature. Chronic heat stress increased the litter pH (P = 0.001), moisture (P < 0.001), temperature (P < 0.001) at d 42, and ammonia volatilization at d 28 (P < 0.001) and d 42 (P < 0.001). Incidence and severity of footpad dermatitis was greater in broiler chickens subjected to chronic heat stress (P < 0.01). Findings of our study indicate that heat stress results in poor growth performance and increases the incidence and severity of footpad dermatitis by lowering the litter quality in broiler chickens. In addition, dietary Zn supplementation may lower the occurrence of footpad dermatitis in broiler chickens without affecting the growth performance, serum Zn, and litter quality.