Efeitos dos tratamentos e dos substratos de cama na criação de frangos de corte: revisão sistemática e meta-análise

Abstract

The objective of this thesis was to produce scientific evidence of the effects of substrate types and treatments of poultry litter on their physicochemical characteristics and performance of broilers. Two systematic reviews and metaanalyses related to the use of different types of substrates and treatments of the poultry litter were performed. From the articles included in the meta-analysis, the mean, standard deviation and sample size of the treatments evaluated were extracted. The size of the effect was analyzed by the mean difference or the standardized mean difference between the treated and control groups. Broilers reared on wood-shavings showed better body weight and feed conversion and lower mortality compared to other types of substrates (sand, sugarcane bagasse, peanut shell, rice husk, grass, hay, mixture, straw, paper and sawdust). In the soubgroup meta-analysis it was observed that different types of litter materials did not affect the feed intake of broilers. However, broilers reared on straw litter presented lower body weight, worse feed conversion and higher mortality rate. Birds reared on rice husk beds showed lower body weight compared to those reared on wood shavings. In the second meta-analysis it was observed that litter treatment with different conditioners reduced ammonia release, moisture and proliferation of pathogenic bacteria and altered pH values in litter compared to control group. In the sub-group analysis, it was observed that acidifiers produced a reduction in pH, ammonia and litter moisture with consequent higher weight gain and lower mortality rate of broilers. On the other hand, alkalizing increased pH, reduced moisture and pathogenic microbiota, but worsened feed conversion and mortality rate of broilers. Gypsum reduced the release of ammonia in litter and improved feed conversion of broilers. Superphosphate reduced pH, while adsorbents reduced litter moisture. None of the treatments significantly influenced the food intake of birds.