Identification of differences in digestive organ weight, bone mineral concentration, and ileal transcriptomic profiles of low and high weight broiler chicks

Abstract A growth monitoring study (0–7 day of age) was conducted involving 87, one-day old Ross 308 male broilers to evaluate organ weights, bone parameters and ileal transcriptomic profile of broiler chicks as influenced by day 7 bodyweight (BW) grouping. The chicks were raised in a deep-litter house under common controlled environmental conditions and commercial starter diet. Chicks were grouped on day 7 into two distinct BW, super performer (SP) and under performer (UP) with bodyweights >260, and <200 g respectively. Results revealed that the SP chicks had significantly higher bone ash, sodium (Na), phosphorus (P) and rubidium (Rb) concentrations compared to the UP chicks on D7. In contrast, the UP chicks had significantly higher tibial cadmium (Cd), caesium (Cs) and lead (Pb) compared to the SP group; the UP chicks also had proportionally heavier relative gizzard weight than the SP chicks. The ileal transcriptomic data revealed differentially expressed genes (DEG) between the two groups of chicks, with 150 upregulated and 83 down-regulated genes with a fold change of ≥1.25 or ≤ 1.25 in the SP chicks relative to the UP chicks. Furthermore, functional annotation and pathway analysis revealed that some of these DEG were involved in various pathways including calcium signalling, Wnt signalling, cytokine-cytokine receptor interaction and mucin type O-glycan biosynthesis. This study revealed that chicks of the same breed and of uniform environmental and diet management exhibited differences in digestive organ weights, tibial bone characteristics and ileal gene expression that may be related to BW.