Comparative impact of conventional and alternative gut health management programs on plasma and tibia attributes in broiler chickens raised in commercial and research settings

Plasma and tibia attributes were investigated in broiler chickens raised on three gut health management programs in commercial farms (study 1) and research station settings (study 2). The programs were: 1) conventional antibiotics (CON), 2) raised without medically important antimicrobials (RWMIA), and 3) raised without antibiotics (RWA). Birds had free access to feed and water from placement to harvest; samples of blood and left tibia were collected on d 28 in both studies and further samples were taken on d 41 in study 2. In both studies, there were no program differences (P > 0.05) on plasma metabolites with exception of enzyme concentrations with notably higher levels of circulating plasma alkaline phosphatase (ALP) in birds reared on the RWA program (P ≤ 0.04). Differences were observed among programs for tibia length in both studies (P < 0.05). Birds reared on RWMIA exhibited significantly (P = 0.016) higher tibia ash than CON on d 41. Observed differences in the plasma enzyme concentrations, tibia length, and ash concentration suggest altered metabolism which could be linked to gut health management programs and their ability to support gut integrity and function in the absence of antibiotics.