Efficiency of xylanase, emulsifier, and guanidinoacetic acid in restoring energy deficit in male broilers fed low metabolisable energy diets

The study aimed to examine the distinct impacts of incorporating xylanase (Xyl), emulsifier (EM), and guanidinoacetic acid (GAA) as dietary supplements in low metabolisable energy (ME) diets on performance, energy and protein efficiency ratios, oxidative biomarkers, gene expression, and gut morphology. Seven hundred one-day-old (Ross 308) male-broilers were assigned to 5 dietary treatments with 5 replicates of 28 birds each. The experimental group denoted as the positive control (PC) fed on diets in accordance with the breed recommendations. The negative control (NC) was subjected to a dietary intervention reducing the ME by 200 kcal/kg compared to the PC. The remaining experimental diets comprised NC diet that were supplemented with 0.01% Xyl, 0.03% EM and 0.06% GAA. Results showed that birds fed low-ME-diets increased their voluntary feed intake to meet their energy needs but was at the expense of their productive efficiency. Only NC+GAA partially restored broiler performance compared to PC. However, compared to the PC group Xyl, EM and GAA improved the energy and growth-related gene expression, oxidative biomarkers, and gut histomorphology (p < 0.05). The key features associated with Xyl and EM were growth-related genes and intestinal mucus, while GAA was associated with energy-related genes, oxidative biomarkers and jejunum-villi height and villus: crypt ratio. In conclusion, Xyl, EM and GAA supplementation to NC group were able to improve the health status of the birds. However, to improve the production efficiency, future research is needed to elucidate the effect of combined products in birds fed on such low ME diets.