Bone parameters and organ morphometry of two broiler chicken lines exposed to heat for different periods (original) (raw)
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Tibia Bone Integrity in Broilers Subjected to Cyclic Heat Stress
Ciência Animal Brasileira
Macroscopic and microscopic changes in the epiphyseal region of the tibia were recorded in the 42nd day of life of broilers subjected to one-hour heat stress in different rearing phases. The treatments comprised both broilers reared under room temperature and humidity conditions from the 1st to the 42nd day of life (control) and broilers subjected to heat stress from the 16th to the 21st, from the 22nd to the 42nd, and from the 16th to the 42nd day of life. The adopted design was completely randomized with six replicates; 35 broilers were used in each experimental unit. Fragments from the epiphyseal region were extracted and sectioned lengthwise for macro and microscopic analyses. Data on tibia lesion scores were analyzed by Kruskal Wallis test at 5%. The one-hour cyclic heat stress did not change the morphologic integrity in the epiphyseal region of the tibia in the different treatments. Broilers subjected to one-hour cyclic heat stress did not develop lesions that suggested tibial...
Revista Brasileira de Ciência Avícola, 2002
The objective of the present study was to assess the development of broiler chicks during the first week post-hatching when reared at three different environmental temperatures. A total of 480 day-old chicks were placed in three environmentally controlled rooms (20, 25 and 35°C) from 1 to 7 days of age. Body weight gain, feed and water intake, as well as liver, gizzard, heart, yolk sac and bursa of Fabricius weights were measured daily. Tibia and femur bones were weighed and their length and width (medial diameter) were also obtained. The chicks reared at 20º C had lower weight gain and ingested less food than chicks reared at 25°C and less water than chicks kept at 35°C. Relative weights of the liver, heart, and gizzard were affected by environmental temperature, whereas yolk sac and bursa of Fabricius relative weights were not. The data showed that all bone parameters increased with bird age. Environmental temperature did not affect tibia or femur width, however a significant incr...
Acta Scientiarum Polonorum seria Zootechnica, 2017
The experiment was conducted during the summer production cycle. Broiler chickens kept on litter-group I and on litter with access to pasture-group II. Throughout the experiment, mortality were recorded. During the second rearing period, when outdoor temperatures were high, radiation and rectal temperature was measured in birds, and blood was collected to determine the levels of thyroid hormones, glucose, corticosterone, and hematocrit. Broiler chickens from group I were characterized by higher mortality compared to group II. In group I, rectal temperature was found to increase during the 6th week of rearing. In broilers from group II, T 3 decreased and T 4 increased with an increase in air temperature. The lower body temperature of broiler chickens and the smaller proportion of dead chickens in the group with outdoor access may suggest that this housing system helped to increase the thermal comfort of birds during the summer heat. It can therefore be concluded that housing with outdoor access improves the welfare of broiler chickens exposed to heat stress.
Brazilian Journal of Poultry Science, 2007
In order to evaluate the effects of broiler genotype and of heat exposure on performance, carcass characteristics, and protein and fat accretion, six hundred one-day-old male broilers were randomly assigned in a 2 x 3 factorial arrangement, according to the following factors: genetic group (selected and non-selected broilers) and pair-feeding scheme (Ad32 - reared under heat stress and fed ad libitum; Ad23 - reared at thermoneutrality and fed ad libitum; Pf23 - reared at thermoneutrality and pair fed with Ad32), with a total of six treatments with four replicates of 25 birds each. Independent of pair-feeding scheme, selected broilers showed better feed conversion, higher carcass yield, and lower abdominal fat deposition rate. However, as compared to non-selected broilers, they reduced more intensively feed intake when heat exposed, which promoted significant breast-yield decrease, and more pronounced changes on carcass chemical composition. These findings allows concluding that, in both genetic groups, both environmental temperature and feed-intake restriction influence abdominal fat deposition rate and other carcass characteristics; however, the impact of heat exposure on broiler performance is more noticeable on the selected line.
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.
Productive features of broiler chickens in hot weather: effects of strain and sex
Semina: Ciências Agrárias, 2018
The objective of the present study was to evaluate the performance of broiler strains (Cobb 500, Ross 308, and Hubbard Flex) in hot weather. Environmental temperatures above thermal comfort trigger responses of the animals to maintain homeothermia, which negatively affects productive performance. A total of 2,160 chicks of both sexes, were distributed in an experimental design that was completely randomized in a factorial arrangement of 3 × 2 (strains and sexes) with six replicates of 60 birds each. Feed intake (FI), live weight (LW), weight gain (WG), and feed conversion (FC) were analyzed at periods of 1–7, 1–21, 1–28, 1–42, and 1–49 days old. At 42 and 49 days old, the carcass weight (CW), carcass yield (CY), breast yield (BY), thigh yield (TY), and drumstick yield (DY) were analyzed. The strains differed in LW and WG in most periods, especially for Cobb broilers in the pre-start period (1–7 days) and Hubbard broilers in the last two periods (1–42 and 1–49 days). Except for the p...