Evaluation of Intestinal Morphology and Serologic Profiles of Commercially Reared Broilers on Conventional and Alternative Feeding Programs

Antimicrobials are categorized into 4 groups with Category I, II, and III classified as important to human medicine while Category IV has low importance. Chemical coccidiostats are not classified as antibiotics. Canadian broilers may be reared on the following programs: conventional (CON, Category III and IV antibiotics and avilamycin permitted), raised without antibiotics of human importance (RWAOHI, Category IV antibiotics and avilamycin permitted), or raised without antibiotics (RWA, no antibiotics permitted from any category). The objective of this study was to evaluate the impact of program on intestinal morphology and serology of commercial broilers to determine if observed breast yield differences were related to gastrointestinal physiology or systemic metabolism. At 28 days of age, 144 birds/program were sampled from 9 farms in Ontario over 6 consecutive flocks. Birds were bled for plasma, euthanized, weighed, and necropsied for liver weight, small intestine weight, length, and jejunal morphology. Analysis of variance was conducted on effect of program over time (Proc Glimmix,SAS 9.4). Program did not (P>0.05) affect BW, small intestine weight or length, jejunal morphology (villus height, crypt depth, VH:CD), plasma proteins or electrolytes. RWA had the largest liver weight compared to CON (P=0.04). Plasma aspartate transaminase (AST, P=0.01) and creatine kinase (CK, P=0.004) were lowest in RWA compared to CON. Lactate dehydrogenase (LDH) was lowest in RWA compared to RWAOHI (P=0.04). RWA had the highest alkaline phosphatase (ALP, P=0.05) and gammaglutamyl transferase (GGT, P=0.03). Elevated enzymes in CON birds may be due to protein turnover related to growth rate. Elevated liver weight and GGT in RWA may indicate compromised liver function. Further investigations are required to determine a link between program, morphology and serology on performance.

Key words: antibiotic, intestine, plasma.

Presented at the 2021 Animal Nutrition Conference of Canada. For information on the next edition, click here.