In the last decades animal production has considerably increased worldwide to sustain an ever-growing human population. Among animal reared for consumption purposes, chickens are undoubtedly one of the most successful, mainly due to their rapid growth rate. The development of broiler farming has been accompanied in recent years by a substantial attention to animal welfare. This study is aimed at assessing the effects of different housing conditions on both feed conversion ratio and mortality of male broiler flocks through a largescale study (more than 100 million birds) involving 977 farms belonging to one major producer. For this, we evaluated nine features of the housing system using a linear model with random effect. The features were: roofing, floor, drinkers, feeders, water source, color curtain color, management, light and ventilation. A total of 3516 poultry flocks were assessed. Positive ventilation, metal and clay roof, dirt floor and owner management were shown to reduced mortality. Concrete floor, negative ventilation, blue curtains, fluorescent lightening, owner management, tap water and well water significantly improved FCR. We discuss our findings in relation with economic constraints and provide advices to encourage farmers using simple devices that will improve both production and chicken survival.

In broiler production, the litter is reused for consecutives flocks, and it is treated during down time between flocks to reduce its microbial load. Although covering the litter with a plastic canvas is a common litter treatment in the field, there is little scientific information available on its efficacy. The aim of this study was to evaluate the effects of covering broiler litter with a plastic canvas for eight days on litter microbiological, physical, and chemical parameters, and on the intestinal microbiota and immunity of broilers. In the first trial, reused litter from a previous flock was distributed into three treatments, with six replicates each: L1 (negative control, litter free from Salmonella Enteritidis (SE) and Eimeria maxima (EM) and not covered), L2 (positive control, litter with SE and EM, and not covered), and L3 (litter with SE and EM, and covered with plastic canvas for eight days). Litter total bacteria, Enterobacteria, Lactobacillus, SE, and EM counts, and litter pH, temperature, moisture, and ammonia emission were determined on days 1 and 8. In the second trial, broilers were housed on those litters according to the treatments described above, and their intestinal microbiota, gut CD4+ and CD8+ lymphocytes and macrophages, and liver and intestinal proinflammatory interleukin (IFN-γ, IL-1β e IL-18) levels were evaluated on days 14 and 28. A significant reduction of litter bacterial populations was observed in the litter covered with plastic canvas. A significantly higher mRNA IFN-γ gene expression (12.5-fold) was observed in the jejunum and liver of broilers reared on the litter with Enterobacteria counts. No EM reduction was observed in the covered litter. Covering reused broiler litter with plastic canvas reduces initial litter bacterial load as a result of the interaction between physical and chemical parameters.