Early age thermal manipulation on the performance and physiological response of broiler chickens under hot humid tropical climate (original) (raw)
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Ambient temperature: a factor affecting performance and physiological response of broiler chickens
International Journal of Biometeorology, 1989
An experiment was conducted to elucidate the influence of four constant ambient temperatures (20 ~ 25 ~ 30 ~ and 35 ~ C) on the performance and physiological reactions of male commercial broiler chicks from 3 to 7 weeks of age. A 12 h light-dark cycle was operated, while relative humidity and air circulation were not controlled. Exposure of broiler chickens to the 20 ~ , 25 ~ , 30 ~ and 35~ treatments showed highly significant (P < 0.0001) depression in growth rate, food intake and efficiency of food utilization, and a significant increase in water consumption for the 30 ~ and 35 ~ C groups_ Mortality was, however, not affected by the temperature treatments. Changes in physiological status, such as increased rectal temperatures, decreased concentration of red blood cells, haemoglobin, haematocrit, and total plasma protein were observed in birds housed in the higher temperature (30 ~ and 35 ~ C) environments_ Moreover, in these broiler chickens, there was an increased blood glucose concentration and a decreased thyroid gland weight. These results indicate that continuous exposure of broiler chickens to high ambient temperatures markedly affects their performance and physiological response.
Electronic Journal of Environmental, Agricultural and Food Chemistry
The main objective of this study was to investigate the appropriate duration of early age thermal conditioning that improves heat tolerance in broiler chickens with minimum reduction in growth performance. Two hundred, unsexed commercial Hubbard® broiler chicks were randomly allocated to a control and four early age thermal conditioning treatments replicated four times, with 10 chicks per replicate in a Completely Randomized Design (CRD). The treatments consisted of exposure to air temperature of 38 ± 1oC for 3, 6, 12 or 24 h at 4 d of age against the control in which chicks were exposed to the prevailing room temperature.
Strategies for preventing heat stress in poultry
World's Poultry Science Journal, 2006
Their higher production performance and feed conversion efficiency make today's chickens more susceptible to heat stress than ever before. The increasing proportion of poultry production in tropical and subtropical regions makes it necessary to reconsider the long-term selection strategy of today's commercial breeding programmes. Also, the importance of the potential use of Naked neck and Frizzle genes is accentuated. Nutritional strategies aimed to alleviate the negative effects of heat stress by maintaining feed intake, electrolytic and water balance or by supplementing micronutrients such as Vitamins and minerals to satisfy the special needs during heat stress have been proven advantageous. To enhance the birds' thermotolerance by early heat conditioning or feed restriction seems to be one of the most promising management methods in enhancing the heat resistance of broiler chickens in the short run. AERTS, J-M., BERCKMANS, D., SAEVELS, P., DECUYPERE, E. and BUYSE, J. (2000) Modelling the static and dynamic responses of total heat production of broiler chickens to step changes in air temperature and light intensity. British Poultry Science 41: 651-659. AIT-BOULAHSEN, A., GARLICH, J.D. and EDENS, F.W. (1995) Potassium chloride improves the thermotolerance of chickens exposed to acute heat stress. Poultry Science 74: 75-87. ALLEMAN, F. and LECLERCQ, B. (1997) Effect of dietary protein and environmental temperature on growth performance and water consumption of male broiler chickens. British Poultry Science 38: 607-610. ALMIRALL, M., COS, R., ESTEVE-GARCIA E. and BRUFAU, J. (1997) Effect of inclusion of sugar beet pulp, pelleting and season on laying hen performance. British Poultry Science 38: 530-536. Heterophil/lymphocyte ratio as a selection criterion for heat resistance in domestic fowls. British Poultry Science 38: 159-163. ARJONA, A.A., DENBOW, D.M. and WEAVER, W.D. (1988) Effect of heat stress early in life on mortality of broilers exposed to high temperature just prior to marketing. Poultry Science 67: 226-231. Early age thermal conditioning and a dual feeding program for male broilers challenged by heat stress. Poultry Science 80: 29-36. (2004) Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram). Poultry Science 83: 1551-1558. BOTTJE, G. and HARRISON, P.C. (1985) The effects of tap water, carbonated water, sodium bicarbonate, and calcium chloride on blood acid-base balance in cockerels subjected to heat stress. Optimum dietary arginine: lysine ratio for broiler chickens in altered during heat stress in association with changes in intestinal uptake and dietary sodium chloride.
2012
The main objective of the study was to investigate the appropriate duration of early age thermal conditioning that would improve heat tolerance in broiler chickens with a minimum reduction in production performance. 200 commercial Hubbard broiler chicks were randomly allocated to five treatments. Each of the five treatments was replicated four times, with 10 chicks per replicate in a completely randomized design (CRD). The treatments consisted of birds exposed to air temperature of 37 ± 1 oC for 3, 6, 12 and 24 hrs at 4 days of age against the control that was raised under standard conditions (35 oC in week 1, and reduced by 3 oC every week until room temperature. Temperatures were reduced by raising the positions of infrared lamps until the desired air temperatures were reached. Early age thermal conditioning significantly (P 0.05) in feed conversion ratio (FCR) between thermal conditioned birds and the control. Birds exposed to 12 and 24 hours of thermal conditioning had a signif...
Techniques to Minimize the Effects of Acute Heat Stress or Chronic in Broilers
Brazilian Journal of Poultry Science, 2019
High environmental temperature is limiting factor in broiler production. In order to minimize the undesirable consequences of acute or chronic heat stress, the techniques of fixed dietary electrolyte balance and early heat conditioning were evaluated. The objective of this study was to evaluate the possible interactions and effects of dietary electrolyte balance and early heat conditioning on feed intake, body weight, feed conversion ratio, mortality, energy bioeconomic index, fecal moisture, abdominal fat, and breast meat color (L*a*b*) of broilers submitted to chronic or acute heat stress. In total, 1280 chicks, were equally divided in experiment I (chronic heat stress, 6h/day at 32ºC from 35 to 39 d of age) and II (acute heat stress, 36 ºC for 6h at 38 days of age). The data of both experiments were combined and analyzed according to a 2x2x2 factorial arrangement (early heat conditioning (ETC) or not; fixed dietary electrolyte balance (EB) or not; and exposure to acute or chronic heat stress). ETC consisted of exposing 5-d-old birds to 36.0 °C for 24 hours. No interaction among the evaluated factors was detected. Birds exposed to acute heat stress presented significantly higher compared with chronic heat stress. Fixed dietary EB resulted in significantly higher fecal moisture. Lower abdominal fat percentage was obtained in birds exposed to chronic relative to acute heat stress. Higher breast meat L* and b* values were observed in birds exposed to acute heat stress than those submitted to chronic heat stress, indicating worse meat quality.
The objective of this study was to determine the effect of elevated air temperature in the first grow period on some physiological indicators of broiler chickens of different origin. Day-old Ross 308 and Hubbard Flex broiler chickens were assigned to 4 groups. Groups I (Ross 308) and II (Hubbard Flex) were kept under standard thermal conditions throughout rearing, and groups III (Ross 308) and IV (Hubbard Flex) were exposed to 10°C higher than recommended air temperature from 1 to 21 days of rearing. At 1, 21 and 42 days of the experiment, blood was collected from 10 birds in each group to determine T3 and T4, total protein, immunoglobulin complex, glucose, hemoglobin and hematocrit levels. The exposure to the thermal challenge decreased T3 and T4 levels at 21 days of rearing in both Ross 308 and Hubbard flex broilers compared to birds raised under standard thermal conditions. At 21 days of the experiment was observed a statistically significantly lower concentration of total protein in group I compared with group III and between group II and IV. There was no effect of elevated air temperature on the immunoglobulin complex concentration in the blood of birds of both genetic groups. In both genetic groups, the exposure to the thermal challenge caused a tendency to decrease the concentration of glucose. Statistically significant differences at 21 days of rearing of the hemoglobin content were observed between Ross 308 birds from groups I and III. The thermal challenge caused a statistically significant decrease in hematocrit levels in birds from both genetic groups at 21 days of the experiment. The thermal challenge upset the body’s homeostasis in both genetic groups of chickens, which possibly suggests that elevated air temperature during the first period of rearing has a negative effect on the welfare of broilers, regardless of their origin.
Effect of thermal conditions on welfare of broiler chickes of different origin
Annals of Animal Science, 2010
The objective of the study was to determine the effect of the stress factor of elevated air temperature during the second rearing period on health, duration of tonic immobility, blood corticosterone levels and heterophil to lymphocyte ratio in commercial broilers representing three commercial lines. Day-old Hybro, Hubbard Flex and Ross 308 broiler chickens were assigned to 6 groups. In the experimental groups, birds were exposed to elevated air temperature (30°C) in the rearing area from 30 to 34 days of age (4 days), and to standard thermal conditions (20–18°C) from 34 to 42 days of the experiment. The control groups consisted of broilers maintained throughout rearing under standard thermal conditions, with the air temperature of 31–33°C during the first days being gradually decreased to 20–18°C at 6 weeks of age. Broiler mortality was monitored in all the groups throughout the experiment. The concentration of plasma corticosterone was determined at 30, 34 and 42 days of the experiment in 7 birds from each group. Blood smears were also performed to count lymphocytes (Ll) and heterophils (H), which made it possible to determine the H:L ratio. At 30, 34 and 42 days of the experiment, the duration of tonic immobility (TI) was examined in 7 birds from each group. The thermal factor applied in the second rearing period elicited a stress reaction in the chickens of all lines, as indicated by the increased level of blood corticosterone. However, Ross 308 broilers were less tolerant of reduced welfare levels associated with elevated air temperature compared to Hybro and Hubbard Flex broilers, as evidenced by higher mortality, the highest increase in blood corticosterone, longer duration of TI, as well as increased heterophil to lymphocyte ratio after the thermal factor was applied. the results of the present experiment show that Ross 308 chickens are probably the least suitable for rearing during the summer production cycles.
EFFECT OF THERMAL CONDITIONS ON WELFARE OF BROILER CHICKENS OF DIFFERENT ORIGIN
the objective of the study was to determine the effect of the stress factor of elevated air tempera- ture during the second rearing period on health, duration of tonic immobility, blood corticosterone levels and heterophil to lymphocyte ratio in commercial broilers representing three commercial lines. day-old hybro, hubbard flex and ross 308 broiler chickens were assigned to 6 groups. in the experimental groups, birds were exposed to elevated air temperature (30°c) in the rear- ing area from 30 to 34 days of age (4 days), and to standard thermal conditions (20–18°c) from 34 to 42 days of the experiment. the control groups consisted of broilers maintained throughout rearing under standard thermal conditions, with the air temperature of 31–33°c during the first days being gradually decreased to 20–18°c at 6 weeks of age. broiler mortality was monitored in all the groups throughout the experiment. the concentration of plasma corticosterone was deter- mined at 30, 34 and 42 days of the experiment in 7 birds from each group. blood smears were also performed to count lymphocytes (l) and heterophils (h), which made it possible to determine the h:l ratio. at 30, 34 and 42 days of the experiment, the duration of tonic immobility (ti) was exam- ined in 7 birds from each group. the thermal factor applied in the second rearing period elicited a stress reaction in the chickens of all lines, as indicated by the increased level of blood corticos- terone. however, ross 308 broilers were less tolerant of reduced welfare levels associated with elevated air temperature compared to hybro and hubbard flex broilers, as evidenced by higher mortality, the highest increase in blood corticosterone, longer duration of ti, as well as increased heterophil to lymphocyte ratio after the thermal factor was applied. the results of the present experiment show that ross 308 chickens are probably the least suitable for rearing during the summer production cycles.
Poultry Science, 2003
Early age thermal conditioning (TC) durably improves resistance of broilers to heat stress and reduces body temperature (Tb). Three experiments on broiler chicks were conducted to evaluate the effects of TC at 5 d of age on Tb variation measured by thermometer between 4 and 7 d of age, under a tropical environment. Because manipulation of chickens to measure Tb with a thermometer may increase Tb, a preliminary experiment on 13 3-to-4-wk-old male broilers compared Tb measured by telemetry to Tb measured in the terminal colon during three successive periods at 22, 33, and 22°C. During heat exposure, Tb rapidly increased by 0.9°C and plateaued over 24 h. During the last period, seven of the broilers rapidly reduced Tb to a plateau lower than the initial Tb, although six broilers exhibited more variable Tb. Mea-(
Poultry science, 2016
The current study aimed to investigate whether embryonic temperature manipulation may alter thermal preference throughout the rearing phase of broiler chickens and how this manipulation may affect response to thermal challenge, metabolism, growth rate and feed intake rate. Eggs were exposed to a constant incubation temperature [machine temperatures: 36°C (Low), 37.5°C (Control), and 39°C (High); eggshell temperature of 37.4 ± 0.08°C, 37.8 ± 0.15°C, and 38.8 ± 0.33°C, respectively] from d 13 till hatching. Low treatment chickens showed lower plasma T3 and GH levels at d 1 of age and lower T3 level at d 42 of age compared to the Control treatment. Preferred ambient, rectal temperature, T4 level, growth rate, food intake rate, and response to thermal challenge were not altered in these chickens. On the other hand, High-treatment chickens exhibited high preferred ambient temperature and rectal temperature during the first 2 wk post-hatch, lower plasma T3 level at d 21 and 42 and a delay...