Effect of Heat Stress and Stocking Density on Growth Performance, Breast Meat Quality, and Intestinal Barrier Function in Broiler Chickens

SIMPLE SUMMARY: There is limited information on the interactive effects of heat stress (HS) and stocking density (SD) on broiler chickens. Our results indicated that both HS and high SD decreased broiler performance. HS affected intestinal barrier function by increasing intestinal permeability, but this result was not found with high SD. No interactive effects were observed between HS and SD for growth performance, meat quality, and intestinal barrier function in broiler chickens. ABSTRACT: The present experiment was conducted to investigate the effect of heat stress (HS) and stocking density (SD) on growth performance, breast meat quality, and intestinal barrier function in broiler chickens. Experimental treatments included two different ambient temperatures (20 °C: thermoneutral conditions, or 27.8 °C: HS conditions) and two different SD (low: 9 birds/m(2) and high: 18 birds/m(2)) in a 2 × 2 factorial arrangement. A total of 1140 21-day-old broiler chickens were allotted 1 of 4 treatments with five replicates. At the end of the experiment (35 days of age), two birds per replicate were euthanized for sample collections. The results indicated no interactions between HS and SD for all measurements. For main effects, HS decreased (p < 0.05) the growth performance of broiler chickens. Similarly, high SD also decreased (p < 0.05) body weight gain and feed intake. HS decreased (p < 0.01) jejunal trans-epithelial electric resistance (TER), whereas high SD did not affect TER. Neither HS nor high SD affected jejunal tight junction-related gene expressions; however, high SD reduced (p < 0.05) occludin expression. In conclusion, HS and high SD are key environmental factors decreasing broiler performance; however, the interactive effects of HS and high SD are not significant under the current conditions.