Upregulated proventricular pepsinogens and improved feed efficiency in broilers by the combination of supplemented sugarcane bagasse and coarsely ground corn in pelleted diets

Measures to improve bird performance have been sought due to the imminent phase out of in-feed antibiotics in poultry and continued demand for higher poultry feeding efficiency. Promotion of gizzard development by physical structure of feed ingredients or addition of dietary fibre is one such strategy with the hypothesis that larger ingredient particles and higher fibre enhance digestive enzyme secretion and feed efficiency in broilers (Kheravii et al., 2017; and Svihus, 2011). This study was conducted to evaluate the effect of increased particle size of corn and inclusion of sugarcane bagasse (SB) on mRNA expression of genes encoding pepsinogen A and C, and feed conversion ratio (FCR). A total of 336 Ross 308 male broilers were assigned in a 2 × 2 factorial arrangement of treatments with 2 particle sizes (coarse 3576 µm or fine 1113 µm geometric mean diameter) and 2 levels of SB (0 g/kg or 20 g/kg). Each treatment had 6 replicate pens of 14 birds. All of the 4 diets based on corn, soybean meal, and meat meal were formulated to meet the minimum nutrient profiles of the Ross 308 specifications. Herein, the composition of diets was diluted when 20 g of SB /kg was added over the top of the complete feed. All the diets were thoroughly mixed and cold pelleted (65◦C). Birds were fed in the phases of starter (d 0 to 10), and grower (d 10 to 24). FCR was measured from d 10-24. The mRNA expression of genes encoding pepsinogen A and C were measured from one bird per pen at d 24. The analysis of gene expression was performed with qBase+ that applied an arithmetic mean method to transform logarithmic Cq value to linear relative quantity using exponential function for relative quantification of genes (Hellemans et al., 2007) and the output data were exported to SPSS statistics version 22 (IBM SPSS, UK) for further analysis. The data were analysed using the General Linear Models (GLM) procedure for the main effect of particle sizes, and SB supplementation along with their interactions and correlations between FCR and the expression levels of these genes were conducted using the Correlate module of SPSS statistics version 22. Differences between mean values were determined using LSD test at the level of P < 0.05. During d 10-24, a significant particle size × SB interaction was observed for FCR (P < 0.01). The birds fed CC (coarsely ground corn) with 2% SB had lower FCR than those fed CC without SB. A particle size × SB interaction was observed for both expression of pepsinogen A and C (P < 0.01). Further, expression of pepsinogen A (P < 0.01 and R = -0.53) and C (P < 0.01 and R = -0.59) were negatively correlated with FCR on d 24. These findings suggest that the combination of CC and SB in broiler diets is beneficial to broiler performance through the upregulation of both proventricular pepsinogen A and C.