ABSTRACT Butyric acid has been studied and utilized intensively in broiler chicken production in order to substitute growth-promoting antibiotics. However, the comprehensive literature on this topic makes it difficult to understand overall results, since there is a noticeable number of studies with conflicting conclusions. Although several research studies have shown that butyric acid may increment broiler chicken’s performance, several other studies show the opposite. This work aimed to organize information to understand, through a meta-analysis, whether butyric acid can be used as a performance-enhancing additive for broiler chickens, and whether it can replace growth-promoting antibiotics. It was clear from the results that the effect of butyric acid depends on the microbiological challenge that broilers receive. When broilers are raised without health challenge, butyric acid and even antibiotics do not influence growth performance. However, when broilers are challenged, butyric acid provided an increase in weight gain and a significant improvement in feed conversion, matching the results of antibiotics. We conclude that butyric acid improves broiler performance and can be used to replace growth-promoting antibiotics.

The effects of the dietary substitution of dry corn by high-moisture corn grain silage (HMCGS) were evaluated on the performance, nutrient digestibility and serum biochemical parameters of broilers reared in an alternative production system and submitted to different environmental temperatures. A total of 288 one-day-old male Cobb chicks were distributed according to a randomized block design in a 3x4 factorial arrangement: three environmental temperatures (hot, thermoneutral or cold) and four levels of HMCGS in substitution of dry corn (0%, 20%, 40% or 60%). The acid analysis showed that the evaluated HMCGS contained average percentage values of ethanol, lactic acid, and acetic acid (expressed in 100% of dry matter) of 0.7690, 2.7320 and 0.0249%, respectively. Propionic and butyric acids were not detected. Dry corn and HMCGS presented pH values of 5.8 and 3.3, respectively. The inclusion of HMCGS reduced dietary pH, as shown by the values of 5.7, 5.4, 5.1 and 4.8 recorded for the diets containing 0%, 20%, 40% and 60% of HMCGS, respectively. There was no significant interaction between diets and environmental temperature. HMCGS may replace up to 40% dry corn in broiler diets when performance, triglyceride levels, and HDL-cholesterol ratio is considered, and up to 60% when nutrient digestibility is evaluated. High environmental temperature impairs broiler performance, nutrient digestibility, and serum biochemistry, demonstrating the influence of environmental temperature on broiler metabolism and performance.