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

Abstract

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 2 per bird) and low stocking density ( LSD ; 0.27 m 2 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.

Avian Pathogenic Escherichia coli and Clostridium perfringens: Challenges in No Antibiotics Ever Broiler Production and Potential Solutions

“…Litter quality is correlated with moisture levels and is impacted by the number of broilers in a flock [ 212 ]; therefore, litter amendments, changing litter, or windrowing may be included in NAE production to reduce microbial load. A recent study suggests stocking density influences litter moisture [ 213 ]. While commercial NAE settings revealed no significant difference in feed conversion, mortality, or body weight gain, a low stocking density (0.27 m 2 ) showed a 2.5% reduction in litter moisture when compared to the higher stocking density (0.23 m 2 ) [ 213 ].…”

“…A recent study suggests stocking density influences litter moisture [ 213 ]. While commercial NAE settings revealed no significant difference in feed conversion, mortality, or body weight gain, a low stocking density (0.27 m 2 ) showed a 2.5% reduction in litter moisture when compared to the higher stocking density (0.23 m 2 ) [ 213 ]. Litter moisture has been associated with increased ammonia levels, increased bacterial load, and increased lesions such as footpad dermatitis, breast blisters, and hock burns [ 70 , 71 , 72 ].…”

“…Reducing stocking densities may mitigate litter moisture, lower housing temperatures, and decrease infection risk. However, lower stocking densities than industry standards did not show any significance in feed conversion, mortality, or BW [ 213 ]. Winkler et al found that litter moisture was highest around water lines at 40.7% in tandem with the increased prevalence of E. coli and C. perfringens in the same locations [ 215 ].…”

“…Commercially available competitive exclusion culture administered via oral infection to White Leghorn chickens on day 1 of placement reduced the number of ESBL/AmpC-producing E. coli in gut cecal contents [234] Environment Reduced stocking density in NAE broiler flocks decreases litter moisture [213] Environment Reduced stocking densities of broilers had higher BW and lowered FCR than high stocking densities [214] Environment Broilers raised at the lower stocking density had higher BW, but lower FCR [235] Genetics No difference in AMR presence of E. coli in fast-growing vs. slow-growing breeds of broilers in an antibiotic-free system [236] Organic Acids…”

Effects of stocking density on the performance, tibia mineralization, and the expression of hypothalamic appetite genes in broiler chickens

“…Previous studies found that HSD decreases the feed intake of broilers (Wang et al, 2014;Madilindi et al, 2018;Cengiz et al, 2018;Sanchez-Casanova et al, 2019;Magnuson et al, 2020;McKeith et al, 2020); however, scanty literature was reported about the mechanism of this action. Hypothalamus plays a critical role in the appetite regulation (Harrold et al, 2012;Everaert et al, 2019).…”