Mapping critical gut homeostasis indices under diverse dietary inputs in broilers

    

A deeper understanding of critical bird homeostasis responses may augment poultry industry efforts for improved bird resilience and production sustainability. The aim of this work was to explore the expression range of critical genes in the broiler gut as responses to diverse dietary inputs. The gene transcripts studied were grouped based on their functional role under functional indices, termed detoxification (DTI), cytoprotection (CTI), and inflammation index (ITI), respectively. A central composite statistical design (CCD) was used to study the effects of dietary metabolizable energy (ME) content, crude protein (CP) content (90–100% of the Ross 308 recommended specifications), and phytogenic inclusion (0–2,000 mg/kg of diet), each at 3 levels, on the functional indices DTI, CTI, and ITI in the duodena and ceca of 42-d-old broilers. A total of 540 1-d-old male Ross broilers were allocated in 36 experimental runs for 42 d. At the end of the trial, 3 broilers per run (108 total) were analyzed for the relative expression of 25 genes, grouped under DTI (5 genes), CTI (8 genes), and ITI (12 genes) per each intestinal segment. Response surface methodology (RSM) was used to assess dietary factor interactions, and empirical models describing the DTI, CTI, and ITI were fitted. The fitted models were significant (P < 0.001) with no lack of fit (P > 0.05) and explained most of the variance in the functional indices, having R2 values of 0.63 and 0.90 for DTI, 0.59 and 0.66 for CTI, and 0.92 and 0.91 for ITI in the duodena and ceca, respectively. The functional indices were significantly (P < 0.05) modulated by dietary ME and CP contents, irrespective of phytogenic inclusion. Reducing dietary ME and CP from 100% to 90% of recommended specifications increased DTI and ITI but decreased CTI. Phytogenic inclusion strongly (P < 0.001) modulated all functional indices, increased CTI, and reduced DTI and ITI levels, resulting in higher cytoprotective and lower detoxification and inflammatory physiological response levels. Defining critical gut homeostasis response levels and how these can be modulated via diet may hold opportunities for better gut function and ultimately sustainable poultry production.

Key Words: Dietary specifications, statistical modeling, gene transcripts.