Indian Journal of Animal Research

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Full Research Article

Effect of Stocking Density on Selected Blood Physiological, Biochemical and Enzymatical Variables of Broilers Grown to 3 kg under Antibiotic-free Conditions

Hammed A. Olanrewaju1,*, Christopher L. Magee1, Stephanie D. Collier1, Joseph L. Purswell1
1US Department of Agriculture, Agricultural Research Service, Poultry Research Unit, Mississippi State, Mississippi, 39762 USA.

ABSTRACT

Background: Reducing stocking densities may play a key role in minimizing difficulties such as physiological welfare when reducing or ending antimicrobials in poultry diets. As the demand for poultry and associated products increases, one of the major concerns centers on the question of whether stocking density influences welfare responses that are characteristic of physiological welfare. This study investigated the effect of stocking density on selected blood physiological variables along with plasma biochemistry variables and enzymes activities of broilers fed antibiotic-free diets grown to 3 kg.

Methods: A total of 888 1-d-old Ross ´ Ross 708 chicks were randomly distributed into 24 pens based on stocking density treatments assignment. The treatments consisted of 4 densities (29, 33, 39 and 42 kg/m2) with six replicates. Treatments were blocked within the room to account for any variations in room conditions. Treatment assignments were randomized within each block. Used litter bedding was obtained from commercial farms to mimic commercial conditions and litter microflora. Birds were provided a three phase-feeding program (Starter: 0-14 d, Grower: 15-28 d and Finisher: 29-42 d) antibiotic-free diets. Feed and water provided ad libitum. Blood samples were collected from the brachial wing vein of 3 males and 3 females’ birds per pen on d 28 and 42 and analyzed immediately for blood physiological variables. Blood plasma samples were analyzed for T3, T4, corticosterone, biochemical variables and enzyme activities.

Result: The only effect of stocking density was observed on partial pressure of CO2 (pCO2) and uric acid which were within physiological ranges for this species. However, blood glucose and plasma corticosterone concentrations were not affected by stocking density, suggesting no signs of physiological stress. Stocking densities up to 42 kg/m2 with proper environmental management may be suitable for both poultry integrators and contract growers to enhance broilers production efficiency without compromising the welfare of broilers grown to 3 kg body weight.

INTRODUCTION

Consumers assume stocking density (SD) to be one of the most crucial factors that influence animal welfare (Vanhonacker et al., 2009), but livestock producers on the other hand assume that reduction of stocking density for advanced animal welfare will have a negative impact on farm profitability. This is because as the number of birds per unit of housing space decreases, the cost of labor, housing, fuel and equipment per bird increases (Estevez, 2007). However, it has been documented that extremely high SD in broilers has been linked to growth retardation, increased proportion of downgraded poultry products, stress, bird’s disruption, lameness and substantial risk of health-related problems (Sanotra et al., 2001; Feddes et al., 2002; Thaxton et al., 2006).

One of the negative implications of extremely high SD is high moisture content of the litter that enhances microbial activities, leading to increased temperature and ammonia in broiler houses (Bessei, 2006). In addition, extreme SD is a predisposing factor in the pathogenesis of intestinal diseases and the mechanisms underlying these effects on poultry body physiological homeostasis. One of the microbial activities is necrotic enteritis, which is defined as an intestinal infection that has a high economic effect on health and welfare of broilers, which pose a threat to public health (Van der Sluis, 2000; Van Immerseel, et al., 2004).
 
Despite the importance of SD as a management practice, no universal SD recommendations exist. The National Chicken Council in the United States bases SD allowances on bird weight, with a range from 32 to 44 kg/m2. In Canada, it is required that broiler SD not exceed 31kg/m2 unless certain conditions are met, in which case SD can be increased up to a maximum of 38 kg/m2. In the European Union (EU), the largest SD is 33 kg/m2, but this can be increased to 39 kg/m2 or 42 kg/m2 if the producer follows specific requirements.

The public health issue of utilizing antibiotics as growth promoters (AGPs) in poultry diets is the claim that AGPs could increase the antimicrobial resistance of bacteria making antibiotics ineffective against foodborne illnesses (Hedman et al., 2020). The Food and Drug Administration (FDA) banned the use of antimicrobials as growth promoters in early 2017 (Singer et al., 2019). The increasing movement away from AGPs together with increasing market weights and alterations of SD, adjustment of traditional methods of housing management and environmental control is necessary to keep or improve production efficiency. But raising poultry without the use of antibiotics is a new challenge to the producers making the birds prone to a number of bacterial diseases (Dibner and Richards, 2005; Diarra and Malouin, 2014). While the need for poultry and related products increases, escalating production and production efficiencies will be important to the continued feasibility of domestic poultry industries in the United State and around the world.
 
Blood sample evaluation along with other biochemical determinations are used to assess the health condition of animals, assessing internal organ functions and systemic homeostasis (Kral and Suchy, 2000; Olanrewaju et al., 2017). Moreover, variations of acid-base balance are the prompt clinical signs of various diseases in both domestic animals including chicken and humans (Gunnerson, 2005; Seifter and Chang, 2016). In addition, alterations in key selected blood parameters are widely used to figure out various effects of environmental, nutritional and pathological factors (Olanrewaju et al., 2017). Concentrations of glucose, T3, T4 and corticosterone among others have been suggested to be sensitive indicators of physiological responses in stressed broiler chickens (Puvadolpirod and Thaxton, 2000; Olanrewaju et al., 2006). In additions, elevated levels of GGT have been documented as a marker of oxidative stress and subclinical inflammation (Kasapoglu et al., 2010). The activities of ALT, AST, LDH and ALP in the broilers are indicators of protein metabolism and hepatic damage or injury (Ognik and Krauze, 2016). It has been documented that green muscle disease, cardiac damage and stress are associated with substantial increase in plasma CK and AST activities (Kong et al., 2021; Estarreja et al., 2024). Hence, in extension of our recent study (Olanrewaju et al., 2024a), this  study running concurrently with the same group of birds, investigated the effect of stocking density on selected blood physiological variables along with plasma biochemistry variables and enzymes activities of broilers fed antibiotic-free diets grown to 3 kg. The outcome of this study will provide information crucial to prevent costly restrictions related to the number of birds per unit of housing space (m2) in poultry industries, while helping them to deliver the best and humane production environments that enhance broilers production efficiency without compromising the welfare of broilers grown to 3 kg body weight.
 

MATERIALS AND METHODS

Birds, experimental design and management
 
This study was carried out at US Department of Agriculture, Agricultural Research Service, Poultry Research Unit in 2024. All procedures relating to the use of live birds in this study were reviewed and approved by the USDA-ARS Animal Care and Use Committee at the Mississippi State location (license number: 19-3). In this study, a total of 888 1-d-old Ross x Ross 708 chicks were randomly distributed into 24 pens based on stocking density treatment assignment. Stocking density treatments of 29, 33, 39 and 42 kg of BW/m2 were selected based on EU (2007), National Chicken Council (2017) and Global Animal Partnership (2017) recommendations. The birds were reared under identical conditions including diets except for SD. Pens were adjusted to a total area of 34 ft2 for this study. Commercial stocking densities of 1 ft2/bird (Dozier et al., 2005; Thaxton et al., 2006) were typically employed to maintain commercially relevant feeder and drinker space allotments to stimulate typical feeding and drinking behavior observed in commercial practice. Each pen was equipped with one tube feeder and nipple drinkers. Pens air temperature was initially set at 32°C and was decreased according to the schedule in Table 1. Lighting was provided with 5000K LED bulbs. Lighting intensity, photoperiod and room temperature were adjusted according to the schedule in Table 1. Birds were fed antibiotic-free (ABF) diets and offered a three phase-feeding program (Starter: 0-14 d, Grower: 15-28 d and Finisher: 29-42 d) diets on a biweekly change schedule with corn-soy diets according to NRC (1994). Starter feed was provided as crumbles and subsequent feeds were offered as whole pellets. Feed and water were provided ad libitum. Litter material was sourced from a commercial farm to mimic commercial conditions and litter microflora.

Table 1: Air temperature and lighting program.


 
Experimental treatments
 
The experimental treatments were 4 densities (29, 33, 39 and 42 kg of BW/m2), which consisted of 30, 34, 40 and 44 chicks per pen, respectively at placement with six replicates. Treatments were blocked within the room to account for any variations in room conditions. Treatment assignments were randomized within each block.

Blood collections and biochemical analyses
 
Blood samples (3 ml) were collected between 0800 and 0900 h from the brachial vein of 6 (3 males and 3 female) randomly selected birds/pen on d 28 and 42 of age within 45 sec after birds were caught. Blood samples were analyzed instantaneously using blood gas electrolyte analyzer (ABL90-Flex, Radiometer America, Westlake, OH) as described previously (Olanrewaju et al., 2016). This ABL-90 Flex blood analyzer was set to reflect a broiler body temperature of 41.5°C as per the manufacturer’s instructions. The mean corpuscular hemoglobin concentration (McHc) in grams per deciliter and arterial oxygen saturation (SaO2), which is the amount of oxyhemoglobin (O2Hb) in blood expressed as a percent of the total amount of hemoglobin able to bind oxygen (O2Hb+deoxyhemoglobin) were determined as described previously (Olanrewaju et al., 2016). The needle mounted on each syringe was then removed, a cap was placed over the needle port. The syringes containing the blood samples were placed into ice. The iced samples were transferred to the laboratory and centrifuged at 4,000×g for 20 min at 4°C. Two milliliters of each of the plasma samples from the syringes were stored in 2.5 mL graduated tubes at -20°C for subsequent laboratory chemical analyses. On the day of analyses, plasma samples were brought out from the freezer, thawed and analyzed for corticosterone (CS) using a universal microplate spectrophotometer (Bio-Tek Instruments Inc., Winooski, VT) with ELISA reagent assay test kits (EIA-CS Kit, Enzo Life Sciences, Farmingdale, NY), according to the manufacturer’s directions. Concentrations of plasma triiodothyronine (T3) and thyroxine (T4) concentrations were determined using a universal microplate spectrophotometer (Bio-Tek Instruments Inc.) with ELISA reagent assay test kits from ALPCO Diagnostics (Salem, NH) according to the manufacturer’s recommendations. Moreover, plasma concentrations and activities of albumin (ALB), total bilirubin (TBILI), blood urea nitrogen (BUN), creatinine (CREAT), total protein (TP), uric acid (UA), cholesterol (CHOL), low density lipoprtein (LDL-C), high density lipoprotein (HDL), triglycerides (TRIG), alanine aminotransferase (ALT), alkaline phosphatase (ALP), amylase (AMYL), aspartate aminotransferase (AST), creatine kinase (CK), Gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH) and lipase (LIP) were evaluated using ACE-AXCEL (Alfa Wassermann Diagnostic Tech, West Caldwell, NJ) through biochemical and enzymatic rate reactions as described previously (Olanrewaju et al., 2023b). Most of these blood variables are indicators of internal organ health and systemic homeostasis.
 
Statistical analysis
 
The experimental design was a randomized complete block design with room location as the blocking factor. Each 4-stocking density treatment was signified by 6 replicate pens. Pen was considered the experimental unit. Treatments were blocked within the room to account for any variations in room conditions. Treatment assignments were randomized within each block. The main effects of stocking density on physiological parameters along with plasma biochemistry variables and enzymes activities were evaluated by using the mixed model ANOVA with PROC MIXED procedure of SAS software, SAS Institute Inc., Cary, USA, (2013). Least-squared means comparisons on day 28 and 42 were separated with Tukey’s Honestly Significant Different Test; significance was considered at P£0.05 unless otherwise said. Analyses of variance combined across days were performed to obtain treatment comparisons averaged across days.
 

RESULTS AND DISCUSSION

Stocking densities in this study were 29, 33, 39 and 42 kg of BW/m2 with 30, 34, 40 and 44 birds/pen, respectively from d1 to 42 d of age and with six replicates. The earlier study investigated the effect of stocking density on growth performance and carcass characteristics of broilers grown to 3 kg under antibiotic free diets (Olanrewaju et al., 2024a). The present study, running concurrently with the same group of birds, investigated the effect of stocking density on selected blood physiological parameters along with plasma biochemistry variables and enzymes activities of broilers fed antibiotic-free diets grown to 3 kg. The data represent the main effects of treatments (stocking densities) over day because there were no effect of treatments and sex for each of the sampling days.

Table 2 shows the main effects of SD on blood gases and acid-base balance. There was only a significant (P<0.013) effect of stocking density of 42 kg/m2 noted on partial pressure of CO2 (pCO2), which was within physiological acid-base ranges for broiler chickens (Martin et al., 2010). These results agree with the earlier studies (Park et al., 2018; Ruby et al., 2022; Olanrewaju et al., 2023a) who said that SD in broilers had no major effect on hematology, blood gases and acid-base balance. Acid-base status is faced daily by environmental factors such as light, temperature, humidity and air quality among others and they influence respiratory and metabolic activities (Parvin et al., 2014; Arowolo et al., 2019; Olanrewaju et al., 2019). The regular role of all physiological processes in the body depends on maintenance of right acid-base balance where the body controls and allocation of acids and bases to accomplish acid-base homeostasis (Bianca et al., 2021). The primary organ systems used in acid-base homeostasis in birds are the lungs and kidneys, supported by the gastrointestinal tract and cardiovascular system that take part in thermoregulatory processes through the adjustment of heat dissipation and oxygen transport (Burggren et al., 2016). The 3 systems (buffer, respiratory and renal systems) function interdependently to regulate and keep acid-base balance, while the function of the liver, kidneys and the brain are among the most important elements in body physiological homeostasis.

Table 2: Main effects of stocking density of broilers grown to 3 kg body weights on BW, pH, blood gases, sO2, SaO2, hematocrit, hemoglobin and McHc along with Mean ± SE.



Table 3 shows the effects of SD on blood electrolytes and anion gap levels. There was no effect of SD on any of the blood electrolytes and anion gap levels, which is consistent with our earlier study (Olanrewaju et al., 2023a). Moreover, the influence of SD on selected blood metabolites is shown in Table 4. There was no effect of SD noted on selected blood metabolites which also agrees with our previous study (Olanrewaju et al., 2023a).

Table 3: Main effects of stocking density of broilers grown to 3 kg body weights on blood electrolytes and Angap along with Mean ± SE.



Table 4: Main effects of stocking density of broilers grown to 3 kg body weights on blood GLU, Osmo, CS, T3 and T4 along with Mean ± SE.



The influence of SD of boilers fed ABF diets on plasma biochemistry variables and enzymes activities are presented in Table 5. The effect of SD was observed only on uric acid levels, but not on the rest selected plasma enzymes activities in the present study. The present results of the biochemical and enzymatical variables in Table 5 are without statistically significant differences between treatments. This shows from the physiological aspect there was no difference in broiler welfare and internal organs health in the investigated stocking densities. The result also is consistent with other studies who found that SD did not cause physiological changes indicative of stress (Dozier et al., 2006; Thaxton et al., 2006). In addition, non-significant effects of SD on hemato-biochemical was reported by Gupta et al., (2017). Uric acid (UA) has been shown to stimulate the immune responses of animals against the invasion of pathogenic microorganisms (Nery et al., 2015). It has also been documented that serum UA concentrations can be an indicator of amino acid use in broilers fed amino acid-suficient and amino acid-deficient diets (Donsbough et al., 2010). Blood metabolites indices of liver, kidney functions and hematological contents may provide good instances of animal health status and physiological condition (Toghyani et al., 2010). Alanine aminotransferase (ALT) and GGT are liver enzymes which are higher at the time of liver damage (hepato-cellular degeneration). Increasing blood glucose levels are termed as an important indicator of stress conditions (Simon, 1984; Gunnerson, 2005). It has been reported that the triglyceride results did not differ significantly in the blood serum of broilers reared at the level density of 11.9 and 17.5 birds/m2, which indicated birds lack of exposure to stress or metabolic disorder (Sturkie, 1986). The nonsignificant difference of HDL and LDL levels observed in this study supported the insignificant results that obtained in the cholesterol values in this study. The results of this study showed that the values of lipid biochemical parameters evaluated did not differ within broilers of the same age at different densities. These values reported here were consistent with results reported by Zabir et al., (2021) who found no effect of SD on serum cholesterol under different bird densities.

Table 5: Main effects of stocking density of broilers grown to 3 kg body weights on plasma biochemical and enzymatical variables along with Mean ± SE.


 
Table 2-5 data display the nonsignificant effect of SD on final BW, selected blood physiological, plasma biochemistry and enzymes variables except pCO2 and uric acid and were within physiological acid-base ranges for broiler chickens (Martin et al., 2010; Al-Nedawi, 2018; Arzour-Lakehal and Boudebza, 2021). The values found for each selected variables (blood physiological variables, plasma biochemistry and enzyme activities) are in broad agreement with those reported in the literature by others (Shailesh et al., 2017; Park et al., 2018; Thema et al., 2022) that would be extremely useful in detecting not only environmental welfare conditions of broilers fed ABF diets, but also metabolic-nutritional disorders of broilers.
 

CONCLUSION

Based on the results of the present study, blood glucose, plasma corticosterone along with other selected biochemistry and enzyme activities welfare indicators were within blood homeostasis reference of this species and were not affected by SD, showing no signs of physiological stress. The study also adds to the accumulating evidence that stocking densities with ABF diets used in this study do not trigger organs and muscle damage, nor do they cause an increase in stress indicators in broiler chickens. This study revealed that SD up to 42 kg/m2 with proper environmental management of broilers fed ABF diets may be suitable for both poultry integrators and contract growers to enhance broilers production efficiency without compromising the welfare of broilers grown to 3 kg BW. In addition, this study will help researchers and the commercial poultry industry uncover critical broiler management information that will lead to profitable broiler production.
 

ACKNOWLEDGEMENT

The authors wish to express their appreciation to the animal care staff, Jeffery Harmon and engineering technicians at USDA-ARS, Poultry Research Unit for their contributions to this study.
 

CONFLICT OF INTEREST

The authors of the manuscript declare no conflicts of interest exist.
 

REFERENCES


  1. Al-Nedawi, A.M. (2018). Reference hematology for commercial ross 308 broilers. Online Journal of Veterinary Research. 22(7): 566-570. 

  2. Arowolo, M.A., He, J.H., He, S.P., Adebowale, T.O. (2019). The implication of lighting programmers in intensive broiler production system. World’s Poultry Science Journal. 75(1): 1-12. 

  3. Arzour-Lakehal, N., Boudebza, A. (2021). Biochemical reference intervals in broiler chickens according to age and strain. Agric. Science and Techn. 13(4): 357-364. 

  4. Bessei, W. (2006). Welfare of broilers: A review. World’s Poultry Science Journal. 62(3): 455-466. 

  5. Bianca, N.Q., Parker, M.D., Occhipinti, R. (2021). The therapeutic importance of acid-base balance. Biochemical Pharmacology. 183: 114278.  doi: 10.1016/j.bcp.2020.114278.

  6. Burggren, W.W., Santin, J.F., Antich, M.R. (2016). Cardio-respiratory development in bird embryos: new insights from a venerable animal model. Revista Brasileira Zootecnia. 45(11): 709-728. 

  7. Diarra, M.S., Malouin, F. (2014). Antibiotics in Canadian poultry productions and anticipated alternatives. Frontiers in Microbiology. 5: 282. doi: 10.3389/fmicb.2014.00282.

  8. Dibner, J.J., Richards, J.D. (2005). Antibiotic growth promoters in agriculture: History and mode of action. Poultry Science. 84(4): 634-643. 

  9. Donsbough, A.L., Powell, S., Waguespack, A., Bidner, T.D. and Southern, L.L. (2010). Uric acid, urea and ammonia concentrations in serum and uric acid concentrations in excreta as indicators of amino acid utilization in diets for broilers. Poultry Science. 89(2): 287-294. 

  10. Dozier III, W.A., Thaxton, J.P., Branton, S.L., Morgan, G.W., Miles, D.M., Roush, W.B., Lott, B.D., Vizzier-Thaxton, Y. (2005). Stocking density effects on growth performance and processing yields of heavy broilers. Poultry Science. 84(8): 1332-1338. 

  11. Dozier, W.A., Thaxton, J.P., Purswell, J.L., Olanrewaju., H.A., Branton, S.L., Roush, W. B. (2006). Stocking density effects on male broilers grown to 1.8 kilograms of body weight. Poultry Science. 85(2): 344-351. 

  12. Estarreja, J, Pimenta, A.C., Botelho, J., Vilares, A.M., Mendes, J.J., Rocha, J., Pinto, R., Mateus, V., Machado, V. (2024). Blood count, endocrine, immunologic, renal and hepatic markers in a case-control animal study of induced periodontitis in female rodents. Frontiers Physiology. 15: 1327399. doi: 10.3389/fphys.2024.1327399.

  13. Estevez, I. (2007). Density allowances for broilers: Where to set the limits? Poultry Science. 86(6): 1265-1272. 

  14. European Union. (2007). Council Directive 2007/43/EC of 28 June 2007 laying down minimum rules for the protection of chickens kept for meat production. Official Journal of the European Union. 182: 19-28. 

  15. Feddes, J.J., Emmanuel, E.J., Zuidhoft, M.J. (2002). Broiler performance, body weight variance, feed and water intake and carcass quality at different stocking densities. Poultry Science. 81(6): 774-779. 

  16. Global Animal Partnership. (2017). 5-Step Animal Welfare Rating Standards for Chickens raised for Meat v3.0. Austin, TX: Global Animal Partnership.

  17. Gupta, S.K., Kumaresh, B., Pradhan, C.R., Aditya, P.A., Kamdev, S., Dayanidhi, B., Lone, S.A., Shinde, K.P. (2017). Influence of stocking density on the performance, carcass characteristics, hemato-biochemical indices of Vanaraja chickens. Indian Journal of Animal Research. 51(5): 939- 943. doi: 10.18805/ijar.10989.

  18. Gunnerson, K.J. (2005). Clinical review: The meaning of acid-base abnormalities in the intensive care unit epidemiology. Critical Care. 9(5): 508-516. 

  19. Hedman, H.D., Vasco, K.A., Zhang, L. (2020). A review of antimicrobial resistance in poultry farming within low-resource settings.  Animal. 10(8): 1264.  doi: 10.3390/ani10081264.

  20. Kasapoglu, B., Turkay, C., Bayram, Y., Koca, C. (2010). Role of GGT in diagnosis of metabolic syndrome: A clinic-based cross-sectional survey. Indian Journal of Medical  Research. 132(7): 56-61. 

  21. Kong, F., Zhao, G., He, Z., Sun, J., Wang, X., Liu, D., Zhu, D., Liu, R., Wen, J. (2021). Serum creatine kinase as a biomarker to predict wooden breast in vivo for chicken breeding. Frontiers Physiology. 12: 711711. doi: 10.3389/fphys. 2021.711711.

  22. Kral, I., Suchy, P. (2000). Hematological studies in adolescent breeding cocks. Acta Veterinaria Brno. 69(3): 189-194. 

  23. Martin, M.P., Wineland, M., Barnes, H.J. (2010). Selected blood chemistry and gas reference ranges for broiler breeders using the i-STATH handheld clinical analyzer. Avian Diseases. 54(3): 1016-1020. 

  24. National Chicken Council. (2017). National Chicken Council Animal Welfare Guidelines and Audit Checklist. Washington, D.C., National Chicken Council. 

  25. Nery, R.A., Kahlow, B.S., Skare, T.L., Tabushi, F.I., do Amaral, C.A. (2015). Uric acid and tissue repair. Arq. Bras. Cirurgia Digest. 28(4): 290-292. 

  26. NRC. (1994). Nutrient Requirements of Poultry. 9th ed. Natl. Acad. Sci., Washington, DC. 

  27. Ognik, K., Krauze, M. (2016). The potential for using enzymatic assays to assess the health of turkeys. World’s Poultry Science Journal. 72(3): 534-546.

  28. Olanrewaju, H.A., Magee, C.L., Collier, S.D., Purswell, J.L. (2024a). Effect of stocking density on growth performance and carcass characteristics of broilers grown to 3 kg under antibiotic free diets. Indian Journal of Animal Research. doi: 10.18805/IJAR.BF-1848. 

  29. Olanrewaju, H.A. Evans, J.D., Collier, S.D., Purswell, J.L., Branton, S.L. (2023b). Age-related effect of high-frequency LED lighting in laying hens on biochemical, enzymatical and electrolytes variables. Journal of Applied Poultry Research. 32(3): 100351. https://doi.org/10.1016/j.japr.2023.100351.

  30. Olanrewaju, H.A., Collier, S.D., Purswell, J.L., Branton, S.L. (2019). Effects of light-sources and photoperiod on hematophysiological indices of broilers grown to heavy weights. Poultry Science.  98(3): 1075-1082. 

  31. Olanrewaju, H.A., Purswell, J.L., Collier, S.D., Branton, S.L. (2017). Effects of light ingress through ventilation fan apertures on selected blood variables of male broilers. International Journal of Poultry Science. 16(8): 288-295. 

  32. Olanrewaju, H.A., Purswell, J.L., Collier, S.D., Branton, S.L. (2016). Effects of light sources and intensity on broilers grown to heavy weights: Hematophysiological and biochemical assessment. International Journal Poultry Science. 15(10): 384-393. 

  33. Olanrewaju, H.A., Purswell, J.L., Evans, J.D., Collier, S.D., Branton, S.L. (2023a). Age-related effects of high-frequency LED lighting in laying hens. Part 1: Blood physiological variables. Canadian Journal of Animal Science. 103(3): 1-4. 

  34. Olanrewaju, H.A., Wongpichet, S., Thaxton, J.P., Dozier III, W.A., Branton, S.L. (2006). Stress and acid-base balance in chickens. Poultry Science. 85(7): 1222-1274. 

  35. Park, B.S., Um, K.H., Park, S.O., Zammit, V.A. (2018). Effect of stocking density on behavioral traits, blood biochemical parameters and immune responses in meat ducks exposed to heat stress. Archives Animal Breeding. pp 425-432. 

  36. Parvin, R., Mushtaq, M.M.H., Kim, M.J. Choi, H.C. (2014). Light emitting diode (LED) as a source of monochromatic light: A novel lighting approach for behavior, physiology and welfare of poultry. World’s Poultry Science Journal. 70(3): 543-556. 

  37. Puvadolpirod, S., Thaxton, J.P. (2000). Model of physiological stress in chickens 4. Digestion and metabolism. Poultry Science. 79(3): 383-390.

  38. Ruby, P., Ahilan, B., Antony, C., Manikandavelu, D. Selvaraj, S., Samuel Moses, T.L.S. (2022). Evaluation of effect of the different stocking densities on growth performance, survival, water quality and body indices of pearlspot (Etroplus suratensis) fingerlings in biofloc technology. Indian Journal of Animal Research. 56(8): 1034-1040. doi: 10.18805/IJAR.B-4922.

  39. Sanotra, G.S., Lund, J.D., Ersboll, A.K., Petersen, J.S., Vestergaard, K.S. (2001). Monitoring leg problems in broilers: A survey of commercial broiler production in denmark. World’s Poultry Science Journal. 57(1): 55-69.

  40. SAS Institute. (2013). SAS User’s Guide Statistics. Software Version 9.4. SAS Inst. Inc., Cary, NC.

  41. Seifter, J.L., Chang, H.Y. (2016). Disorders of acid-base balance: New perspectives. Kidney Diseases. 2(4): 170-186. 

  42. Shailesh, K., Kumaresh, G.B., Pradhan, C.R., Acharya, A.P., Sethy, K., Behera, D., Lone, S.A., Shinde, K.P. (2017). Influence of stocking density on the performance, carcass characteristics, hemato-biochemical indices of Vanaraja chickens. Indian Journal of Animal Research. 51(5): 939- 943. doi: 10.18805/ijar.10989.

  43. Simon, J. (1984). Effects of daily corticosterone injections upon plasma glucose, insulin, uric acid and electrolytes and food intake pattern in the chicken. Diabetes Metabolism. 10(3): 211-217.

  44. Singer, R.S., Porter, L.J., Thomson, D.U., Gage, M., Beaudoin, A., Wishnie, J.K. (2019). Raising animals without antibiotics: U.S. producer and veterinarian experiences and opinions. Frontiers Veterinary Science. 6(6): 452. https://doi.org/ 10.3389/fvets.2019.00452.

  45. Sturkie, P.D. (1986). Avian Physiology 4th Ed. Springer-Verlag, New York, Berlin, Heidelberg, Tokyo.

  46. Thaxton, J.P., Dozier III, W.A., Branton, S.L., Morgan, G.W., Miles, D.M., Roush, W.B., Lott, B.D., Vizzier-Thaxton, Y. (2006). Stocking density and physiological adaptive responses of broilers. Poultry Science. 85(5): 819-824. 

  47. Thema, K.K., Mnisi, C.M., Mlambo, V. (2022). Stocking density- induced changes in growth performance, blood parameters, meat quality traits and welfare of broiler chickens reared under semiarid subtropical conditions. Plos One. 17(10): e0275811. https://doi.org/10.1371/journal.pone.0275811.

  48. Toghyani, M., Toghyani, M., Gheisari, A., Ghalamkari, G., Mohammadrezaei, M. (2010). Growth performance, serum biochemistry and blood hematology of broiler chicks fed distinct levels of black seed (Nigella sativa) and peppermint (Mentha piperita). Livestock Science. 129(1-3): 173-178. 

  49. Van der Sluis, W. (2000). Clostridial enteritis is an often underestimated problem. World’s Poultry Science Journal.  16(2): 42-43. 

  50. Van Immerseel, F., De Buck, J., Pasmans, F., Huyghebaert, G., Haesebrouck, F., Ducatelle, R. (2004). Clostridium perfringens in poultry: an emerging threat for animal and public health. Avian Pathology. 33(6): 537-549. 

  51. Vanhonacker, F., Verbeke, W., Van Poucke, E., Buijs, S., Tuyttens, F.A.M. (2009). Societal concerns related to stocking density, pen size and group size in farm animal production. Livestock Science. 123: 16-22.

  52. Zabir, M., Miah, M.A., Alam, M., Bhuiyan, M.E.J, Haque, M.I, Sujan, K.M. (2021). Impacts of stocking density rates on welfare, growth and hemato-biochemical profile in broiler chickens.  Journal of Advanced Veterinary and Animal Research. 8(4): 642-649. 
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