Prediction of Lead Intake and Tissue Lead Concentrations in Broiler Chickens Using Feather Lead Concentrations.

The present experiment was conducted to derive equations for predicting daily lead (Pb) intake and tissue Pb concentrations in broiler chickens using feather Pb concentrations. A total of 800 3-day-old broiler chickens were allotted to one of five dietary treatments with 16 replicates, each replicate consisting of 10 birds, in a completely randomized design. Dietary Pb concentrations were set to 0, 50, 100, 200, or 400 mg/kg by adding a lead acetate. The experimental diets were provided ad libitum for 32 days. Results indicated that growth performance and serum measurements were not affected by increasing concentrations of Pb in diets, which represented that the toxic level of dietary Pb may exceed over 400 mg/kg in broiler diets. Increasing concentrations of Pb in diets increased Pb concentrations in the liver (linear and quadratic, P < 0.05), breast (linear, P < 0.01), and feather (linear, P < 0.01). Feather Pb concentrations were greater than Pb concentrations in the liver and breast, indicating that the feather is highly responsive tissue of broiler chickens to various dietary Pb concentrations. Consequently, the equations for predicting daily Pb intake and Pb concentrations in the liver and breast were derived from Pb concentrations in the feather. Resulting equations indicated that feather Pb concentrations in broiler chickens can be used to predict both daily Pb intake and Pb concentrations in the liver and breast.

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

The present experiment was conducted to investigate the effect of heat stress (HS) andstocking density (SD) on growth performance, breast meat quality, and intestinal barrier functionin 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/m2 andhigh: 18 birds/m2) in a 2 × 2 factorial arrangement. A total of 1140 21-day-old broiler chickens wereallotted 1 of 4 treatments with five replicates. At the end of the experiment (35 days of age), twobirds per replicate were euthanized for sample collections. The results indicated no interactionsbetween HS and SD for all measurements. For main effects, HS decreased (p < 0.05) the growthperformance of broiler chickens. Similarly, high SD also decreased (p < 0.05) body weight gain andfeed intake. HS decreased (p < 0.01) jejunal trans-epithelial electric resistance (TER), whereas highSD did not affect TER. Neither HS nor high SD affected jejunal tight junction-related geneexpressions; however, high SD reduced (p < 0.05) occludin expression. In conclusion, HS and highSD are key environmental factors decreasing broiler performance; however, the interactive effectsof HS and high SD are not significant under the current conditions.