Effect of stocking density and dietary antimicrobial inclusion of male broilers grown to 35 days of age1 Part 1: Biochemical and enzymatical variables

Authors: Olanrewaju, Hammed; Purswell, Joseph - Jody; Collier, Stephanie; BRANTON, SCOTT - Retired ARS Employee

Submitted to: International Journal of Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2020
Publication Date: 9/10/2020
Citation: Olanrewaju, H.A., Purswell, J.L., Collier, S.D., Branton, S.L. 2020. Effect of stocking density and dietary antimicrobial inclusion of male broilers grown to 35 days of age1 Part 1: Biochemical and enzymatical variables. International Journal of Poultry Science. 19:403-410. https://scialert.net/abstract/?doi=ijps.2020.403.410.
DOI: https://doi.org/10.3923/ijps.2020.403.410

Interpretive Summary: Stocking Density (SD) high SD may restrict bird movement, increase litter moisture, microbial growth, and impede air flow among others, thereby affecting production performance and welfare. Currently, consumers perceive stocking density to be one of the most important factors that influence animal welfare and the application of optimal welfare standards where low stocking density is believed to result in a higher product quality. Furthermore, antimicrobials have been added in animal feed to improve growth, feed conversion ef'ciency and to prevent diseases. However, there are concerns that the use of antibiotics leads to development of antimicrobials resistance that posing a potential threat to human health. Therefore, a significant expansion of antibiotic-free (ABF) broiler production is expected to continue as demand for poultry products continues to increase. In each trial of 2 trials, we evaluated the effects of stocking density, dietary antimicrobial inclusion and their interaction if any on selected blood plasma biochemical, enzymatical variables, and electrolytes levels of male broilers grown to 35 days of age to ensure the health and welfare of broilers. Results show that only uric acid was affected by stocking density. However, in comparison to broilers fed the ABF diet, broilers with AGP+ had significant effects on most of the examined variables, but all these changes are still within the normal body homeostasis and physiological ranges of this species indicating an absence of physiological stress. The results are in broad agreement with those reported in the literature and contribute to our knowledge of blood metabolites and homeostatic variation in developing male broilers. It was concluded that stocking densities up to 39 kg/m2 with appropriate environmental management regardless of antimicrobial addition in the diets may be suitable for both poultry integrators and contract growers to enhance broilers production efficiency without compromising the welfare of broilers grown to 35 days of age.

Technical Abstract: This study investigated the effects of recommended stocking densities and dietary antimicrobial inclusion of male broilers grown to 35 days of age on selected hematobiochemical and enzymatical variables. Materials and Methods: A total of 1952 1-d- old Ross x Ross 708 male chicks were randomly distributed into 32 pens based on 4 assigned stocking density treatments. The treatments consisted of 4 densities (27, 29, 33, 39 kg/m2) and 2 diets (AGP+, ABF) arranged in a 4 × 2 factorial with eight replicates. Conventional (antimicrobial-growth-promoters, AGP+) and antibiotic free (ABF) diets were equally assigned to each pen with feed and water provided ad libitum. Blood samples were collected from the brachial wing vein of 3 birds per pen on d 15, 28, and 35. The collected blood samples were centrifuged to separate the plasma and used to determine the concentration of biochemical parameters and enzyme activities using an ACE-AXCEL automatic analyzer. Results: Results show that only UA was affected by stocking density. However, in comparison to broilers fed the ABF diet, broilers with AGP+ had significant effects on ALB, TP, ALP, GGT, Ca2+, and K+ along with lower TBILI. The results are in broad agreement with those reported in the literature and contribute to our knowledge of blood metabolites and homeostatic variation in developing male broilers. Conclusion: The results indicating that stocking densities up to 39 kg/m2 with appropriate environmental management regardless of antimicrobial addition in the diets may be suitable for both poultry integrators and contract growers to enhance broilers production efficiency without compromising the welfare of broilers grown to 35 days of age.