What Temperature To Hatch Chicken Eggs: A Comprehensive Guide

Incubation Temperature and Post-Hatching Adaptive Response

The effect of temperature manipulation during the embryogenesis on post-hatch adaptive stress response may be explained by mRNA expression of genes involving stress response, thermoregulatory and metabolic programming (Loyau et al. , 2016). Comparing thermally manipulated and control chicks under heat stress conditions showed that 759 genes were differently expressed (Loyau et al. , 2016). There are proteins called heat shock proteins (Hsp) that help cells deal with heat stress and keep structural proteins intact. Al-Zghoul. (2018) found an increase in Hsp70 expression in heat-stressed chickens exposed to incubation temperatures of 38. 5–39. 5°C for 18 h from ED12 to 18 of embryogenesis. Because heat stress causes inhibition of protein synthesis, an increase in Hsp70 mRNA expression in heat-stressed chickens would be associated with an improvement in protecting cell integrity in chickens (Al-Zghoul et al. , 2013). It was also shown that genes that code for parts of the CRF signaling pathway change how they are expressed in the hypothalamus of chicks that have been heated or cooled. This shows that heating or cooling the hypothalamus causes epigenetic changes (David et al. , 2019).

The studies also attempt to evaluate lower incubation temperature and its effect on adaptive response. Shinder et al. (2011) found that between ED18 and 19, a short (30 min) exposure to 15°C cold did not affect the ability to hatch, but it did speed up growth and lower the risk of ascites. Similarly, 6 h/d low temperature (36. The temperature increase (6°C) from ED10 to 18 made broilers gain weight and become better at handling cold. This led to long-term changes in their antioxidant defenses and energy metabolism (Aksit et al. , 2013; Loyau et al. , 2014). When embryos and day-old chicks were kept at 36°C for 36 hours, changes were seen in the levels of antioxidants and fatty acids in their brain and liver tissues. 6°C, 6 h/d from ED10 to 18. These changes may be accepted as coordinated adaptive reactions of chicks (Yalcin et al. , 2012b).

Several studies have also shown that high temperatures promote muscle development and myoblast proliferation in day-old chicks. Piestun et al. (2009) showed that during late-term embryogenesis (ED16 to 18), high incubation temperature (39.5°C for 3 or 6 h daily) increased muscle insulin-like growth factor I (IGF-I), which enhanced muscle cell proliferation and differentiation, and myofibers diameter. However, as the study was ended at post-hatch d 13, if muscle development was affected at slaughter age is unknown. Our recent finding (Yalcin et al., 2021) suggested that exposing Ross308 and Cobb embryos to 38.8°C between ED10 and 14 resulted in heavier body weight and higher insulin-like factor-1 (IGF-I) expression, and larger fiber area in breast muscle of broiler chickens at slaughter age. However, breast muscle properties of strains, i.e., expression of vascular endothelial growth factor-A and myogenin, carcass part yields, pH24, and water holding capacity of strains responded differently to temperature manipulation (Yalcin et al., 2021). This result supports further evidence that the effect of thermal manipulation is strongly related to the strain.

In conclusion, the studies showed that the effect of incubation temperature during embryonic development is undoubtedly crucial for adaptive stress response. Incubation temperature could program the chick to construct traits in adaptation to a post-hatching temperature environment. This response may be explained by the imprinted epigenetic changes in the hypothalamus that trigger a response when the chickens are again exposed to high or low temperatures (David et al., 2019). The studies tell us that interaction among timing, duration, and temperature shape embryo development and adaptive stress response. Indeed, Wilsterman et al. (2015) showed that exposure of embryos to slightly higher temperatures either early, late, or whole incubation period had an impact on the pattern of glucocorticoid release, however, the specific response of chicks and broilers varied with the timing. Currently, it is unclear how the sensitive period and temperature interact with the other environmental factors in the incubator and maternal factors (strain, breeder age, egg composition, and egg quality). Nevertheless, during the second half of incubation, the embryo may be more sensitive to temperature manipulation signals to have a long-lasting post-hatch effect. Further studies are needed to understand the effect of epigenetic modifications during embryonic development, their molecular mechanisms underlying these changes, and their long-term effects.

Role of light stimulation during incubation on embryonic muscle growth and stress. HPA, Hypothalamus-Pituitary-Adrenal; GHRH, Growth Hormone-Releasing Hormone; CRH, Corticotrophin Releasing-Hormone; ACTH, Adrenocorticotropic Hormone; TRH, Thyrotropin-Releasing Hormone; GH, Growth Hormone; IGF-1, Insulin-like Growth Factor-1.

Therefore, photostimulation at early or late periods of embryonic development has been investigated in the studies to see if lighted incubation affected embryo development and hatching performance. However, not only the critical periods but also the duration of photostimulation per day and characteristics of light including intensity, color (wavelength), and color temperature of light are important. In this part of the paper, we review the effect of light provision during incubation on embryo development and post-hatching growth, and the post-hatching adaptive response of chicken, taking into account timing, duration, color, and intensity.

Effects of Light on Embryo Development and Post-Hatching Growth

Chicken embryos can detect color differences. Several studies have been conducted to investigate the effect of light color on embryonic development and post-hatching growth. As compared with blue light and dark incubation conditions, continuous green light during the incubation enhances the post-hatch body weight of male broilers, improves the feed conversion ratio, increases the satellite cell mitotic activity of the pectoral muscle with upregulation of MyoD, myogenin, and myostatin mRNA expression in late embryos and newly hatched chicks, and muscle growth with no noticeable changes in chemical composition and meat quality characteristics (Zhang et al., 2012, 2014). Providing green light intermittently (light/dark cycles of 15 min) during incubation also increases hypothalamic expression of growth hormone-releasing hormone (GHRH), liver growth hormone receptor (GHR), levels (Dishon et al., 2017). Dishon et al. (2021) compared intermittent green light stimulation throughout the incubation (ED0-21) with different stimulation periods starting from ED15, 16, and 18 of incubation and observed a higher expression of the somatotropic axis genes in all lighting treatments than in dark incubation. They suggested that photostimulation of embryos only last 3 days of incubation would be enough to stimulate the somatotropic axis since photostimulation of embryos from ED18 to hatch resulted in similar expression levels of hypothalamic GHRH, liver GHR, and IGF-1 genes and GH plasma levels to the positive control group (lighted from E0-21). These findings deserve to be investigated further to establish a clear conclusion regarding the critical period for the growth-stimulating effect of green light on broiler embryos.

The pineal gland of the chick embryo shows a selective sensitivity to different wavelengths (color) of the light spectrum. Drozdova et al. (2019) found a higher biosynthesis of pineal melatonin during scotophase under red (632 nm) and white (a peak wavelength of 448 nm) lighting compared to green (517 nm) and blue (463 nm). Further research from the same group showed that red-lighted incubation resulted in higher body weights in broiler chicks during the post-hatch rapid growth phase (from 18 to 21 days) compared to blue light (Drozdova et al., 2021). Although there is not much information regarding the effect of red light on the somatotropic axis, increased growth of chicks incubated under red light may be related to the early entrainment of melatonin rhythms. Not only the light color but also the color temperature of polychromatic light would be important. The cool white LED (5,000 K) containing more blue wavelength could improve weight gain and reduce stress and fear responses of broilers as compared to warm white LED (2,700 K) (Archer, 2018). However, it was shown that incubation in warm and cold white light did not significantly influence embryonic melatonin biosynthesis in the pineal, T3, T4, corticosterone hormone levels in the blood and immune system-related genes, presenilin-1, and avian betadefensin1, in the duodenum and bursa Fabricius (Drozdova et al., 2020). The authors concluded that selective effects of distinct wavelengths on embryonic and post-embryonic development might be more profound than the effects of change in the color temperature of polychromatic light.

Limited research is available regarding the effect of lighting during the incubation on bone growth and leg health, and the results are not consistent. An improvement in leg health of broilers was found using a 16L:8D (van der Pol et al., 2017) or 12L:12D (van der Pol et al., 2019) at 500 lux white LED lighting compared to continuous light or dark incubation conditions. However, in a recent study, Güz et al. (2021) did not find any significant effect of green LED light on tibia bone parameters when they used a 16L:8D photoschedule. It is necessary to clearly reveal whether the light color will affect bone development.

The intensity of light has also been the subject of interest. In a recent study, Yu et al. (2018) reported that 50 lux intensity using green LED light (16L:8D) increased chick length, weight, hatchability, testosterone, and T4 hormone levels and reduced hatching time, i.e., an earlier peak of 12 h, in newly hatched chicks compared to 150 and 300 lux. However, the transmission of light into the eggs significantly varies with the level of pigmentation and the conductance of eggshells (Shafey et al., 2002). Shafey et al. (2002) compared the spectral absorption rate of pigmented and non-pigmented eggshells over the wavelength range between 200 to 1,100 nm. Brown pigmented eggs had a max absorption rate of 99.96% for the near-ultraviolet region (wavelength ≤380 nm) of the light spectrum, which was higher than the absorption rate of 99.88% for long wavelengths, about 1,075 nm at the near-infrared region. Shafey et al. (2005) also compared two high intensities changing between 1,430–2,080 and 900–1,380 lux using a green fluorescent light source and different pigmentation levels of brown eggshells. They reported that higher intensity resulted in higher embryo mortality and decreased hatchability in light pigmented brown eggshells while there was no negative effect for dark drown eggshells (Shafey et al., 2005). Yu et al. (2016) confirmed that eggshell pigmentation and the region of the eggshell determine the transmission of visible wavelength (380–780 nm) into the egg. These findings support the hypothesis that the evolution of eggshell pigmentation for selective transmission of different wavelengths into eggs is based on preventing the negative effects of ultraviolet and infrared light (Maurer et al., 2011). Maurer et al. (2015) supplied further evidence from wild birds and concluded “avian eggshell properties, including eggshell structure and pigmentation, which are consistent with an evolutionary pressure to both enhance and protect embryo development”. Huth and Archer (2015) investigated the effect of eggshell pigmentation on the spectrum of light filtered by eggshell. They reported that the spectrum of light filtered by white eggshells was quite similar to unfiltered light; however brown eggshells produced a redder spectrum as evidence of higher transmission of long wavelengths into eggs. Recently Güz et al. (2021) observed that a green LED light source with a peak light spectrum of 522 nm yielded a 536 nm peak in the light spectrum after passing through the eggshell of broiler breeder eggs showing that pigmented eggshell may change wavelength reach into the egg. It is clear that the wavelength and intensity of light that reach the embryo are limited by eggshell properties. It should also be considered that the lux unit is based on human spectral sensitivity. Bird’s spectral sensitivity to short (400–480) and long (580–700) wavelengths is higher than humans due to their additional cone type of photoreceptor cells (Lewis and Morris, 2006). Therefore, eggshell properties, wavelength, and intensity of light both outside and inside of the egg should be taken into account in future studies to have a finely tuned lighting program for broiler embryos.

The available data presented above show that there is no accepted standard lighting procedure in the incubator until now. It can be concluded that green light is the most effective for stimulating growth and improving muscle development. However, homogenous intensity should be kept with lower intensities inside the incubator. Red light may have a more profound effect on innate immunity while green light may affect the immune and inflammation, and stress response of broiler chicks. However, further research is needed underlying mechanism for early immune programming and interactions between the light source and embryo development.

Incubating Chickens is SUPER Easy!

FAQ

What is the best temperature for hatching eggs?

In the incubator, put the eggs in the egg tray so that the wider end faces up and the narrow end faces down. Set the temperature to 100. 5 degrees Fahrenheit with 50-55 percent humidity.

Is 75% humidity too high for hatching eggs?

Ideal Humidity Ranges for Different Eggs Chicken eggs: 35-55% during incubation, 65-75% during hatching. Duck eggs: 50-60% during incubation, 65-80% during hatching. Reptile eggs: Varies depending on the species, but generally between 60-70% is common.

How can you tell when a chicken egg is ready to hatch?

Chickens can hatch between 19–22 days after you put the eggs in the incubator. Signs to look for include the egg being cracked by the beak of the chick and chirping from them as they start to emerge.

What is the optimum temperature for incubation?

Incubation temperature ranging between 37 and 38°C (typically 37. 5–37. 8°C) optimizes hatchability. However, the temperature inside the egg called “embryo temperature” is not equal to the incubator air temperature.

What are the optimal conditions for incubating and hatching chicken eggs?

The optimal conditions for incubating and hatching chicken eggs involve maintaining specific temperature and humidity levels. Here’s a summary of the optimal conditions: Incubation Temperature: The ideal temperature for incubating chicken eggs is around 37. 5 to 37. 8 degrees Celsius (99. 5 to 100 degrees Fahrenheit).

How long does it take for chicken eggs to hatch?

A: Chicken eggs hatch in about 21 days, but this can change depending on the breed and the conditions of the incubator. Q: Can I use LED bulbs in my incubator? A: Yes, LED bulbs are a suitable alternative to traditional incandescent bulbs and can provide the right spectrum of light for hatching eggs.

What temperature should a chicken egg be incubated at?

Research shows that the optimal temperature range for chicken egg incubation is 99 to 102 degrees Fahrenheit. Straying outside this range—even briefly—can result in developmental issues or failed hatching. Think of the embryo as a complex machine that’s programmed to operate at a certain temperature; deviating from the norm causes malfunctions.