Browsing by Publisher "Poultry Science Association"

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    Criteria for Evaluating Husbandry Practices to Alleviate Heat Stress in Broilers
    (Poultry Science Association, 2003) Yalçin S.; Özkan S.; Çabuk M.; Siegel P.B.
    This study was undertaken to investigate the effects of management techniques used under heat stress on growth as well as developmental instability, duration of tonic immobility (TI), and heterophil-to-lymphocyte ratios (H:L) of broilers. Three-hundred sixty cockerels obtained from a commercial hatchery were randomly assigned to 12 floor pens. When the cockerels reached 21 d of age, three pens were kept as controls. Broilers in the other nine pens were moved to a room heated from 32 to 35°C between 1000 and 1700 h each day from 21 to 42 d of age. Broilers in the heated room were randomized into three treatment groups consisting of 1) conditioned (chicks exposed to 36°C for 24 h at 5 d of age), 2) feed-restricted (during the heat stress, feed was withdrawn 2 h before the hot period, and chicks were fed between 1700 and 0800 h), 3) and heat-stressed only. Conditioned and feed-restricted broilers gained 3.2 and 2.8%, respectively, more BW than heat-stressed broilers. Relative asymmetry (RA) averaged across several bilateral traits for the prolonged heat stressor was more informative than the RA for a single bilateral trait. Corrrelations suggest that RA were not closely associated with duration of TI and H:L under the conditions of this experiment.
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    Pre- and postnatal conditioning induced thermotolerance on body weight, physiological responses and relative asymmetry of broilers originating from young and old breeder flocks
    (Poultry Science Association, 2005) Yalçin S.; Özkan S.; Çabuk M.; Buyse J.; Decuypere E.; Siegel P.B.
    The present experiment was conducted to examine the effects of pre- and postnatal conditioning to induce thermotolerance in broilers hatching from eggs orginating from younger and older breeder flocks. From each flock, 500 eggs were randomly divided into 2 groups and incubated at standard (SIT) and high (HIT) temperatures. At hatch, chicks were allotted to 36 floor pens. At 5 d of age 3 pens per parent age per incubation temperature were heat conditioned (C) for 24 h. At 21 d of age, 3 pens per parent age per incubation temperature were kept under standard (S) rearing temperatures, whereas the remaining broilers (including C) were moved to a heated room (H). Thus, there were 3 groups from 21 to 49 d including S, H, and C+H. The results indicated that to incubate eggs from younger parents at HIT before conditioning at 5 d may reduce deleterious effects of heat stress on body weight at slaughter age. However, HIT temperature decreased slaughter weight of broilers from older parents regardless of rearing temperature. Although conditioning did not prevent increments in rectal temperatures of broilers after 1 wk of heat stress (28 d), adaptation occurred thereafter for broilers from younger parents but not for broilers from older parents. Incubation temperature had no effect on plasma glucose, creatine kinase, uric acid, or triiodotryronine (T3) levels at d 21. There were no differences at 22, 25, or 28 d for T3 concentrations between the H and C+H groups. Overall relative asymmetry was not influenced by treatments on d 49. The results suggest that although pre- and postnatal conditioning may help broilers cope with heat stress, age of parent plays a major role in the ability of broilers to thermoregulate. This is especially the case for broilers originating from younger parents. ©2005 Poultry Science Association, Inc.
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    Effect of dietary fat type on broiler breeder performance and hatching egg characteristics
    (Poultry Science Association, 2008) Bozkurt M.; Çabuk M.; Alçiçek A.
    The effect of dietary fat type on broiler breeder performance was evaluated in the experiment. Three different fat sources (sunflower oil, fish oil, tallow) were supplemented into a corn-soybean meal-based broiler breeder diet. The control diet included no supplemental fat. All diets were isocaloric and isonitrogenous. Feeding of experimental diets was initiated when breeders (Ross 508) were 22 wk old. Body weights of hens and males were not affected by dietary treatments during the experimental period. Tallow supplementation to breeder diet significantly decreased hen-day egg production and cumulative settable egg yield (P < 0.01) when compared with other treatments. Hens fed with tallow and sunflower oil-added diets produced significantly heavier settable eggs than control and fish oil treatments. However, settable egg weight of hens fed with fish oil was lower than other dietary treatments (P < 0.01). Egg yolk weight, albumen weight, and eggshell weight were not affected by dietary treatments. These data suggest that supplementation of different fat sources at a level of 1.5% to the corn-soybean meal diet may affect egg production performance, fertility, egg weight, chick weight, hatch of eggs set, and specific gravity without any adverse effects on body weight and settable egg characteristics. © 2008 Poultry Science Association, Inc.
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    Acclimation to heat during incubation: 3. Body weight, cloacal temperatures, and blood acid-base balance in broilers exposed to daily high temperatures
    (Poultry Science Association, 2008) Yalçin S.; Çabuk M.; Bruggeman V.; Babacanoǧlu E.; Buyse J.; Decuypere E.; Siegel P.B.
    The aim of the present study was to investigate the effects of parental age and heat acclimation during incubation on BW, cloacal temperature, and blood acid-base balance in fast-growing broilers exposed to daily cyclic high ambient temperatures from 21 to 42 d posthatch. Eggs obtained from 32- (younger), 42- (middle-aged), and 65-wk-old (older) breeders were divided into 2 groups. One group of eggs was incubated at the control incubation temperature (IT CONT) and the second group was heat acclimated at 38.5°C for 6 h/d from d 10 to 18 of incubation (ITHA). Chicks were reared at standard brooding temperatures from d 1 to 21. From d 21 to 42, half of the broilers per incubation temperature and parental age were kept as controls (ATCONT) and the other half were exposed to daily cyclic heat treatment (ATHIGH) to impose a stress response. The reduction in BW at ATHIGH was more pronounced for progeny from older compared with younger parents. However, this reduction in BW was more or less abolished for broilers from eggs incubated at ITHIGH, implying an increased tolerance to heat stress. Compared with ITCONT, ITHA reduced BW of broilers from 32- and 42-wk-old parents while having no effect on those from 65-wk-old parents when reared at ATCONT. Higher blood pH, and lower partial pressure CO2 and HCO3- at ATHIGH were associated with greater cloacal temperatures throughout the heat stress from d 21 to 42. Increases in cloacal temperature by AT HIGH were greater for ITCONT than for ITHA broilers. The ATHIGH and ITHA broilers had lesser blood partial pressure CO2 concentrations than ATCONT and ITCONT, respectively. Although at ATHIGH, blood HCO 3 - was lower for broilers from all parental ages, it was more pronounced for those from 65-wk-old parents. It is concluded that these changes in blood acid-base balance reflected adaptive responses to heat stress, and incubating eggs at ITHA improved thermotolerance of fast-growing broilers. ©2008 Poultry Science Association Inc.
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    Acclimation to heat during incubation. 1. Embryonic morphological traits, blood biochemistry, and hatching performance
    (Poultry Science Association, 2008) Yalçin S.; Çabuk M.; Bruggeman V.; Babacanoǧlu E.; Buyse J.; Decuypere E.; Siegel P.B.
    Eggs obtained from broiler breeders at 32 (young), 42 (middle aged), and 65 wk (old) were used to measure the effects of heat acclimation during incubation on morphological, physiological, and metabolic traits at internal pipping (IP) and at hatch. All eggs were from the same stock, and hatching performance was also evaluated. Eggs from each breeder age were incubated at control (CONT) or 38.5°C for 6 h daily from d 10 to 18 of incubation (HA). On d 10 after heat exposure and on d 14, absolute and proportional weights were significantly lower for HA than CONT embryos. By the time of hatching, HA chicks were heavier than CONT chicks, which suggested accelerated growth. This effect was consistent across ages. Liver and heart weights were lower for HA than CONT chicks. At IP, pH was similar for HA and CONT embryos, whereas pO2 and Na + were significantly higher and pCO2, HCO3 ?, and K+ significantly lower for HA than CONT embryos. Blood pH was higher in embryos from older than for younger and mid-aged parents at IP. At hatch there was no effect of heat acclimation for blood HCO 3?, Na+, and K+ levels, whereas plasma triglyceride and T3 levels were higher and plasma uric acid, glucose, and lipid peroxidation levels were lower for HA than CONT chicks. Embryonic mortality was similar among parental ages for CONT. In contrast for HA, embryonic mortality from older parents was higher than for younger and middle-aged parents. A delay in external pipping and hatching time with high incubation temperature was consistent across the breeder ages. It was concluded that lower blood pCO2, HCO3?, K+, and higher pO2 at IP stage, plus increased plasma triglyceride concentrations at hatch, indicate adaptive responses of embryos. ©2008 Poultry Science Association Inc.
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    Acclimation to heat during incubation. 2. Embryo composition and residual egg yolk sac fatty acid profiles in chicks
    (Poultry Science Association, 2008) Yalçin S.; Baǧdatlioǧlu N.; Bruggeman V.; Babacanoǧlu E.; Uysal I.; Buyse J.; Decuypere E.; Siegel P.B.
    The aim of the research was to evaluate embryo composition and changes in egg yolk fatty acid composition during embryonic development as a function of incubation temperature and age of breeders. Eggs obtained from a common breeder stock at 3 ages: 32 (younger), 42 (mid age), and 65 (older) wk were divided into 2 groups and placed into 2 incubators: the control and the second where eggs were heat-acclimated (HA) at 38.5°C for 6 h daily from d 10 to 18 of incubation. Body composition of embryos and chicks were measured on d 14, 18, and at hatch, respectively. Fatty acid profiles of yolk and residual egg yolk sac of chicks were analyzed before incubation and at hatch, respectively. Moisture content of embryos was highest on d 14 and then decreased regardless of parental age and incubation temperature. Moisture content of chicks at hatch from 42- and 65-wk parents were lower than those of chicks from 32-wk parents, whereas the trend in chick fat content was opposite. Incubation temperature had no effect on composition of chicks. Consistently lower cis-4,7,10,13,16,19- eicosapentaenoic (docosahexaenoic acid, DHA; 22:6n-3) and cis-11,14,17- eicosatrienoic (20:3n-3) fatty acids in the residual yolk sac of chicks than in egg yolks before incubation may have resulted from preferential uptake from the yolk. The DHA content in the residual yolk sac was considerably higher in chicks from older parents incubated at HA, whereas, in contrast, levels of 18:3n-3 were lower. Also, chicks from younger parents in the HA treatment had lower transported 18:3n-3 and higher levels of transported DHA. It may be concluded that this process observed during the high incubation temperature may be related to a protective strategy and thus contributes to postnatal heat adaptation. ©2008 Poultry Science Association Inc.
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    Acclimation to heat during incubation: 4. Blood hormones and metabolites in broilers exposed to daily high temperatures
    (Poultry Science Association, 2009) Yalçin S.; Bruggeman V.; Buyse J.; Decuypere E.; Çabuk M.; Siegel P.B.
    The objective of the present experiment was to study the effects of parental age and heat acclimation of embryos on blood metabolites and hormones of broilers exposed to daily cyclic ambient temperatures from d 21 to 42. Eggs obtained from 32 (younger), 42 (middle-aged), and 65 wk (older) breeders were divided into 2 groups. One group of eggs was incubated at control incubation temperature (ITCONT), whereas the second group was heat-acclimated at 38.5°C for 6 h/d from d 10 to 18 of incubation (ITHA). Chicks were reared at standard brooding temperatures from 1 to 21 d. From d 21 to 42, half of broilers/incubation temperature/parental age was kept as the control (ATCONT), whereas the other half was exposed to daily cyclic heat treatment (ATHIGH) to impose a stress response. There was a reduction in plasma triiodothyronine (T3) levels in ITHA broilers. On d 28, plasma T3 levels were similar regardless of parental age of eggs incubated at ITCONT, whereas ITHA resulted in lower levels of T3 in broilers from 65 wk parents. At the same age, ATHIGH reduced plasma triglycerides with the effect greater for ITHA than ITCONT broilers. Plasma uric acid was also lower for ITHA than ITCONT broilers for the offspring of 65 wk parents on d 28. There was an increase in plasma creatine kinase activity on d 42 in ATHIGH broilers regardless of parental age and incubation temperature. Plasma corticosterone was consistently lower for the ITHA than ITCONT treatment, being significant on d 21 and 42. It was concluded that these changes in blood metabolites and hormones may enhance the thermoregulatory ability of ITHA broilers when exposed posthatch to daily high temperatures. © 2009 Poultry Science Association Inc.