Poultry or Avian Science Commons^™

Impact Of Reducing Ammonia Concentration By Ozone Technology And Its Potential Improvement On Broiler Performance, Odilpio Quintana Ortega

Graduate Theses and Dissertations

The employment of ozone in livestock production as a means of mitigating ammonia is used for enhancing air quality within animal confinement facilities, such as swine or poultry barns. Ammonia is a byproduct of animal excrement. Elevated ammonia concentrations can adversely affect the well-being of both animals and humans. The aim of this thesis was to investigate the effects of Ozone Technology Machine Unit (OTMU) utilization in poultry barns regarding ammonia concentration and its potential benefit in terms of broilers performance and welfare. In recent years, there has been a significant boom in technological advances. New devices that help mitigate …

Assessment Of Dietary Energy And Amino Acid Diet Formulation In The Modern Broilers, Matheus Freitas Costa

Graduate Theses and Dissertations

As a result of the advancement of genetics, understanding broiler requirements for dietary energy and amino acids is essential for improving live performance and carcass characteristics. The energy system used to formulate diets in poultry is based on metabolizable energy (ME); this equation can be described as the total amount of energy in the feed minus gases and feces. However, the net energy (NE) system may be the best depiction of the energy utilized by birds for production and maintenance purposes once the heat increment (HI) is measured. Thus, a series of studies were conducted to establish the responsiveness of …

Controlling Salmonella: Strategies For Feed, The Farm, And The Processing Plant, Tomi Obe, Timothy Boltz, Mike Kogut, Steven C. Ricke, Lasheda A. Brooks, Ken Macklin, Ashley Peterson

Poultry Science Faculty Publications and Presentations

Controlling Salmonella in poultry is an ongoing food safety measure and while significant progress has been made, there is a need to continue to evaluate different strategies that include understanding Salmonella-poultry interaction, Salmonella-microbiota interactions, Salmonella genetics and response to adverse conditions, and preharvest and postharvest parameters that enable persistence. The purpose of this symposium is to discuss different strategies to consider from feed milling to the farm to the processing environment. This Poultry Science Association symposium paper is divided into 5 different sections that covers 1) immunological aspects of Salmonella control, 2) application of Salmonella genetics for targeted …

Innovative Approaches To Poultry Processing Wastewater Treatment: The Stainless Steel Ultrafiltration Membrane As A Viable Option, Saubana Olorunrola Dada, Chidambaram Thamariselvan, Mahmood Jebur, Sumith Ranil Wickramasinghe

Chemical Engineering Faculty Publications and Presentations

In pursuit of sustainability, we explored replacing conventional dissolved air floatation (DAF) in poultry processing wastewater (PPW) treatment with a precisely tuned 0.02 µm stainless-steel ultrafiltration (SSUF) membrane. SSUF is a robust, homogenously porous membrane with strong chemical resistance, ease of cleaning, and exceptional resistance to organic fouling. Unlike polymeric membranes, it can be regenerated multiple times, making it a cost-effective choice due to its compatibility with harsh chemical cleaning. The PPW used for the study was untreated wastewater from all processing units and post-initial screening. Our study revealed the SSUF membrane’s exceptional efficiency at eliminating contaminants. It achieved an …

An Amplification-Free Crispr-Sers Biosensor For Specific, Sensitive And Rapid Detection Of Salmonella Typhimurium In Poultry, Fei Jia, Bingyan Li, Yawen He, Yafang Shen, Juhong Chen, Xingmin Li, Yanbin Li

Biological and Agricultural Engineering Faculty Publications and Presentations

CRISPR (Clustered regularly interspaced short palindromic repeats) has been a cutting-edge biotechnology in both gene editing and biosensing due to its desirable features, such as high base resolution and set-and-forget operation. However, as a nucleic acid detection method, an DNA/RNA amplification procedure is still inevitable in CRISPR biosensors. In this study, a highly-ordered nanopore array SERS substrate, coated with silver nanoparticles, was fabricated and utilized as a platform for the specific detection of Salmonella Typhimurium (S. Typhimurium) without the time-consuming DNA amplification step. The smart sensing strategy was established by introducing an ssDNA labeled with a Raman active molecule …

Characterizing The Impact Of Enterococcus Cecorum Infection During Late Embryogenesis On Disease Progression, Cecal Microbiome Composition, And Early Performance In Broiler Chickens, Marcela Arango, Aaron Forga, Jing Liu, Latasha Gray, Randy Moore, Makenly E. Coles, Abdiel Atencio, Carolina Trujillo, Juan David Latorre, Guillermo Tellez-Isaias, Billy Hargis, Danielle Graham

Poultry Science Faculty Publications and Presentations

Enterococcus cecorum (EC) has been associated with septicemia and early mortality in broiler chickens. There is limited research investigating the pathogenicity of EC field strains obtained from affected birds. The purpose of this study was to evaluate the effect of in-ovo administration into the amnion with different EC field isolates at d 18 of embryogenesis (DOE18). In Exp 1, 7 EC field isolates alone or in combination (EC1–EC3, EC4–EC5, EC6, and EC7) were selected based on phenotypic characteristics and evaluated at different concentrations (1 × 10², 1 × 10⁴, and 1 × …

Understanding Functional Benefits Of Isoleucine And Arginine On Poultry Performance And Health., Roshan Adhikari, Jason T. Lee, Keith Haydon

Proceedings of the Arkansas Nutrition Conference

Poultry industry is rapidly moving towards utilizing the best ingredients to precisely feed the birds for better performance, welfare, health, and profitability. One of the practices that evolved over time with research is better optimization of amino acid utilization in the diets thus changing the crude protein landscape. Historically, if we compare the modern diets to diets from 1980, significant changes are visible in the use of unbound or crystalline amino acids leading to reduced levels of CP and reduced unutilized nitrogen in the diets. Multiple feed-grade amino acids are available in a cost-effective manner in poultry diets. Multiple research …

Potent Bile Acid Microbial Metabolites Modulate Clostridium Perfringens Virulence, Tahrir Jatli Alenezi, Ying Fu, Bilal Alrubaye, Thamer Alanazi, Ayidh Almansour, Hong Wang, Xiaolun Sun

Poultry Science Faculty Publications and Presentations

Clostridium perfringens is a versatile pathogen, inducing diseases in the skin, intestine (such as chicken necrotic enteritis (NE)), and other organs. The classical sign of NE is the foul smell gas in the ballooned small intestine. We hypothesized that deoxycholic acid (DCA) reduced NE by inhibiting C. perfringens virulence signaling pathways. To evaluate the hypothesis, C. perfringens strains CP1 and wild-type (WT) HN13 and its mutants were cultured with different bile acids, including DCA and isoallolithocholic acid (isoalloLCA). Growth, hydrogen sulfide (H₂S) production, and virulence gene expression were measured. Notably, isoalloLCA was more potent in reducing growth, H …

Isolation, Characterization, And Experimental Infection Of Streptococcus Gallolyticus Subspecies Pasteurianus From Commercial Turkeys With Acute Septicemia: A Pilot Study, L. S. Gray, J. D. Latorre, D. Hernandez-Patlan, B. Solis-Cruz, V. Petrone-Garcia, X. Hernandez-Velasco, K. M. Robbins, R. W. Moore, C. N. Vuong, A. Stein, L. Laverty, K. Martin, M. E. Coles, R. Señas-Cuesta, J. M. Diaz-Gomez, I. Loeza, I. Castellanos-Huerta, J. A. Maguey-Gonzalez, B. D. Graham, B. M. Hargis, G. Tellez-Isaias

Poultry Science Faculty Publications and Presentations

Streptococcus gallolyticus (SG) is a Gram-positive cocci found as commensal gut flora in animals and humans. SG has emerged as a cause of disease in young poults between 1 and 3 wk of age. SG is associated with septicemia resulting in acute mortality with no premonitory signs in turkeys. Three SG isolates were obtained from clinical field cases of acute septicemia of commercial turkeys and used in three independent experiments. In Experiment 1, embryos were inoculated 25 d of embryogenesis with varying concentrations of SG1, SG2, or SG3. In Experiment 2, day of hatch, poults were inoculated with varying concentrations …

Feed Formulation: Expanding Our Horizons Beyond The Simple Provision Of Least-Cost Diets, Rick Kleyn, Mariana Ciacciariello

Proceedings of the Arkansas Nutrition Conference

Commercial feed formulation is typically based on linear programming (LP) algorithms that derive a least-cost solution for a blend of ingredients that meet specific nutrient criteria. This methodology has been effectively used for decades, but how we achieve our primary goal, which is sustainable poultry production, needs to be reconsidered in broader terms. Some of the issues that this paper will deal with are: not all parameters that we consider are linear and additive; we are still unsure of how to build the matrix required for feed formulation; dealing with the variability encountered in every batch of ingredient remains a …

Reducing Feed’S Environmental Footprint: Where Are The Opportunities?, Lara Moody

Proceedings of the Arkansas Nutrition Conference

Working with animal food industry members and stakeholders up- and down-stream in the supply chain, the Institute for Feed Education and Research (IFEEDER) developed a ‘Sustainability Road Map’ to support the U.S. animal food industry as it pursues continuous improvement on impacts important to industry members and their customers. For IFEEDER and the American Feed Industry Association (AFIA), sustainability is defined and managed by each individual organization to deliver measurable, continuous improvements on the impacts related to people, planet and governance that are most important to them and their stakeholders.

No Antibiotic Ever (Nae) Versus Conventional Broiler Production: It’S Complicated, Marcos H. Rostagno

Proceedings of the Arkansas Nutrition Conference

Broiler production has evolved significantly over the years to meet a constant growing demand for animal protein. Rooted on major advances in genetics, facilities and environmental conditions, management, and specially, in nutrition and health, the U.S. broiler industry improved tremendously in productivity and efficiency, clearly demonstrated by a marked reduction of the average market age (i.e., days to market), while significantly increasing average market weight, breast meat yield and feed efficiency (National Chicken Council, 2023). For decades, conventional broiler production was dominant, with extensive use of antibiotics to promote growth and manage disease challenges (prevention and control). However, concerns over …

Organic Trace Minerals In Environmentally Sustainable Systems, Sergio L. Vieira, Julmar C. Feijó, André Favero

Proceedings of the Arkansas Nutrition Conference

Essential trace minerals (Zn, Cu, Fe, Mn, Se and I) are traditionally included as supplements through mineral premixes in poultry feeds. In comparison to other essential nutrients, as well as energy, they are scarcely studied. The essentiality of a nutrient, by definition, refers to the nutrient role in normal body function, such as growth or egg production, and considers that they cannot be synthesized by the body and, therefore, must be supplied from the feed.

Application Of New Molecular Tools To Assess Virus Viability In Production Animals, Declan C. Schroeder

Proceedings of the Arkansas Nutrition Conference

Persistent viral infections routinely impose an inconvenient, always costly but thankfully not all too often catastrophic outcome on our modern food system. Managing viruses is key for all concerned if our objective is to meet the ever-growing demand to high-value animal protein. Whether it’s the impact influenza A virus (IAV) has on the avian or swine industries, Porcine reproductive and respiratory virus (PRRSV) on the swine or Deformed wing virus (DWV) on honey bees in both the honey and pollinator sectors - the negative impact and damaging cost to the individual producer, country and global economy cannot be overstated.

A View Of Poultry Production In The Americas, Michael Donohue

Proceedings of the Arkansas Nutrition Conference

The primary goal of the presentation is to share a long-term overview of how broiler production has changed over the last 35 years in areas of bird performance, production costs, particularly in the area of feed ingredient cost per lb. and illustrating how poultry nutritionists have adapted feed formulations to meet the changes in performance and cost.

Alkaline Pretreatment And Air Mixing For Improvement Of Methane Production From Anaerobic Co-Digestion Of Poultry Litter With Wheat Straw, Yuanhang Zhan, Jun Zhu, Yiting Xiao, Leland C. Schrader

Biological and Agricultural Engineering Faculty Publications and Presentations

Alkaline pretreatment (AL) and air mixing (air) both have the potential to improve anaerobic co-digestion (Co-AD) of poultry litter with wheat straw for methane production. In this study, the effects of the combination of AL (pH 12 for 12 h) and air mixing (12 mL·d⁻¹) on the Co-AD process were investigated. The substrate hydrolysis was enhanced by AL, with soluble chemical oxygen demand increased by 4.59 times and volatile fatty acids increased by 5.04 times. The cumulative methane yield in the group of Co-AD by AL integrated with air (Co-(AL + air)), being 287 mL·(g VS_added) …

Evaluation Of Clostridium Septicum Hemolytic Activity, Administration Route, And Dosage Volume Of A Clostridial Dermatitis (Cellulitis) Bacterin-Toxoid On Humoral Immune Response In Commercial Turkeys, Aaron Forga, Kabel Robbins, Andrew Smith, Makenly Coles, Guillermo Tellez-Isaias, Christine N. Vuong, Billy Hargis, Danielle Graham

Poultry Science Faculty Publications and Presentations

Clostridial cellulitis or dermatitis affects commercial turkey flocks, primarily as they approach market age. In the field, this disease has been effectively controlled with antibiotics, but alternatives to antibiotics are needed. Bacterin-toxoid vaccination programs have been shown to prevent clostridial diseases in other species, including humans. Results from previous field studies indicate that vaccination with an experimental whole-cell Clostridium septicum (CS) bacterin-toxoid oil emulsion vaccine reduced clostridial dermatitis-associated mortality and antibiotic usage for some commercial turkey flocks, but vaccination was not always efficacious. To improve vaccine efficacy, studies were conducted to optimize the antigenic component of the experimental …

Dietary Histidine: Broiler Responsiveness With And Without Endogenous Histidine Reserve Consideration, Kenneth Blake Nelson

Graduate Theses and Dissertations

In the past, histidine warranted little concern from poultry nutritionists because it was seldom deficient in practical broiler diets. With most essential amino acids now commercially available as feed-grade forms to partially replace intact protein ingredients, histidine and its minimum in least-cost formulation are receiving fresh attention. Published histidine requirement data for broilers are sparce, and many of these studies have been conducted on males within the first three weeks post-hatch. Moreover, rudimentary dose-response experimental designs may not be applicable to estimate histidine requirements in later growth periods because histidine is uniquely stored within the body. In times of dietary …

Research Note: Isolation, Speciation, And Anticoccidial Sensitivity Of Eimeria Spp. Recovered From Wild Turkey Feces In The United States, Carolina Trujillo-Peralta, Aaron Ashcraft, Roberto Señas-Cuesta, Makenly Coles, Xochitl Hernandez-Velasco, Callie Selby, Aaron Forga, Guillermo Tellez-Isaias, Christine Vuong, Lisa Bielke, John R. Barta, Billy Hargis, Danielle Graham

Poultry Science Faculty Publications and Presentations

Between 2018 and 2020, over 100 wild turkey fecal samples were collected from the Eastern and Central thirds of the United States, where commercial turkey production is uncommon. We hypothesized that anticoccidial-sensitive Eimeria spp. would be present in wild turkey fecal samples. Samples containing Eimeria spp. oocysts were amplified in vivo. If propagation was successful, the samples were PCR-speciated and subjected to anticoccidial sensitivity testing (AST) for key members of both ionophore and chemical categories of anticoccidial drugs. The purpose of this study was to isolate Eimeria spp. relevant to commercial turkey production that possessed sensitivity to monensin, …

Assessing The Effects Of A Mixed Eimeria Spp. Challenge On Performance, Intestinal Integrity, And The Gut Microbiome Of Broiler Chickens, Danielle Graham, Victor Petrone-Garcia, Xochitl Hernandez-Velasco, Makenly E. Coles, Marco A. Juarez-Estrada, Juan D. Latorre, Jianmin Chai, Stephanie Shouse, Jiangchao Zhao, Aaron Forga, Roberto Señas-Cuesta, Lauren Laverty, Kristen Martin, Carolina Trujillo-Peralta, Ileana Loeza, Latasha Gray, Billy M. Hargis, Guillermo Tellez-Isaias

Poultry Science Faculty Publications and Presentations

A mixed Eimeria spp. challenge model was designed to assess the effects of challenge on broiler chicken performance, intestinal integrity, and the gut microbiome for future use to evaluate alternative strategies for controlling coccidiosis in broiler chickens. The experimental design involved broiler chickens divided into two groups: a control group (uninfected) and a positive control group, infected with Eimeria acervulina (EA), Eimeria maxima (EM), and Eimeria tenella (ET). At day-of-hatch, 240 off-sex male broiler chicks were randomized and allocated to one of two treatment groups. The treatment groups included: (1) Non-challenged (NC, n = 5 replicate pens); and (2) challenged …

Editorial: Fat Metabolism And Deposition In Poultry: Physiology, Genetics, Nutrition Volume Ii, Sami Dridi

Poultry Science Faculty Publications and Presentations

Editorial on the Research Topic

Fat metabolism and deposition in poultry: physiology, genetics, nutrition Volume II

Horizontal Transfer Of Probable Chicken-Pathogenicity Chromosomal Islands Between Staphylococcus Aureus And Staphylococcus Agnetis, Douglas D. Rhoads, Jeff Pummil, Nnamdi S. Ekesi, Adnan A.K. Alrubaye

Cell and Molecular Biology Faculty Publications and Presentations

Staphylococcus agnetis is an emerging pathogen in chickens but has been most commonly isolated from sub-clinical mastitis in bovines. Previous whole-genome analyses for known virulence genes failed to identify determinants for the switch from mild ductal infections in cattle to severe infections in poultry. We now report identification of a family of 15 kbp, 17–19 gene mobile genetic elements (MGEs) specific to chicken osteomyelitis and dermatitis isolates of S. agnetis. These MGEs can be present in multiple copies per genome. The MGE has been vectored on a Staphylococcus phage that separately lysogenized two S. agnetis osteomyelitis strains. …

In Vitro And In Vivo Evaluation Of Chlorhexidine Salts As Potential Alternatives To Potassium Dichromate For Eimeria Maxima M6 Oocyst Preservation, Lauren Laverty, Lesleigh C. Beer, Kristen Martin, Xochitl Hernandez-Velasco, Marco A. Juarez-Estrada, Marcela Arango-Cardona, Aaron Forga, Makenly E. Coles, Christine N. Vuong, Juan D. Latorre, Roberto Señas-Cuesta, Ileana Loeza, Latasha Gray, John R. Barta, Billy M. Hargis, Guillermo Tellez-Isaias, Brittany D. Graham

Poultry Science Faculty Publications and Presentations

Introduction: Coccidiosis caused by the Eimeria spp., an Apicomplexan protozoon, is a major intestinal disease that affects the poultry industry. Although most cases of coccidiosis are subclinical, Eimeria infections impair bird health and decrease overall performance, which can result in compromised welfare and major economic losses. Viable sporulated Eimeria oocysts are required for challenge studies and live coccidiosis vaccines. Potassium dichromate (PDC) is typically used as a preservative for these stocks during storage. Although effective and inexpensive, PDC is also toxic and carcinogenic. Chlorhexidine (CHX) salts may be a possible alternative, as this is a widely used disinfectant with less …

Impact Of Eimeria Meleagrimitis And Intermittent Amprolium Treatment On Performance And The Gut Microbiome Composition Of Turkey Poults, Carolina Trujillo-Peralta, Juan David Latorre, Jianmin Chai, Roberto Señas-Cuesta, Aaron Forga, Makenly Coles, Jiangchao Zhao, Xochitl Hernandez-Velasco, Guillermo Tellez-Isaias, John R. Barta, Lisa Bielke, Billy Hargis, Danielle Graham

Poultry Science Faculty Publications and Presentations

Introduction: Drug-sensitive live coccidiosis vaccines have been used to control coccidiosis and renew drug sensitivity in commercial chicken operations. However, only limited species coverage vaccines have been available for commercial turkey producers. This study aimed to assess the effect of an E. meleagrimitis vaccine candidate, with and without amprolium intervention, on performance and oocyst shedding. Additionally, the effect of vaccination, amprolium treatment, and E. meleagrimitis challenge on intestinal integrity and microbiome composition was evaluated.

Methods: Experimental groups included: (1) NC (non-vaccinated, non-challenged control); (2) PC (non-vaccinated, challenged control); (3) VX + Amprol (E. meleagrimitis candidate vaccine + amprolium); and …

Peripheral And Central Impact Of Methionine Source And Level On Growth Performance, Circulating Methionine Levels And Metabolism In Broiler Chickens, Craig W. Maynard, Elizabeth Gilbert, Frances Yan, Mark A. Cline, Sami Dridi

Poultry Science Faculty Publications and Presentations

The present study was designed to evaluate the effects of DL-methionine (DL-Met) 2-hydroxy-4-(methylthio) butanoic acid (HMTBa), or S-(5′-Adenosyl)-L-methionine chloride (SAM), using feeding trial and central administration, on live performance, plasma metabolites, and the expression of feeding-related hypothalamic neuropeptides in broilers raised to a market age (35 d). Final average body weight (BW) and feed conversion ratio (FCR) from the feeding trial exceeded the performance measurements published by the primary breeder. At d35, the MTBHa group had better BW and lower feed intake, which resulted in a better FCR than the DL-Met group at 87 TSAA to lysine. At the molecular …

Impact Of Phytase Supplementation On Meat Quality Of Heat-Stressed Broilers, C. J. Maynard, C. W. Maynard, Garrett J. Mullenix, Alison Ramser, Elizabeth S. Greene, Mike R. Bedford, Sami Dridi

Poultry Science Faculty Publications and Presentations

Heat stress (HS) is one of the most challenging stressors to poultry production sustainability. The adverse effects of HS range from feed intake and growth depression to alteration of meat quality and safety. As phytase supplementation is known to improve nutrient utilization and consequently growth, we undertook the present study to evaluate the effects of dietary phytase on growth and meat quality in heat-stressed broilers. A total of 720 day-old hatch Cobb 500 chicks were assigned to 24 pens within controlled environmental chambers and fed three diets: Negative Control (NC), Positive Control (PC), and NC diet supplemented with 2000 phytase …

Temporal, Phenotypic, And Quantitative Characterization Of Thyroid Infiltrating Mononuclear Cells During Development Of Spontaneous Autoimmune Thyroiditis In Obese Strain Chickens, Katelyn M. Clark

Poultry Science Undergraduate Honors Theses

The Obese strain (OS) of chickens spontaneously develops autoimmune thyroiditis and is a well-established biomedical model for Hashimoto’s thyroiditis in humans. Both conditions are characterized by the infiltration of the thyroid glands with mononuclear cells resulting in destruction of the thyroid tissue and impairment of the thyroid’s endocrinological functions. Past studies have described mononuclear cell infiltration in thyroids of the OS chickens, but the time-course, cell composition, and relative amounts of the various mononuclear cells infiltrating the thyroids has not been well defined. In this project, the mononuclear cell infiltrate was characterized phenotypically and quantitatively in OS chickens over the …

Poultry Pose Estimation With Deeplabcut, Chiyou Vang

Computer Science and Computer Engineering Undergraduate Honors Theses

This honors thesis dives into the realm of deep learning-based pose estimation research and investigates the potential of DeepLabCut (Lauer, et al., 2021) in accurately and efficiently estimating the pose of poultry. With accurate pose estimation being a crucial aspect in understanding the behavior and movement of animals, this thesis aims to contribute to the development of more effective methods for pose estimation, especially for poultry.

To comprehensively evaluate the performance of DeepLabCut, two different types of chickens were tested in this thesis: a model toy chicken and actual live chickens. Videos were recorded for both types, and key points …

Optimum Time To Add The Feed Additive Availa-Zmc To Reduce The Incidence Of Bacterial Chondronecrosis With Osteomyelitis Lameness In Broiler Chickens, Ashley Ault

Biological Sciences Undergraduate Honors Theses

Lameness is a health condition threatening the welfare of broiler chickens in the poultry industry. It can be caused by a bacterial infection called Bacterial Chondronecrosis with Osteomyelitis (BCO). Zinpro has created Avalia-ZMC, a feed additive that has been proven to reduce lameness by 20% in wire-flooring pens and 25% in litter-flooring pens (Alrubaye et al., 2020). This experiment focuses on the optimal time to add Availa-ZMC to the diet of the broiler chickens to help reduce the incidence of lameness. This trial took 56 days with 26 pens at the University of Arkansas Poultry Research Farm. At the start …

Effects Of Cyclic Heat Stress On The Acute Inflammatory Response In Broilers, Alessandro J. Rocchi

Poultry Science Undergraduate Honors Theses

Heat stress (HS) is a growing concern in broiler production due to increasing environmental temperatures. Little is known of the overall effect of HS on innate immunity. Lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria, is commonly used to study the inflammatory response. In avian species, the local tissue and systemic inflammatory activities in response to LPS may be determined concurrently, over time, in an individual, using the growing feather (GF) pulp dermal test along with blood measurements (dual-window approach). To examine the effect of cyclic HS on the local and systemic acute inflammatory responses, Cobb 500 male broiler …