Egg Incubation Temperature Research Articles

Effects of inclusion of the blend of essential oils, organic acids, curcumin, tannins, vitamin E, and zinc in the maternal diet, and of incubation temperature on early and late development of quail

The maternal diet and egg incubation temperature are some of the factors that can influence the embryonic development and performance of the newly chicks at 15 d of age. This study evaluated the effects of adding a blend of organic acids, essential oils, curcumin, tannins, vitamin E, and zinc microencapsulated in to the diet of female quails (Coturnix coturnix japonica) on their productive, reproductive performance and redox parameters of their eggs and the interaction of maternal diet × incubation temperature on embryo (E16 and E18) and chicks development. At 98 d of age, 64 female quails with a mean body weight of 150 g ± 0.5 were distributed into two treatments: a Basal diet or a diet supplemented with blend (Sannimix). The eggs from each female were incubated at 37.5°C (Control) and 38.5°C (High Temperature) throughout the incubation period. After hatching, chicks were distributed in a 2 (maternal diet) × 2 (incubation temperature) factorial design. Female quails supplemented with Sannimix showed better productive and reproductive performance and produced higher-quality embryos. Their offspring had greater weight at hatch and at 15 d of age. The eggs and offspring of supplemented with Sannimix female quails showed better oxidative stability. At E16 and E18, High Temperature increased yolk sac utilization and gene expression of the growth hormone receptor (GHR). At E16, embryos from supplemented with Sannimix female quail had higher expression of insulin-like growth factor type I (IGFI) and heat shock protein 70 kDa genes. At 15 d of age, highest expression of the GHR and IGFI genes was observed in chicks from female quails fed the Sannimix diet, regardless of incubation temperature. Regarding the maternal diet × incubation temperature an improved result was observed for chicks from female quails fed with Sannimix even when eggs are exposed to High Temperature during the incubation. The supplementation of quail diets with blend Sannimix improves productive and reproductive performance, egg quality and their embryos, as well as their offspring quality.

Exploring the impact of biocontrol and temperature variations on the population dynamics of Paracoccus marginatus

The mealybug (Paracoccus marginatus) is one of the most important pests of papaya (Carica papaya L.). The high potential damage of this pest threatens papaya production. The objective of this paper is to explore the impact of biocontrol and temperature variations on the population dynamics of Paracoccus marginatus (P. marginatus). We first propose and study a mathematical model for the dynamics of P. marginatus within a papaya field. This model consists of a time-delayed non-autonomous system of differential equations that takes into account the egg incubation period, temperature variations, plant compensation and predators that are natural enemies of the papaya pest. We provide the basic properties of the model, compute the basic offspring number N0 and show that there exists two threshold parameters N_0 and ξ0 such that N_0≤N0≤ξ0≤1 and N0≥N_0>1 provide conditions for the extinction and persistence of the pest within the papaya field, respectively. After, we investigate the impact of biocontrol on the pest population. We found that the use of a control strategy based on constant releases of predators could reduce the pest population by 35.62 percent and increase the biomass by 77.50 percent, while the use of impulsive releases of predators result in a decrease of 96.31 percent of the pest population and an increases of 55.74 percent of the biomass. We also combine the use of continuous predator releases and bio-pesticides and discovered that a spray applied 90 days after germination could completely eliminate the pest population and boost the biomass by 81.58 percent.

ВЛИЯНИЕ ПЕРИОДИЧЕСКОГО СНИЖЕНИЯ ТЕМПЕРАТУРЫ В ИНКУБАЦИОННЫЙ ПЕРИОД НА РЕЗУЛЬТАТЫ ИНКУБАЦИИ И РАЗВИТИЕ СУТОЧНЫХ БРОЙЛЕРОВ КРОССА «СМЕНА 9»

Periodic egg incubation temperature decrease gives the possibility to increase hatchability by 0.81 to 3.59% and chicks hatching by 1.48 to 4.10% at the expense of the first category embrios quantity increasing by 9 to 12.18% and second category by 4.91 to 11.05% and the third category decreasing by 4.12 to 1.16%. This helps to increase day old chick body weight by 0.97 to 4.73% and body length by 1.16 to 5.20%. Besides it stimulates blood, breath, digestive and immune chick systems development. Optimal scheme is egg cooling to 30oC on the 6 or 7 days, to 28oC on the 9–11 days and to 26oC on the 13–18 days.

Thermal conditioning of quail embryos has transgenerational and reversible long-term effects

BackgroundIn the current context of global warming, thermal manipulation of avian embryos has received increasing attention as a strategy to promote heat tolerance in avian species by simply increasing the egg incubation temperature. However, because of their likely epigenetic origin, thermal manipulation effects may last more than one generation with consequences for the poultry industry. In this work, a multigenerational and transgenerational analysis of thermal manipulation during embryogenesis was performed to uncover the long-term effects of such procedure.ResultsThermal manipulation repeated during 4 generations had an effect on hatchability, body weight, and weight of eggs laid in Japanese quails, with some effects increasing in importance over generations. Moreover, the effects on body weight and egg weight could be transmitted transgenerationally, suggesting non-genetic inheritance mechanisms. This hypothesis is reinforced by the observed reversion of the effect on growth after five unexposed generations. Interestingly, a beneficial effect of thermal manipulation on heat tolerance was observed a few days after hatching, but this effect was not transgenerational.ConclusionsOur multigenerational study showed that thermal conditioning of quail embryos has a beneficial effect on post-hatch heat tolerance hampered by transgenerational but reversible defects on growth. Assuming that no genetic variability underlies these changes, this study provides the first demonstration of epigenetic inheritance of traits induced by environmental temperature modification associated with long-term impacts in an avian species.

The effects of egg incubation temperature and parental cross on the swimming activity of juvenile brown trout Salmo trutta

Personality varies among individuals and is influenced by the environment. Here, we tested the hypothesis that egg incubation temperature had carry-over effects on swimming activity of juvenile brown trout, Salmo trutta. Eggs from different crosses involving anadromous and lacustrine-adfluvial parents were incubated under two temperature regimes, unheated (cold) or heated c. 2.5 °C above ambient temperature (warm), until first exogenous feeding. In the laboratory, we used open-field tests to quantify swimming activity in a new environment, and mirror-image tests to measure time spent swimming and resting motionless near a mirror, measures often used as proxies for aggression. These tests were conducted for two cohorts, with one tested in June 2018 and the other in June and August 2019, enabling us to test for repeatability and if differences persisted over the summer. In June, when adjusting for differences in body size between cold- and warm-incubated trout, we found that juvenile trout incubated as embryos at cold temperatures showed more swimming activity and took less time to initiate swimming for their size than those incubated in warm water. There were also body size and year effects but no effects of parental cross. For August, none of the incubation temperature effects observed in June persisted, but cold-incubated trout spent a larger proportion of their time motionless near the mirror than warm-incubated trout and there was a general body size effect on time to initiate swimming. The lack of any persistent effects of incubation temperature between June and August suggests that the effect is ephemeral. Notwithstanding, these results support the hypothesis that incubation temperature has short-term effects on activity of juvenile of brown trout during their first summer.Significance StatementWe studied the effect of embryonic temperature on juvenile fish behavior, focusing on swimming activity under different conditions. Brown trout eggs were incubated under two temperature regimes, cold and warm. We show that juvenile trout originating from cold conditions as embryos spent a greater proportion of time swimming and less time to initiate swimming than trout originating from warm conditions. These effects were present in June but not August, which suggests that the effect is short-lived, and occurs during the first summer when mortality of juveniles is high. The duration of the effects needs further study as our previous studies have shown persistent embryonic temperature effects on metabolism, body shape, reproductive potential and emigration of subsequent life stages of salmonids. These results also have bearing on ongoing climate change as even small differences in embryonic temperature may have ecological consequences for subsequent life stages.

Olive Ridley Sea Turtle Incubation in Natural Conditions Is Possible on Guatemalan Beaches

The Guatemalan strategy for sea turtle conservation was defined by the National Council of Protected Areas (CONAP) in 1989. Hatcheries lie at the core of this strategy: egg collectors are allowed to deliver 20% of a nest to a hatchery in exchange for selling or eating the remaining eggs. Consequently, nearly 100% of nests are collected, with no nests being left on the beaches. Hatchery design promotes shading using roofs made from vegetation. The logic behind this recommendation is that the natural incubation of eggs is supposedly impossible due to the overly high temperatures on the beach. However, changing the incubation temperature of sea turtle eggs can profoundly alter the sex ratio in sea turtles with temperature-dependent sex determination. It can also modify the physiology or behavior of juvenile turtles. Here, we test whether incubation in natural conditions is possible on Guatemalan beaches, and for the first time, we determine the thermal reaction norm of embryo growth to ensure hatching success in sea turtles. We show that incubation in natural conditions is possible since three out of the four monitored nests produced hatchlings. We urge the Guatemala National Council of Protected Areas to reevaluate its strategy for sea turtle conservation in Guatemala in light of these results.

The impact of egg thermal regimes on the response to food deprivation and refeeding in juvenile European Sea bass (Dicentrarchus labrax)

Fish are ectotherms and this means they are highly vulnerable to changes in ambient temperature, particularly during early developmental stages when temperature can induce persistent effects on phenotypic traits. In this study, the effect of egg incubation temperature on the response of juvenile European sea bass (Dicentrarchus labrax) to food deprivation and recovery after refeeding was assessed. Eggs were incubated at 11, 13.5 and 16 °C until hatching and then were reared at a common temperature until 9 months when fish were deprived of food for one week. The recovery from food deprivation was evaluated at 10 h and 2 days post-refeeding. Food deprivation in fish from eggs incubated at the highest temperature (16 °C) compared to 11 and 13.5 °C exhibited the most morphological and metabolic changes in the liver and foregut. Liver metabolism was changed as revealed by the significant reduction in lipid area and the increased number of hepatocyte nuclei. Foregut atrophy was coupled to a significant up-regulation of transcripts associated with gluconeogenesis (pck1) and peptide absorption (pept1). A modified metabolic response to the fast-refeed regime was revealed by the significantly decreased levels of plasma lactate, which may result from up-regulation of transcripts of the thyroid axis, deiodinase 2 (dio2) in the foregut. Fish incubated as eggs at a lower temperature (11 °C) exhibited less changes following the fast-refeed regime. Food deprivation did not significantly modify the morphology of the foregut and the liver parenchyma recovered sooner in fish from the 11 °C egg thermal regime compared to fish from the other thermal regimes following refeeding. The latter group of fish had a temporary stimulation of the GH-IGF axis with significant up-regulation of liver insulin-like growth factor I and II (igf-1 and igf-2) after fasting. The liver parenchyma of fish from the 13.5 °C egg thermal regime (the standard temperature of the hatchery stage) did not recover by the end of the experiment and transcripts of catalase (cat), encoding an antioxidant enzyme, were significantly downregulated compared to fish from the other egg thermal regimes. Our results suggest that thermal imprinting at the egg stage in European sea bass modified the juvenile metabolic response to food deprivation and the recovery response when feeding was resumed.

Differential methylation between sex in adult green sea turtle skin biopsies

In marine turtles, the sex of hatchlings is determined by their egg incubation temperature. Global warming may increase the extinction risk by skewing hatchling sex ratios. Assessment of this risk at the population level requires the identification of sex in hatchlings and juveniles. However, available methods are typically lethal, highly invasive, or difficult to conduct at a large scale. Changes in DNA methylation, an epigenetic modification, have been characterized as part of sex differentiation pathways in some species with environmentally determined sex, but so far not in marine turtles. Neither have epigenetic biomarkers for sex been developed into rapid assays suited to research on wildlife. In this study, we aimed to develop a rapid, minimally invasive, and inexpensive method to identify the sex of marine turtles. We used reduced representation bisulfite sequencing DNA methylation data from adult green sea turtle (Chelonia mydas) skin biopsies to identify 16 genomic regions exhibiting differential methylation between males and females (adjusted p-value < 0.01). We designed methylation sensitive qPCR assays for these regions and tested their capacity to identify the sex of turtles ranging in age between 3-34 years. The qPCR assay identified the correct sex in turtles > 17 years. However, the sex of younger turtles could not be accurately identified. This suggests the sex differences distinguishable by the assay were adult specific, reflecting the training data on which the sex-specific regions were identified, and likely linked to late-stage ontogenetic changes associated with sexual maturity. Epigenetic biomarkers are a promising tool for wildlife research because they can be minimally invasive and high throughput. Future research into sex-specific differentially methylated regions in hatchlings and juveniles should be based on genome-wide DNA methylation data from a wider age range, which includes hatchlings.

Thermal imprinting during embryogenesis modifies skin repair in juvenile European sea bass (Dicentrarchus labrax)

Fish skin is a multifunctional tissue that develops during embryogenesis, a developmental stage highly susceptible to epigenetic marks. In this study, the impact of egg incubation temperature on the regeneration of a cutaneous wound caused by scale removal in juvenile European sea bass was evaluated. Sea bass eggs were incubated at 11, 13.5 and 16 °C until hatching and then were reared at a common temperature until 9 months when the skin was damaged and sampled at 0, 1 and 3 days after scale removal and compared to the intact skin from the other flank. Skin damage elicited an immediate significant (p < 0.001) up-regulation of pcna in fish from eggs incubated at higher temperatures. In fish from eggs incubated at 11 °C there was a significant (p < 0.001) up-regulation of krt2 compared to fish from higher thermal backgrounds 1 day after skin damage. Damaged epidermis was regenerated after 3 days in all fish irrespective of the thermal background, but in fish from eggs incubated at 11 °C the epidermis was significantly (p < 0.01) thinner compared to other groups, had less goblet cells and less melanomacrophages. The thickness of the dermis increased during regeneration of wounded skin irrespective of the thermal background and by 3 days was significantly (p < 0.01) thicker than the dermis from the intact flank. The expression of genes for ECM remodelling (mmp9, colXα, col1α1, sparc, and angptl2b) and innate immunity (lyg1, lalba, sod1, csf-1r and pparγ) changed during regeneration but were not affected by egg thermal regime. Overall, the results indicate that thermal imprinting of eggs modifies the damage-repair response in juvenile sea bass skin.

On the Asymptotic Stability of Discrete Crocodilians Model

The sex ratio of crocodiles is strongly biased towards females, often as high as 10 females to 1 male. In crocodilians, the temperature of egg incubation is the environmental factor determining sex. If the temperature is low, around 30˚C, the hatchlings are all females. Higher temperature, around 34˚C, hatch all males. This study was made to consider the asymptotic stability of a positive equilibrium point in a nonlinear discrete model of the basic nesting population model, which is described in three-region depending on the temperature of egg incubation. This model is based on key life-historical data and Murray’s research. To study above, we have applied the classical linearization method and P. Cull’s method and moreover, we employ non-standard discretization methods for later our Equations (6)-(8) and (15).

Temperature Incubation Influences Gonadal Gene Expression during Leopard Gecko Development.

During development, sexual differentiation results in physiological, anatomical and metabolic differences that implicate not only the gonads but also other body structures. Sex in Leopard geckos is determined by egg incubation temperature. Based on the premise that the developmental decision of gender does not depend on a single gene, we performed an analysis on E. macularius to gain insights into the genes that may be involved in gonads' sexual differentiation during the thermosensitive period. All the genes were identified as differentially expressed at stage 30 during the labile phase of sex differentiation. In this way, the expression of genes known to be involved in gonadal sexual differentiation, such as WNT4, SOX9, DMRT1, Erα, Erβ, GnRH, P450 aromatase, PRLand PRL-R, was investigated. Other genes putatively involved in sex differentiation were sought by differential display. Our findings indicate that embryo exposure to a sex-determining temperature induces differential expression of several genes that are involved not only in gonadal differentiation, but also in several biological pathways (ALDOC, FREM1, BBIP1, CA5A, NADH5, L1 non-LTR retrotransposons, PKM). Our data perfectly fit within the new studies conducted in developmental biology, which indicate that in the developing embryo, in addition to gonadal differentiation, sex-specific tissue and metabolic polarization take place in all organisms.

Fasting/refeeding: an experimental model to study the impact of early thermal manipulation on hepatic metabolism in mule ducks.

An increase in egg incubation temperature was previously shown to enhance the metabolism of mule ducks and increase liver fattening after overfeeding, through a metabolic programming mechanism. Here, we examined whether fasting (F) followed by refeeding (RF) in 11-wk-old mule ducks could become an accelerated model to study the mechanisms of metabolic programming following embryonic thermal manipulation. This study investigated the hepatic response of mule ducks subjected to 23 h of fasting and 1 h of refeeding, in control or thermally programmed animals (with an increase of 1°C, 16 h per day from days 13 to 27 of embryogenesis). Liver weight and energy composition, hepatocyte structure, plasma parameters, and gene expression levels were measured at 1, 2, and 4 h after RF. All these parameters were strongly affected by RF, whereas significant impacts of embryonic programming were measured in cell size (+1 µm on average), lipid composition (+4.2% of saturated fatty acids 4 h after the meal), and relative gene expressions (including HK1, SCD1, ELOVL6, and FASN). In addition to confirming previously identified molecular targets of thermal manipulation, this study revealed new ones, thanks to kinetic sampling after RF. Finally, the detailed description of the impact of the F/RF challenge on the liver structure, composition, and gene expression, but also on plasma parameters allowed us to draw a parallel with these same traits measured during overfeeding. This comparative analysis suggests that this protocol could become a pertinent model to study the mechanisms involved in embryonic liver thermal programming, without overfeeding.

Nature vs. Nurture: Disentangling the Influence of Inheritance, Incubation Temperature, and Post-Natal Care on Offspring Heart Rate and Metabolism in Zebra Finches.

A historic debate in biology is the question of nature vs. nurture. Although it is now known that most traits are a product of both heredity (“nature”) and the environment (“nurture”), these two driving forces of trait development are rarely examined together. In birds, one important aspect of the early developmental environment is egg incubation temperature. Small changes (<1°C) in incubation temperature can have large effects on a wide-array of offspring traits. One important trait is metabolism, because it is related to life-history traits and strategies, organismal performance, and energetic and behavioral strategies. Although it has been shown that embryonic and post-hatch metabolism are related to egg incubation temperature, little is known about how this may vary as a function of genetic differences or post-hatching environmental conditions. Here, we investigated this question in zebra finches (Taeniopygia guttata). We experimentally incubated eggs at two different temperatures: 37.5°C (control), which is optimal for this species and 36.3°C (low), which is suboptimal. We first measured embryonic heart rate as a proxy of embryonic metabolic rate. Then, at hatch, we cross-fostered nestlings to differentiate genetic and pre-hatching factors from post-hatching environmental conditions. When offspring were 30 days-old, we measured their resting metabolic rate (RMR; within the thermoneutral zone) and thermoregulatory metabolic rate (TMR; 12°C; birds must actively thermoregulate). We also measured RMR and TMR of all genetic and foster parents. We found that embryonic heart rate was greater in eggs incubated at the control temperature than those at the low temperature. Further, embryonic heart rate was positively related to genetic father RMR, suggesting that it is both heritable and affected by the pre-natal environment. In addition, we found that post-hatch metabolic rates were positively related to genetic parent metabolic rate, and interactively related to incubation temperature and foster mother metabolic rate. Altogether, this suggests that metabolism and the energetic cost of thermoregulation can be influenced by genetics, the pre-natal environment, and the post-natal environment. Our study sheds light on how environmental changes and parental care may affect avian physiology, as well as which traits may be susceptible to natural selection.

Latitudinal Variation in the Pattern of Temperature-Dependent Sex Determination in the Japanese Gecko, Gekko japonicus.

Simple SummaryIn egg-laying lizards, sex is determined by genetic factors in species with sex chromosomes or egg incubation temperatures in species without sex chromosomes, i.e., temperature-dependent sex determination (TSD). Surprisingly, recent studies find sex chromosomes and TSD co-occur in the same species in some lizards. The Japanese gecko from Japan may be this case. However, Japanese gecko with TSD from a Chinese population does not have sex chromosomes, suggesting that the pattern of TSD in this gecko may vary among populations. We incubated gecko eggs from three populations in China at constant temperatures of 24, 26, 28, 30, and 32 °C to quantify the sex determination pattern. We found that the temperature yielding an equal number of sons and daughters of the low-latitude population was lower than that of the two high-latitude populations. Moreover, the low-latitude population had a narrower temperature range producing mixed sex offspring at lower temperatures, but a wider range at higher temperatures. Sex ratio was almost 1:1 for the low-latitude population when incubated from 26 to 30 °C. Conversely, more male offspring were produced at 28 or 30 °C in the two high-latitude populations. Our study may provide an interesting system to explore the evolution of sex determination mechanisms in animals.Identifying latitudinal variation in the pattern of temperature-dependent sex determination (TSD) may provide insight into the evolution of sex determining system in vertebrates, but such studies remain limited. Here, we quantified TSD patterns of three geographically separated populations of the Japanese gecko (Gekko japonicus) along the latitudinal cline of China. We incubated gecko eggs from the three populations at constant temperatures of 24, 26, 28, 30, and 32 °C to quantify the TSD pattern. Our study demonstrated that G. japonicus exhibited a FMF pattern of TSD, with the low and high incubation temperatures yielding significantly female-biased hatchlings, and the medium temperatures producing male-biased hatchlings. More interestingly, we found latitudinal variations in the TSD pattern in terms of pivotal temperatures (Tpivs), transitional range of temperatures (TRT), and the sex ratios at the medium temperatures. The Tpivs for the low-latitude population were lower than those for the two high-latitude populations. The low-latitude population has a narrower FM TRT, but a wider MF TRT. The sex ratio is almost 50:50 for the low-latitude population when eggs were incubated from 26 to 30 °C. Conversely, the sex ratio is male-biased for the two high-latitude populations at 28 or 30 °C. Therefore, G. japonicus may provide an interesting system to explore the evolution of TSD in reptiles given the diversity of TSD patterns among populations.

Egg incubation temperature influences the population-specific outmigration rate of juvenile brown trout Salmo trutta.

The present experiment tested if temperature during embryogenesis and parental heritage affected the migratory behaviour of young brown trout Salmo trutta. Two parental forms were used, a freshwater resident form and an anadromous form, both from the same river system but geographically isolated since 1993–95. Four groups of young S. trutta were produced and reared from (a) freshwater resident parents spawning in a tributary to the River Imsa, Norway, (b) anadromous parents spawning in the main stem of the same river system, (c) resident male × anadromous female parents and (d) resident female × anadromous male parents. The eggs were incubated until first exogenous feeding in River Imsa water, either unheated or heated c. 2.7°C above ambient temperature. Thereafter, all fish experienced the same ambient river temperature until release. Groups were released below an impassable waterfall 900 m upstream of the mouth of the River Imsa, either as age‐0 in October 2019 or as age‐1 in May 2020. About 7.5% of the released fish moved downstream and were captured in a trap at the outlet. For any given body size, the proportion of warm incubated trout that moved downstream was greater than the proportion of cold incubated trout. It was also found that most emigrants of the October‐released S. trutta were caught within a month of release. Also, most May‐released S. trutta emigrated in October. The offspring of the freshwater resident parents emigrated to a larger extent than offspring of anadromous parents. Thus, the difference in emigration with regard to embryonic temperature was phenotypically plastic and may be associated with an epigenetic effect of the thermal conditions during early development. The effect of parental origin suggests there may be genetic divergence between the geographically isolated populations.

Early Phenotype Programming in Birds by Temperature and Nutrition: A Mini-Review

Early development is a critical period during which environmental influences can have a significant impact on the health, welfare, robustness and performance of livestock. In oviparous vertebrates, such as birds, embryonic development takes place entirely in the egg. This allows the effects of environmental cues to be studied directly on the developing embryo. Interestingly, beneficial effects have been identified in several studies, leading to innovative procedures to improve the phenotype of the animals in the long term. In this review, we discuss the effects of early temperature and dietary programming strategies that both show promising results, as well as their potential transgenerational effects. The timing, duration and intensity of these procedures are critical to ensure that they produce beneficial effects without affecting animal survival or final product quality. For example, cyclic increases in egg incubation temperature have been shown to improve temperature tolerance and promote muscular growth in chickens or fatty liver production in mule ducks. In ovo feeding has also been successfully used to enhance digestive tract maturation, optimize chick development and growth, and thus obtain higher quality chicks. In addition, changes in the nutritional availability of methyl donors, for example, was shown to influence offspring phenotype. The molecular mechanisms behind early phenotype programming are still under investigation and are probably epigenetic in nature as shown by recent work in chickens.

Identification of different critical embryonic periods to modify egg incubation temperature in mule ducks

Egg incubation of mule ducks, mainly used for fatty liver production, is one of the critical phases in this sector. Based on hatching rate, the best incubation parameters have already been well described for poultry, but the literature on ducks is lacking. In this study, we tested different incubation conditions by varying two important factors, temperature and relative humidity, in mule ducks. These variations were applied at different periods during embryogenesis in order to measure the impact of environmental disturbances on different zootechnical performances. The temperature was increased by 1.5 °C (16 h/24) and the relative humidity was set up to 65%, during 10 days. Six 10-day developmental windows were tested, from embryonic day 9 to embryonic day 14. Our results are in line with previous reports showing that increasing incubation temperature, even when relative humidity is adjusted, can have a negative impact on duck embryonic mortality up to 24.5% for the condition E10-E20 (P < 10−5). However, the hatchability can be maintained at the level of the control groups when these modifications are applied on the latest windows (from the 11th embryonic day). Sex ratio, hatching BW, and internal temperature are also sensitive to these incubation changes, and their modification could have a major impact on later zootechnical performance. These results should contribute to the development or embryonic temperature programming approaches, especially for the fatty liver production industry.

Effects of rearing temperature on yolksac volume and growth rate in Lake Sturgeon, A. fulvescens, from hatch to age-1

In fishes, differences in egg incubation and water temperature in early rearing environments can have a significant impact on phenotypic development. This is particularly relevant during the first year of life when growth rate peaks and influences an individual's life history trajectory. In the present study, we examined the effect of differences in egg incubation, water temperature and overwintering on growth in Lake Sturgeon, A. fulvescens, throughout the first year of life. Developing embryos were incubated at 12–14 °C supplied with flow-through water and ambient light conditions in MacDonald hatching jars or allowed to adhere to substrate. Upon hatch (~9 days post-fertilization, dpf) larvae from each incubation treatment were then transferred to 16, 18 or 20 °C water increasing at a rate of 0.5 °C.day−1 and held at those temperatures until approximately 24 days post-hatch (dph). Experimental treatments were then transferred to a common garden set-up where duplicate treatment tanks were fed flow through river water at ambient temperature with natural light cycles. These were compared to fish transferred from a standard hatchery rearing treatment to the common garden tanks at the same time. Experimental fish were fed ad libitum twice daily throughout the growing season, but food was withheld when water temperature reached 1.5 °C (~6 months post-hatch, mph). Food was re-introduced at the start of spring the following year when water temperature exceeded 2 °C for three days in a row, (~ 10.5 mph). In experimental treatments, growth rate was highest in the 20 °C group during the first 3 months but converged with all other experimental treatments during winter before once again exceeding the other treatments following recovery from overwintering. Our data suggest that a temperature dependent growth phenotype was fixed during the first month of life in Lake Sturgeon that could have significant implications on hatchery rearing of this endangered species for conservation purposes.

Embryonic thermal manipulation impacts the postnatal transcriptome response of heat-challenged Japanese quails

BackgroundThe thermal-manipulation (TM) during egg incubation is a cyclic exposure to hot or cold temperatures during embryogenesis that is associated to long-lasting effects on growth performance, physiology, metabolism and temperature tolerance in birds. An increase of the incubation temperature of Japanese quail eggs affected the embryonic and post-hatch survival, growth, surface temperatures and blood characteristics potentially related to thermoregulation capacities. To gain new insights in the molecular basis of TM in quails, we investigated by RNA-seq the hypothalamus transcriptome of 35 days-old male and female quails that were treated by TM or not (C, control) during embryogenesis and that were exposed (HC) or not (RT) to a 36 °C heat challenge for 7 h before sampling.ResultsFor males, 76, 27, 47 and 0 genes were differentially expressed in the CHC vs. CRT, CRT vs. TMRT, TMHC vs. TMRT and CHC vs. TMHC comparisons, respectively. For females, 17, 0, 342 and 1 genes were differentially expressed within the same respective comparisons. Inter-individual variability of gene expression response was observed particularly when comparing RT and HC female animals. The differential expression of several genes was corroborated by RT-qPCR analysis. Gene Ontology functional analysis of the differentially expressed genes showed a prevalent enrichment of terms related to cellular responses to stimuli and gene expression regulation in both sexes. Gene Ontology terms related to the membrane transport, the endoplasmic reticulum and mitochondrial functions as well as DNA metabolism and repair were also identified in specific comparisons and sexes.ConclusionsTM had little to no effect on the regulation of gene expression in the hypothalamus of 35 days-old Japanese quails. However, the consequences of TM on gene expression were revealed by the HC, with sex-specific and common functions altered. The effects of the HC on gene expression were most prominent in TM females with a ~ 20-fold increase of the number of differentially expressed genes, suggesting that TM may enhance the gene response during challenging conditions in female quail hypothalamus. TM may also promote new cellular strategies in females to help coping to the adverse conditions as illustrated by the identification of differentially expressed genes related to the mitochondrial and heat-response functions.

Incubation of Oryzias woworae Eggs at Different Temperature on Embryo Development and Hatching Performance

Oryzias woworae is one of Muna Island's endemic fish, Sulawesi, which needs to be developed in cultivation and can be used as ornamental fish with high economic value. However, information on fish farming is not yet well available, especially at egg incubation temperatures. This study aims to determine the optimal temperature of the incubation water medium for the hatching performance of O. woworae eggs. The study used experimental methods with the treatment of differences in egg incubation temperatures at 24-26°C (temperature fluctuations in the laboratory), 24°C, 28°C and 32°C. The research parameters were analyzed descriptively, namely embryogenesis, hatching time, and hatching rates. The results showed that differences in incubation temperature affected the embryogenesis of O. woworae eggs. The obtained fastest time for hatching eggs O. woworae at a temperature of 32°C with six days 5 hours 49 minutes and 100% hatching. The egg incubation temperature 24-26°C is the lowest hatching time and hatching rate, nine days 11 hours 38 minutes and 53.33%. The use of 32°C in the incubation medium is the optimal temperature to accelerate embryogenesis and the hatching rate of O. woworae eggs.