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Effects of 3 eggshell temperatures (EST; 36.7. 37.8, and 38.9°C) in 2 genetic laying hen crossbreds (AB and BB; same hen line, different rooster line) on embryonic metabolism and hatchling quality were investigated. EST were applied from day 14.5 of incubation (E14.5) until hatching. The experiment consisted of 6 consecutive batches with eggs weighing between 59 and 61 g. Heat production was determined continuously from E14.5 onward. In fresh eggs, yolk weight tended to be higher (Δ = 0.28 g; P = 0.08) in the AB crossbred than in the BB crossbred. At E14.5 and E18.5, yolk-free body mass (YFBM) and residual yolk (RY) weight did not differ between genetic crossbred and EST. Hatching time after the start of incubation was not affected by genetic crossbred, but was longer in the 36.7°C (517 h) than in the 38.9°C (505 h), with 37.8°C in between (506 h). At 6 h after hatching, no differences between crossbreds were found for chicken quality parameters, such as chicken weight, chicken length, RY, YFBM, and organ weights, but heart weight was higher in the 36.7°C EST than in the other 2 EST (Δ = 0.24 to 0.30% of YFBM, P = 0.005). Intestinal weight was higher at 36.7°C EST than at 38.9°C EST (Δ = 0.79% of YFBM; P = 0.02), with 37.8°C EST in between. Heat production between E14.5 and E18.5 was higher in the AB crossbred than in the BB crossbred (Δ = 2.61%, P < 0.001) and regardless of crossbred higher at an EST of 38.9°C than at other 2 EST (Δ = 3.59% on average; P < 0.001). Hatchling quality determined at pulling (E21.5) was not affected by EST, but AB chickens were lighter (Δ = 0.46 g; P = 0.03), had less red hocks (Δ = 0.03; P = 0.02), more red beaks (Δ = 0.10; P < 0.001), and a higher (worse) navel score (Δ = 0.11; P < 0.001) than BB chickens. It can be concluded that not only incubation temperature, but also the rooster line appears to play a role in layer crossbred embryo metabolism and hatchling quality. [ABSTRACT FROM AUTHOR]

Two experiments were conducted in which effects of floor eggs, washed floor eggs, and clean nest eggs were investigated on incubation characteristics and performance in later life of broiler chickens. In both experiments, a young and an older breeder flock were used in a 3 x 2 factorial design during incubation. In the second experiment, male and female chickens were reared separately until d 35 of age in floor pens. During this grow out trial, an extra group was created in which chickens obtained from clean nest eggs were mixed with chickens obtained from floor eggs, meaning that grow out period was set up as a 4 x 2 x 2 factorial design with 4 egg types, 2 breeder ages, and 2 sexes. In both experiments, fertility and hatchability of fertile eggs were lower in floor and washed eggs than in clean nest eggs (hatchability: experiment 1: 74.4 vs. 70.6 vs. 92.6% for floor eggs, washed floor eggs and clean nest eggs, respectively, P < 0.001; experiment 2: 78.3 vs. 81.7 vs. 90.2%, respectively, P < 0.001). In experiment 2, BW at d 0 of chickens obtained from clean nest eggs was higher than that of chickens from floor eggs and washed floor eggs (41.5 vs. 40.4 and 40.3 g, respectively; P < 0.001). This difference disappeared during the grow out period and was absent at slaughter age at d 35 of age. Feed intake (FI), feed conversion ratio (FCR), and mortality during the grow out period were not affected by egg type. Incidence and severity of hock burns and footpad dermatitis were not affected by egg type or breeder age. Litter friability at d 35 of age tended to be lower in pens with chickens obtained from washed floor eggs compared to clean nest eggs. We conclude that incubation of floor eggs or washed floor eggs resulted in lower fertility and hatchability compared to clean nest eggs, but that performance during the grow out period was not affected. [ABSTRACT FROM AUTHOR]

In a series of experiments, effects of storage of eggs in water on internal egg quality, embryonic development, and hatchling quality were investigated. In experiment 1, unfertilized eggs were stored for 4 to 14 d in water (W) or air (control; C). In experiment 2, fertilized eggs were stored for 3 to 14 d in water or air and thereafter incubated for 9 d. In experiment 3, eggs were stored for 16 d in water or air and incubated for 1 to 9 d thereafter. In experiment 4, eggs were stored for 14 d in water or air, incubated thereafter, and hatching time and hatchling quality were determined. In all experiments, egg weight loss in the C treatment increased with duration of storage, whereas W eggs gained weight during storage. Albumen and yolk pH after storage and during incubation were greater in the C eggs compared with the W eggs. In experiment 3, embryonic development at d 4 and 9 was advanced in the W eggs compared with the C eggs. In experiment 4, the number of viable embryonic cells after storage and after trypsinization was lower in the C treatment than in the W treatment (30,188 vs. 69,618; P < 0.001). Hatching time was postponed in the W treatment com- pared with the C treatment (501 vs. 495 h; P < 0.05). Hatchling length was greater in the C treatment (19.7 vs. 20.3 cm; P = 0.01), and residual yolk was less in the C treatment than in the W treatment (4.9 vs. 8.3 g; P < 0.00 1). We concluded that storage of eggs in water for a prolonged period positively affects internal egg characteristics and early embryonic development, but negatively affects hatchling quality. The reason for the loss of the head start with progressing incubation needs further investigation. [ABSTRACT FROM AUTHOR]

Embryo development and heat production (HP) were studied in eggs of similar size (60 to 65 g) that were incubated at normal (37.8°C) or high (38.9°C) eggshell temperature (EST) and exposed to low (17%), normal (21%), or high (25%) O2 concentration from d 9 through 19. High EST initially increased HP, but gradually O2 became more important for HP than EST. Finally, HP was highest for the combination of high EST with high O2 and lowest for the combination of high EST with low O2. High EST decreased hatch time, BW, yolk free BW, and relative heart weight. The EST had no effect on residual yolk weight, chick length, or relative liver weight. Increased O2 increased yolk free BW and chick length and decreased residual yolk weight at hatch. No interactions between EST and O2 were observed with regard to embryo development and hatchling characteristics. If embryo development is reflected by HP, it can be concluded that high EST primarily increased embryonic development until the second week of incubation. During the third week of incubation, O2 had a greater effect in determining embryo development than EST. [ABSTRACT FROM AUTHOR]

An experiment was conducted to study the effects of different eggshell temperature (EST) profiles during incubation on embryo mortality, hatchability, and embryo development. Furthermore, chicks from different EST profiles were reared under low and high housing temperatures to investigate subsequent posthatch growth and rectal temperature. Two batches of eggs were used in this experiment. Hatching eggs were subjected to 36.7 or 37.8°C EST during the first week, to 37.8°C EST during the second week, and to 37.8 or 38.9°C EST during the third week of incubation. Posthatch housing temperature decreased from 35°C at d 1 to 30°C at d 7 (high) or decreased from 30°C at d 1 to 25°C at d 7 (low). The difference between machine temperature and EST (DT) was used to illustrate the effect of EST on heat production during incubation. DT differed per batch, and was smallest when eggs were incubated at 36.7°C instead of 37.8°C during wk 1. High EST during wk 3 of incubation (38.9°C instead of 37.8°C) reduced DT only in batch 2. Embryo development was most retarded in eggs incubated at 36.7°C EST compared with at 37.8°C during the first week of incubation. However, highest hatchability and embryo development were always found when EST was maintained at 37.8°C constantly throughout incubation. Chicks that hatched from eggs incubated at low EST during wk 1 of incubation had lower rectal temperature after hatching, especially under low housing temperatures, and this effect lasted until 7 d posthatch in batch 1. The highest rectal temperatures were always found in chicks incubated at 37.8°C EST constantly throughout incubation. Eggs and chicks from different batches require different environmental conditions for optimal embryo development, hatchability, and posthatch growth. Rearing temperature and incubation conditions affect the ability of young chicks to maintain their rectal temperature during the first week posthatch. [ABSTRACT FROM AUTHOR]

Nutrients in the egg and oxygen diffused through the eggshell and membranes are two important factors affecting the metabolism and growth of avian embryos (WILSON, 1997; WANGENSTEEN and RAHN, 1970). The composition of the egg is influenced by breeder age (Marion et al., 1960) and similar sized eggs of an old compared to young breeder flock showed a higher yolk size and consequently higher energy content (NANGSUAY et al., 2013). To optimise nutrient use and development during the incubation and post-hatch period, embryos originating from different breeder ages that differ in their initial nutrient availability might therefore require different oxygen concentrations during incubation. To test this hypothesis, the current study investigated effects of breeder age and oxygen concentration during incubation on embryonic metabolism and development, and post-hatch chick performance. Similar sized eggs of a young (29 weeks) or old (53 weeks) Cobb 500 breeder flock were incubated at 3 oxygen concentrations (17%, 21% or 25%) from day 7 of incubation until 6 hrs after emergence from the eggshell. Egg composition at set, embryonic weight and heat production during incubation and post-hatch performance until 7 days of age was evaluated. Results showed that eggs of the old compared to the young flock were 1.2 g heavier and had 3.9 g more yolk (P < 0.01). No interactions between breeder age and oxygen concentration were found for the characteristics described below. Embryonic heat production was significantly higher from ED14 until ED18 with a higher oxygen concentration (P < 0.05). Yolk-free body mass at 6 hours after hatch was only affected by oxygen concentration, where the 21 and 25% treatment showed a higher weight than the 17% treatment (P < 0.01). This difference disappeared at 7 days of age (P > 0.10). Body weight and relative intestine weight at 7 days of age was higher in chickens of the old compared to the young breeder flock (P < 0.05). Other relative organ weights were not affected by the treatments (P > 0.05). FCR was affected by the oxygen concentration during incubation; the 17% treatment had the highest FCR and the 21% treatment had the lowest FCR, whereas the 25% treatment was intermediate (P < 0.05). Although the higher yolk weight of the eggs of the old compared to the young flock probably increased the energy content and nutrient availability for the embryo, this did not result in a higher metabolic rate or development when oxygen concentration was increased during incubation. This suggests that other factors such as the development and functionality of the yolk sac membrane and/or CAM may limit embryonic metabolism and development. The higher post-hatch growth of chickens of the old compared to the young breeder flock might be related to differences in physiology or development of supply organs, such as the intestines. Embryonic development was positively influenced by a higher oxygen concentration during incubation, but this effect disappeared in the post-hatch period. A higher O2 concentration during incubation did improve the nutrient efficiency for post-hatch growth until day 7 of age, expressed by a lower FCR. [ABSTRACT FROM AUTHOR]

The interaction between carbon dioxide concentration and eggshell temperature during the second half of incubation on broiler chicken embryo development was investigated. The experiment was setup as a 2 × 3 factorial design with eggshell temperatures (EST) and CO2 concentrations as main factors. The experiment was executed in six consecutive batches. Two EST (37.8 or 38.9°C) and 3 CO2 concentrations (0.1, 0.4, or 0.8%) were applied from d 8 of incubation onward. Within each batch, both EST were applied, but CO2 concentration varied among batches. CO2 concentrations were based on the following findings: 0.1% CO2 is a common concentration in a multistage incubator, 0.8% CO2 is incidentally happening in single stage incubators at the end of incubation, and 0.4% CO2 is in between, to investigate whether effects are linearly or not. Within all treatments, the O2 concentration was remained the same at 20.95%. During incubation heat production was determined continuously and embryo and hatchling quality was determined. Cobb 500 eggs (105 per batch) were selected on an egg weight of 62-65 gram from broiler flocks of 37-45 weeks. At day 18 of incubation and within 6 hours after hatching, embryos or chickens were used for determination of embryo or chicken development (weight, length, YFBM, RY, organ weights), blood variables (glucose, lactate, uric acid) and hepatic glycogen. Data will be available during the workshop. [ABSTRACT FROM AUTHOR]

Little is known about applying various eggshell temperatures (EST) during the last week of incubation. In particular, the effect of an EST below 37.8°C during the last week of incubation is poorly investigated. Therefore, we investigated effects of EST of 35.6, 36.7, 37.8, or 38.9°C applied from d of incubation (E) 15, E17, or E19 on hatching pattern, embryonic organ development and first week broiler development and performance. A total of 2,850 first grade eggs of a 43 wk old Ross 308 broiler breeder flock were incubated at an EST of 37.8°C until E15. From E15, E17, or E19 onward, eggs were incubated at an EST of 35.6, 36.7, 37.8, or 38.9°C. Moment of internal pipping (IP), external pipping (EP), and hatch were determined and organ development was measured at E15, E17, E19, IP, EP, and hatch. Chick quality was determined at placement in the broiler house and organ development was measured at d7. BW was determined at placement, d4, and d7. Feed intake (FI) was measured at d4 and d7 and G:F was calculated between placement and d4, and between d4 and d7. A lower EST extended incubation duration compared to a higher EST. The longer incubation duration was mainly caused by the extended time until IP, whereas time between IP and hatch hardly varied between treatments. Relative organ weight was affected by EST. Relative heart weight was affected by EST already from 2 d after start of EST treatment on E15, and effects became more pronounced at longer exposure time to various EST treatments. At hatch, the largest difference in relative heart weight was found between an EST of 35.6 and 38.9°C started at E15 (Δ=64.4%). From E17 onward, EST affected yolk-free body mass (YFBM) and relative stomach weight, where a lower EST resulted in a lower YFBM and relative stomach weight before IP and a higher YFBM and relative stomach weight after IP. From E19 onward, a lower EST resulted in a higher relative liver and spleen weight regardless start time of treatment. Yolk weight and relative intestine weight were not affected by EST before and at E19, but a higher EST resulted in a higher yolk weight and lower relative intestine weight from IP onward. Chick quality at placement was higher at an EST of 35.6°C compared to all other EST treatments, expressed by a longer chick length and highest prevalence of closed navels. BW d7 was higher at an EST of 36.7°C compared to all other EST treatments, which was not caused by a higher FI during the first week. A higher G:F between d0 and d7 was found at an EST of 36.7°C compared to 35.6 and 38.9°C. At d7, a higher relative heart weight was found at an EST of 35.6 compared to 38.9°C. This study indicates that an EST of 38.9°C applied from E15 onward negatively affected chick quality, based on the lower YFBM and lower relative organ growth found at hatch. In addition, an EST of 38.9°C applied from E15 onward negatively affected organ development, and G: F until d7 compared to 37.8°C. Moreover, an EST of 36.7°C had a clear positive effect on embryo development, chick quality, organ development, G:F, and growth performance until d7. An EST of 35.6°C resulted in equal or higher chick quality and organ weights compared to 36.7°C, but this was not reflected in performance parameters. [ABSTRACT FROM AUTHOR]

The effects of circadian lighting schedules during incubation on broiler leg bone development and leg health were investigated in two experiments. In the first experiment, applying a circadian lighting schedule of 12 hours of light, followed by 12 hours of darkness (12L:12D) resulted in higher tibial cortical area and thickness and a better distribution of bone material at hatch compared to continuous light (24L) as revealed by MicroCT scanning. It was furthermore found that 12L:12D resulted in a lower incidence of tibial dyschondroplasia at day 35 post hatch compared to 24L. Continuous darkness (24D) was mostly intermediate. In the second experiment, 24L or 24D were compared to a circadian lighting schedule of 16 hours of light, followed by 8 hours of darkness (16L:8D). At day 35 post hatch, incidence and severity bacterial chondronecrosis with osteomyelitis and epiphyseal plate abnormalities were lowest for broilers exposed to 16L:8D throughout incubation, and tibial dyschondroplasia tended to be lower for 16L:8D than for 24D. Another pathway that may affect embryonic bone development is activity. Between embryonic day (E)14 and E16, heart rate was found to be higher for 24D than for 24L. However, by E19, heart rate was higher for 16L:8D than for both 24D and 24L. This suggests that embryonic activity and/or metabolism were affected by lighted incubation, with effects depending on incubation phase. The overall findings suggest that applying a light-dark rhythm during incubation may improve embryonic leg bone development and leg health at slaughter age compared to continuous light and continuous darkness, while continuous light during incubation had a detrimental effect on embryonic and early post hatch leg bone development and health. [ABSTRACT FROM AUTHOR]

An experiment was conducted to study the effect of egg size on embryo development, heat production, and energy partitioning between egg and hatchling. Small (56.1 ± 0.12 g SEM) and large (70.0 ± 0.11 g SEM) hatching eggs were incubated in climate respiration chambers, and eggshell temperature was maintained constant at 37.8°C in both egg weight classes by adjusting machine temperature. Dry matter, ash, protein, and fat contents were determined in albumen, yolk, yolk-free body (YFB); and residual yolk (RY), and carbohydrate contents and caloric values were calculated. To achieve a constant eggshell temperature, machine temperature needed to be set lower from d 15 onward, coinciding with increased heat production in large eggs compared with small eggs. Selective nutrient uptake resulted in higher fat content and lower protein content in RY in chicks that hatched from small eggs compared with large eggs. The respiration quotient in small and large eggs was the same, and embryos in small and large eggs were equally efficient in the transfer of energy from egg to YFB. The surplus availability of nutrients in large eggs was therefore held responsible for the absolute and relative higher weight of RY in chicks that hatched from large eggs compared with small eggs. [ABSTRACT FROM AUTHOR]

During incubation, development of embryos is affected by eggshell temperature (EST). A constant EST of 37.8°C has been considered so far to result in most optimal embryo development. However, it can be hypothesized that a higher EST in week 2 in combination with a lower EST in week 3 stimulates embryo development and subsequent grow-out performance. In this study, 468 eggs of a 44-week-old Ross 308 breeder flock were incubated at different incubation temperature patterns in a 2 × 2 factorial arrangement. In week 2, EST was either 37.8°C or 38.9°C, and in week 3, EST was either 37.8°C or 36.7°C. At hatch, chick quality was determined. Thereafter, 320 broilers were grown in 32 pens (8 replicates/treatment) for 6 wk. Weekly BW and ADFI were determined, and at day 40, slaughter yield from 128 broilers (4 per pen) was determined. Results showed that EST in week 2 did not interact with EST in week 3 for any variable. An EST of 38.9°C in week 2 resulted in a 1 mm longer chick length (P < 0.001) and 0.4 mmol/L lower blood glucose level (P = 0.04) at hatch than an EST of 37.8°C. Grow-out performance was not affected by EST in week 2 of incubation. An EST of 36.7°C in week 3 resulted in a 1 mm shorter chick length (P = 0.02), 1.0 mmol/L higher blood glucose level (P < 0.001), and higher relative heart (P = 0.01) and stomach weights (P = 0.03) at hatch than an EST of 37.8°C. Additionally, an EST of 36.7°C in week 3 resulted in lower BW, ADG, and ADFI on slaughter age (all P < 0.03) than an EST of 37.8°C. In conclusion, no interaction between EST in week 2 and 3 of incubation was found for any variable. A higher EST in week 2 had minor effects at hatching and during rearing, whereas a lower EST in week 3 seemed to result in better organ development, but resulted in lower grow-out performance. [ABSTRACT FROM AUTHOR]

The current study aimed to investigate whether diet density affects growth performance and nutrient digestion during the first wk after hatch and digestive organ weight at 7 d of age. Effects were studied using a dose-response design consisting of 5 dietary fat levels (3.5, 7.0, 10.5, 14.0, and 17.5%). The dietary fat level was increased through soybean oil inclusion. Amino acids, minerals, and the premix were increased at the same ratio as dietary fat. Consequently, diets were kept neither isocaloric nor isonitrogenous. Broiler chickens were weighed on d 0 and d 7 after hatch, whereas feed intake was measured daily. Excreta produced from d 0 to d 7 was collected at d 7. Dietary dry matter and nitrogen metabolizability, as well as fat digestibility were calculated as an average over 7 days. Broiler chickens were sampled at d 7 to determine carcass yield, breast meat yield, and organ weights. Average daily gain (P = 0.047) and average daily feed intake (P < 0.001) decreased linearly as diet density increased, while gain to feed ratio increased linearly (P < 0.001). An increased diet density resulted in a linear decrease of crop, liver, and pancreas weight relative to body weight (BW; P < 0.05). Duodenum, jejunum, ileum, and cecum length (expressed as cm/kg of BW) and empty weight (as % of BW) increased linearly with increased diet density (P < 0.05). Dietary dry matter metabolizability decreased linearly as diet density increased (P < 0.001), whereas fat digestibility and nitrogen metabolizability were not affected (P > 0.05). In conclusion, one-week-old broiler chickens respond to increased diet densities by increasing intestinal weight and length, while decreasing liver and pancreas weight. This may be an adaptive response to cope with an increased nutrient concentration in the diet. [ABSTRACT FROM AUTHOR]

In 6 experiments, it was investigated whether the pattern of warming from storage temperature to incubation temperature affects early embryonic mortality in broiler eggs. The warming profile (WP) from 21°C to the final incubation temperature of 37.8°C was divided into 2 equal parts (above and below 29.4°C) and the duration of warming in both parts was varied (3 to 17 h). In all experiments, eggs were stored for 13 to 16 d at a storage temperature of 18±2°C. In experiment 1, embryo morphology was evaluated at several time points during a linear warming curve of 24 h from 21°C to an eggshell temperature (EST) of 37.8°C. Results from experiment 1 showed that during the 24 h of warming, embryos did not advance in morphological stage (P = 0.74). Results of experiment 2 and 3 showed that the duration of the WP below 29.4°C (3 to 17 h) had no effect on early embryonic mortality (P ≥ 0.77). Experiment 4 and 6 showed that in eggs from prime breeders, a slow WP (>12 h) above 29.4°C resulted in lower embryonic mortality during the first 2 d of incubation (on average 5.0%) compared to a fast WP of 3 to 6 h (on average 11.3%). In experiment 6, an interaction was found between WP and breeder flock age for embryonic mortality till day 7 of incubation (P = 0.002). Warming profile did not affect embryonic mortality during the first 7 d of incubation in eggs from the young breeder flock. However, in eggs from the prime breeder flock, a WP of 12 h in the first part of warming, followed by 17 h in the second part of warming (WP12-17) had 6.2% lower embryonic mortality in the first 7 d of incubation compared to WP12-3. It can be concluded that a slower WP above 29.4°C reduces early embryonic mortality in long stored eggs, especially those of prime breeder flocks. At this moment, it remains unclear which mechanisms are involved in this phenomenon. [ABSTRACT FROM AUTHOR]

Breeder age and broiler strain influence the availability of nutrients and oxygen through yolk size and eggshell conductance, and the effects of these egg characteristics on nutrient metabolism might be influenced by eggshell temperature (EST). This study aims to determine effects of breeder age, strain, and EST on nutrient metabolism of embryos. A study was designed as a 2 × 2 × 2 factorial arrangement using four batches of in total 4,464 hatching eggs of 2 flock ages at 29 to 30 wk (young) and 54 to 55 wk (old) of Ross 308 and Cobb 500. EST of 37.8 (normal) or 38.9◦C (high) was applied from incubation day 7 (E7) until hatching. Wet yolk weight was determined mainly by breeder age (P = 0.043). Energy content in yolk (P = 0.004) and albumen + yolk (P = 0.005) were higher in old flock eggs than in young flock eggs, but did not differ between broiler strains. Eggshell conductance was higher in Ross 308 eggs than in Cobb 500 eggs (P < 0.001). Old flock embryos used more energy (P = 0.046) and accumulated more energy into yolk free body mass (YFBM; P = 0.030) than young flock embryos, whereas heat production (HP), energy lost, and efficiency of converting energy used to YFBM (EYFB) did not differ. Ross 308 embryos used more energy (P = 0.006), had a higher energy lost (P = 0.010), and a higher HP between E15 to E18 (P < 0.05) than Cobb 500 embryos. Energy content in YFBM did not differ between strains and EYFB (P = 0.024) was lower in Ross 308 than in Cobb 500. High EST resulted in higher HP than low EST from E11 to E15 (P < 0.05), but not after E15. Amount of energy used (P = 0.006) and energy accumulated in the YFBM (P < 0.001) was lower for embryos incubated at an EST of 38.9 than that of 37.8◦C, whereas EYFB did not differ. In conclusion, breeder age, broiler strain, and EST differentially influence embryonic metabolism and particularly the availability of oxygen could have contributed to these differences. [ABSTRACT FROM AUTHOR]

We investigated effects of eggshell temperature (EST) of 35.6, 36.7, 37.8, or 38.9°C applied from d of incubation (E) 15, E17, or E19 onward on chicken embryo physiology. A total of 2,850 first-grade eggs of a 43-week-old Ross 308 broiler breeder flock were incubated at an EST of 37.8°C until E15. From E15, E17, or E19 onward, eggs were incubated at an EST of 35.6, 36.7, 37.8, or 38.9°C. Plasma glucose, uric acid, and lactate concentrations, and hepatic glycogen amount and concentration were measured at E15, E17, E19, internal pipping (IP), external pipping (EP), and hatch. An EST of 38.9°C applied from E15 onward decreased the amount of hepatic glycogen from E19 to IP and resulted in a lower glycogen amount at IP compared to all other EST. At EP, when oxygen (O2) becomes largely available, an EST of 38.9°C resulted in a higher glycogen amount and concentration compared to IP, which suggests that plasma glucose between IP and EP might be used for building up hepatic glycogen reserves. However, hepatic glycogen levels remained considerably lower at IP, EP, and hatch at an EST of 38.9°C, compared to an EST of 35.6 and 36.7°C. Opposite to an EST of 38.9°C, from IP onward, an EST of 35.6°C resulted in a higher glycogen amount and concentration compared to all other EST, which might be caused by the higher O2 availability relative to the lower metabolic rate, which provided time to build up glycogen stores from excessive glucose. A higher availability of hepatic glycogen might contribute to an improved physiological status of the broiler chicken embryo toward hatch. Hepatic gluconeogenesis is crucial for developing embryos, as glucose is the major energy source from IP until hatch. At hatch, no effect of EST was found for glucose, uric acid, or lactate. Results of this study emphasize that EST of 35.6 and 36.7°C from E15 onward appear to be beneficial for chicken embryo physiology. [ABSTRACT FROM AUTHOR]

Little is known about applying various eggshell temperatures (EST) during the last week of incubation. In particular, the effect of an EST below 37.8°C during the last week of incubation is poorly investigated. Therefore, we investigated effects of EST of 35.6, 36.7, 37.8, or 38.9°C applied from d of incubation (E) 15, E17, or E19 on first week broiler development and performance. A total of 2,850 first grade eggs of a 43 wk old Ross 308 broiler breeder flock were incubated at an EST of 37.8°C until E15. From E15, E17, or E19 onward, eggs were incubated at an EST of 35.6, 36.7, 37.8, or 38.9°C. Chick quality was determined at placement in the broiler house and organ development was measured at d 7. BW was determined at placement, d4, and d7. Feed intake (FI) was measured at d4 and d7 and G:F was calculated between placement and d4, and between d4 and d7. Chick quality at placement was higher at an EST of 35.6°C compared to all other EST treatments, expressed by a longer chick length and highest prevalence of closed navels. BW d 7 was higher at an EST of 36.7°C compared to all other EST treatments, which was not caused by a higher FI during the first week. A higher G:F between d 0 and d 7 was found at an EST of 36.7°C compared to 35.6 and 38.9°C. At d 7, a higher relative heart weight was found at an EST of 35.6 compared to 38.9°C. This study indicates that an EST of 38.9°C applied from E15 onward negatively affected chick quality, organ development, and G:F until d 7 compared to 37.8°C. Moreover, an EST of 36.7°C had a clear positive effect on chick quality, organ development, G:F, and growth performance until d 7. An EST of 35.6°C resulted in equal or higher chick quality and organ weights compared to 36.7°C, but this was not reflected in performance parameters. [ABSTRACT FROM AUTHOR]

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 delayed increase in respiratory movement in response to thermal challenge compared to the Control treatment. However, chickens subjected to the Control and High treatments did not differ in T4 and GH level and performance. We conclude that exposure to high temperature during late embryonic development has long-lasting effects on the thermoregulatory system of broiler chickens by affecting the heat tolerance of these chickens. Moreover, the preferred ambient temperature of the chickens from heat-treated eggs correspond to those recommended for the strain under study, whereas for the cold-treated and control-chickens it was 1°C below, indicating that incubation temperature might have consequences on the ambient temperature chickens require during the rearing phase. [ABSTRACT FROM AUTHOR]

We investigated the effects of an eggshell temperature (EST) of 35.6, 36.7, 37.8, and 38.9°C applied from d of incubation (E) 15, E17, and E19 on hatching pattern and embryonic organ development. A total of 2,850 first-grade eggs of a 43-week-old Ross 308 broiler breeder flock were incubated at an EST of 37.8°C until E15. From E15, E17, or E19 onward, eggs were incubated at an EST of 35.6, 36.7, 37.8, or 38.9°C. Moment of internal pipping (IP), external pipping (EP), and hatch was determined, and organ development was measured at E15, E17, E19, IP, EP, and hatch. A lower EST extended incubation duration compared to a higher EST. The lower incubation duration was mainly caused by the extended time until IP, whereas time between IP and hatch hardly varied between treatments. Relative heart weight was affected by EST already from 2 d after the start of EST treatment on E15, and effects became more pronounced at longer exposure time to various EST treatments. At hatch, the largest difference in relative heart weight was found between an EST of 35.6 and 38.9°C started at E15 (Δ = 64.4%). From E17 onward, EST affected yolk-free body mass (YFBM) and relative stomach weight, where a lower EST resulted in a lower YFBM and relative stomach weight before IP and a higher YFBM and relative stomach weight after IP. From E19 onward, a lower EST resulted in a higher relative liver and spleen weight regardless of start time of treatment. Yolk weight and relative intestine weight were not affected by EST before and at E19, but a higher EST resulted in a higher yolk weight and lower relative intestine weight from IP onward. Based on the higher YFBM and higher relative organ growth found at hatch, we concluded that an EST lower than 37.8°C from E15 onward appears to be beneficial for optimal embryo development. [ABSTRACT FROM AUTHOR]

Colibacillosis is a poultry disease that negatively affects welfare and causes economic losses. Treatment with antibiotics raises concerns on antimicrobial resistance. Consequently, alternative approaches to enhance poultry resilience are needed. Access to feed and water directly after hatch (early feeding) may enhance resilience at later ages. Additionally, a high eggshell temperature (EST) during mid incubation may improve chick quality at hatch, supporting potential positive effects of early feeding. Effects of EST [37.8°C (control) or 38.9°C (higher)] during mid-incubation (embryo days 7–14) and feeding strategy (early feeding or 48 h delayed feeding) were tested in a 2 × 2 factorial arrangement. At hatch, ̴ 1,800 broilers were divided over 36 pens and grown for 6 wk. At d 8 post hatch, avian pathogenic E. coli (APEC) was inoculated intratracheally as model to investigate broiler resilience against respiratory diseases. Incidence and severity of colibacillosis, local infection, and systemic infection were assessed at 6 moments between 3 h and 7 d postinoculation. Broilers were weighed daily during 13 d postinoculation and weekly thereafter. At higher EST, early feeding resulted in higher incidence of systemic infection compared to delayed feeding whereas at control EST, systemic infection was not different between feeding strategies. Regardless of EST, early compared to delayed feeding resulted in lower incidence of local infection, fewer BW deviations, and higher growth until d 35. In conclusion, early feeding could be considered as a strategy to enhance broiler resilience, but only when EST is not too high. [ABSTRACT FROM AUTHOR]

Early life experiences are known to be of great importance for later life. For instance, exposure to stress during early life can increase fearfulness at later age. In broilers, delayed feeding after hatch may cause metabolic stress. Besides, delayed feeding after hatch may affect neonatal broiler development and thermogenesis and consequently preferred ambient temperature. Moreover, these effects of feeding strategy may be dependent on late incubation temperature. To study this, eggs (n = 1,338) from a 54-wk-old Ross broiler breeder flock were incubated at 37.8°C (control) or 36.7°C (lower) eggshell temperature (EST) during late incubation (≥ embryonic d 17). At hatch, two feeding strategies were applied (direct access (early feeding) or 51 to 54 h delayed access (delayed feeding)). Broilers (n = 960) were equally divided over 32 pens and grown for 3 wk. Stress was assessed by determination of corticosterone in blood at 0 h, 48 h, 96 h and d 21 after hatch. Fearfulness was assessed by tonic immobility at d 13. Temperature preference was assessed at d 2 and d 12. Broiler development was determined at 0 h, 48 h, and 96 h after hatch. There was no EST × feeding strategy interaction for any parameter (P ≥ 0.07). Early feeding resulted in a 2.5× lower plasma corticosterone concentration at 48 h (P < 0.01) and a 2.2°C and 2.0°C lower preference temperature for d 2 and d 12 respectively (P = 0.01) compared to delayed feeding. Tonic immobility was not affected. In conclusion, early feeding reduces exposure to stress in the short term and stimulates thermoregulatory ability of broilers in the longer term. [ABSTRACT FROM AUTHOR]

A progressive selection for broiler live and processing performance traits has changed broiler growth patterns during the post hatch period. However, limited information is available to understand whether changes have also occurred during the embryonic stages. This study aims to examine influences of broiler strain on nutrient availability, embryonic development, and nutrient metabolism during incubation. Hatching eggs of Ross 308 and Cobb 500 fast feathering were selected from breeder flocks aged 43 to 46 weeks at an egg weight range of 60 to 63 g. Eggs were obtained in 2 batches, 120 eggs per strain per batch. For each batch, 20 eggs per strain were used to determine egg composition and nutrient availability. The remaining eggs were incubated separately in one of 2 climate respiration chambers at an eggshell temperature of 37.8°C. The results showed that Ross 308 eggs had a higher yolk:albumen ratio with 0.9 g more yolk and 0.7 g less albumen than Cobb 500. Albumen + yolk of Ross 308 eggs had a higher dry matter (Δ = 0.24 g) and crude fat (Δ = 0.23 g) than that of Cobb 500 eggs, but a similar amount of crude protein. Albumen and yolk of Ross 308 eggs had a higher energy content (Δ = 8.9 kJ) compared to Cobb 500 eggs. At 3 h after hatch, Ross 308 chicks were 0.2 cm longer and had a 0.6 g heavier yolk free body mass (YFBM) than Cobb 500 chicks. During incubation, Ross 308 embryos used 13.9 kJ more energy than Cobb 500, and the efficiency of converting energy used to YFBM (EYFB) was approximately 7.6% lower compared to Cobb 500. Ross 308 chicks hatched approximately 4 h later and had less hepatic glycogen (Δ = 5 mg) than Cobb 500 chicks. It can be concluded that, Cobb 500 and Ross 308 differ in egg nutrient availability and have different trajectories for embryonic development and nutrient metabolism during incubation. [ABSTRACT FROM AUTHOR]

Selection for production traits of broilers and layers leads to physiological differences, which may already be present during incubation. This study aimed to investigate the influence of strain (broiler vs layer) on egg nutrient availability, embryonic development and nutrient metabolism. A total of 480 eggs with an egg weight range of 62.0 to 64.0 g from Lohmann Brown Lite and Ross 308 breeder flocks of 41 or 42 weeks of age were selected in two batches of 120 eggs per batch per strain. For each batch, 30 eggs per strain were used to determine egg composition, including nutrient and energy content, and 90 eggs per strain were separately incubated in one of two climate respiration chambers at an eggshell temperature of 37.8°C. The results showed that broiler eggs had a higher ratio of yolk: albumen with 2.41 g more yolk and 1.48 g less albumen than layers. The yolk energy content of broiler eggs was 46.32 kJ higher than that of layer eggs, whereas total energy content of broiler eggs was 47.85 kJ higher compared to layer eggs. Yolk-free body mass at incubation day 16 and chick weight and length at hatch were higher in broilers compared to layers. Respiration quotient of broiler embryos was higher than layer embryos during incubation day 8 to incubation day 10. A 0.24 g lower residual yolk at the hatch of broiler embryos than for the layer embryos indicated that broiler embryos used more yolk and had a higher energy utilization and energy deposition in yolk-free body mass. Heat production of broiler embryos was higher than that of layer embryos from incubation day 12 to incubation day 18, but efficiency of converting egg energy used by embryos to form yolk-free body mass was similar. In conclusion, broiler and layer embryos have different embryonic development patterns, which affect energy utilization and embryonic heat production. However, the embryos are equal in efficiency of converting the energy used to yolk-free body mass. [ABSTRACT FROM PUBLISHER]

Leg problems in broiler chickens may partly be prevented by providing optimal circumstanc-es for skeletal development during incubation. One of the factors demonstrated to affect bone development is eggshell temperature (EST), which provides a re-liable reflection of embryo temperature. The present experiment aimed to investigate the effect of EST on development and asymmetry of the femur, tibia, and metatarsus in broiler chicken hatchlings. Eggs were incubated from d 0 until hatch at 1 of 4 EST: low (36.9°C), normal (37.8°C), high (38.6°C), and very high (39.4°C). At hatch, chick quality was determined in terms of chick length, yolk-free body mass, navel score, and organ weights. Tibia, femur, and metatarsus were weighed, their length and width (mediolateral diam-eter) and depth (craniocaudal diameter) at the middle of the shaft were measured, and their ash content was determined. Relative asymmetry of the leg bones was determined from their relative dimensions. Hatchabil-ity, chick quality, and organ development were lower for very high EST compared with all other treatments. Very high EST resulted in lowest tibia and metatar-sus lengths (-3.1 to -8.4%) compared with all other treatments, and lower metatarsus weight (-9.1%) and femur length (-4.9%) compared with high EST. Rela-tive asymmetry and ash content did not differ among treatments and no relation between EST and bone pa-rameters was found. To conclude, very high EST result-ed in lower bone development, hatchability, and chick quality. Few differences in bone development and chick quality were found between low, normal, and high EST. [ABSTRACT FROM AUTHOR]

The current study evaluated effects of hatch moment and immediate feed and water access within a 24-h hatch window on chicken growth and development. Five hundred four male chickens obtained from a 49-wk-old Ross 308 breeder flock were assigned to 72 cages based on hatching moment (early, midterm, or late; selected during periods of 475 to 481, 483 to 487, and 489 to 493 h after onset of incubation). At the end of each hatching period, chickens were moved to the grow-out facility and one-half of the chickens received feed and water ad libitum immediately. Remaining chickens received feed and water from 504 h after onset of incubation (d 0). Body weight gain and feed intake for each cage were recorded at d 0, 1, 4, 7, 11, and 18. Chickens were sampled at d 4 and 18 for organ and carcass development. Early hatchers had lower BW at placement compared with midterm and late hatchers but compensated for this afterward, resulting in a higher BW at d 4 (112.8, 107.1, and 103.3 g, respectively). From d 0 to 18, early hatchers tended to have higher BW gain than both other groups. Relative breast meat yield at d 18, expressed as percentage of carcass weight, was higher for early (30.4%) than midterm (28.5%) and late hatchers (27.8%). Up to d 7, direct feed access resulted in higher BW gain (6.1%) and feed intake (4.2%) compared with delayed feed access. No effect of moment of feed access on feed efficiency or organ weights was found. Direct feed access resulted in a higher weightdength ratio of the jejunum (12.5%) and ileum (7.5%) at d 4 compared with delayed feed access. These results suggest that early hatchers have a different developmental and growth pattern than midterm or late hatchers within a 24-h hatch window. A mild delay in feed access after hatch affects growth and development during the first week after hatch. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of eggshell temperature (EST) and carbon dioxide (CO2) concentration during only the hatching phase on embryonic development and chick quality. Three batches of eggs were incubated at an EST of 37.8°C until d of incubation (E) 19. From E19, embryos were incubated at low (36.7°C), normal (37.8°C), or high (38.9°C) EST and at low (0.2%) or high (1%) CO2 concentration. Organ growth and embryo and chick quality were measured at E19, internal pipping (IP), hatch, and 12 h after hatch. A few interactions between EST and CO2 were found at IP, hatch, and 12 h after hatch, but all of these interactions were temporary and in most cases weak. High EST resulted in a lower relative heart weight compared with low (∆ = 0.05) and normal EST (∆ = 0.06) at IP, compared with low (∆ = 0.11) and normal EST (∆ = 0.08) at hatch, and compared with low (∆ = 0.11) and normal EST (∆ = 0.08) at 12 h after hatch. At hatch, high EST resulted in a lower YFBM compared with low EST (∆ = 0.65). At 12 h after hatch, high EST resulted in a lower relative liver weight compared with low EST (∆ = 0.12). At low EST, greater relative intestinal weight was found compared with normal (∆ = 0.41) and high EST (∆ = 0.37). The effect of CO2 solely was found at 12 h after hatch at which a higher relative heart weight (∆ = 0.05) and a higher relative lung weight (∆ = 0.0542) was found at high CO2 compared with low CO2. High EST during only the hatching phase negatively affected chick development, mainly expressed by the lower relative heart weight at IP, hatch, and 12 h after hatch and lower YFBM at hatch. The resolving effect of CO2 demonstrates that CO2 only seem to have a temporary effect during the hatching phase. [ABSTRACT FROM PUBLISHER]

The objective of this study was to investigate the effect of eggshell temperature (EST) and carbon dioxide concentration during only the hatching phase on physiological characteristics of embryos and chicks. Three groups of eggs were incubated at an EST of 37.8°C until d 19 of incubation (E19). From E19, embryos were incubated at a low (36.7°C), normal (37.8°C), or high (38.9°C) EST and at a low (0.2%) or high (1.0%) CO2 concentration. For E19, internal pipping (IP), hatch, and 12 h after hatch, blood parameters were analyzed and hepatic glycogen was determined. At IP, hatch, and 12 h after hatch, interactions were found between EST and CO2, but all these interactions were temporary and in most cases weak. High EST resulted in a lower hepatic glycogen concentration compared with low (∆ = 21.1) and normal EST (∆ = 14.43) at IP, and a lower hepatic glycogen concentration compared with low EST (∆ = 6.24) at hatch. At hatch, high EST resulted in lower hematocrit value (∆ = 2.4) and higher potassium (∆ = 0.5) compared with low EST. At 12 h after hatch, high EST resulted in a higher lactate concentration compared with low (∆ = 0.77) and normal EST (∆ = 0.65). And high EST resulted in higher potassium compared with low (∆ = 0.4) and normal EST (∆ = 0.3). An effect of CO2 solely was only found at IP, at which high CO2 resulted in a lower pH (∆ = 0.03) and a lower hepatic glycogen concentration (∆ = 7.27) compared with low CO2. High EST during only the hatching phase affected embryo and chick physiology, indicated by the lower hepatic glycogen levels at IP and hatch. High CO2 affected pH and hepatic glycogen at IP. Effects of CO2 were only found at low EST, which emphasizes the large effect of EST during the hatching phase. [ABSTRACT FROM PUBLISHER]

Previous studies have shown that RH during incubation of chicken eggs influences water loss from the egg and embryonic mortality. In those stud-ies, eggshell temperatures (EST) were not monitored or controlled. Because RH influences the egg's heat loss through evaporation, EST might have been different between RH treatments, influencing embryonic mortal-ity and development. To eliminate the effect of EST, in the current study eggs were incubated at an EST of 37.8°C from embryonic d (E) 0 until E18 and at a high (55 to 60%) or low (30 to 35%) RH from E2 until hatch. Embryonic mortality, hatch curve, and several chick quality characteristics (length, weight, navel quality, organ weights, and DM of the yolk free body mass and yolk) were determined on E18 and at hatch. Low RH increased egg weight loss between E0 and E18 (+3.0%) and third week embryonic mortality (+3.0% of fertile eggs) and decreased hatch of fertile eggs (--2.9% of fer-tile eggs) compared with high RH. Hatch duration and chick quality characteristics did not differ between RH treatments. To assess the effect of RH during incuba-tion on posthatch performance under suboptimal con-ditions, hatchlings were brooded at a normal (35.0°C at d 0, decreasing to 27.0°C at d 4) or cold (27.8°C at d 0, decreasing to 25.6°C at d 4) temperature until 4 d posthatch. Incubation RH and brooding temperature significantly interacted with posthatch growth but not development. Both low and high RH x cold brood-ing temperature resulted in lower (--6.9 and --6.0 g, respectively) BW than high RH x normal brooding temperature at 4 d of age. The cold brooding tempera-ture resulted in lower daily feed intake (--1.3 g/chick) than the normal brooding temperature. In conclusion, incubating eggs at a low RH compared with a high RH and maintaining the EST at 37.8°C decreased hatch of fertile eggs, but had little effect on chick quality or posthatch performance. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to study the interaction between breeder age and egg size on the energy utilization (experiment 1) and heat production (experiment 2) of broiler embryos. In experiment 1, a total of 4,800 Ross-308 hatching eggs from 2 breeder ages (29 and 53 wk of age, or young and old) and, within each age, 2 egg sizes (57 to 61 g and 66 to 70 g, or small and large) were used. In experiment 2, a total of 240 Ross-308 hatching eggs from 2 breeder flocks at 29 (young) and 53 (old) wk of age, and which were selected from the same egg weight range (58 to 61 g), were tested in 2 replicate chambers. In experiment 1, it was shown that the amount of yolk relative to albumen was higher in the old flock eggs, and this effect was more pronounced in the large eggs. The old flock eggs, especially the larger egg size, contained more energy as a result of a greater yolk size. Energy utilization of the embryos was positively related to yolk size and the amount of energy transferred to yolk-free body (YFB) was largely determined by the available egg energy. The efficiency of converting egg energy into chick body energy (EYFB) was equal for both egg sizes and both breeder age groups. Chick YFB weight of young and old flock eggs was equal. However, dry YFB weight of chicks from old flock eggs was higher than in chicks from young flock eggs, which was associated with more protein and fat content and thus more energy accumulated into YFB. As a consequence, embryos derived from old flock eggs produced more heat from d 16 of incubation onward than those of the young flock eggs. In conclusion, the higher energy deposition into chick YFB of old flock eggs, leading to higher embryonic heat production, is the result of a higher amount of available energy in the egg and is not due to changes in EYFB. [ABSTRACT FROM AUTHOR]

Chicken eggs are commonly incubated for 17 to 18 d in setters, after which they are transferred to the hatchery for the last 3 to 4 d of incubation. Whereas eggs are positioned vertically with the air cell up during the first incubation phase, they are placed horizontally for the hatching phase. It is unknown whether egg position in the last phase of incubation is of importance to the hatching process and chick quality. An experiment was conducted to investigate effects of egg position in the last 4 d of incubation on the hatching process and chick quality. The experiment consisted of 2 identical trials, where 300 fertile eggs per trial were transferred to a hatching cabinet at embryo day 17. Eggs were placed in 1 of 3 positions: with the air cell up (ACU), with the air cell down, or horizontally (HOR). Starting at embryo day 18, the following data were collected for each egg at 3-h intervals: time of internal pipping (IP), external pipping (EP), hatching, and position of EP. Approximately 6 h after hatch, BW, chick length, and chick quality based on the Pasgar score, were determined for each chick. In addition, residual yolk weight and yolk-free body mass were determined in every fourth chick that hatched. Time of IP was not affected by egg position, but EP occurred 5 h later in ACU eggs, and thus, the IP-EP interval was increased by 3 to 4 h in this group compared with the other egg positions. Hatching occurred 1 to 2 h earlier in HOR eggs than in the other 2 positions. Body weight, yolk weight, and yolk-free body mass were not affected by egg position. Chick length was 1 to 2 mm shorter and the Pasgar score was slightly lower in air cell-down eggs compared with ACU and HOR eggs, mainly caused by a high incidence of poor navel quality, red hocks, and red beaks. Hatchability was not affected by egg position. We concluded that egg position in the last phase of incubation affects the duration of the hatching process, and has small effects on chick quality. [ABSTRACT FROM AUTHOR]

A multilevel housing system for broilers was developed, named Patio (Vencomatic BV, Eersel, the Netherlands), in which the hatching and brooding phase are combined. In a Patio system, climate conditions differ from those provided in the hatchers currently in use. We compared the physiology of broilers hatched in a hatcher or in a Patio system, and included the effects of hatching time. Eggs from 1 breeder flock were incubated until embryonic d 18 in a setter and subsequently placed in a hatcher or the Patio until the end of incubation. From each hatching system, 154 chicks were collected per hatching time, at 465 h (early), 480 h (midterm), and 493 h (late) of incubation, from which 24 chicks/group were decapitated for analyses of blood plasma and organ weights. The remaining 130 chicks in each group from both systems were individually labeled and placed together in the Patio system. All chicks were given access to feed and water directly after hatch and were housed up to d 45 to monitor growth. From embryonic d 18 until the end of incubation, average ambient temperature and RH were 38.1°C and 50.8% in the hatcher and 35.2°C and 29.7% in the Patio system. Glucose and corticosterone were slightly higher in hatcher chicks, whereas organ weights were not affected by the hatching system. Although hatchling weights were lower in hatchery chicks, growth from d 0 to 45 was not affected by the hatching system. In both systems, glucose increased with hatching time, whereas lactate and triiodothyronine levels decreased. Yolk weights decreased with hatching time, whereas absolute and relative weights of the yolk-free body, intestines, stomach, lungs, and heart increased, indicating more advanced maturation of organs. Growth up to d 21 was depressed in chicks in the late group, which was possibly related to lower thyroid hormone levels at hatching. We conclude that the hatching system had minor effects on hatchling physiology and that posthatch growth and livability were not affected. Because hatching time affected broiler physiology, it seems important to take hatching time into account in future studies related to hatchling physiology. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of incubation conditions on the developmental and physiological status of birds in the perinatal period, which spans the end of incubation until the early posthatch period. Embryos were incubated at a normal (37.8°C) or high (38.9°C) eggshell temperature (EST) and a low (17%), normal (21%), or high (25%) O2 concentration from d 7 until 19 of incubation. After d 19 of incubation, EST was maintained, but O2 concentrations were 21% for all embryos. Body and organ weights, and hepatic glycogen levels were measured at d 18 of incubation and at 12 and 48 h after emergence from the eggshell. In addition, blood metabolites were measured at 12 and 48 h after emergence from the eggshell. Embryos incubated at a high EST and low O2 concentration had the highest mortality in the last week of incubation, which may be related to their low yolk-free body mass (YFBM) or a reduced nutrient availability for hatching (i.e., hepatic glycogen). High EST, compared with normal EST, decreased YFBM. This may be due to the shorter incubation duration of 8 h, the lower weight of supply organs (i.e., heart and lung), or a lack of glucose precursors. Because of this lack of glucose precursors, embryos incubated at high EST may have used proteins for energy production instead of for body development at the end of incubation. The YFBM at d 18 of incubation increased with an increase in O2 concentration. However, differences between the normal and high O2 concentration disappeared at 12 and 48 h after emergence, possibly because the high O2 concentration had difficulties adapting to lower O2 concentrations in the perinatal period. Blood metabolites and hepatic glycogen were comparable among O2 concentrations, indicating that the physiological status at hatch may be related to the environment that the embryo experienced during the hatching process. In conclusion, EST and O2 concentration differentially influence the developmental and physiological status of broilers during the perinatal period. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In practice, many hatchability and chick quality problems have been related to the control of embryo temperature (ET) during incubation. Within an incubator, set at a constant machine temperature (MT), ET can vary substantially. Embryo temperature is the result of the balance between heat transfer to and from the embryo and heat production (HP) of the embryo. We investigated which factors theoretically could account for the variation in ET within an incubator. First, the effects egg weight, MT, and oxygen availability on HP of embryos were quantified. Differences in HP could be due only to differences in the amount of energy utilized from the egg or to differences in the efficiency of the conversion of energy in the egg to energy in the chicken, indicated as EYFB. Results of these analyses showed that differences in HP attributable to egg weight or oxygen availability were mainly a result of the amount of energy used from the egg constituents and not of a change in EYFB. However, at a given MT, this variation in HP could account for a maximum increase in ET of only 1.21°C, suggesting that other factors played a role because in practice within an incubator, larger differences in ET have been found. The most important factor was probably the difference in air velocity within an incubator, resulting in differences in heat transfer. Because of this variation, ET varied within an incubator and with increasing ET, EYFB decreased, resulting in an even higher HP and consequently ET. We concluded that this theoretical approach could explain the wide variation in ET, and consequently could explain the negative effects of high ET on hatchability and chick quality found in the literature. This indicates that, in both practice and in incubation experiments, it is of great importance to realize that any factor affecting HP or heat transfer influences ET. We strongly suggest that ET (or eggshell temperature) be controlled in any iiicubation experiment involving hatchability or energy utilization. [ABSTRACT FROM AUTHOR]

Negative effects of prolonged egg storage on hatchability and chick quality may be caused by changes in the embryo or in the egg characteristics, or by both. The aim of this experiment was to investigate whether prestorage incubation (PSI), frequent warming during storage (FW), or hypercapnic incubation (HI) during the first 5 d of incubation affect egg characteristics, embryonic development, hatchability, and chick quality. The experiment had a 2 × 2 × 2 randomized design: PSI (yes-no), FW (yes-no), and HI (yes-no). All eggs were stored for 15 d at 16°C and 75% RH. On the second day after oviposition, half of the eggs were incubated for 7 h (PSI). During storage, half of the eggs were warmed 6 times for 30 mill in water at 37.8°C (FW). During the first 5 d of incubation, the CO2 concentration in the incubator was maintained between 0.70 and 0.80% (HI) or increased from 0.05 to 0.20% (control). Prestorage incubation and FW increased the stage of embryonic development and the number of viable embryonic cells, but these treatments did not have a pronounced effect on egg characteristics, hatchability, or chick quality. Hypercapnic incubation decreased total albumen pH, which was measured at 18, 42, 66, and 90 h of incubation, and the percentage of eggs classified as infertile (Δ = 1.2%). In contrast, HI retarded embryonic development, decreased hatchability of fertile eggs by 1.3%, but did not affect chick quality. We conclude that both PSI and FW did not improve hatchability and chick quality, although the stage of embryonic development and the number of viable embryonic cells increased due to the treatments. Hypercapnic incubation decreased total albumen pH, which may be related to the increased number of embryos that continued their development at the onset of incubation. Because HI retarded further embryonic development and decreased hatchability, long-term stored embryos were probably sensitive to the CO2 concentration of 0.70 to 0.80% between 48 and 72 h of incubation. [ABSTRACT FROM AUTHOR]

To investigate the effect of incubation conditions on layer hatchlings, an experiment was performed in which layer eggs were incubated at a normal (37.8°C) or high (38.9°C) eggshell temperature (EST) and a hole was punctured in the air cell of half of the eggs in both EST treatments from d 14 of incubation onward. Chick development, plasma metabolites, and hepatic glycogen were measured at 12 h after emergence from the eggshell. Embryo mortality was not affected by the EST or hole treatment. At the high EST, yolkfree body mass was 0.7 g lower and residual yolk weight was 0.7 g higher than at the normal EST. This may be related to the shorter incubation duration at the high EST. Relative heart, lung, stomach, liver, spleen, and intestinal weights were lower in the high EST than in the normal EST group. Yolk-free body mass did not differ between eggs with or without a hole, but residual yolk weight was slightly lower in eggs with a hole (0.3 g). Relative lung weights were higher in eggs with than without a hole, whereas no effect on other organs was found. Plasma glucose, lactate, and uric acid concentrations did not differ between the EST or hole treatments. Hepatic glycogen was lower in the high EST (7.3 mg) than in the normal EST group (11.2 mg) at 12 h after emergence from the eggshell, and this effect may be related to the shorter hatching process at the high EST. Hepatic glycogen levels were lower in eggs with a hole (8.6 mg) compared with eggs without a hole (10.0 mg), and this may be related to the longer period between external pipping and hatching in eggs with a hole. In conclusion, the EST and hole treatment did not interact, and neither treatments affected embryonic survival. High EST negatively affected hatchling development and seemed to change the carbohydrate metabolism in layer embryos. The effect of a hole in the air cell was limited. [ABSTRACT FROM AUTHOR]

The current study investigated the effects of temperature manipulation (TM) during late embryogenesis on temperature preference, response to high environmental temperature, behavior, and performance in young layer chicks. Control (CC) embryos (n =96) were incubated at 37.8°C eggshell temperature throughout incubation. Thermally manipulated embryos (n = 96) were incubated at 37.8°C eggshell temperature throughout incubation and were exposed to 40°C for 4 h/d from embryonic d 14 to 18 (TM chicks). After hatch, chicks from each treatment were divided into 3 subgroups (n = 32 per group) and were subjected to a temperature preference test at d 1, 7, or 33. One day after the temperature preference test, each subgroup was exposed to 1 thermal challenge for 4 h (d 2, 40°C; d 8, 40°C; or d 34, 35°C). Effects of TM on (fearfulness) behavior of chicks were investigated in a tonic immobility test and during home pen observations. Temperature manipulation decreased incubation time with 7 h (P < 0.0001) and body temperature at hatch with 0. °C (P = 0.002). The TM chicks preferred a lower ambient temperature in the temperature preference test (P < 0.05) and showed a higher body temperature response than CC chicks to the thermal challenge at d 2 and 8 (P < 0.05). No effects of TM on behavior and performance were observed. Because most TM studies are conducted in broilers, this study is the first attempt to unravel the effects of TM during late embryogenesis on posthatch environmental adaptation in layer chicks. The results demonstrated that effects of our TM on postnatal temperature preference and response to high environmental temperatures are only found until d 8 of age. This may suggest 1 of 3 options: a) the timing or the level, or both, of TM and duration were not at the sensitive period of embryogenesis or not sufficient, or both, respectively; b) the level of the postnatal thermal challenge was not strong enough to induce a hyper- thermic response; and c) the postnatal effects of TM in layers are limited in time. [ABSTRACT FROM AUTHOR]

When eggs are stored beyond 7 d, hatchability and chick quality decrease. The cause of the negative effects of prolonged egg storage is not clear. The negative effects may be caused by a decrease in embryo viability due to an increase in cell death. The optimal time and curve of preincubation warming (the preincubation warming profile) may be different for eggs stored over short and long periods of time because embryo viability is dependent on egg storage time. The aim of this study was to investigate whether preincubation warming profiles affect embryonic development, hatchability, and chick quality when eggs are stored for a short or prolonged time. Two experiments were conducted. In both experiments, a 2 x 2 completely randoinized design was used with 2 storage times (4 and 14 d at 17°C in experiment I and 4 and 13 d at 19°C in experiment II) and 2 preincubation warming profiles (within 4 or 24 h from storage temperature to 37.8°C). In experiment I, results suggested that the effect of preincubation warming profile on hatchability was dependent on storage time. However, because a low number of eggs were used in this experiment, these differences were not significant. In experiment II, the interaction between storage time and preincubation warming profile was observed for embryonic mortality during the first 2 d of incubation and hatchability (P = 0.006 and P = 0.01, respectively). When storage time was 13 d, embryonic mortality during the first 2 d of incubation decreased by 4.4% and hatchability increased by 5.7% when the 24-h preincubation warming profile was used instead of the 4-h preincubation warming profile. However, no effect of preincubation warming profile was observed when storage time was 4 d. In both experiments, chick quality decreased when storage time increased but was not affected by preincubation warming profile. We concluded that a slow preincubation warming profile is beneficial for hatchability when storage time is prolonged but does not affect chick quality. [ABSTRACT FROM AUTHOR]