Efficiency of different incubation systems for the in vitro production of bovine embryos.

SummaryThis study aimed to compare the efficiency of different incubation systems for in vitro embryo production in bovine. Oocytes/embryos were cultured in three incubators: conventional - CONV, mini bench - MINI and portable - PORT. After in vitro maturation (IVM), oocytes were verified for maturation rate. The remaining structures were submitted to in vitro fertilization and culture to verify cleavage (day 2) and blastocyst (day 7) rates. Reactive oxygen species (ROS) were evaluated in post-IVM oocytes and embryos (days 2 and 7) using arbitrary fluorescence units (AFUs). No significant difference (P>0.05) was observed for maturation rate. The CONV system (74.0%) produced the highest cleavage rate (P0.05) to MINI (65.0%). The same pattern and differences were observed for blastocyst rate: CONV (33.3%), MINI (32.3%) and PORT (21.9%). ROS levels were not different (P>0.05) in post-IVM oocytes: CONV (35.6±4.5), MINI (29.4±4.0) and PORT (35.6±4.5). For day-2 embryos, ROS levels were higher (P0.05) was observed in blastocysts. In conclusion, although it produced high ROS levels at day 2 of culture, the MINI system was as efficient as the CONV system for blastocyst production. This option may be an interesting and economical for the in vitro embryo industry.

Effect of Embryonic Thermal Exposure on Heat Shock Proteins (HSPs) Gene Expression and Serum T3 Concentration in Two Broiler Populations.

The present experiment was conducted to evaluate the Hsp-70, 27 and Ubiquitin mRNA expressions and serum T3 concentration in synthetic colored broiler female lines, Punjab Broiler-2 (PB-2), and Naked neck (NN) broiler chicken whose eggs were exposed to 2°C increased incubation temperature for 3 hours each on the 16th, 17 th, and 18th day of incubation. Another set of eggs were incubated at normal conditions that were utilized as the control. A total of 432 chicks, 216 from each breed (PB-2; NN) and treatment (Heat exposed: HE; normal: N), were randomly distributed and reared at high ambient temperatures (32°C-45°C) during the summer season in battery brooders. Birds were sacrificed at 0 and the 28th day post hatch and different tissues (heart, liver, muscle, spleen, and bursa) were collected to study Hsps and ubiquitin mRNA expression. There was no difference between the breeds and age of slaughter in Hsp-70 mRNA expression. The Hsp(70, 27, and ubiquitin) mRNA expression was significantly (P≤0.001) lower in HE birds than that of N birds in PB-2 chickens. Nonsignificant variation was observed in NN chicken. The Hsp-70 mRNA expression was highest in bursa and lowest in muscle and liver. Serum T3 concentration was similar in both HE and N birds. The study concludes that exposure to increased temperature during incubation results in reduced expressions of Hsp mRNA in almost all tissues indicating better thermotolerance of the HE birds.

Multilevel sensor for monitoring external and internal environment of eggs.

Although it is well known that incubation environment has a great influence on embryogenesis and post-hatching performance of birds, not much is known about how external thermal, sound and light stimuli are isolated by eggshells and perceived by embryos. In this context, this study aimed to develop, calibrate and evaluate a multilevel sensor for integrated monitoring of the external (incubator) and internal environment of eggs. The variables of interest for the external environment were air temperature and relative humidity. For the internal environment, shell temperature, internal temperature, luminosity and sound pressure level were considered. The sensor was developed with an ATmega328 microcontroller, in open-source prototyping, using electronic components which are compatible with the egg's physical structure. Calibrations were carried out in a controlled environment, comparing the multilevel sensor with commercial equipment, obtaining coefficients of determination of R 2 > 0.90 for all variables studied. The multilevel sensor was also validated, simulating a commercial incubation situation and comparing eggs with 2 shell colors (white and brown) and internal volume (intact and empty). Validation results showed that white-shelled eggs insulate less external light (P < 0.001) and full eggs presented higher internal temperatures, greater light and lower sound pressure levels compared to empty eggs (P < 0.001). The multilevel sensor developed here is an innovative proposal for monitoring, simultaneously and in real time, different variables of interest in the commercial incubation environment.

The effects of light stimulation during incubation on indicators of stress susceptibility in broilers.

Providing light during incubation has been shown to decrease bilateral physical asymmetry of broilers posthatch, which may indicate that early light stimulation reduces later stress susceptibility. This experiment evaluated the effects of lighting during embryogenesis on other measures of stress responsiveness in broilers. Cobb 500 eggs (n = 1,404) were incubated under 0L:24D, 1L:23D, 6L:18D, or 12L:12D; the light level was 550 lx. The broilers were then raised in floor pens under a 12L:12D lighting regimen, and various stress parameters were measured during wk 3 to 6 of age. There was an effect of incubation lighting regimen on posthatch stress responses. Following 1 h of crating, the change in corticosterone (CORT) concentration was less in the 12L:12D (-0.06 ng/mL, P < 0.05) treatment than all other treatments (pooled mean = 0.24 ng/mL); however, there were no treatment differences in CORT response to adrenocorticotropic hormone administration (pooled mean pre- vs. 1 h postadministration = 17.5 ng/mL, P > 0.05). Anti-keyhole limpet hemocyanin titers were higher in the 12L:12D birds (92,395 units/mL; P < 0.05) than all other treatments (pooled mean = 68,407 units/mL) on d 1 postcrating. Additionally, composite asymmetry scores were lower in the 12L:12D treatment (0.92 mm) than all other treatments (pooled mean = 1.14 mm, P < 0.05). These results demonstrate that providing 12 h of light per day during incubation can reduce the stress susceptibility of broilers posthatch.

Effects of interaction of incubator CO2 levels and mixing hatching eggs of different embryo growth trajectory on embryo physiological and hatching parameters.

1. Two experiments were designed to investigate the effects of mixing eggs of different genotype and incubating with different CO2 concentrations on embryonic parameters. Half of the eggs were incubated in a CO2 controlled incubator (VCO2) during the first 10 d of incubation and the other half was incubated at standard incubation ventilation rate (SV). 2. From 10 to 18 d of incubation, thick albumen and embryos were weighed. Blood samples were collected at d 18 of incubation, at internal pipping and at hatch for determination of triiodothyronine (T3), thyroxine (T4) and corticosterone concentration. During the last 2 d of incubation, hatching events of individual eggs were monitored every 2 h. 3. From 4 to 5 d of incubation in the SV group of Experiment 1, pH values of Ross strain chickens were lower than those of Isa Brown. From d 12 of incubation onwards, Ross embryos grew faster than those of Isa Brown. At 14 and 16 d of incubation, Ross eggs in the CO2 controlled incubator had lower albumen weights compared to all other treatments. 4. T3 concentrations in Ross embryos were higher than those of Isa Brown embryos. Chicken weight at hatch was in the following order: Isa Brown SV < Isa Brown VCO2 = Ross SV < Ross VCO2. 5. In Experiment 2, incubation time of VCO2 eggs until internal pipping, external pipping and hatch was significantly shorter than that of SV eggs. 6. It was concluded that mixing of hatching eggs of differential embryo developmental trajectory affects their hatching process.

Effects of pre-incubation storage duration and nonventilation incubation procedure on embryonic physiology and post-hatch chick performance.

This study investigated the effects and possible interactions of storage and nonventilation during incubation for eggs from Sasso broiler breeder flock on pre- and post-hatch incubation results. A total of 1,260 Sasso eggs from a 58-wk-old broiler breeder flock were individually numbered, weighed and stored for 7 d or for 18 d in a climate-controlled room (16°C, 75% RH). After storage, eggs were weighed, and randomly assigned equally into 2 incubators. One of the incubators was ventilated (V) for the entire incubation and the second was nonventilated (NV) for the first 12 d. At d 18, the eggs were weighed, candled, and fertile eggs were transferred from the turning trays to hatching baskets. During the last 3 d of incubation, hatching eggs were checked individually every 3 h for hatching events and hatchability of fertile eggs. After pull out at d 21.5, post-hatch performances was determined until 1 wk of age. Results showed that, embryo weights from eggs in NV incubator was significantly higher (P < 0.05) in both stored eggs compared to those from eggs in ventilated incubator, but embryos from eggs stored for 18 d were smaller (P < 0.05) than those from eggs stored for 7 d. Hatchability was higher (P < 0.0001) in NV incubator compared to V incubator in both 7 d and 18 d stored eggs and an interaction was found between incubation ventilation and storage duration on both hatchability and embryonic mortality (P < 0.0001). Chick weights from NV incubator at 7 d post-hatch was greater (P = 0.0009) than those from V incubator. Serum Tri-iodothyronine (T3) and Thyroxin (T4) concentrations were significantly higher (P < 0.05) in NV compare to V group. It was concluded that the effect of long-term pre-incubation storage on embryonic physiology and post-hatch growth interacted significantly with incubation ventilation and that nonventilation can compensate for the negative effects of storage on some hatching and post-hatch performances.

The effects of incubation temperature on the sex of Japanese quail chicks.

The effects of incubation temperature on the sex of Japanese quail chicks were investigated in this study. The study was conducted on Japanese quail. In all, 4500 eggs obtained from 2 generations were used. At the beginning of the study, a new flock was formed from available hatching eggs. Hatching eggs were gathered at 3 different ages (8 to 10 weeks, 16 to 18 weeks and 22 to 24 weeks of age) from the laying period in this flock. These eggs were exposed to 5 different incubation temperatures (36.7, 37.2, 37.7, 38.2, and 38.7°C). The hatching results were evaluated for each group. Chicks obtained from these temperature groups were reared separately to obtain quail for breeding. Eggs for incubation were gathered from these breeding quail when they were between 15 and 18 weeks of age. These eggs were placed in an incubator at a standard (37.7°C) temperature, separated by F(1)-generation temperature groups. The chicks in all groups were reared separately, and the sex of the chicks was determined at maturity. Statistical differences (P < 0.05) were found for the sex of the chicks in the third group (22 to 24 weeks) of the F(1) generation, compared with other groups. This result confirmed the hypothesis that different incubation temperatures for the first generation (at the embryo stage) might influence the sex of the next generation of chicks. Further studies are needed to investigate the effects of incubation temperature on chicks from different perspectives.

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.

Effect of incubator tray location on broiler chicken growth performance, carcass part yields, and the meat quality defects wooden breast and white striping.

Large variations in hatching egg incubation temperatures have been previously shown to negatively impact posthatch growth in broiler chickens. The objective was to determine whether small incubation temperature variations owing to incubator tray location (LOC) could alter posthatch female and male broiler growth performance and carcass characteristics. Broiler hatching eggs were obtained from a 40-week-old commercial broiler breeder flock and incubated in trays placed in the bottom (BOT), middle (MID), and top (TOP) thirds of the racks (n = 4 racks per incubator tray LOC) in a single-stage incubator in a commercial hatchery. Chicks hatched from the 3 LOC (n = 720 per LOC) were vent sexed, vaccinated, and separate-sex reared with 12 birds per pen in a floor-pen facility and fed a common corn and soybean meal-based diet for 41 d. At day 41, all birds (n = 720) were processed to determine carcass and carcass part yields and incidence and severity of the meat quality defects wooden breast (WB) and white striping (WS). No LOC × Sex interactions were observed (P > 0.05). Growth performance and incidence and severity of WB and WS were similar among LOC (P > 0.05). However, broilers from BOT trays had heavier tender and breast weights than broilers from warmer MID trays (P < 0.05). Broilers from the BOT trays had higher breast meat yield as a proportion of carcass weight (25.00%) than warmer MID (24.54%) broilers (P < 0.05). However, broilers from warmer MID trays had greater carcass yield than those from cooler TOP trays (P < 0.05). As expected, male broilers had heavier carcass, breast, tender, wings, drumsticks and thighs weights and were more severely affected by WB than females (P < 0.05). Overall, these data indicate that the inherent differences in environmental factors among incubation LOC can impact broiler carcass and breast meat yields.

Results of hatching and rearing broiler chickens in different incubation systems.

Hatchery efficiency is based on hatchability and the number of salable chicks. The hatchery sector has been seeking new alternatives to optimize production rates, including the use of different systems (multistage [MS] or single-stage [SS] machines) to improve incubation conditions. The present study aimed to compare results for hatchability, chick quality, and broiler performance of chicks from 2 incubator systems-MS and SS. The experimental design for hatchability, hatch window, egg weight loss, and chick performance variables was completely randomized with 2 treatments (MS and SS). Performance variables were analyzed as a 2 x 2 factorial arrangement (incubator type x chick sex). Egg weight loss between incubation and transfer was higher for eggs incubated in MS (P < 0.05). Hatchability was higher for eggs incubated in SS (P < 0.05), and chicks in SS had a longer hatch window (P < 0.05). Embryo diagnosis revealed higher final mortality for embryos incubated in MS (P < 0.05), as well as higher percentages of alive and dead pipped and cracked eggs (P < 0.05). Physical quality was better for chicks from SS (P < 0.05). There was no interaction between the studied factors for performance results (P > 0.05). Incubator type did not affect broiler performance for any of the studied ages (P > 0.05), whereas male broilers had better performance than females (P < 0.05). The SS incubation system proved better than the MS system at meeting embryo requirements during embryo development, with better hatching rates and chick quality, although performance variables were not influenced by incubation type.

Effects of green light emitting diode light during incubation and dietary organic macro and trace minerals during rearing on tibia characteristics of broiler chickens at slaughter age.

This study was designed to evaluate the effects of green light emitting diode (LED) light during incubation and dietary organic macro and trace minerals during rearing on tibia morphological, biophysical, and mechanical characteristics of broiler chickens at slaughter age. The experiment was setup as a 2 × 2 × 2 factorial arrangement, with the following treatments: 1) light during incubation (green LED light or darkness), 2) macro mineral source during rearing (organic or inorganic Ca and P), and 3) trace mineral source during rearing (organic or inorganic Fe, Cu, Mn, Zn, and Se). A total of 2,400 eggs (Ross 308) were either incubated under green LED light (16L:8D) or in complete darkness. After hatch, a total of 864 male broiler chickens were reared until slaughter age (day 42) and provided with 1 of 4 diets, differing in macro and/or trace mineral source. During rearing, the experiment had a complete randomized block design with 9 replicate pens per treatment and 12 chickens per pen. At slaughter age (day 42), 2 chickens per replicate were randomly selected and tibia bones were obtained. Tibia weight, length, thickness, osseous volume, pore volume, total volume, mineral content, mineral density, ultimate strength, and stiffness were determined. Green LED light during incubation did not affect any of the tibia characteristics. Dietary organic macro minerals positively affected most of the tibia morphological, biophysical, and mechanical characteristics compared to the inorganic macro minerals, whereas trace mineral sources did not affect tibia characteristics. It can be concluded that dietary organic macro minerals Ca and P stimulated tibia characteristics, whereas green LED light during incubation and dietary trace minerals during rearing did not affect tibia characteristics, locomotion, or leg disorders.

In vitro maturation and development of porcine oocytes cultured in a straw or dish using a portable incubator with a CO2 chamber.

We investigated the effects of a portable incubator with a CO(2) chamber on the viability and development of porcine oocytes/embryos for their transportation and examined the operational suitability of a straw or dish as a container for culturing the oocytes or embryos in the portable incubator. In the first experiment, the cumulus-oocyte complexes (COCs) were placed either in a dish or straw; and they were then cultured for 44 h in a standard CO(2) incubator, in the CO(2) chamber in an incubator, or in the CO(2) chamber in a portable incubator. The matured oocytes were fertilized with frozen-thawed spermatozoa and then cultured in a dish in the standard CO(2) incubator for 8 days. There were no differences in the proportions of oocytes reaching metaphase II stage among the groups. However, the proportions of cleavage and development to blastocysts derived from oocytes matured in a straw were lower than those from oocytes matured in a dish, irrespective of the type of incubator used. In the second experiment, the COCs were matured in a dish in the standard CO(2) incubator, and the matured oocytes were fertilized and then placed either in a dish or straw. These were then cultured for 8 days in the standard CO(2) incubator or portable incubator. Some zygotes cultured in the portable incubator developed to the blastocyst stage. The proportions of cleavage and development to blastocysts were significantly lower for putative zygotes cultured in straw than for those cultured in dish, irrespective of the type of incubator used. Our results indicate that a portable incubator with a CO(2) chamber can maintain the viability and development of oocytes/embryos, but the straw is not a suitable system for in vitro culture of the oocytes/embryos during transportation.

Effect of providing light during incubation on the health, productivity, and behavior of broiler chickens.

Environmental stimuli present during incubation can affect the behavior and health of birds posthatch. Commercial broiler chickens are often incubated in complete darkness, receiving light only intermittently when the incubator is opened. To determine the effect of providing light during the prehatch period, we incubated Cobb broiler eggs (n = 664) under continuous light (24L:0D), no light (0L:24D), or 12 h of light (12L:12D); the light level was 550 lx. Various parameters were measured posthatch in these broilers (n = 506), which were raised in floor pens on a 12L:12D regimen. There were no incubation treatment differences in hatchability, mortality, growth, feed consumption, feed conversion ratio, gait score, overall feeding behavior activity, or general behavioral activity. However, broilers hatched from eggs incubated under 24L:0D or 12L:12D had greater feeding activity (P < 0.05) than the 0L:24D broilers during the 2 h after the lights came on. Eye dimensions did not differ between treatments, but the eyes of the 12L:12D broilers weighed less (P < 0.05) than those of the other treatments. Broilers incubated under 0L:24D had a greater level of composite physical asymmetry (1.87 +/- 0.11 mm), considered to be an indicator of developmental stress, than did 12L:12D (1.57 +/- 0.09 mm; P = 0.05) broilers; they also tended to have more composite asymmetry than 24L:0D (1.62 +/- 0.11 mm; P = 0.10) broilers. The results of this study indicate that providing light during incubation has no detrimental effect on production or health of broilers, but does have potential benefits in terms of reducing the effects of stressors associated with production and growth.

Broiler incubation. 2. Interaction of incubation and brooding temperatures on broiler chick feed consumption and growth.

The effect of either hot or cool brooding litter temperature on feed consumption, BW, and mortality of broiler chicks that had been exposed to either normal or high temperature during latter stages of incubation was studied in 2 experiments. The duration of experiments 1 and 2 was 14 and 21 d, respectively, with BW and feed consumption determined at 2, 5, 7, and 14 d of age in experiment 1 and at 7, 14, and 21 d of age in experiment 2. High incubator temperature after embryonic d 16 decreased chick feed consumption and BW at all ages in both experiments. Hot brooding litter temperature increased feed consumption at 2 and 5 d in experiment 1 and at 7 d in experiment 2 but decreased feed consumption at 14 and 21 d in experiment 2. Feed consumption was also influenced by the incubation temperature x brooding litter temperature interaction. From 0 to 2 d or 0 to 7 d in experiments 1 and 2, respectively, the highest to lowest feed consumption was exhibited by the normal-hot, high-hot, normal-cool, and high-cool interaction groups but the order changed to normal-cool, normal-hot approximately high-cool, and high-hot from 7 to 14 and 14 to 21 d in experiment 2. Significant effects on mortality were observed in experiment 2 only where males exhibited greater mortality that was most evident in the combination of high temperature incubation followed by cool brooding. Excessive (high) eggshell temperature during the latter stages of incubation reduced feed consumption and BW through 21 d of age. However, the results showed that the hot brooding litter temperature supported increased feed consumption during the first few days of brooding even for the chicks that had been subjected to high incubation temperature. Hot brooding also reduced male mortality in experiment 2. Nonetheless, hot brooding litter temperatures should be limited as extending beyond a few days eventually decreased feed consumption.

The effect of increased concentration of carbon dioxide during the first 3 days of incubation on albumen characteristics, embryonic mortality and hatchability of broiler hatching eggs1.

Three experiments were conducted to determine the effects of increased CO2 concentration during the first 3 d of incubation on albumen height and pH, embryonic mortality, and hatchability of broiler hatching eggs. Hatching eggs were obtained from commercial broiler breeder flocks of Ross 308 at 39 and 37 wk of age in Experiments 1 and 2, respectively. In Experiment 3, eggs were collected at 28 and 35 wk of age. Eggs were incubated under either standard conditions (Control-CO2) for the entire incubation or increased CO2 concentrations during the first 3 d of incubation (High-CO2) in 3 experiments. In Experiments 1 and 2, the CO2 concentration was gradually increased from the beginning of incubation onwards to reach 0.80% at 72 h by manual injection of CO2 into airtight laboratory incubators. In the control incubators, the CO2 concentration remained below 0.10% during the same period. Prior to setting, and at 3 d of incubation, the eggs were opened for albumen height and pH measurements in Experiments 1 and 2. In Experiment 3, the eggs were set in commercial incubators. During the first 3 d of incubation, the CO2 concentration was gradually increased to reach 0.70% at 72 h naturally (High-CO2). In the Control-CO2 incubator, the CO2 concentration remained below 0.10%. After 3 d, incubation was continued with the control incubator conditions for all eggs from both groups in the 3 experiments. The albumen height was not affected by CO2 treatment, but the treatment significantly decreased albumen pH at 3 d in Experiments 1 and 2 (P < 0.05). A greater CO2 concentration during early incubation reduced fertile hatchability due to increased early embryonic mortality by 2% in the 3 experiments (P ≤ 0.05). The differences in pH might provide one explanation why increased CO2 concentration during early incubation resulted in increased early embryonic mortality. These data indicated that at the beginning of the incubation, ventilation was necessary to prevent increases in CO2 concentration for optimum hatchability results.

Effect of egg weight and position relative to incubator fan on broiler hatchability and chick quality.

Two experiments, which included 3 incubators, were carried out to investigate the effects of egg weight and position relative to incubator (setter) fan on embryonic mortality, second quality chicks, and fertile hatchability of broiler eggs. Three egg weight groups termed small (approximately 62.4 g), average (approximately 65.4 g), and large (approximately 68.9 g) were set in either the incubator trolley most distant from the fan (FAR) or in the incubator trolley nearest the fan (NEAR) as would be the case during single-stage operation in this type of incubator. Fertile hatchability decreased in the large egg weight group due to increased percentage late embryonic mortality in experiment 1, and both percentage early and late embryonic mortality in experiment 2. Percentage late embryonic mortality and second quality chicks increased and percentage fertile hatchability decreased for eggs in the FAR position in experiment 1 only. A significant interaction of incubator position x egg weight group for late embryonic mortality, second quality chicks, and fertile hatchability was found in experiment 1, but only late embryonic mortality was so affected in experiment 2. Experiment 2 was conducted so that eggshell temperatures could be measured. Large eggs in the FAR position at transfer time (E 18) exhibited significantly higher eggshell temperatures than did the other groups probably because air velocity or air distribution was modified in the FAR position of the incubator and large eggs were most negatively influenced in the trolley in this position.

Non-ventilation during early incubation in combination with dexamethasone administration during late incubation: 1. Effects on physiological hormone levels, incubation duration and hatching events.

This study investigated the effect of non-ventilation of the incubator during the first 10 days of incubation and its combination with dexamethasone administration at day 16 or 18 of incubation on hatching parameters and embryo and post-hatch chick juvenile physiology. A total of 2400 hatching eggs produced by Cobb broiler breeders were used for the study. Blood samples were collected at day 18 of incubation, at internal pipping stage (IP), at the end of hatch (day-old chick) and at 7-day-post-hatch for T(3), T(4) and corticosterone levels determination. From 448 to 506 h of incubation, the eggs were checked individually in the hatcher every 2h for pipping and hatching. The results indicate that non-ventilation during the first 10-day shortened incubation duration up to IP, external pipping (EP) and hatch, had no effect on hatchability and led to higher T(3) levels at IP but lower corticosterone levels at 7-day-post-hatch. The injection of dexamethasone at days 16 and 18 of incubation affected hatching and blood parameters in both the ventilated and non-ventilated embryos differentially and the effect was dependent on the age of the embryo. Dexamethasone increased T(3) levels and T(3)/T(4) ratios but the effect was greater with early non-ventilation of eggs. Dexamethasone decreased hatchability but the effect was greater when injected at day 16 and especially in ventilated embryos. The effects of incubation protocols and dexamethasone treatments during incubation were still apparent in the hatched chicks until 7 days of age. The changes in T(3), T(4) and corticosterone levels observed in response to the early incubation conditions and late dexamethasone treatments in this study suggest that incubator ventilation or non-ventilation may influence the hypothalamic-pituitary-adrenal axis (HPA) regulation of stress levels (in terms of plasma corticosterone levels) and thyroid function in the embryo with impact on incubation duration, hatching events and early post-hatch life of the chick. Our results also suggest that some stages of development are more sensitive to dexamethasone administration as effects can be influenced by early incubation protocols.

Single stage incubators and Hypercapnia during incubation affect the vascularization of the chorioallantoic membrane in broiler embryos.

Incubation management can have direct effects on neonate health and consequently affect post-hatching development. The effects of incubation in multiple and single stage incubators with different concentrations of CO2 were evaluated in terms of the vessel density in the chorioallantoic membrane, hatching, heart morphology, and body development of the neonate up to the tenth day. A total of 2,520 fertile eggs were used and distributed in a completely randomized design with 4 levels of CO2 in 4 single-stage incubators (4,000; 6,000; 8,000; and 10,000 ppm) and a control treatment based on multiple-stage incubation, totaling 5 treatments. The levels of CO2 were used during the first 10 d of the incubation period, and after this period, all eggs were submitted to the same level of CO2 (4,000 ppm). Eggs that were incubated in multiple-stage incubators presented a lower percentage of vessels in the chorioallantoic membrane, lower yolk absorption by the embryo, wall depth of the right ventricle, and greater humidity losses in the eggs when compared to eggs in the single-stage incubators. The eggs submitted to hypercapnia, between 5,000 and 6,000 ppm of CO2, had a higher percentage of vessels in the chorioallantoic membrane; the embryos originating from these eggs had higher weight, with higher relative weight of the liver. However, the same levels reduced the yolk absorption. Single-stage incubation with moderate levels of hypercapnia is an efficient tool to be adopted by the hatcheries when attempting to improve chick quality.

Successful pig embryonic development in vitro outside a CO2 gas-regulated incubator: effects of pH and osmolality.

We investigated the effects of HEPES in the medium (to maintain pH) and paraffin oil covering the medium (to maintain osmolality) on the developmental ability of porcine embryos produced in vitro using tightly closed glass tubes in the absence of a CO2 gas-regulated incubator. Putative porcine zygotes obtained by in vitro fertilization (IVF) of in vitro-matured (IVM) oocytes (day of IVF=Day 0) were cultured in 5% CO2 gas-equilibrated NCSU-37 media containing pyruvate and lactate during Days 0-2, and glucose during Days 2-6, in open glass tubes in a CO2 incubator or tightly closed glass tubes without a CO2 incubator at 38.5 degrees C. The following four media were used: (1) medium covered with paraffin oil and supplemented with HEPES; (2) medium covered with paraffin oil but with no HEPES supplementation; (3) medium not covered with paraffin oil but supplemented with HEPES; (4) medium not covered with paraffin oil and with no HEPES supplementation. As a control group, zygotes were cultured in medium with neither paraffin oil coverage nor HEPES supplementation using a four-well dish in a CO2 gas-regulated incubator. After culture, the osmolality in each of the four closed conditions was maintained at approximately 285-286 mOsm, lower (P<0.05) than that in the control (291 mOsm). In the two HEPES-supplemented media groups in the closed-tube system, the pH was maintained at 7.5-7.7, and the blastocyst development rates (15.5% in non-oil covered and 18.5% in oil covered group) did not differ significantly from that of the control (20.2%), although the mean cell numbers in the blastocysts in the two closed-tube condition groups (28.2 and 33.0) were lower (P<0.05) than in the control (43.5). In contrast, the pH was higher in the two groups without HEPES supplementation (approximately 8.0) than the control (7.4; P<0.05), and the blastocyst development rates (10.9% in non-oil covered and 7.5% in oil covered group) or total cell numbers in the blastocyst (24.8 and 28.7) in the two non-HEPES groups were drastically decreased (P<0.05) compared to those in the control (20.2% and 43.5). These results suggested that maintenance of pH is important for successful in vitro porcine embryo culture under closed-air conditions, whereas the range of osmolality that suits embryo development is not limited to a small range. Furthermore, blastocyst production was possible in a glass tube without a CO2 incubator, although blastocyst quality was lower compared to those produced in an incubator.

Incubation temperature alters thermal preference and response to heat stress of broiler chickens along the rearing phase.

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.