Thermal Manipulation Mid-term Broiler Chicken Embryogenesis: Effect on Muscle Growth Factors and Muscle Marker Genes

2020

Veterinary Sciences

Decades of selective breeding for commercial purposes have rendered the broiler chicken (Gallus gallus domesticus) highly susceptible to heat and cold stress. A multitude of studies have documented the effects of thermal manipulation (TM) on broiler thermotolerance during periods of post-hatch heat stress, but very few have focused on the effect of TM on a broiler’s ability to withstand cold stress. Therefore, the primary objective of the current study is to determine the effects of TM on the acquisition of thermotolerance in broilers via their expression of the stress-associated 70 kilodalton heat shock protein (Hsp70) gene and heat shock factor 3 (HSF3) gene. Briefly, Hubbard broiler embryos were subject to TM by increasing the incubation temperature to 39 °C and 65% relative humidity (RH) for 18 h daily, from embryonic days (ED) 10 to 18. Broilers were then exposed to cold stress by decreasing the room temperature to 16 °C during post-hatch days 32 to 37. After thermal challenge, broilers were euthanized and hepatic and splenic tissues were collected. Our results showed that TM decreased the hatchability rate and body temperature but improved the body weight gain. TM generally decreased the hepatic expression but did not change the splenic expression of HSF3 during cold stress. In contrast, both hepatic and splenic Hsp70 expression decreased during cold stress. The results of the present study may suggest that TM significantly affects a broiler’s genetic response to cold stress.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

HSF3 and Hsp70 Expression during Post-Hatch Cold Stress in Broiler Chickens Subjected to Embryonic Thermal Manipulation

Tarkhan

Saleh

2020

Veterinary Sciences

“…Similarly, previous studies reported that chicks incubated at 39.5 °C for 3 h/d during ED 8–10 had unaffected weights during post-hatch life. However, other studies reported that increasing the incubation temperature to 38.5 °C during ED 16–18 and to 39 °C 18 h/d during ED 12–18 resulted in increased broiler body weights [34,35]. Furthermore, egg incubation at 39.5 °C for 12 h/d during ED 7–16 led to increased myofiber diameters and enhanced muscle growth, up to 35 days of age [36].…”

Section: Discussionmentioning

confidence: 99%

Effect of Acute Heat Stress on the mRNA Levels of Cytokines in Broiler Chickens Subjected to Embryonic Thermal Manipulation

Saleh

2019

Animals

Heat stress significantly impacts the immunity and cytokine expression of chickens. However, the effects of embryonic thermal manipulation (TM) on cytokine expression in broiler chickens (broilers) is unclear. The objective of the current study was to evaluate the effects of TM on the splenic mRNA expression dynamics of certain cytokines—namely, 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) 10–18. On post-hatch day 28, AHS was carried out for 7 h at 40 °C. At 0 h and after 1, 3, 5, and 7 h of AHS, splenic tissues were collected from all study groups to evaluate mRNA expression by relative-quantitative real-time (RT)-PCR. Plasma was collected to measure IL-4, IL-8, and IFN-γ levels. At 0 h, TM significantly reduced 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. IFN-α, IL-8, IL-15, IL-17, and IL-18 expression all significantly increased during AHS in both TM and control chicks, but expression dynamics were improved in TM chicks for all cytokines (except IL-17). AHS resulted in increased plasma IFN-γ levels in TM chicks only, and 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 cytokine expression dynamics of broilers, especially during AHS. Therefore, TM may improve heat tolerance acquisition by increasing the expression of signaling proteins important to tissue stability and to repair mechanisms that are employed during and/or after heat stress recovery.

“…In addition, TM immediately affects miRNA expression profiles of breast and hind muscles of chicken embryos and is associated with minor long term expression of miRNAs broiler chickens [19]. However, the molecular bases for promoting muscle development and growth requires further investigation [12, 13, 16, 20]. Therefore, the current study aimed to investigate the effect of different daily TM conditions, namely TM 1 (38.5°C for 18 h), TM 2 (39°C for 18 h), TM 3 (39.5°C for 18 h) and TM 4 (40°C for 18 h) during embryonic days (ED) 12 to 18, on body (BW) and internal organ weights and expression of muscle growth and transcription factor genes of broiler chickens.…”

Section: Introductionmentioning

confidence: 99%

Thermal manipulation of the broilers embryos: expression of muscle markers genes and weights of body and internal organs during embryonic and post-hatch days

El-Bahr

2019

BMC Vet Res

Background In broilers chickens, the molecular bases for promoting muscle development and growth requires further investigation. Therefore, the current study aimed to investigate the effects of daily thermal manipulation (TM) during embryonic days (ED) 12 to 18 on body, carcass and internal organ weights as well as on the expression of muscle growth markers genes during late embryogenesis and post-hatch days. 1500 fertile Cobb eggs were divided into five groups. The first group was a control group and incubated at 37.8°C. The other four groups were thermally manipulated (TM) and exposed to 38.5°C (TM 1 ), 39°C (TM 2 ), 39.5°C (TM 3 ) and 40°C (TM 4 ) daily for 18 h, respectively, with a relative humidity of 56%. Body weights (BW) from ED 12 to 18 and on post-hatch days 1, 2, 3, 4, 5, 6, 7, 14, 21, 28 and 35 were recorded. mRNA expression levels of muscle growth factor genes (IGF-1 and GH) and muscle marker genes (Myogenic Differentiation Antigen; MyoD), Myogenin, Pax7, and PCNA) during ED 12 to 18 and on post-hatch days 1, 3, 5, 7, 14 were analyzed. On post-hatch day 35, the carcass and internal organ weights have been also evaluated. Results TM during certain days of embryogenesis (ED 12 to 18) did not affect the BW of broilers during their embryonic lives. However, TM, particularly TM 1 and TM 2 , significantly increased BW, carcass and internal weights of hatched chicks near to the marketing age (post-hatch days 28 and 35). Most of TM protocols induced up-regulation of muscle growth factor genes (IGF-1 and GH) and muscle marker genes (MyoD, Myogenin, Pax7, and PCNA) during embryonic life (ED 12 to 18) and on post-hatch days. Conclusion Among the various TM conditions, it seems that,TM 1 and TM 2 induced a significant increase in BW, carcass and internal weights of hatched chicks near to the marketing age. This increase in BW induced presumably via up-regulation of muscle growth factor genes and muscle growth markers genes during embryonic life (ED 12 to 18) and on post-hatch days. Both protocols (TM 1 and TM2) can be used in real-world applications of poultry industry for maximum benefit.