PHYSIOLOGICAL PARAMETERS IN BROILER CHICKENS REARED UNDER DIFFERENT HOUSING SYSTEMS DURING A PERIOD OF HIGH TEMPERATURES (original) (raw)
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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.
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.
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 Environmental Heat Stress on Performance and Carcass Yield of Broiler Chicks
World’s Veterinary Journal , 2019
Environmental heat stress is one of the most challenging conditions which have adverse effect on the poultry industry. Broiler chickens are sensitive to heat stress mainly due to not having sweat glands. The current study was conducted to observe the effect of heat stress on performance of Ross-308 broiler chickens. 1600 Ross-308 broiler day old chicks were obtained from local hatchery and randomly divided into two groups, the heat stress group A (n=800) and heat free group B (n=800). Group A was reared in high temperature (101 0 F) whereas group B was reared in ideal temperature. To evaluate the physiological stress indicators blood glucose levels and total blood cell count were checked on day 21 and 28. The parameters observed were; feed intake, body weight gain, feed conversion ratio, water intake and carcass yield. The results indicated that feed intake, weight gain, water intake, feed conversion ratio and carcass yield were significantly higher in group B compared to group A. It was concluded that heat stress has deleterious effect over the performance of broiler Ross-308 chicken.
Journal of Thermal Biology, 2020
Initial brooding temperature is critical for post-hatch growth of broiler chickens. A study was conducted to investigate the early age thermal manipulation (EATM) on the performance and physiological responses broiler chickens under hot humid tropical climate. A total of 260 unsexed day-old Arbor-acre broiler chicks were assigned to five thermal treatments of brooding temperature regimens having 4 replicates of thirteen birds each. The heat treatments were: initial brooding temperature of 35 � C for the first 2 days, and then decreased subsequently, gradually to 22 � C at 21 d of age (CT), initial temperature of 35 � C, sustained for the first 4 days and then decreased gradually (conventionally) (FD), initial temperature of 35 � C for the first 7 days (SD), the birds in CT, but the brooding temperature was raised to 35 � C again for another 3 days from day 7 (SD3), initial brooding temperature of 35 � C for the first 10 days (TD). Data were collected on daily feed intake and weekly body weights. Blood samples were collected from 8 birds per treatment weekly for the determination of plasma uric acid, triglycerides, triiodothyronine (T 3) and creatinine kinase. Data obtained were laid out in a Completely Randomized Design (CRD). Results showed that the final weights of the birds in FD were higher (P < 0.05) than those of the other treatments at the finisher phase. Feed intake of the birds in FD was higher than those of SD3 and TD. FCR of broiler chickens in CT, SD, SD3 and TD was higher than that of FD. The rectal temperature, plasma MDA and blood glucose of the thermally challenged birds in FD was generally better (P < 0.05) than those of the other treatments. It was concluded that EATM can be used to improve performance and also protect broiler chickens from acute heat stress at market age.
Indian Journal of Animal Research, 2019
A study was conducted to find out the effect of thermal stress on the physiological as well as reproductive performances of broiler breeder hens. The birds were exposed to 37±1°C and RH 70% for 6 hours daily for a period of 10 days in the psychrometric chamber (THI >90). In the heat exposed group, body weight gain and feed intake (P lee than 0.05) were negatively affected, whereas water consumption and water:feed intake ratio were much higher during the period of study. Even after 12hrs of heat exposure, surface temperature of feathered regions; neck and back were significantly high (P less than 0.05). The serum cholesterol level in heat treated birds was increasing (P less than 0.05), whereas calcium and phosphorus levelswere showing lower values (P less than 0.05) on the 3rd and 10th day of study. A significant change in serum protein or glucose could not be observed. The reduction in HDEP and internal egg quality parameters like albumen index, Haugh unit score, yolk index etc....