Research Note: Stocking density effects on production qualities of broilers raised without the use of antibiotics.

In no antibiotics ever (NAE) broilers, enteric diseases pose a threat to intestinal health and generally welfare, which can be exacerbated because of stocking density. Through knowledge of litter condition and management, disease can be minimized, and broiler welfare can be improved. To evaluate how stocking density influences NAE broilers raised in conventional housing, we evaluated production traits for broilers raised at two stocking densities within a single commercial house. Over the course of 4 flocks, 78,960 Cobb 500 broilers were raised in an industry-style tunnel ventilated house. The house was divided into four equally sized pens, each representing one of two stocking densities. An industry standard stocking density (SSD; 0.23 m per bird) and low stocking density (LSD; 0.27 m per bird) were each assigned to two pens per flock and were alternated for each subsequent flock raised. Litter moisture content, body weight, mortality, and feed conversion (FCR) were evaluated and averaged over all four flocks for both stocking densities. Data were analyzed in JMP with an ANOVA, and means were separated by Tukey's honestly significant difference. As expected, the litter moisture content was significantly larger in the more densely packed SSD pens at weeks 2, 3, 4, and 6, totaling 0.242 moisture content on average at week 6 vs. 0.217 in LSD pens at the same flock age (P = 0.035). Weekly body weight and final flock FCR were not significantly impacted by stocking density. No association was observed in mortality between the broilers raised in SSD and LSD. The results from this study indicate that the two densities examined were comparable in their growth and efficiency. Additional management pressure would exist to handle the increase in litter moisture in flocks placed at SSD in a production setting; although, raised in the same barn at the same time, the impact of SSD vs. LSD was minimal in this study.