Response of YPM x Ross 708 male broilers to diets containing varying inclusions of phytase, calcium butyrate, and bacitracin methylene disalicylate during the grower and finisher periods–Part 2:Intestinal health and physioloy

Authors: GULIZIA, J - Auburn University; KHALID, Z - Auburn University; TERRA-LONG, M - Auburn University; VARGAS, J - Auburn University; HERNANDEZ, J - Auburn University; PACHECO, W - Auburn University; KREHLING, J - Auburn University; MACKLIN, K - Auburn University; DOZIER, III, W - Auburn University; McCafferty, Klinton; HAUCK, R - Auburn University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2025
Publication Date: 1/31/2025
Citation: Gulizia, J.P., Khalid, Z., Terra-Long, M.T., Vargas, J.I., Hernandez, J.R., Pacheco, W.J., Krehling, J.T., Macklin, K.S., Dozier, Iii, W.A., Mccafferty, K.W., Hauck, R. 2025. Response of YPM x Ross 708 male broilers to diets containing varying inclusions of phytase, calcium butyrate, and bacitracin methylene disalicylate during the grower and finisher periods–Part 2:Intestinal health and physioloy. Poultry Science. 104:104862. https://doi.org/10.1016/j.psj.2025.104862.
DOI: https://doi.org/10.1016/j.psj.2025.104862

Interpretive Summary: The use of antibiotic growth promoters (AGP) such as bacitracin methylene disalicylate (BMD) has been an important feed additive for improving the growth performance and health of broilers because it helps prevent diseases caused by gram-positive bacteria. Its antimicrobial properties help reduce the pathogenic bacterial load in the intestine and may help modulate the intestinal microbiota in a positive way. However, consumers have placed demands to reduce the use of AGP. The removal of AGP from broiler diets has led to increased incidences of subclinical enteric infections which has decreased broiler productivity and increased economic losses. Therefore, microbiota modulating feed additives (MMFA) that are not antibiotics such as calcium butyrate (CB) are needed to help maintain broiler intestinal health in the absence of AGP. However, the efficacy of non-antibiotic MMFA may be affected by other commonly used feed additives such as phytase. This study determined that the supplementation of phytase, CB, and BMD all influenced intestinal health and physiology of broilers. However, the supplementation of phytase and BMD or CB in combination had more pronounced effects on jejunal tight junction and mucin gene expression, as well as on cecal microbiome diversity and predicted bacterial metabolic function than when supplemented alone. Therefore, microbiota modulating potential of BMD and CB appears to be dependent on phytase concentration. Improving broiler intestinal health and performance of broilers without AGP will require a comprehensive understanding of non-antibiotic MMFA on broiler intestinal health and microbiome as well as the interactive effects with other feed additives.

Technical Abstract: This study evaluated the effects of calcium butyrate (CB) and bacitracin methylene disalicylate 50 (BMD) combined with different phytase concentrations on broiler intestinal health and physiology. Day-old YPM x Ross 708 male broilers (2,880) were distributed in 72 floor pens and assigned to 1 of 9 treatments (8 replicates/treatment). This experiment was a factorial arrangement including 2 phytase concentrations (500 or 1,500 FTU/kg) and 4 microbiota modulating feed additive levels (MMFA; (1) none, (2) only CB (0.5 g/kg of diet), (3) only BMD (55 ppm/kg of diet), or (4) both CB and BMD). Additionally, a negative control without phytase and MMFA was included. Intestinal permeability was assessed on d 27. Jejunum wall and cecal content samples were collected on d 28 and 42 to assess jejunum villus height (VH), crypt depth, tight-junction and mucin gene expression, cecal microbiome diversity, and predicted bacterial metabolic pathways. Phytase and MMFA did not influence intestinal permeability (P > 0.05). Combining both CB and BMD with 1,500 FTU/kg of phytase compared to 500 FTU/kg lowered d 28 VH (P = 0.05). Jejunal expression of CL-1, CL-4, CL-5, and ZO-2 on d 28 as well as CL-2 on d 42 changed between MMFA when combined with 1,500 FTU/kg of phytase but not 500 FTU/kg (P = 0.05). Day 42 Pielou’s evenness increased when 1,500 FTU/kg of phytase was combined with both CB and BMD compared to no MMFA, whereas d 42 observed features was higher with 500 FTU/kg and no MMFA compared to both CB and BMD (P = 0.05). Phytase concentration shifted the cecal microbial beta-diversity for both CB and BMD, but not for the other MMFA (P = 0.05). Overall, broiler intestinal health and physiology were influenced by CB and BMD depending on phytase concentration, demonstrating the complex interactions between these feed additives.