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Articles by J.L. Purswell
Total Records ( 19 ) for J.L. Purswell
  J.L. Purswell , B.D. Lott , W.A. Dozier III , W.B. Roush and S.L. Branton
  Proper management of the thermal environment during brooding is essential to performance in broilers. Brooding programs used in the broiler industry are prescriptive, but little information exists about thermal comfort in chicks. Identifying thermal conditions that chicks prefer would allow for better management of the thermal environment during brooding. The objective of this study was to determine thermal conditions that are preferred by broiler chicks. Thirty broiler chicks at seven days of age were fitted with a harness holding a miniature temperature data logger; air temperature directly above the chicks` backs was measured every 3 minutes for 7 days from 8 to 14 days of age. Air temperature in the room was measured in 25 locations on the same interval as the harnesses. The room was held at 32.2oC for the first week and reduced to 29.4oC the second week. Air temperature, as measured by the bird harnesses, was significantly higher than measured in the room. Overall least squares means for harness and room temperatures were 33.0 and 29.2oC, respectively and were significantly different (P < 0.0001). The estimated difference between harness and room temperature was 3.8oC with a standard error of 0.06oC; the least significant difference was calculated as 0.15oC.
  H.A. Olanrewaju , W.A. Dozier III , J.L. Purswell , S.L. Branton , D.M. Miles , B.D. Lott , A.J. Pescatore and J.P. Thaxton
  Four trials were conducted to evaluate growth responses, blood chemistry and heart characteristics of broiler chicks subjected to progressive concentrations (0, 3,000, 6,000, 9,000 ppm) of carbon dioxide (CO2) gas from 1-14 days of age, which were then discontinued throughout the remainder of the trial (42 days of age). On days 14 and 42 of each trial, 20 birds per chamber were randomly selected for immediate analysis of blood partial pressure of CO2 (pCO2), blood partial pressure of O2 (pO2), blood pH, hematocrit (Hct), hemoglobin (Hb), blood electrolytes (Na+, K+, Ca2+ and Cl-) and determination of heart characteristics. Body and feed weights were recorded at 0, 14, 28 and 42 days of age for growth performances. Final body weight (BW) gain and feed conversion were similar among the treatments, but cumulative mortality significantly increased as CO2 increased (P ≤ 0.05) from 3,000-9,000 ppm. Treatments did not alter blood pCO2 and pO2 concentrations at age 14 and 42 days of age. Increasing CO2 up to 9,000 ppm failed to reveal differences for heart weight characteristics at 14 days of age, but total heart and left ventricle weights were increased at 42 days of age. These results indicate that subjecting chicks to progressive concentrations of CO2 from 1-14 days of age does not adversely alter blood chemistry or cumulative growth performance, but increased the incidence of late-mortality.
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
  This study examined the response of different aged birds of the same genetic strain exposed to ammonia (NH3) at set concentrations on blood gases, electrolytes and acid-base balance under environmentally controlled conditions. The experiment consisted of a 4x4 factorial with a randomized design. The 16 treatments consisted of 4 levels (0, 25, 50 and 75 ppm) of NH3 concentrations and 4 different ages (1-d, 7-d, 14-d and 21-d) of birds. Venous blood samples were collected at the end of each 7 d of atmospheric NH3 exposure. Partial pressure of CO2 (pCO2), pH, Hematocrit (Hct) and Hemoglobin (Hb) increased significantly (p<0.05), whereas partial pressure of O2 (pO2), bicarbonate (HCO3-) and K+ decreased with increasing NH3 concentration compared with 0 ppm. In addition, pO2, pCO2, HCO3-, Hct, Hb, Na+ and Anion gap (Angap) increased significantly (p<0.05), while pH, glucose and corticosterone decreased as bird’s age increased. Ammonia x age interactions were observed for pH, anion gap and HCO3-. Plasma corticosterone concentrations were significantly different for age and were not affected by NH3. The effect of age was more pronounced than that of NH3 on examined variables. This effect of age on examined blood physiological variables improved as the age of birds increased from 1-d to 21-d old birds. Most blood physiological variables of different aged birds of the same genetic strain respond differently to set NH3 concentrations of 0 to 75 ppm and younger birds have a more intense reaction to the NH3 than older birds.
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
  Two trials were conducted concurrently to determine and compare, blood pH, blood gases, hematocrit and hemoglobin in F-strain Mycoplasma gallisepticum (FMG) inoculated layers and FMG contact-infected broilers. At the termination of the study, FMG-inoculated layers had the highest partial pressure of O2 and the lowest partial pressure of CO2 as compared with the other treatment groups. Blood pH values were unaffected by FMG inoculation. Hematocrit and blood concentrations of hemoglobin were slightly higher and HCO3- levels were lowest in FMG contact-infected broilers in comparison to the other treatments groups. Mycoplasma gallisepticum inoculated layers also resulted in a significant increase in blood concentrations of K+, a decrease in Na+, but no significant effects on blood concentrations of Ca2+ and Cl-. There were no differences in plasma glucose, cholesterone, triglyceride and anion gap, but osmolality was significantly reduced in FMG contact-infected broilers. Results indicate that inoculation of layers with FMG vaccine results in changes in plasma acid-base status along with changes in other blood metabolic variables. However, the FMG inoculation did not prevent homeostatic regulation of acid-base balance, as indicated by constant blood pH. The significant increase in pO2 in FMG inoculated layers is generally associated with an oxygen-dependent improvement in tissue oxygenation. Elevated arterial partial pressure of oxygen is beneficial to maximize oxygen transport capacity along with high concentrations of hemoglobin and hematocrit to carry oxygen throughout the body. It was concluded that in addition to protecting birds from MG infection, an FMG vaccine may improve the layer chicken’s ability to withstand the harmful effects of stressors on their performance and well-being.
  K.J. Barker , J.L. Purswell , J.D. Davis , H.M. Parker , M.T. Kidd , C.D. McDaniel and A.S. Kiess
  A common practice in the commercial broiler industry is to reuse litter over multiple broiler flocks. Over time the bacterial populations in the reused litter increases but how those organisms are spatially distributed throughout the litter bed is unclear. Therefore, the goal of this project was to investigate the distribution of bacteria at three different depths of litter. Litter samples were collected from three commercial broiler houses on three different farms. Four samples from each house were collected using clear PVC pipes which were driven through the litter bed to the clay floor. Each pipe was transported up-right to the lab, where they were cut into three sections (top, middle and bottom) exposing the litter for processing. Litter from each section was serially diluted in peptone and streaked onto either tryptic soy agar or Levin eosin methylene blue agar plates. Plates were incubated under the appropriate atmospheric condition for 24 h at 37oC. After 24 h, plates were counted for total aerobes, anaerobes and coliforms. Results of this study indicate a significant difference (p<0.05) in bacterial counts between the different sections of the litter. The middle and bottom sections had significantly lower anaerobe and coliform counts compared to the bacterial counts in the top sections. In conclusion, the results suggest that the middle and bottom section of litter provide a less favorable environment for bacterial growth than the top section.
  J.D. Davis , J.L. Purswell , E.P. Columbus and A.S. Kiess
  An alternative broiler litter to pine shavings may be switchgrass, a high yielding forage crop (8-12 tons per acre) that can grow across the Southeastern U.S. A study was conducted to determine the efficacy of chopped switchgrass as a litter material for broiler chickens. Pine Shavings (PS) and Switchgrass (SG) were used as litter treatments with 10 replications each. Body weight, body weight gain, feed consumption, feed conversion, carcass weights and mortality were not different between treatments. However, the incidence of foot pad dermatitis was significantly decreased with SG litter. Live performance and carcass weights were not affected by using chopped SG as a litter material when rearing broilers over a short duration (one flock cycle).
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
  The effects of ambient temperature, light intensity and their interaction on growth performance and carcass characteristics of broilers were investigated in 2 trials. The experiment was consisted of a factorial arrangement of treatments in a randomized complete block design. The 9 treatments consisted of 3 levels (Low = 15.6, Moderate = 21.1, High = 26.7oC) of temperatures from d 21-56 d of age and 3 levels (0.5, 3.0, 20 lx) of light intensities from 8-56 d of age at 50% RH. Five hundred and forty Ross 708 chicks were randomly distributed into 9 environmentally controlled chambers (30 males and 30 females chicks/chamber) at 1 d of age. Feed and water were provided ad libitum. Birds were provided a four phase-feeding program (starter: 1 to 14 d, grower: 15-28 d, finisher: 29-42 d and withdrawal: 43-56 d). At 56 d of age, both feed intake and birds’ weight were recorded for the growth performance. Also, 20 (10 males and 10 females) birds from each chamber were processed to determine weights and yields. Broilers subjected to high ambient temperature of 26.7oC had significantly (P<0.05) lower BW, BWG, FI, carcass weight and pectoralis major and minor weights along with a significant (P<0.05) increased in FCR when compared with low and moderate ambient temperatures broilers. Plasma corticosterone concentrations were not statistically affected by temperature, light intensity or their interaction, suggesting an absence of stress. These results indicate that exposure of modern heavy weight broilers to high ambient temperature of 26.7oC in comparison with low and moderate ambient temperatures has a negative effect on growth performance and carcass characteristics, suggesting that they need to be grown under lower ambient temperature than previously reported.
  J.B. Wells , C.D. Coufal , H.M. Parker , A.S. Kiess , J.L. Purswell , K.M. Young and C.D. McDaniel
  Previous research has indicated that a single exposure of eggs to Ultraviolet Light (UV) in combination with 3% hydrogen peroxide (H2O2) results in a greater reduction of eggshell microorganisms compared to eggs treated with either UV or H2O2 alone. The objective of this study was to determine if hatchability would be affected if eggs were treated by repeated applications of UV and H2O2. In the first experiment, eggs receiving H2O2 and UV light for 2 min 6 times yielded the greatest reduction in aerobic plate counts (5.3 log10CFU/egg) when compared to other treatment groups that utilized various repetitions of H2O2 and UV light. The second experiment determined the effect on hatchability when using this combination tested in Experiment 1. In Experiment 2, a 4 log10CFU/egg reduction in eggshell aerobic plate counts was observed for eggs treated with UV and H2O2 when compared to untreated control eggs. There were no differences in hatchability, hatch residue, chick weight, residual yolk weight, or egg weight loss between control and treated groups. In conclusion, multiple applications of UV and H2O2 effectively reduced aerobic microorganisms on the eggshell to low levels with no detrimental effects on broiler breeder egg hatchability or chick quality parameters.
  H.A. Olanrewaju , W.W. Miller , W.R. Maslin , S.D. Collier , J.L. Purswell and S.L. Branton
  The effects of varying light-intensity on ocular, immune, fear and leg health of broiler chickens grown to heavy weights under environmentally controlled conditions were evaluated. Four identical trials were conducted with two replications per trial. In each trial, 600 Ross 308 chicks were randomly distributed into 10 environmentally controlled chambers (30 males and 30 females chicks/chamber) at 1 d of age. Each chamber was randomly assigned one of five light intensities (25, 10, 5, 2.5 and 0.2 lx) from d 22 to 56 d of age. Feed and water were provided ad libitum. Humoral immune response was determined on d 28, while ocular health and general well-being assessments were performed on d 42 and 49, respectively. Results indicated that total Anti-Sheep Red Blood Cells (SRBC) antibody was not significantly (p>0.05) affected by the treatments, but there was significant (p<0.05) sex effects under 25 and 2.5 lx treatments. There were no differences among treatments for either ocular weight relative to BW, ocular assessments, gait scoring test or tonic immobility responses, suggesting that these levels of light intensities did not compromise welfare of the birds. This study shows the positive impact on profits to commercial poultry facilities that are using low lighting environment to reduce hyperactivity, pecking damage and energy costs without compromising the welfare of the broilers.
  J.L. Purswell , J.D. Davis , B.D. Luck , E.J. Kim , H.A. Olanrewaju , A.S. Kiess and S.L. Branton
  Improvements in modern broiler housing have substantially reduced air leakage, making proper operation of ventilation systems critical to maintaining a suitable environment. Fuel prices have increased in recent years, leading to reduced minimum ventilation in order to conserve fuel which increases carbon dioxide (CO2) concentrations within the house. Four trials were conducted to assess the effects of increased CO2 concentrations on birds aged 28 to 49 days. Each trial used 300 straight-run broilers placed in environmentally controlled rooms where CO2 concentrations were maintained with no added CO2 (control), 2500 ppm at all times, 2500 ppm (day) and 4500 ppm (night), or 2500 ppm (day) and 6500 ppm (night) from 28 to 42 days. No differences in live production (body weight, body weight gain, feed intake and feed conversion) or processing yields were observed. Analysis of ventilation rates to maintain the test conditions for a commercial broiler house showed that while supplemental heat requirements are lower with reduced ventilation needed to maintain either 4500 or 6500 ppm, the associated ventilation rates are inadequate for moisture removal.
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
  This study investigated the effects of varying levels of light intensities (25, 10, 5, 2.5 and 0.2 lx) on growth performance and carcass characteristics of broiler chickens grown to heavy weights. Four identical trials were conducted with two replications per trial. In each trial, 600 1-d-old Ross 308 chicks were randomly distributed into 10 environmentally controlled chambers (30 male and 30 female chicks/chamber). Each chamber was randomly assigned one of five light intensities from d 22 to 56. Feed and water were provided ad libitum. Birds were provided a four phase-feeding program (starter, grower, finisher and withdrawal). Birds and feed were weighed on 0, 14, 21, 28, 42 and 56 d of age for growth performance. Also at 56 d of age, 20 birds (10 males and 10 females) from each chamber were randomly selected and processed to determine weights and yields. There was no effect of light intensity on growth performance, except significant (p<0.054) difference in FCR on 28 d of age under 25 and 5 lx. Broilers reared under 5 lx had significantly higher live weight (p<0.046) and carcass weight (p<0.026) in comparison with 0.2 and 25 lx. Birds reared under 5 and 10 lx had significantly higher fillet (p<0.025) and tender (p<0.034) weights when compared with birds reared under 0.2 and 25 lx. Mortality was not affected by light intensity treatments. In addition, plasma corticosterone concentrations were not statistically affected by light intensity, suggesting an absence of physiological stress. These results indicate that the range of light intensity used in this study has no effect on most production performances of broilers reared up to 56 d of age, but did affect some carcass characteristics. Therefore, using lower lighting intensity may be beneficial to commercial poultry facilities that are using low lighting environment to reduce hyperactivity, pecking damage and energy costs without physiological stress effects on broiler welfare.
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
  This study investigated effects of varying levels of light intensities (25, 10, 5, 2.5 and 0.2 lx) from 22 to 56 d of age at 50% RH on blood acid-base balance, metabolites and electrolytes of heavy broilers reared under environmentally controlled conditions. Four identical trials were conducted with two replications per trial. In each trial, 600 1-d-old Ross 308 chicks were randomly distributed into 10 environmentally controlled chambers (30 males and 30 females chicks/chamber). Each chamber was randomly assigned one of five light intensities from d 22 to 56 d of age. Birds were provided a four phase-feeding program (starter: 1 to 14 d, grower: 15 to 28 d, finisher: 29 to 42 d and withdrawal: 43 to 56 d). Feed and water were provided ad libitum. Venous blood samples were collected on d 21 (base line), 28, 42 and 56. The lowest light intensity of 0.2 lx significantly (p<0.05) increased pH, Na+, K+, Cl- and reduced pCO2, Hb and Hct. However, all these acid-base changes are still within the normal acid-base homeostasis physiological ranges. In addition, exposure of modern heavy broilers to varying light intensity produced no significant effect on pO2, sO2, Ca2+, mOsm, McHc, Angap, T3, T4 and CS. Acid-base regulation during light intensity exposure did not deteriorate despite a lower pCO2 which consequently increased blood pH that resulted in a compensatory mechanism for mild alkalosis. This study shows the positive impact on profits to commercial poultry facilities that are using low lighting environment to reduce hyperactivity, pecking damage and energy costs without the induction of physiological stress effects on broiler welfare.
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
  The effects of photoperiod, light intensity and their interaction on growth performance and carcass characteristics of broilers were investigated in 2 trials. The experiment was consisted of a factorial arrangement of treatments in a randomized complete block design. In each trial, all treatment groups were provided 23L:1D with 20 lx of intensity from placement to 7 d and then subjected to the treatments. The 9 treatments consisted of 3 photoperiods [long/continuous (23L:1D) from d 8-d 56; regular/intermittent (2L:2D) and short/non-intermittent (8L:16D) from d 8-d 48 and 23L:1D from d 49-d 56, respectively] and exposure to 3 light intensities (10, 5.0 and 0.5 lx) from d 8 through d 56 at 50% RH. Birds were provided a four phase-feeding program and water was provided ad libitum. Birds and feed were weighed on 0, 14, 28, 42 and 56 d of age for growth performance evaluation. At 56 d of age, 20 (10 males and 10 females) birds from each room were randomly selected, slaughtered and processed to determine weights and yields. Broilers subjected to a short/non-intermittent photoperiod showed the significantly (P<0.05) lowest BW, BW gain, feed intake, carcass weight and pectoralis major and minor weights as compared with broilers reared under long/continuous and regular/intermittent photoperiods. Feed conversion and mortality were not affected by treatments. There was no effect of light-intensity or photoperiod x light intensity interactions on all examined variables. Corticosterone concentrations were not affected by treatments, suggesting an absence of physiological stress. These results indicate that long/continuous and regular/intermittent photoperiods equally improved broiler performance as compared with a short/non-intermittent photoperiod with no significant effect due to light intensity treatments.
  H.A. Olanrewaju , W.W. Miller , W.R. Maslin , S.D. Collier , J.L. Purswell and S.L. Branton
  The effects of photoperiod, light-intensity and their interaction on health indices of broiler chickens grown to heavy weights under environmentally controlled conditions were evaluated in 2 trials. In each trial, 540 Ross × Ross 708 chicks were randomly distributed into 9 environmentally controlled chambers (30 male and 30 female chicks/chamber) at d of hatch, provided with 23L:1D with 20 lx of intensity from placement to 7 d and then subjected to the following treatments. The treatments consisted of 3 photoperiod (long/continuous (23L:1D) from d 8 to d 56; regular/intermittent (2L:2D) and short/non-intermittent (8L:16D) from d 8 to d 48 and 23L:1D from d 49 to d 56, respectively) and exposure to 3 light intensities (10, 5.0 and 0.5 lx) from d 8 through d 56 at 50% RH. All birds were fed the same nutritionally complete diet. Feed and water were provided ad libitum. Ocular health and general health assessments were performed on d 42 and 49, respectively, while foot pad score was evaluated on d 56 of age. There were only significant (P < 0.05) effects of photoperiod on live BW and eye weight, but no differences on ocular weight relative to BW. Food pad lesions quality was significantly decreased with decreasing in photoperiod. There were no differences among treatments on ocular assessments, gait scoring test or tonic immobility responses, suggesting that these treatments did not compromise welfare of the birds. These results indicate that long/continuous and regular/intermittent photoperiods equally improved broiler performance compared with short/non-intermittent photoperiod and no significant effect of light intensity treatments was observed in this study.
  E.J. Kim , J.L. Purswell and S.L. Branton
  The objectives of this study were to determine the maximum inclusion rates of a low fat distillers dried grains with solubles (LF-DDGS) in broiler diets fed during the finisher I phase (28 to 42 d) and the finisher II phase (43 to 56 d) and the subsequent effects on live performance and carcass characteristics. These ages were specifically chosen to determine effects of feeding LF-DDGS to broilers grown to heavy weights (>3.0 kg). Experimental diets were formulated to contain 0, 8, 16, 18, 24, or 30% LF-DDGS for finisher I phase and 0, 18, 16 and 24% LF-DDGS for finisher II phase. Diets were formulated to be isocaloric and to meet or exceed the minimum nutrient requirements. Birds were fed common diets until d 27 or 41 and experimental diets were fed until d 42 and d 56, respectively. Upon completion of the experimental periods, all birds and feed were weighed to determine body weight, body weight gain, feed consumption and feed conversion ratio for the experimental periods. On d 43 and 57, after an overnight fast, 6 birds per pen were tagged, weighed and processed to determine hot carcass weight and abdominal fat pad. After a period of chilling, carcasses were deboned to determine breast and tender weights. For the Finisher I period, body weight gain (BWG) was significantly (p<0.05) decreased and FCR was significantly increased for birds fed diets containing 30% LF-DDGS. At 43 d, carcass yield was found to be significantly decreased (p<0.05) for birds fed 30% LF-DDGS when compared to birds fed no LF-DDGS. For the Finisher II period, there were no significant effects of LF-DDGS inclusion on live performance and resulting carcass parameters. These results indicate that finishing broilers (28 to 56 d) can tolerate up to 24% LF-DDGS in the later phases of production without any detrimental effects on live performance and carcass parameters.
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
  Background and Objective: Increasing broiler house size and ventilation capacity have resulted in increased light ingress through ventilation system component apertures. The effective photoperiod for broilers may create local increases in light intensity, which may also impact broiler’ body homeostasis. This study was conducted to investigate the influence of aperture light ingress in grow-out houses on selected blood variables of male broilers reared to 63 days of age. Materials and Methods: Sixty male broiler chicks were randomly distributed to each of 16 environmentally-controlled rooms (960 total birds). Birds were provided a diet formulated to meet or exceed NRC recommendations with feed and water provided ad libitum. The two treatments consisted of a constant (C) light intensity at 2.5 lx at 16L:8D based on prescriptive intensities in typical heavy broiler lighting programs and a variable (V) light intensity and photoperiod program that was based on field measurements near tunnel fans in a solid walled broiler house. The lighting program to 35 days was identical for both treatments and the treatments were initiated at 36 days. Blood samples were collected from the wing brachial vein of 6 birds per room on day 35 (before treatments) and 63, which were then analyzed immediately for whole blood physiological variables. Selected blood plasma biochemistry, enzyme activities and electrolyte levels were evaluated. Results: In comparison to broilers exposed to a ‘C’ light intensity of 2.5 lx, broilers exposed to ‘V’ lighting that mimicked areas near tunnel fans, had significantly lower levels of pH, Ca2+, K+, CK and higher levels of angap, which were within physiological acid-base ranges. Also, age have significant contributor effects on most selected variables. In addition, blood glucose and plasma corticosterone concentrations were not affected by treatment, suggesting an absence of physiological stress and an uncompromising welfare of the birds. Conclusion: It is concluded that there may be a need to mitigate light ingress through ventilation system components to improve live performance of broilers.
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
  Objective: Effects of light sources, photoperiods and strains on blood physiological variables of broilers grown to heavy weights (>3 kg) were investigated in 2 trials. Materials and Methods: The experimental design was a 4×2×2 factorial consisting of 4 light sources [incandescent (ICD, standard), compact fluorescent (CFL), neutral LED (Neutral-LED) and cool poultry specific LED (Cool-PS-LED)], 2 photoperiods (Regular/intermittent [2L:2D] and Short [8L:16D] and 2 strains (A, B). In each trial, 480 (240 males/240 females) 1-d-old chicks of each strain from different commercial hatcheries were equally and randomly distributed into 16 environmental-control rooms (30 males +30 females/room) at 50% RH. Each room was randomly assigned one of 16 treatments from 1-56 days of age. Birds were provided similar diets. Feed and water were provided ad libitum. Venous blood samples were collected on d 14, 28, 42 and 56 of age and analyzed immediately. Results: Light sources had significant (p<0.05) effects on BW, electrolytes, pCO2, angap, T3 and T4 in comparison with birds reared under ICD. Short photoperiod significantly (p<0.05) reduced BW, pH, pO2, SaO2, electrolytes, Osmo and T3, along with significantly (p<0.05) increased pCO2, Hb, Hct and McHc compared with regular intermittent photoperiod. Acid-base regulation during the short photoperiod exposure had not deteriorated despite higher pCO2 that consequently decreased blood pH due to a respiratory acidosis. Also, Strain B had significantly (p<0.05) increased BW, pCO2, HCO3-, McHc, electrolytes, angap, Osmo and T3, along with significantly (p<0.05) reduced pH level, pO2, SaO2, Hb, Hct and T4 in comparison with Strain A. All these changes were within broilers normal acid-base homeostasis ranges. Plasma corticosterone and blood glucose concentrations were not affected by treatments, indicating an absence of physiological stress. Conclusion: The results indicating that the 3 light sources evaluated along with a regular/intermittent photoperiod in commercial poultry facilities would reduce energy costs and optimize production without compromising the welfare of broilers grown to heavy weights.
1 Part 1: Biochemical and Enzymatical Variables"> Effect of Stocking Density and Dietary Antimicrobial Inclusion of Male Broilers Grown to 35 Days of Age1 Part 1: Biochemical and Enzymatical Variables
  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
 

Objective: This study investigated the effects of recommended stocking densities and dietary antimicrobial inclusion of male broilers grown to 35 days of age on selected hemato biochemical and enzymatical variables. Materials and Methods: In each study, a total of 1024 1-day-old Ross×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 uric acid (UA) was affected by stocking density. However, in comparison to broilers fed the ABF diet, broilers with AGP+ had higher significant (p<0.05) effects on albumin (ALB), total protein (TP), alkaline phosphatase (ALP), Gamma-glutamyl transferase (GGT), Ca2+ and K+ along with lower total bilirubin (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.

  H.A. Olanrewaju , J.L. Purswell , S.D. Collier and S.L. Branton
 
Audio:

Objective: This study investigated the effects of recommended stocking densities and dietary antimicrobial inclusion of male broilers grown to 35 days of age on selected blood physiological variables. Materials and Methods: In each study, a total of 1024 1-day-old Ross×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 day 15, 28 and 35, which were then analyzed immediately for whole blood physiological variables. Blood plasma samples were analyzed for T3, T4 and corticosterone. Results: Results show there was no effect of stocking density on any of the selected physiological variables. However, in comparison to broilers fed with ABF diet, broilers with AGP+ had significant higher levels of pO2, sO2, SaO2, Ca2+ and K+ which were within physiological ranges. In addition, blood glucose and plasma corticosterone concentrations were not affected by treatments, suggesting an absence of physiological stress. Conclusion: In conclusion, 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.

 
 
 
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