Effects Of Thermal Manipulation Research Articles

Effect of thermal manipulations during embryogenesis and early age post-hatching on growth performance and meat quality in dual-purpose chickens

Effect of thermal manipulations during embryogenesis and early age post-hatching on growth performance and meat quality in dual-purpose chickens

Effects of Thermal Manipulation During the Second Half of Incubation on Embryo Physiology, Hatching Parameters, and Quality of Broiler Chickens in Tropical Climate of Togo

Chickens are sensitive to environmental challenges caused by temperature. The current study aimed to determine the effects of heat manipulation during embryonic development on the physiological responses of Goliath chickens. A total of 2000 hatching eggs from 48-week-old breeders were weighed, numbered, and randomly distributed equally into 4 incubators. Each incubator received 500 eggs (4 replicates of 125 eggs each). Eggs in two of the incubators were rotated hourly at a 45° angle and maintained at 37.8°C and 60% relative humidity (T0 groups). Between embryonic days (ED) 10 and 18 of incubation, the eggs from the other two incubators were heated to 38.5°C for 6 hours per day (T1 groups). The eggs were reweighed and candled, and viable eggs were moved to the hatching baskets at ED 18 of incubation. Hatching eggs were examined individually for hatching events every three hours during the final three days of incubation. On day 21, blood samples were collected from 12 chicks per group for hormonal and biochemical analyses. The evaluated blood parameters included Triiodothyronine (T3), T4 (thyroxine), cortisol, uric acid, lactate dehydrogenase, and total protein. At hatch, chicks were weighed and their quality (survival after hatching and performance standards) was evaluated. Data were collected on embryonic development, hatching window, hatching events, biochemical parameters, and hormonal concentrations. Results indicated that hatchability, chick’s weight, Tri-iodothyronine, and corticosterone were higher in the T1 group, compared to the control group. At hatch on day 21, the pipping muscle of chicks in the treated group (T1) was significantly heavier than that of the control group, while the embryonic mortality rate was significantly higher in the T0 group. In conclusion, applying heat treatment for 6 hours at 38.5°C from ED10-ED18 of embryogenesis increased significantly the hatching rate, the pipping muscle, and the chick’s weight in this study. Keywords: Embryonic development, Physiology, Slow-growing broiler, Thermal manipulation, Tropical climate

Effect of thermal manipulation on the biological and mechanical characteristics of horizontal platelet rich fibrin membranes

BackgroudRegardless of application scenarios, proper mechanical characteristics and degradation properties are prerequisites for horizontal platelet rich fibrin (H-PRF) to manifest its ability. Among the methods used to modify PRF, thermal manipulation is promising as it is easy to handle without adding extra additives. Yet there is no consensus on optimal temperature treatment. This study aimed to investigate the effects of heating on the biological and mechanical characteristics of H-PRF and explore the optimum heating temperature for H-PRF thermal treatment.MethodsWe employed a series of temperature gradients, room temperature, 50℃, 75℃, 90℃, 105℃. The microstructure and the mechanical properties were recorded by Scanning Electron Microscope (SEM) and tensile strength tests respectively. The degradation rate of H-PRF membranes was examined by digestion assay with plasmin and trypsin. The viability of cells within H-PRF membranes and the proliferation of osteoblasts cultured with extracts from different H-PRF groups was evaluated using CCK-8 assays.ResultsCompared with the nonheated group, overheated manipulation beyond 90℃ can significantly prolong the degradation properties for up to 3 to 4 weeks and enhance the mass stress of H-PRF membranes. A high-temperature treatment of 105℃ accompanied by the cell activity beneath H-PRF reduced more than half, and thus, the biological effect on human osteoblasts (hFOBs) also reduced dramatically.ConclusionsHigh thermal manipulation can prolong the degradation properties and enhance the mechanical properties of PRF membranes accompanied by the loss of biological effect.

Effect of thermal manipulation on embryonic development, hatching process, and chick quality under heat-stress conditions

Thermal stress is a risk that threatens poultry welfare and productivity. Thermal manipulation during egg incubation is considered a prevention strategy used to mitigate the detrimental effects of high ambient temperatures on birds. This study aimed to investigate the impact of thermal manipulation, applied to chicken breeder's eggs during the incubation period, on embryonic development, hatching characteristics, and chick quality, as well as posthatch thermotolerance and performance. A total of 1,200 fertile eggs were randomly and equally assigned into 2 groups of 3 replicates (200 eggs/replicate), using a randomized experimental design followed by t test. The first group eggs (G1) were subjected to a commercial setter temperature of 37.5°C with 55% relative humidity (RH) throughout the incubation period (1-18 d) and served as a control, while the second group eggs (G2) were treated the same commercial setter conditions until the 11th day of the incubation, then the eggs were exposed to a higher temperature of 39.5°C with 60% RH for 4 h daily from the 12th to the 18th day of incubation. All eggs in both groups were exposed to the same temperature condition of 37.2°C with 70% RH from the 19th to the 22nd days of the incubation (hatching period). Three hundred hatched female chicks per each treatment group were transferred into a closed-system house and distributed randomly into 20 floor pens (15 birds per pen). At the 8th week of age, birds were exposed to a daily heat challenge by raising the temperature to 35°C for 6 h until the 18th week of the chick's age. According to the results, thermal manipulation at 12 to 18 d of egg incubation positively (P ≤ 0.05) affected several studied traits. It improved some embryonic development traits, such as embryonic weight and tibia length, as well as some hatching parameters, such as hatching time and pipped eggs. It also improved hatched chick quality traits, including the chick's weight, length, and activity. In addition, it enhanced the posthatch chick's thermotolerance and body weight. Hatched chicks of G2 had significantly (P ≤ 0.05) higher total protein, albumin, IgM, glucose, calcium, total antioxidant, and T3 than G1 chicks. They also had significantly (P=0.001) higher body weight (23%) at the 18th week of age than G1, as well as a lower feed conversion ratio (20.71%) than G1 chicks at 8 to 18 wk of age. Therefore, it is recommended to apply thermal manipulation during egg incubation, particularly at 12 to 18 d, for its positive effects on the pre- and posthatch performance.

Effect of thermal manipulation during embryogenesis on gene expression of myogenic upstream activation factors pre- and post-hatch in broilers

This study aimed to determine the optimum timing of embryonic thermal manipulation (TM) that may result in improvement of mRNA expression of myogenic upstream activation factors viz. Wnt family member-3 (Wnt-3), sonic hedgehog gene (Shh), proliferating cell nuclear antigen (PCNA) and paired-box transcription factor-7 (Pax-7) during development and histogenesis of broiler muscle. Fertile eggs (1440) were divided randomly and equally into 5 treatment groups including control (no TM) and four treatment groups (TM1, TM2 TM3 and TM4) that were daily subjected to 39 ̊C for 18 h with 65% relative humidity during embryonic days ED 7–11, ED 11–15, ED 15–18 and ED 7–18 respectively. Pectoral and thigh muscle mRNA expressions of myogenic upstream activation factors were evaluated by semi-quantitative real-time RT-PCR. Out of TM conditions that were investigated, TM1 resulted in a significant improvement of Wnt-3, Shh, PCNA and Pax-7 expressions in broiler pectoral and thigh muscles during embryonic and post-hatch life when compared to the control. Thus, thermal manipulation during early embryongenesis (embryonic days ED 7-11) enhance broiler skeletal muscle myoblast proliferation by triggering and inducing transcription factors that regulates myogenesis and subsequently may lead to improve cell number and size of skeletal muscle. The outcome of this study indicates that TM during ED7-11 improved muscle response to heat stress, was safe to the pectoral and thigh muscles and this method may enhance myogenesis and muscle growth in a positive manner.

Effects of Thermal Manipulation on mRNA Regulation of Response Genes Regarding Improvement of Thermotolerance Adaptation in Chickens during Embryogenesis

The phenomenon of increasing heat stress (HS) among animals is of particular significance when it is seen in economically significant industries, such as poultry. Due to the identification of the physiological, molecular, and genetic roots of HS responses in chickens, a substantial number of studies have focused on reducing the effects of HS in poultry through environmental management, dietary manipulation, and genetic alterations. Temperature manipulation (TM) during embryogenesis has been claimed to increase the thermal tolerance and well-being of chickens without affecting their capacity for future growth. There has been little investigation into the vulnerability of the epigenome involving TM during embryogenesis, although the cellular pathways activated by HS have been explored in chickens. Epigenetic changes caused by prenatal TM enhance postnatal temperature adaption and produce physiological memory. This work offers a thorough analysis that explains the cumulative impact of HS response genes, such as genes related to heat shock proteins, antioxidants, and immunological genes, which may aid in the enhanced adaptability of chickens that have undergone thermal manipulation during their embryonic stages.

Effect of thermal manipulation during embryogenesis on gene expression of myogenic regulatory factors pre and post hatch in broilers

A total of 1,440 fertile eggs were divided randomly and equally into 5 treatment groups; control (no TM) and 4 treatment groups: TM1, TM2, TM3, and TM4 that were thermally subjected to 39°C for 18 h with 65% relative humidity daily, during embryonic days ED 7–11, ED 11–15, ED 15–18 and ED 7–18, respectively. Out of TM conditions that were investigated, TM1 resulted in a significant improvement in expression of myogenic factor-5 (Myf5), myoblast determination protein (MyoD) and myogenin (MyoG) in pre and post hatch broiler muscle when compared to the control. This study aimed to determine the optimum time for thermal manipulation during embryogenesis that may result in improvement in expression of myogenic regulatory factors (MRFs): Myf5, MyoD, MyoG and myostatin (MSTN) in broiler muscle. Thus, the results of this research may provide a means of improvement of myogenesis of pectoral and thigh muscles of broilers proceeding from early embryogenesis (ED7) through post-hatch day.

Effect of thermal manipulation during incubation and heat challenge during the early juvenile stage on production parameters of broilers reared under a tropical climate

Abstract Heat stress induces economics losses in poultry production. Several studies have shown that this negative effect can be reduced by heat treatments like thermal manipulation during incubation (TMI) and early age thermal conditioning (ETC). The aim of this study was to investigate the effects of TMI on embryo development and the effects of TMI and ETC on productive performances of broilers under a tropical climate. The study involved 1000 Ross 308 broiler hatching eggs incubated at standard incubation conditions (37. 8°C at 60% relative humidity = RH) until embryonic day (E) 7. Then the eggs were divided into two groups: a control group (Ci) incubated at standard conditions until hatch and a treatment group (Ti) subjected to TMI (39. 5°C at 65% RH) for 12 h/d from E7 to 16. Chicks were assigned to one of two treatments at 3 days of age: chicks from the Ci group were assigned to CiP0 (chicks from eggs incubated normally and reared without ETC) and CiP1 (chicks from eggs incubated normally but exposed to ETC). Chicks from the Ti group were allocated to TiP0 (chicks from incubation with TMI and reared without ETC) and TiP1 (chicks from incubation with TMI and exposed to ETC). Microclimatic data (temperature 22– 34°C and 58–70% RH) were recorded. Results indicated higher (p˂0.001, p = 0.002) hatchability and chick quality in the Ci group. Final body weight was influenced by TMI and ETC. Feed conversion and feed intake were reduced by TMI, but not by ETC, which had an effect on mortality rate. A significant effect of TMI × ETC was observed on daily weight gain and mortality rate. In conclusion, ETC had a good and lasting impact on growth and survival and TMI improved FCR of broilers under a chronic hot environment. ETC plus TMI adversely impacted growth but improved survivability of broiler chickens.

Effects of thermal manipulation during embryogenesis and post‐hatch acute heat stress on the mRNA expression dynamics of cytokines in broiler chickens

Heat stress significantly impacts chicken immunity and cytokine expression, but, the effects of embryonic thermal manipulation (TM) on cytokine expression in broiler chickens is unclear. The aim of the present study was to evaluate the effects of TM on the splenic mRNA expression dynamics of certain cytokines (IFN‐α, IFN‐β, IFN‐γ, IL‐4, IL‐8, IL‐15, IL‐16, IL‐17 and IL‐18) in broilers during subsequent exposure to acute heat stress (AHS). TM was performed by elevating the incubation temperature to 39°C at 65% relative humidity (RH) for 18 h daily during embryonic days (ED) 10 to 18. AHS was carried out by raising the temperature to 40°C for 7 h on post‐hatch day 28. At 0, 1, 3, 5, and 7 h of AHS, the spleen was collected from all groups to evaluate mRNA expression by relative‐quantitative real‐time RT‐PCR, and blood was collected to measure plasma levels of IL‐4, IL‐8, and IFN‐γ. At 0 h, TM led to a significant reduction in the basal mRNA level of IFN‐β and the plasma level of IFN‐γ and IL‐8. Moreover, AHS significantly decreased IFN‐β in control chicks, decreased IL‐4 in both TM and control chicks, and increased IFN‐γ and IL‐16 in TM chicks. IL‐8, IL‐15, IL‐17, IFN‐α, and IL‐18 expression significantly increased during AHS in both TM and control chicks, but expression dynamics was improved in TM chicks for all cytokines except IL‐17. AHS resulted in increased plasma IFN‐γ levels in TM chicks only, and it increased IL‐8 levels at 3 and 5 h of AHS in TM chicks but at 7 h in control chicks. Lastly, 3 h of AHS increased IL‐4 plasma levels in control chicks. The results of this study may indicate that TM has a long‐term effect on the expression dynamics of cytokines, especially during AHS, suggesting that TM affects post‐hatch immunity. Furthermore, this study may suggest that TM improves heat tolerance by increasing the expression of signaling proteins important to the wound‐healing process.Support or Funding InformationDeanship of Research/Jordan University of Science & Technology (Grant#: 128/2017).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effect of thermal manipulation during embryogenesis on the promoter methylation and expression of myogenesis-related genes in duck skeletal muscle

Avian embryos are an ideal system to investigate the effect of incubation temperature on embryonic development, but the characteristics and mechanisms of temperature effects on poultry embryonic myogenesis are unclear. In this study, we investigated the effect of increasing the incubation temperature by 1 °C on the expression of nine myogenesis-related genes in ducks and then explored the correlation between the alteration of promoter methylation and the expression of two of the nine genes under thermal manipulation (TM). The qRT-PCR results showed that TM during embryonic days (ED) 1–10 promoted (P < 0.05) the expression of genes in breast muscle (PAX3, PAX7, MYOG, MCK, SIX1, TNNC1) and leg muscle (MYOD, MYOG, MYF5, MCK, AKIRIN2, TNNC1). TM during ED10-20 promoted the expression of PAX3, MYF5 and MCK and inhibited AKIRIN2 expression in breast muscle (P < 0.05); however, it inhibited the expression of PAX3, PAX7, MYOD, MYOG, MYF5, SIX1, AKIRIN2 and TNNC1 and promoted MCK expression in leg muscle (P < 0.05). TM during ED20-27 inhibited the expression of genes in breast muscle (PAX7) and leg muscle (MYOD, MYOG, MYF5, TNNC1) and promoted MCK expression in breast and leg muscle (P < 0.05). Furthermore, with the Sequenom MassARRAY platform, it was observed that the average methylation level of AKIRIN2 (ED10) and TNNC1 (ED20) in leg muscle decreased (P < 0.05) after TM. Notably, we found significant (P < 0.05) inverse correlations between the methylation and mRNA levels of AKIRIN2 under TM during ED1-10 (r = − 0.969) and ED10-20 (r = − 0.805). Taken together, TM during ED1-10 was more favorable for improving duck myogenesis-related gene expression than TM during ED10-20 and ED20-27. TM during duck embryogenesis seemed to have a greater effect on the development of leg muscle than breast muscle and might alter AKIRIN2 expression by changing its promoter methylation status. These findings may be helpful to understand temperature effects on the muscle development of avian embryos and to explore the role of epigenetic regulation during this process.

Effect of thermal manipulation during Broiler chicken embryogenesis on the differential expression of Heat shock protein and Factor during heat stress on post‐hatch chicken

The objective of this study was to determine the effect of thermal manipulation during broiler chicken embryogenesis on the differential expression of heat shock proteins (HSPs) and heat shock factors (HSFs) during thermal stress at post hatch days 14 and 28 of age. Fertile chicken eggs (n=1500) were divided into five incubation treatment groups (300 each): control group was maintained at 37.8 °C 56% relative humidity (RH) throughout the incubation period; TM1 was subjected to TM at 38.5°C for 24 h and 65% RH daily during ED12–18; TM2 was subjected to TM at 39°C for 24 h and 65% RH daily during ED12–18; TM3 was subjected to TM at 39.5°C for 24 h and 65% RH daily during ED12–18 and TM4 was subjected to TM at 40°C for 24 h and 65% RH daily during ED12–18. At post‐hatch days 14 and 28 of age, chicks in TC groups were subjected to thermal challenge (TC) at 41.0°C for 6 h while naïve chicks were kept under regular conditions. Chick's response to TC was evaluated by determination of body temperature (Tb) and differential muscle mRNA expression of Hsp108, Hsp90, Hsp70 and Hsp60. During TC at days14 and 28 of age, the Tb of TM chicks was significantly lower than those of the controls. When compared to the control, TM resulted in a rapid significant increase in mRNA levels of Hsps and HSFs in the muscle during TC at post hatch days 14 and 28 of age.Support or Funding InformationDeanship of Research, Jordan University of Science and Technology (Project ID# 66/2016).

Thermal manipulation during late embryogenesis: Effect on body weight and temperature, thyroid hormones, and differential white blood cell counts in broiler chickens

The effects of thermal manipulation (TM) at 38.5°C and 40°C for 6 h at embryonic day (ED) 16, 9 h at ED 17, and 12 h at ED 18 on body weight (BW) and cloacal body temperature (Tb) during the first wk and later at post-hatch d 10, 14, 21, 28, and 42 were evaluated. Furthermore, chicks’ ability to cope with a thermal challenge (TC; 41°C for 6 h) at post-hatch d 14 and 42 was also evaluated. A chick's response to TC was measured by determining the cloacal body temperature; the plasma thyroid hormones (thyroxin (T4) and triiodothyronine (T3)); the packed cell volume (PCV); the heterophil (H), lymphocyte (L), monocyte, basophil, and eosinophil percentages; and the heterophil-to-lymphocyte ratios (H/L). Thermal manipulation did not affect the hatchability. However, the body weight of TM chicken was higher compared with controls at marketing age (post-hatch d 42). At post-hatch d 14 and 42, no significant changes in Tb were observed among the different treatment groups. However, during TC at d 14 and 42, the Tb of TM chicks was lower compared with the controls. During TC, a significant increase in plasma T4 and a significant decrease in plasma T3 of TM chicks compared with controls were reported. Furthermore, during TC, a significant increase in the PCV and heterophil, monocyte, and H/L ratios, and a reduction in the lymphocyte percentages also were observed in TM chicks compared with the controls. Results of this study showed that chicks subjected to heat manipulation during late embryogenesis respond better to heat stress later in the growth and development period.

Effects of thermal manipulation during late incubation period on post-hatch thermotolerance in ostrich

The effects of thermal manipulation (TM) during late ostrich embryonic development on hatchability, body weight, biochemical and hormonal changes, and the ability of hatching chicks to cope with thermal challenge in days 6-8 of age were examined. At 35 days of incubation, two hundred fertile eggs were weighed and divided into two equal groups with five replicates. The first group was exposed to 36.5°C and 25% relative humidity (RH) (control), while the second group was exposed to 38.5°C and 45% RH for 3 h daily in days 35-37 of incubation (thermal manipulation). At days 6-8 of age, the hatched chicks from each treatment were randomly divided into two groups: control group (exposed to 32 ± 1°C), and thermal challenge group (exposed to 40 ± 1°C for 3 h daily). Hatchability rate was significantly lower with high incubation temperature as compared to the normal incubation temperatures. Embryonic TM and thermal challenge in days 6-8 of age reduced significantly total protein, albumin, and triiodothyronin concentrations and elevated uric acid, creatinine, triglycerides, and glucose concentrations as compared with the control. The level of corticosterone was significantly higher in the thermal challenge group as compared to the control. In conclusion, exposing the ostrich embryos to TM (38.5°C) during late embryonic development induced physiological changes that may represent epigenetic adaptation to TM. The same mechanisms are employed for increasing the ability to improve thermotolerance post-hatch.

Thermal manipulation during broiler chicken embryogenesis: Effect on mRNA expressions of Hsp108, Hsp70, Hsp47 and Hsf-3 during subsequent post-hatch thermal challenge

Effects of thermal manipulation during broiler chicken embryonic days 12–18 on body temperature (Tb) and mRNA expressions of Hsp108, Hsp70, Hsp47 and Hsf-3 in muscle, heart and brain tissues during subsequent thermal challenge (TC) were investigated. Fertile chicken eggs were divided randomly into four groups (n=375): eggs in the control group were maintained at 37.8°C and 56% (RH). Eggs in TM1 group were subjected to TM at 39°C for 9h during ED 12–18. Eggs in the TM2 and TM3 groups were subjected to the same protocol of TM1 except for increasing the period of exposure to 12h and 18h, respectively. During TC (43°C for 6h) at days 10 and 28, Tb of TM chicks was significantly lower compared to controls. Furthermore, significant changes in mRNA expressions of Hsp108, Hsp70 and Hsp47 in muscle, heart and brain tissues were observed.

Hsp90, Hsp60 and HSF-1 genes expression in muscle, heart and brain of thermally manipulated broiler chicken

The effect of thermal manipulation (TM) during embryogenesis (ED 12–18) on mRNA expressions of heat shock proteins (Hsp90, Hsp60 and HSF-1) in muscle, heart and brain tissues during thermal challenge (TC) at post-hatching days 10 and 28 was investigated. Fertile chicken eggs were randomly divided into four groups: Control group (37.8 °C), TM1 (39 °C for 9 h), TM2 (39 °C for 12 h) and TM3 (39 °C for 18 h). At days 10 and 28 of age, chicks in TC groups were subjected to thermal challenge (TC) at 43.0 °C for 6 h while naïve chicks were kept under regular conditions. When compared with the control, TM resulted in a significant increase in mRNA levels of Hsp90, Hsp60 and HSF-1in muscle, heart and brain tissues during embryogenesis and during TC at days 10 and 28 post-hatching. These results indicate a long-term enhancement of Hsp90, Hsp60 and HSF-1 gene expressions associated with improved thermotolerance acquisition in thermally manipulated chicks.

The effects of thermal manipulations during early and late embryogenesis on body temperatures of Japanese quails (Coturnix coturnix japonica)

The aim of this study was to determine the effect of thermal manipulations during early embryogenesis (EE) and late embryogenesis (LE) on body temperature of Japanese quails (Coturnix coturnix japonica). Incubation conditions from day 0 to day 17 were 37.7°C and 55% relative humidity for control group. In the thermally treated eggs during EE (EE6, EE7 and EE8 days), incubation temperature was increased to 41°C and relative humidity to 65% for 3 hours (12:00–15:00) on the sixth, seventh and eighth days of incubation. Also, in the LE stage (EL12, EL13 and EL14 days), incubation temperature was increased to 41°C and relative humidity to 65% for 3 hours (12:00–15:00) on the 12th, 13th and 14th days of incubation. Average temperature, relative humidity and total heat of indoor air were changed from 28.71 to 30.44°C, from 45.69 to 57.15% and from 14.67 to 16.16 kcal kg–1 dry air, respectively. Higher total heat of indoor air in 10–11 weeks than that of other weeks was found. Significant differences between the control (41.52±0.26°C) and manipulation groups were found, but no significant difference between the EE (41.23±0.40°C) and LE (41.26±0.37°C) groups with respect to body temperatures. Body temperatures of quails were measured as 41.55±0.31°C, 41.56±0.26°C; 41.17±0.33°C and 41.07±0.30°C at 10, 11, 12 and 13 weeks of age, respectively. In addition, differences among the weeks in point of body temperatures of quails were found to be significant (p<0.01).

Incubation and Fertility Research Group {WPSA Working Group 6 (Reproduction)} 2011 Meeting - Ede, the Netherlands, 30th-31st August 2011

The 2011 Incubation and Fertility Research Group {WPSA Working Group 6 (Reproduction)} conference took place on 30-31 August 2011 in Ede, The Netherlands. Speakers from all over the world took part and considered all aspects of incubation and fertility in a variety of avian species. We are delighted to present abstracts from 27 of the presentations given at the meeting. The topics include: improving the fertility of cryopreserved poultry semen; sexing of day zero unincubated chicken eggs; hypoxia effects on embryonic development; the effects of thermal manipulation during early embryogenesis; antimicrobial activity of egg white; egg size variation in double yolked duck eggs; treatments to preserve hatchability during storage; and the question of how to engineer the heart of broiler chickens during incubation.

The effect of thermal manipulations during embryogenesis of broiler chicks (Gallus domesticus) on hatchability, body weight and thermoregulation after hatch*1

The effect of thermal manipulations during embryogenesis of broiler chicks (Gallus domesticus) on hatchability, body weight and thermoregulation after hatch*1

The effect of thermal manipulations during embryogenesis of broiler chicks ( Gallus domesticus) on hatchability, body weight and thermoregulation after hatch

The significant developments in the genetic selection of fast-growing broiler chickens cause difficulties for broilers in coping with extreme environmental conditions. This study was conducted to elucidate the effect of repetitive short-term increases in incubation temperature on hatchability and chick's body weight (BW) and thermoregulation immediately after hatch. Thermal manipulation (TM) had no effect on hatchability when the three trials were combined for statistical analysis, and had no effect on chick's BW. It caused a significant reduction in chicks T b, and significant decline in plasma thyroid hormones concentration, but had no effect on plasma corticosterone concentration. It can be concluded that TM did not affect BW but had a positive effect on thermoregulation, most probably in reducing metabolic rate.