Effect of a synbiotic supplement as an antibiotic alternative on broiler skeletal, physiological, and oxidative parameters under heat stress

Authors: HU, JIAYING - Purdue University; MOHAMMED, AHMED - Assiut University; MURUGESAN, RAJ - Biomin America, Inc; Cheng, Heng-Wei

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2022
Publication Date: 2/1/2022
Citation: Hu, J., Mohammed, A.A., Murugesan, R.M., Cheng, H. 2022. Effect of a synbiotic supplement as an antibiotic alternative on broiler skeletal, physiological, and oxidative parameters under heat stress. Poultry Science. 101(4). Article 101769. https://doi.org/10.1016/j.psj.2022.101769.
DOI: https://doi.org/10.1016/j.psj.2022.101769

Interpretive Summary: Heat stress is one of the most detrimental environmental stressors facing the broiler chicken industry. Subtherapeutic antibiotics have been used as feed additives to prevent infectious diseases and to promote growth performance in broiler production since the 1920s. However, use of antibiotics in animal husbandry has raised public concerns about drug residues in meat products and the development of antibiotic-resistant bacteria. The objective of this study was to determine if the effects of synbiotics on production, skeletal health, immune response, and oxidative status are comparable with antibiotics in broilers subjected to heat stress. Our results showed that antibiotic, bacitracin methylene disalicylate, can promote broiler growth performance but may lose its efficacy under heat stress. The synbiotic supplement attenuates negative effect of heat stress by improving body weight, foot health, leg strength, and immunity in stressed broilers. The data suggests the synbiotic has the potential as an antibiotic alternative in broiler production, especially in the tropical and subtropical regions.

Technical Abstract: The aim of this study was to examine if synbiotics function as alternatives to antibiotics in broiler production under heat stress (HS). Five hundred and twenty-eight day-old broiler chicks were randomly placed in 48 floor pens within 2 temperature-controlled rooms (11 birds/pen and 24 pens/room). The pens of each room were evenly divided among 3 treatments (n=8): basal diet (CON), the basal diet mixed with 50 ppm of bacitracin methylene disalicylate (BMD) or a synbiotic (50 ppm of PoultryStar® meUS, SYN). On day 15, HS was applied to room 1 at 32oC for 9 hrs (0800 to 1700) (HS-CON, HS-BMD, and HS-SYN), while room 2 was under thermoneutral (TN) conditions (TN-CON, TN-BMD, and TN-SYN). Treatment effects on footpad dermatitis, gait score, and latency to lie (LTL) test were detected on day 27 and day 41; and 1 broiler/pen was sampled on day 28 and day 42, respectively. Body, liver, and spleen weight were determined. Plasma levels of interleukins (IL), heat shock protein 70, immunoglobulin (Ig)Y, liver superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzyme activities were examined. Heat stress suppressed BW and IgY concentrations on both day 28 and day 42, while it only suppressed plasma IL-6 concentrations, SOD activities, and LTL duration on day 28 only (P < 0.05). Among all treatments, SYN birds had the best foot and skeletal health scores on both day 27 and day 41 (P < 0.05). On day 42, SYN increased BW, and TN-SYN birds had higher relative spleen weight than both TN-BMD and TN-CON birds (P < 0.05). Antibiotic BMD increased BW (P < 0.05) but decreased SOD activities (P < 0.05) on day 42. These results indicate the SYN supplementation decreases HS negative effects on broilers by improving BW, foot, and skeletal health, while BMD improves BW but also increases oxidative stress in broilers. The data suggest the synbiotic has the potential as an antibiotic alternative in broiler production, especially in the tropical and subtropical regions.