Effects of incubation temperature on hatching and carcass performance of broilers

The effects of exposure to cold during incubation on developmental stability, fear, growth, and carcass traits in Japanese quails

The aim of this study was to determine the effects of 6 h/day cold (35.0 °C) acclimatization between the 9^th and 15^th days of incubation of Japanese quail embryos on hatchability, livability, chick quality, developmental stability, fear response, live weight, and slaughter-carcass characteristics. Two homologous incubators and a total of 500 hatching eggs were used in the study. Randomly selected half of the eggs were exposed to cold according to the eggshell temperature. The cold acclimation of Japanese quail embryos had no adverse effects on all mentioned traits, except for chick quality. Chicks in the control group had higher Tona scores (99.46) than those exposed to cold (99.00) (P < 0.05). In addition, there were differences among the treatment groups in terms of the parameters of mature weight (β₀), instantaneous growth rate (β₂), and inflection point coordinates of the Gompertz growth model (P < 0.05 for all). It was found that exposing embryos to cold during the incubation changed the shape of the growth curve. As the development of embryos exposed to cold slows down, a compensatory growth occurs in the early posthatch period. Thus, the growth rate increased in the period before the inflection point of the growth curve.

Effect of temperature manipulation during incubation on body weight, plasma parameters, muscle histology, and expression of myogenic genes in breast muscle of embryos and broiler chickens from two commercial strains

1. This study evaluated the effect of a higher incubation temperature on body weight, plasma profile, histology and expression of myogenin (MYOG), insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor A (VEGFA) genes in breast muscle of embryos and broilers from two commercial strains.2. A total of 784 eggs from Ross 308 and Cobb 500 broiler breeder flocks were used. Half of the eggs per strain were incubated at control temperature (37.8°C), whereas the other half were exposed to heat treatment (HT) of 38.8°C between embryonic day (ED) 10 and 14, for 6 h/day. Embryos and chicks were sampled on ED 19 and at hatch. A total of 480, one-day-old chicks per strain and incubation temperature were reared up to 42 d post-hatch.3. The HT increased hatch weight of Ross chicks and 42-d body weight of broilers from both strains. Lower plasma triacylglycerol levels were measured for HT embryos and broilers on ED 19 and 42 d post-hatch, respectively. HT reduced plasma T₃ levels in Ross embryos and broilers for the same periods. Hepatic TBARS concentrations were elevated by HT compared to the control incubation.4. The HT reduced breast muscle VEGFA gene expression of Cobb embryos on ED 19, whereas expression was stimulated in day-old chicks. At 42 d post-hatch, fibre area was increased by HT regardless of strain. Compared to the control incubation, HT increased the breast yield of Ross broilers and leg yield of Cobb. Ross-HT broilers had a higher pH at 24 h after slaughter and better water holding capacity than Cobb-HT broilers.5. These results suggested that HT increased body weight, fibre area, IGF-I gene expression and lowered plasma triacylglycerol levels of broiler chickens from both strains at 42 d. However, HT influenced the expression of VEGF-A and MYOG genes and meat quality differently between the broiler strains.

Effects of repeated thermal manipulation of broiler embryos on hatchability, chick quality, and post-hatch performance

The current study aimed to evaluate the effects of embryonic thermal manipulation (TM) on hatching criteria, chick quality, and subsequent growth performance of broiler chickens under heat stress (HS) condition. Two thousand fertile eggs were randomly divided between 2 groups and incubated under standard (37.8 °C and 56% relative humidity (RH)) and TM (39.5 °C and 65% RH) conditions. Temperature and humidity were identical in both groups within the first 10 days. The eggs in the TM group were exposed to 39.5 °C and 65% RH for 3 h/day from 11 to 16 days of incubation. Egg weight (EW) was measured in 1, 11, and 18 days of incubation, and eggshell temperature (EST) was recorded daily. Chick quality was, also, evaluated according to the Tona method on hatch day. Samples of the chicks (n = 20) were euthanized and dissected at 0-day post-hatch, and different carcass parts were weighed, and blood samples were collected for hormones analysis. The post-hatch growth performance of both groups was also recorded under HS (37 °C for 5 h beginning at 22 days) condition. The results showed that TM did not significantly affect hatchability and embryonic mortality (P > 0.05). The female chick percentage was higher in the TM group (P < 0.05). Eggshell temperature and serum concentrations of corticosterone and T₄ were significantly higher in the TM compared with the control chicks (P < 0.05). The chick length was considerably shorter in TM chicks (P < 0.05). Chick quality was not influenced by TM. There was no significant difference between the two groups in the post-hatch growth performance (P > 0.05). In conclusion, exposing broiler embryos to the controlled TM did not have adverse effects on chick quality and post-hatch growth performance.

Production traits of artificially and naturally hatched geese in intensive and free-range systems - II: slaughter, carcass and meat quality traits

1. This study investigates the slaughter, carcass and meat quality traits of artificially and naturally hatched geese in intensive and free-range production systems. 2. The study was conducted with 114 naturally hatched and 102 artificially hatched geese. From each replicate of the intensive and free-range systems, one female and one male goose were slaughtered at the ages of 14, 16 and 18 weeks (a total of 32 geese per slaughter week). 3. Artificially hatched geese had higher slaughter weights (5280 vs. 4404 g), carcass weights (3520 vs. 2863), dressing percentages (66.6-65.2% vs. 65.0-63.6%) and carcass part, feather and edible inner organ weights. The ratio of both edible inner organs and abdominal fat was higher in naturally hatched geese. Breast meat L*, a* and pH values and thigh meat dry matter values were higher in artificially hatched geese, whereas thigh meat b* and pH values were higher in naturally hatched geese. 4. Intensively reared geese had higher slaughter weights (4900 vs. 4783 g), carcass weights (3253 vs. 3130 g) and abdominal fat weights (280 vs. 250 g), as well as higher dressing percentages (66.3-64.9% vs. 65.3-63.9%). Breast meat b* and thigh meat L* values were higher in the intensive system, while breast and thigh pH values, dripping loss and cooking loss were higher in the free-range system. Water-holding capacity was higher in the intensive system. 5. In conclusion, artificially hatched, intensively reared geese had the highest slaughter weights; however, both artificially and naturally hatched geese raised in a free-range system reached acceptable slaughter weights and can thus be recommended for use with this type of production system.

Influence of thermal stimulation during the late phase of incubation on hatching results and post-hatch broiler performance under commercial conditions

Two experiments, which differed in breeder age, strain and season, were conducted to study the influence of low-intensity, short-duration thermal stimuli during the late phase of incubation on hatchability and performance. The first experiment conducted in April-June used eggs from Cobb × Ross broiler breeders at 35-41 weeks of age and the second experiment performed in February-April used eggs from Hubbard × Cobb broiler breeders at 49-53 weeks of age. Eggs in the test group had the same physical environment as eggs in the control group except that incubation temperature was increased by 1˚C for 2 h/d above the control group from 18 to 20 d of incubation (DI). The results demonstrated that thermal stimulation of 1˚C for 2 h/d above control incubation temperature during 18-21DI did not have any adverse effects on hatch and post-hatch performance of broilers. In both experiments, treatment did not significantly alter the secondary sex ratio in hatched chickens, but hatch residue showed that the proportion of unhatched male embryos was significantly lower in the test groups than in the control groups. In the first experiment, thermal stimulation improved feed conversion by 1.82% compared with the control.

Effects of thermal manipulations during embryogenesis of broiler chickens on developmental stability, hatchability and chick quality

Stress based on high temperature and humidity reduces the production performance of fast-growing broilers and causes high mortality. Temperatures higher than optimum have been applied to broilers in the embryonic period in order to overcome thermal stress. This study was conducted to investigate the effects of exposure to two long-term high-thermal environments on the developmental stability of embryonic growth, hatchability and chick quality. For this purpose, 600 broiler eggs were incubated. Treatments consisted of eggs incubated at 37.8°C at 55% relative humidity throughout (control), heated to 39.6°C at 60% relative humidity for 6 h daily from 0 to 8th day, and heated to 39.6°C at 60% relative humidity for 6 h daily from the 10 to 18th day. Embryo weights and lengths of face, wing, femur, tibia and metatarsus were measured daily between the 10th and 21st day of the experiment. Daily relative asymmetry values of bilateral traits were estimated. The hatchability, the weight of the 1-day-old chicks and chick quality were determined. In conclusion, no negative effects of the treatments of the long-term high-thermal environment in the early and late stages of incubation for epigenetic adaptation were determined on the embryo morphology, development stability and weight of the chick. Moreover, regressed hatchability of embryos that were exposed to a long-term high-thermal environment was detected. Especially between the 10 and 18th day, the thermal manipulation considerably reduced the quality of the chicks. Acclimation treatments of high temperature on the eggs from cross-breeding flocks should not be made long term; instead, short-term treatments should be made by determining the stage that generates epigenetic adaptation.

The effects of different eggshell temperatures on embryonic development, hatchability, chick quality, and first-week broiler performance

The aim of the current study was to determine the effects of different eggshell temperatures (EST) during 10 to 18 d of incubation on embryonic development, hatchability, chick quality, first-week broiler performance. The EST were maintained within the temperature ranges of 33.3 to 36.7, 37.8 to 38.2, and 38.9 to 40.0°C for the low, control, and high EST treatments, respectively. From d 15 to 18, embryo weight and relative embryo weight were found to be similar in the low and high EST groups. Salable chicks and hatchability of total eggs was found to be higher in the control EST group. Between d 10 and 17 of incubation, embryonic mortality in low, control, and high EST groups was determined to be 1.6, 0.8, and 2.0%, respectively. From d 18 to hatch, embryonic mortality and rate of dead and cull chicks were found to be significantly different. Hatching in high EST group was completed 26 h early, although hatching in low EST group was completed 10 h later than the control EST group. On the of hatching day, chick weight and length were found to be 39.5, 41.0, and 42.5 g, and 18.5, 21.4, and 19.1 cm in low, control, and high EST groups, respectively. The highest residual yolk sac weight and relative residual yolk sac weight were observed in high EST group as 7.7 g and 18.7%. Yolk-free chick weight and relative yolk-free chick weight were highest in the control EST group. At 1 wk of age, the BW in low, control, and high EST groups were determined as 131.1, 140.0, and 140.8 g, respectively. No significant difference was found for feed intake and feed conversion among treatments for wk 1. The mortality during the first week did not differ among groups; however, a higher mortality rate was observed numerically in the high EST group. In conclusion, embryo development, incubation parameters, chick quality, and the first week performance are affected by small changes in the EST.

Effects of slaughter age and mass selection on slaughter and carcass characteristics in 2 lines of Japanese quail

The aim of this study was to evaluate the relationship between slaughter age and slaughter-carcass characteristics in 2 quail lines. With this aim, a Japanese quail flock subjected to mass selection to increase BW for 4 generations and a control flock that randomly mated for 4 generations were used. Birds of both lines were slaughtered at 4, 5, 6, 7, and 8 wk of age. Weights of carcass, breast, leg, wing, edible inner organs, and abdominal fat, and their percentages in BW were measured. Short-term mass selection for increased BW resulted in an increase for all slaughter and carcass traits, except edible inner organ percentage. Slaughter age had a significant effect on the studied traits, indicating that the BW and weight of carcass, carcass parts, abdominal fat, edible inner organs, and percentage of abdominal fat increased with increased slaughter age. Conversely, the carcass yield and percentages of carcass parts and edible inner organs were decreased with an increase in slaughter age. The present study showed that deterioration in carcass quality occurred with an increase in slaughter age. Furthermore, the differences between the carcass weights over the different ages ranged between 16.83 to 22.45% in favor of the selection line after a short-term mass selection.

Effects of incubation temperature on the bone development of broilers

Manipulating the development of the leg bone by making simple changes to incubation temperature could help reduce the incidence of abnormalities. This study tested the hypothesis that increasing or decreasing the temperature of chick incubation by 1°C for 3 d during ED 4 to 7 affects hatchability, growth, and leg abnormalities of Cobb 500 broilers fed 3 diets: a diet that induced tibial dyschondroplasia, a Ca-deficient diet that induced rickets, and a P-deficient diet that induced rickets. In experiment 1, eggs hatched earlier, and more eggs hatched, at 38.5°C (92.77%) compared with at 37.5°C (86.22%). Body weight was lower in chicks incubated at the higher temperature compared with those incubated at the lower temperature (44.66 vs. 42.92 g). In experiment 2, egg setting times were +17 h for 36.5°C eggs and -10 h for 38.5°C compared with standard setting at 37.5°C (508 h). Hatchability of fertile eggs (92.92%) was highest at 37.5°C and decreased at 36.5°C (89.82%) and 38.5°C (81.55%). Body weight was lower (48.98 g) at 36.5°C than at 37.5°C (49.57 g) and at 38.5°C (50.56 g). Experiment 3 separated effects of incubation temperature and incubation time and was conducted with control and Ca-deficient diets. No main effects or interactions between incubation temperature or time and bone abnormalities were detected. It is important to note that eggs hatched at different times in this study. A difference as little as 1°C for 3 d during ED 4 to 7 affected hatching time and weight.

High eggshell temperatures during incubation decrease growth performance and increase the incidence of ascites in broiler chickens

High eggshell temperatures (EST; ≥38.9°C) during the second half of incubation are known to decrease the body and organ development of broiler hatchlings. In particular, relative heart weights are decreased by a high EST, and this may increase the incidence of metabolic disorders that are associated with cardiovascular development, such as ascites. The current study investigated the effects of a high EST on chick quality, subsequent performance, and the incidence of ascites later in life. Eggs were incubated at a normal (37.8°C) or high (38.9°C) EST from d 7 of incubation onward. After hatching, the chickens were housed per EST in pens, and a normal or cold temperature schedule was applied during the grow-out period. Hatchability, hatchling quality, BW, feed conversion ratio, total mortality, mortality associated with ascites, slaughter characteristics, and ascites susceptibility at 6 wk of age were evaluated. Except for total ventricle weight, no interaction was found between EST and the grow-out temperature. Hatchability was comparable between the EST treatments, but the percentage of second-grade chickens was 0.7% higher at the high EST. Yolk-free body mass was 3.0 g lower, and heart weights were 26% lower at hatch in the high compared with the normal EST treatment. Body weight continued to be less during the grow-out period after the high EST incubation. However, breast meat yield was 1.0% higher in the high than in the normal EST. Feed conversion ratio did not differ between EST treatments. Total mortality was 4.1% higher and mortality associated with ascites was 3.8% higher in the high compared with the normal EST treatment. The ratio between the right and total ventricle was 1.1% higher in the high compared with the normal EST treatment at slaughter age. In conclusion, a high EST from d 7 of incubation onward decreased hatchling quality and growth performance, but increased breast meat yield. Furthermore, high EST incubation increased the incidence of ascites, which may be related to the reduced heart development at hatch.