Meta-análise dos efeitos da inclusão de fontes de mandioca na alimentação de frangos de corte sobre o desempenho

Abstract

Broiler production costs have increased in recent years. Given that this cost is mainly linked to food, research on alternative ingredients to replace corn and soybean meal becomes fundamental. Cassava (Manihot esculenta crantz) stands out for being a plant present in human consumption and that during industrial processing it generates by-products with high potential for the composition of poultry feed. Studies on various sources of cassava by-products in the feed of broiler chickens are available in the literature, however, there is a lack of information on the standardization of by-products, as well as the level of replacement of cassava in relation to the energy source of the diet and its effects on performance. By meta-analytic approach, the objective was to evaluate the effect of replacing corn in the diet with cassava by-products (bagasse, flour and pulp) on the performance of confined and free-range broilers. Eighteen studies were analyzed, 14 about confined chickens and four about free-range chickens, totaling 117 treatment means. The effects were evaluated by the raw mean difference (RMD), with a p-value < 0.05. According to the performance results of confined broilers, the inclusion of cassava by-product sources in the feed reduced body weight gain. For feed intake there was no effect, however, there was a worsening of feed conversion. These data showed a high heterogeneity value (greater than 50%), which indicates interference in their responses not only from the inclusion of cassava, but from other factors, such as the source of cassava by-product, in addition to the level and period of inclusion. Thus, to explore heterogeneity, each source was classified according to levels. There was a reduction in the weight gain of confined chickens for all sources. As for the consumption of feed, there was a reduction in birds fed with the cassava bagasse source. Cassava flour resulted in worsening of feed conversion. When evaluating the inclusion of cassava by period, above 21 days of age, there was no statistical difference for the performance of the confined birds. According to the performance results for free-range broilers, the inclusion of cassava by-products, in general, increased feed intake and worsened feed conversion. However, despite the high heterogeneity, it was not possible to evaluate the sources, in addition to the levels and periods of inclusion of these by-products, separately, due to the small number of studies available in the literature. In conclusion, it is recommended the cassava pulp up to 15% in the diet of confined broilers, above 21 days of age, without affecting performance. In addition, it is important to develop studies about the cost-benefit analysis of cassava by-products as poultry feed.