Time Of Hatching Research Articles

Rapid egg cooling rate after oviposition influences the embryonic development, hatchability, and hatch time of young and old broiler hatching eggs

This study investigated the effect of the egg cooling profile after oviposition on blastoderm development, embryonic mortality, hatchability, and hatch time of broiler hatching eggs from young and old breeder flocks. Hatching eggs were obtained from commercial Ross 308 broiler breeders at 28 wk (young) and 64 wk (old) of age. A total of 3,150 eggs laid within a 15-min period were collected and randomly assigned to 2 temperature-controlled chambers in both flocks. The eggshell temperature (EST) was cooled to 24°C either within 6 h (control) or 45 min (rapid). After the EST reached 16°C in the chambers in all groups, eggs were transported to the commercial hatchery. Eggs were stored for 6 d at 16°C and 75% relative humidity. The development of the blastoderm in sampled eggs (25 embryos in each batch) was determined immediately after egg collection and before transport to the hatchery (after cooling) on a farm in each flock. At each flock age, there were 5 replicate trays of 150 eggs per egg cooling treatment set in a single commercial incubator. The results showed that the embryonic developmental stage was retarded by rapid cooling and by the younger flock. A flock age×cooling rate interaction was observed for fertile hatchability and early and late embryonic mortality (P < 0.001). In the young flock eggs, the fertile hatchability was significantly lower in the rapid than in the control cooling treatment (88.7 vs. 92.8%) due to higher early and late embryonic mortality, whereas rapid cooling reduced early embryonic mortality (P < 0.01) and numerically increased the fertile hatchability (88.7 vs. 87.2%) in the old flock eggs. Hatch time was affected by the cooling treatment. The average hatch time was delayed by 3 h by rapid cooling (486.2 vs. 489.2 h) after oviposition compared with the control. This study showed that cooling the EST to 24°C within 45 min (rapid cooling) compared to 6 h (control) after laying retarded the blastoderm developmental stage and hatch time of eggs from both young and old broiler breeder flocks. This was apparently detrimental for the young flock as indicated by the higher early and late embryonic mortality but beneficial for the old flock due to the lower early embryonic mortality. The differences in hatchability between young and old flock eggs resulting from a rapid cooling rate might depend on the differences in embryonic development at oviposition.

The Hatching Time of Broiler Chickens Modifies Not Only the Production Traits but Also the Early Bacteriota Development of the Ceca.

This trial was carried out to find out the effects of the parent flock and hatching time of broiler chickens on the production traits and bacteriota development of animals. Two sets of 730 hatching eggs were collected from two different parent flocks with ages of 25 and 50 weeks. In the hatchery, both groups were divided into two subgroups: those hatched during the first 10 and the subsequent 10 h of the hatching window. A feeding trial was carried out afterwards, using the four treatments in six replicate floor pens and feeding commercial starter, grower, and finisher diets that contained all the nutrients according to the breeder's recommendations. The day-old chickens of the older parent flock and those hatched later were heavier, and this advantage remained until the end of the production period. The different ages and origins of the parent flocks failed to modify the microbiological parameters of the chicken's ceca; however, the hatching time significantly influenced the different bacteriota diversity indices: the late-hatched chickens showed higher Bacteroidetes and lower Firmicutes and Actinobacteria abundances at day 11. These treatments resulted in differences in the main families, Ruminococcaceae, Lactobacillaceae, and Bacteroidaceae. These differences could not be found at day 39.

Towards early response to desert locust swarming in eastern Africa by estimating timing of hatching

Desert locust (Schistocerca gregaria) plagues threaten agricultural production, food security and the environment across Africa, the Middle East, and Southwest Asia. Control methods targeting adult desert locusts present significant challenges and financial costs. Recognizing this, we developed a ground-breaking fuzzy set Mamdani type inference model that provides an innovative solution for early warning alerts. The model aids in predicting the juvenile stages of locust development, thereby preventing wide-scale locust swarming and mitigating its extensive damages and socioeconomic costs. The novelty of our approach lies in our unique application of environmental variables relevant for locust breeding to estimate the timing and location of desert locust hatching. Additionally, we improved the algorithmic handling of these variables, with localized desert locust bands data used as a proxy for hatching timing with a temporal offset of 35 days. The model's boundary conditions were determined using a training area in Sudan, where comprehensive ground data was available. This rule set was subsequently applied to Turkana County in Kenya, a data-scarce region, demonstrating the model's applicability and success in different contexts. The model's accuracy, assessed by data from the Sudan training site, demonstrated a remarkable score of 82% for true predictions. Furthermore, the model correctly identified the months of highest hatching probabilities in Turkana during 2020, demonstrating its real-world effectiveness and practical value. A correlation analysis affirmed that hatching was associated with increases in chlorophyll levels and precipitation accumulations. Our study marks a significant advancement in predicting the timing of hatching using fuzzy logic in data-scarce environments. By operationalizing more targeted early responses to desert locust infestations, our model facilitates more effective locust control. This study stands as an important contribution to locust management strategies, with substantial implications for agricultural production and food security in affected regions.

Maturation and refinement of the maculae and foveae in the Anolis sagrei lizard

The fovea is a pit in the center of the macula, which is a region of the retina with a high concentration of photoreceptor cells, which accounts for a large degree of visual acuity in primates. The maturation of this primate visual acuity area is characterized by the shallowing and widening of the foveal pit, a decrease in the diameter of the rod-free zone, and an increase in photoreceptor cells packing after birth. Maturation occurs concurrently with progressing age, increasing eye size, and retinal length/area. These observations have led to the hypothesis that the maturation of the fovea might be a function of mechanical variables that remodel the retina. However, this has never been explored outside of primates. Here, we take advantage of the Anolis sagrei lizard, which has a bifoveated retina, to study maturation of the fovea and macula. Eyes were collected from male and female lizards–hatchling, 2-month, 4-month, 6-month, and adult. We found that Anolis maculae undergo a maturation process somewhat different than what has been observed in primates. Anole macular diameters actually increase in size and undergo minimal photoreceptor cell packing, possessing a near complete complement of these cells at the time of hatching. As the anole eye expands, foveal centers experience little change in overall retina cell density with most cell redistribution occurring at macular borders and peripheral retina areas. Gene editing technology has recently been developed in lizards; this study provides a baseline of normal retina maturation for future genetic manipulation studies in anoles.

Effects of different light-emitting diode light on hatch performance, embryo development, eye structure, and plasma melatonin in layer incubation

Light intensity, wavelength, and photoperiod have a combined effect on chicken incubation. This study was conducted to evaluate the effect of 12-h light, 12-h dark (12L:12D) photoperiod of white light (380-780 nm, WL), blue light (455/447.5-462.5 nm, BL), and green light (525/515-535 nm, GL) in chicken perceived light intensity during layer incubation on hatching performance, embryo development, eye structure, and melatonin concentration. Three batches of eggs from Jinghong No. 1 layer breeder were used in this experiment. Light stimulation had no effect on hatchability, and no consistent effect on embryo weight and newly hatched chick weight. However, the average hatching time of white light group and green light group was 7.3 h and 5.5 h later than that of the control group. Therefore, the holding period of chicks was significantly shortened (P=0.001) in these 2 light groups. Light stimulation had a significant effect on the thickness of retinal layers (P < 0.05), retinal layers of white light group was thicker than that of the other 3 groups. Melatonin levels of chicks hatched in the green light and blue light were significantly higher than that of chicks hatched in the white light and darkness (P < 0.05). It indicated that the monochrome green and blue light promoted the expression of melatonin in chicken embryos. No significant diurnal rhythms were found at the level of plasma melatonin in 4 groups on d 21 using cosine analysis. It was concluded that green light has a positive effect on embryo development and melatonin secretion, while white light probably has positive effect on eye development. Furthermore, both green and white light stimulation resulted in late hatch for layer egg incubation. The obtained results are important in determining the light protocol for chicken incubation.

Growth Priorities of the Four Riverine Cyprinids during Early Ontogeny.

Growth patterns during early development of four species of riverine cyprinids, common dace (Leuciscus leuciscus L.), ide (Leuciscus idus L.), chub (Squalius cephalus L.) and common barbel (Barbus barbus L.), over 30 days of rearing, were analyzed. The study period covered three successive phases of larval development (preflexion, flexion, postflexion) and part of the juvenile development. The growth analysis carried out in the present study shows that significant allometric growth occurred mainly in preferentially localized body parts (head and tail) and was also associated with an increase in body height. The replacement of temporary structures (e.g., fin fold absorption) and the appearance of definitive structures around 21 mm TL (beginning of the juvenile period) corresponds to a stabilization of the relative growth of most parts of the body. This is probably due to the fact that the studied species had completed the most important part of the remodeling process (metamorphosis) and had achieved a body shape that allows juveniles to colonize faster water habitats. The results also indicate that individuals of species that are less developmentally advanced at the time of hatching (common barbel, chub) show greater initial dynamics of change in growth rate than individuals of species whose individuals are more advanced in ontogeny (common dace, ide). In addition, the small differences observed in growth parameters between successive periods analyzed, supported by the results of previous studies on these species, probably reflect the lack of abrupt changes in the behavior and habitat of the species studied.

Length of Hatching, Hatching Weight and Sex Ratio in Domestic Chickens Crossed with Three Types of Roosters

The aim of the study was to determine hatching time, hatch weight, and sex ratio of domestic chickens crossed with various good males. The research was conducted in Mbatakapidu Village, Kota Waingapu District, East Sumba Regency for two months. This study used 30 native chickens aged 10 months in addition to three bangkok, ciliper or plucker, and pakhoy chickens. Parameters observed included: hatch time, hatch weight, and sex ratio. Data were analyzed using the ANOVA test. The results showed: 1) the average hatching time of native chickens crossed with three roosters: Pakhoy took 18.87 days, Ciliper took 18.53 days, and Bangkok took 18.53 days. 2) hatching weight of three roosters crossed with native chickens was 34.23 g for Bangkok, 33.18 g for Ciliper, and 31.72 g for Pakhoy. (3) The average sex ratio of DOC native chickens crossed with three roosters is Bangkok: male DOC is 20.41 percent, while female DOC is 44.90 percent. Caliper or Plucker: 14.29% male DOC, 33.67% female DOC, and Pakhoy: 7.00% male DOC and 27.55% female. The effect on the three observed parameters was determined by crossing native chickens with three roosters. Sex ratio had no effect on determining the sex of DOCs resulting from crossing native chickens with three roosters, however the use of three roosters had an effect on hatching time and weight. The sex ratio shows a very weak correlation with hatching time and hatching weight. To increase the productivity of free-range chickens it is important to cross them with several roosters.

EVALUATION OF TOXICITY OF BENZIMIDAZOLE DERIVATIVES AND THEIR EFFECT ON FUNCTIONAL PARAMETERS OF CERIODAPHNIA DUBIA RICHARD, 1894

Recently, due to active development of the pharmaceutical industry, an acute problem of environmental pollution with synthetic biologically active compounds has arisen. Benzimidazole cycle is one of the most frequently encountered pharmacophores in drugs. Substances containing even microquantities of benzimidazole have a toxic effect on living systems. Besides, being alien to nature, benzimidazoles are not included in metabolic processes and do not decompose for a long time. Evaluation of benzimidazole toxicity, its stability in the aquatic environment, benzimidazole impact on biological parameters will make it possible to predict possible changes in the populations of ceriodaphnia and other aquatic organisms.&#x0D; The purpose of the work is to evaluate the toxicity of benzimidazole derivatives and their effect on the survival and fertility of Ceriodaphnia dubia Richard, 1894.&#x0D; Materials and Methods. In acute and chronic experiments, the authors determoined parameters standard for toxicological studies: median lethal concentrations (LC50), life expectancy, total number of offspring, number of litters per female, and average hatching time. The stability of the toxicity of benzimidazole derivatives was established in terms of Ceriodaphnia dubia lethality during a 30-day exposure.&#x0D; Results. The authors evaluated the toxicity of benzimidazole and its seven derivatives for ceriodaphnia in terms of the 48-hour median lethal concentration, depending on their structure. The highest toxicity was noted for 5-bromo-2-(trifluoromethyl)-1H-benzimidazole (LC50 2.4 mg/l), the lowest one for 2-methyl-1H-benzimidazole (LC50 109.7 mg/l). It has been shown that long-term exposure (38 days) to potassium salt of pyrido[1,2-a]benzimidazole-7-carboxylic acid (LC50 69.18 mg/l) at a concentration of 20 mg/l in a chronic experiment does not lead to a statistically significant change in survival and fertility parameters of ceriodaphnia. Stability evaluation of toxicity of the potassium salt of pyrido[1,2-a]benzimidazole-7-carboxylic acid and residual toxicity of its degradation products revealed a relatively low stability of the compound toxicity.&#x0D; Conclusion. The toxicological evaluation of benzimidazole derivatives for hydrobionts showed the correlation between the degree of their toxicity and structural features.

Resting eggs of Ceriodaphnia cornuta can sense predation risk and population crowding signals but cannot distinguish the types of predation risk

AbstractCladocerans can produce dormant stages to avoid unfavorable environments, such as predation pressure and population crowding. However, only a few studies evaluated the influences of the biochemical signals of predation risk and population crowding on the termination of dormant stages of cladocerans. This study aimed to investigate the influences of predation risk signals from different predators and crowding signals from high‐density populations on the hatching of cladoceran resting eggs and the anti‐predation defensive traits of hatched offspring. We collected resting eggs of Ceriodaphnia cornuta from the surface of lake sediments and incubated them under different biochemical signals (fish kairomones, Chaoborus kairomones, alarm signals, and crowding signals) in the laboratory. In response to fish kairomones, Chaoborus kairomones, and alarm signals, the hatching time of resting eggs was delayed to a certain extent, and the body length of the offspring hatched from resting eggs increased at their birth and decreased at their first reproduction. This indicated that the offspring hatched from C. cornuta resting eggs possibly can sense predation risk signals but cannot distinguish the type of signals. In addition, the effects of crowding signals on the resting eggs were similar to those of fish kairomones, both of which can increase the body length of hatched offspring at birth, but these influences would not be further enhanced in the simultaneous presence of fish kairomones and crowding signals. This study will contribute to a better understanding of the perception of resting eggs to environmental biochemical signals and the corresponding hatching strategies of cladocerans.

Green light during incubation: Effects on hatching characteristics in brown and white laying hens

Providing light during incubation is being investigated as a method to improve welfare in later life in poultry. This incubation method would more closely approximate chicken natural environment compared to the current incubation in darkness. Previous studies showed promising results of light during incubation on broiler welfare, but little is known about effects of light during incubation on laying hens. Especially, information about its effects on hatching characteristics (hatch time, hatchability, chick quality, body weight and embryonic age of death) is scarce and requires investigation in both white and brown egg layers. In the current study, Dekalb White (DW) and ISA Brown (ISA) eggs were incubated in complete darkness (dark) or in a light:dark cycle of 12L:12D throughout incubation (light), resulting in four treatment groups: DW-dark, DW-light, ISA-dark, and ISA-light. In the light treatments, green LEDs of 520 nm wavelength were used, at an intensity of 400 lux. First, light transmission through the eggshell was measured through 27 eggs. Then, an analysis of the effects of light during incubation on hatching characteristics was performed on 711 chicks in two consecutive experimental rounds. Light transmission was higher through white eggshells than through brown eggshells (N = 27, p < 0.001). Light during incubation had no effects on hatching characteristics (N = 711, p ≥ 0.1). Despite the difference of light transmission through eggshell between hybrids, there was no interaction between incubation treatment and hybrid on hatching characteristics (N = 471, p ≥ 0.06). Hatch time was longer and navel quality was better in DW than in ISA, while body weight and embryonic age of death were lower in DW than in ISA (all p < 0.001). Males and females had similar chick quality scores except for the beak quality, which was better for males (N = 486, p = 0.003). To conclude, green light during incubation did not negatively affect hatching characteristics in either DW nor ISA laying hen hybrids. Future research should therefore focus on its potential benefits for laying hen welfare.

Determining spatiotemporal trends in hatch and metamorphosis timing of young-of-year southern flounder Paralichthys lethostigma) in Texas bays

It is important to monitor spatiotemporal shifts in the timing of key life history events (i.e., hatch and metamorphosis) since these can influence larval survival and juvenile recruitment success. We use otolith microstructure analysis to examine spatiotemporal trends in hatch and metamorphosis timing of a widespread and economically-valuable finfish, southern flounder Paralichthys lethostigma, in Texas. We use linear regressions that predict otolith-based age from length for young-of-year (YOY) individuals caught coastwide from 2019 to 2021 to calculate hatch and metamorphosis dates of YOY individuals caught coastwide across a 39-yr time series from 1980 to 2018. Also, we use YOY hatchery-reared individuals to indirectly validate the association between otolith accessory growth centers and larval metamorphosis. Our analysis reveals that on the middle coast average hatch timing is shifting toward earlier in the year across the 39-yr time series. In contrast, we find that coastwide, and especially on the middle coast, average metamorphosis timing is shifting toward later in the year across the 39-yr time series. On average, YOY individuals show similar hatch and metamorphosis timing coastwide. We find that on the middle coast and across the 39-yr time series, higher maximum water temperature correlates with earlier average hatch timing. In contrast, we find that coastwide, and especially on the lower and middle coast, higher average water temperature (later years in time series) correlates with later average metamorphosis timing across the 39-yr time series. Fishery-independent monitoring shows no concurrent evidence of individuals emigrating earlier in the fall to spawn offshore. We interpret the spatiotemporal trends in average hatch and metamorphosis timing as evidence of a narrowing survival window where (1) individuals caught on the middle coast that hatch earlier experience higher survival during years with higher maximum water temperature and (2) individuals caught coastwide that metamorphose later experience higher survival during years with higher average water temperature (later years in time series). We highlight the ecological and management implications of the impact of water temperature on hatch and metamorphosis timing and in turn, larval survival and juvenile recruitment success.

Larval cisco and lake whitefish exhibit high distributional overlap within nursery areas

AbstractCoregonine fishes, including lake whitefish (Coregonus clupeaformis) and cisco (C. artedi), are socioecologically important in the Laurentian Great Lakes and of conservation concern, but the processes driving recruitment variability are unclear. In Lake Ontario, cisco and lake whitefish exhibit similar spawning behaviours and early life histories, but population trajectories are diverging. One hypothesis is that sympatric cisco and lake whitefish larvae occupy distinct habitats and experience dissimilar local environmental conditions, despite co‐occurrence within nursery areas. We described the spatiotemporal distributions of larval cisco and lake whitefish among multiple Lake Ontario embayment nursery areas, characterised physical habitat features associated with their distributions, determined the degree of spatial habitat partitioning between species and evaluated how habitat niche divergence occurred along an ontogenetic progression. Both species were widely distributed across larval nursery areas, though lake whitefish were less abundant and more narrowly distributed than cisco. Within the yolk sac stage, lake whitefish occupied more nearshore, shallower and colder waters than cisco, indicating potential habitat niche partitioning between congeners. However, distributional differences were subtle and likely driven by differential hatch timing and staggered ontogenetic habitat shifts. Combined, our results illustrate similar habitat use between cisco and lake whitefish through the larval stage and demonstrate that ontogeny and species‐specific phenology influence habitat use for these species. This study provides additional evidence that the early life histories of cisco and lake whitefish are highly similar and does not support the hypothesis that larval habitat use differences are a major driver of differential recruitment success for these species.

Diet and Temperature Effects on the Survival of Larval Red Deep-Sea Crabs, Chaceon quinquedens (Smith, 1879), under Laboratory Conditions

Declines in commercial crustacean species (such as lobsters, king crab, etc.) have caused an increased interest in the harvest of the red deep-sea crab Chaceon quinquedens. The red deep-sea crab is a federally managed fishery; however, little is known about the species’ general biology, especially the conditions required for larval survival. We aimed to answer two main questions about the life history of the red deep-sea crab. First, is there a common larval hatching pattern between adult female crabs? Specifically, our inquiries are about the duration of the hatching process, daily peak hatching time, and the relationship between female morphometry and the total larvae hatched. Second, which are the factors affecting the survival and development of larval red deep-sea crabs? In order to answer these research questions, we studied the effects of diet (rotifers, Artemia sp., algae, and unfed), temperature (9 °C, 15 °C, and 20 °C), and aquaculture settings. Ovigerous females were obtained from commercial traps and transported to the NOAA James J. Howard Laboratory, NJ. They were placed in the Females Husbandry and Hatching Collection System (FHCS), where the larvae hatched. Hatching of adult females was monitored and measured by volume. A simple linear regression (SLR) was calculated to predict the number of larvae hatched based on the measured volumes, and it was significant (F = 1196; df = 1, 13; R2 = 0.9892, p = 3.498 × 10−14). Duration of hatching period showed an approximate 30 days for adult females red deep-sea crabs, with a common daily maximum hatching time at 22:00 hrs (hatching time seem to follow the sun cycle and the first hours after sunset, Perez, pers. observation). Linear polynomial quadratic regressions were conducted for both years with an interaction term for the two continuous variables (diet and temperature), and were used to model the proportion of larval survival through time. In both years, a highly significant difference was obtained (F = 56.15; df = 4, 2134; R2 = 0.09353; p = &lt; 2.2 × 10−16). There is an effect of diet and temperature in the survival of red deep-sea crabs, but not a combined effect of them.

Nitrate and Conductivity Effects in Fish Embryo-Larvae.

Nitrate concentrations have been rising in surface waters over the last century and now frequently exceed drinking water standards and environmental safety benchmarks globally. Health-wise, these trends are concerning because nitrate has been shown to disrupt endocrine function and developmental outcomes. This project investigated potential sublethal effects of nitrate on developing fathead minnows. Fish were exposed from fertilization through 21 days post fertilization (dpf) to environmentally relevant concentrations of nitrate (0, 2, 5, 10, 25, or 100 mg/L NO3 -N as NaNO3 ). Nitrate effects on hatch timing, heart rate and rhythm at 3 dpf, growth through 21 dpf, swim bladder inflation timing and size, scoliosis, pericardial edema, and mortality were assessed. Because adding NaNO3 increases water conductivity, two conductivity controls were included to match the ionic strength of the 10 and 100 mg/L NO3 -N treatments. Increasing nitrate delayed posterior swim bladder (PSB) inflation in a dose-dependent manner, with possible inhibition of anterior swim bladder (ASB) inflation at higher doses, although nitrate did not affect swim bladder size. Conversely, nitrate did not affect hatch timing or cardiac endpoints at 3 dpf or induce pericardial edema or scoliosis, although there was a noted brood effect on these latter defects. As was observed with increasing nitrate, higher ion concentrations in the conductivity controls caused dose-dependent increases in fish body size at 21 dpf. Increased ionic strength also hastened ASB inflation independent of nitrate. As in other published studies, the observed delay in PSB inflation suggests that nitrate disrupts the thyroid axis and warrants further investigation. Additionally, this work supports the need for conductivity controls in nitrate toxicity studies to distinguish nitrate-specific effects. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2023;00:0-0. © 2023 SETAC.

Effects of day-of-hatch intramuscular administration of a herbal extract mixture and its re-supplementation in drinking water on growth performance, stress indicators, and antioxidant status of broiler chickens reared under hot summer conditions.

Broilers under oxidative stress from high ambient temperatures may benefit from the use of additives that have antioxidant properties. This experiment investigated the efficacy of a herbal extract mixture (HEM; aqueous extracts from Ferula gummosa, Thymus vulgaris, and Trachyspermum copticum) in day-old chicks, injected intramuscular (deep pectoral muscle; (0, 30, 60, and 90 μL/0.1 mL of sterilized and distilled water)), and supplemented in drinking water (0 and 0.25 mL/L) during the rearing period. Broilers were reared in battery cages under summer temperature conditions, with average maximum temperature of 35.5°C, average minimum temperature of 25.5°C, and average relative humidity of 50-60%. A total of 400 1-day-old Ross 308 male broiler chicks were randomly assigned to 8 treatment groups (5 replicates/treatment with 10 birds per replicate). From d1 to d10, the indoor air temperature was adjusted to match fluctuating outdoor summer temperatures, and was set at 30-34°C and 50-60% relative humidity; and from d10 onwards, no adjustments were made. Injection of HEM linearly decreased feed:gain (P = 0.005), heterophile-to-lymphocyte (H/L) ratio (P = 0.007), and serum concentrations of cholesterol (P = 0.008), low-density lipoprotein cholesterol (LDL) (P < 0.001), malondialdehyde (P = 0.005), and cortisol (P = 0.008). The 60 μL of HEM injection produced the best results in terms of final body weight (BW; P = 0.003), overall average daily gain (ADG; P = 0.002), European performance index (P < 0.001), carcass yield (P < 0.001), and serum glutathione peroxidase activity (P < 0.001). Supplementation of HEM in drinking water also increased final BW (P = 0.048), overall ADG (P = 0.047), high-density lipoprotein cholesterol (P = 0.042), and total antioxidant capacity (P = 0.030), while decreasing the H/L ratio (P = 0.004) and serum LDL concentration (P = 0.031). There were interactions between injection and water supplementation for BW (day 24; P = 0.045), carcass yield (day 42; P = 0.014), and serum superoxide dismutase activity (day 42; P = 0.004). In conclusion, administering an injection of HEM at a dose of 60 μL at the time of hatching, followed by supplementation at a dose of 0.25 mL/L via drinking water during the rearing period could be a useful strategy for improving the performance and health status of heat-stressed broiler chickens.

Thyroid hormone manipulation influences development of endothermy and hatching in white leghorn chickens (Gallus gallus)

Chickens experience rapid change in their physiology and metabolism during hatching. We propose that thyroid hormones play a major role in regulating the developmental changes associated with attaining endothermy. To better understand the role thyroid hormones play in hatch timing and development of thermogenic capacity and metabolic rate we manipulated plasma thyroid hormone levels in chicken embryos beginning at 80% development (day 17 of a 21-day incubation) with either a single dose of triiodo-L-thyronine (T3) or the thyroperoxidase inhibitor methimazole (MMI). Manipulation of thyroid hormones altered the timing of hatching, accelerating hatching under hyperthyroid conditions, and prolonging hatching with hypothyroid conditions. Effect sizes comparisons of morphological variables between treatment groups revealed larger heart and body masses in hyperthyroid 1-day post hatch animals. Thyroid hormone manipulation influenced the thermal neutral zone for O2 consumption and body temperature during gradual cooling from 35 to 15 °C of externally pipped embryos and 1-day post hatch chicks. Hyperthyroid EP animals had a wider thermal neutral zone during cooling when compared to control animals. At the temperatures tested, the hypothyroid animals did not exhibit a thermal neutral zone. Similar differences between treatments in the breadth of the thermal neutral zone carried through to 1-day post hatch chickens. These findings suggest that thyroid manipulations influence the timing and development of the animal’s thermogenic response to cooling.

Biology of Patanga japonica (Orthoptera, Acrididae): Nymphal growth, host plants, reproductive activity, hatching behavior, and adult morphology

The biology of Patanga japonica (Bolívar, 1898), including seasonal nymphal growth, host plants, mating, oviposition, hatching, and adult morphology, was studied under outdoor and indoor conditions in central Japan. A field census showed that this grasshopper had a univoltine life cycle and overwintered in the adult stage. Body size was found to increase with a delay in the time of adult emergence in females but not in males, and protandry was observed. The insects were mainly associated with a few plant species. Feeding tests showed that at least one of the 5 test nymphs molted to the second stadium on 37 plant species, and more than 50% did so on 23 plant species. Mating was frequently observed in April and May under outdoor conditions, and the daily maximum number of copulating pairs was positively correlated with air temperature. Copulatory behavior, including stridulation, is described in detail. Oviposition was frequently observed in May and June under outdoor conditions. Larger females produced more eggs per pod, and a negative relationship was observed between egg lengths and the number of eggs per pod, showing a trade-off. On average, female adults had 124 ovarioles. Egg hatching occurred at different times during the daytime, but the eggs from each pod hatched synchronously. Synchronous hatching was also observed in eggs kept in groups of 2, 4, and 10, but hatching occurred earlier in larger group sizes. Eggs achieved synchronous hatching by either delaying or advancing hatching time. Two eggs separated by several millimeters hatched less synchronously than those kept in contact with one another. However, similarly separated eggs restored hatching synchrony when connected by thin wire, suggesting the involvement of vibrational signals in embryo–embryo communication. Morphometric analysis suggested that P. japonica adults change some morphometric ratios in response to crowding. Variation in pronotum shape was not significantly affected by crowding.

Degree-day-based model to predict egg hatching of Philaenus spumarius (Hemiptera: Aphrophoridae), the main vector of Xylella fastidiosa in Europe.

Philaenus spumarius L., the main vector of Xylella fastidiosa (Wells) in Europe, is a univoltine species that overwinters in the egg stage, and its nymphs emerge in late winter or spring. Predicting the time of egg hatching is essential for determining the precise times for deploying control strategies against insect pests. Here, we monitored P. spumarius eggs from oviposition to egg hatching together with the daily temperatures and relative humidities at four field locations that were located at different altitudes in central Spain. The collected data were used to build a growing degree day (GDD) model to forecast egg hatching in the Iberian Peninsula. Furthermore, the model was validated with field observations that were conducted in Spain. The model was then used as a decision-support tool to calculate the optimum timing for applying control actions against P. spumarius. Our results suggest that controlling nymphs at two different dates would target the highest percentages of nymphal populations present in the field. Our model represents a first step for predicting the emergence of nymphs and adopting timely control actions against P. spumarius. These actions could limit disease spread in areas where X. fastidiosa is present.

Identification of Embryonic Chicken Proteases Activating Newcastle Disease Virus and Their Roles in the Pathogenicity of Virus Used as In Ovo Vaccine.

In ovo vaccination is an attractive immunization approach for chickens. However, most live Newcastle disease virus (NDV) vaccine strains used safely after hatching are unsafe as in ovo vaccines due to their high pathogenicity for chicken embryos. The mechanism for viral pathogenicity in chicken embryos is poorly understood. Our previous studies reported that NDV strain TS09-C was a safe in ovo vaccine, and the F protein cleavage site (FCS) containing three basic amino acids (3B-FCS) was the crucial determinant of the attenuation of TS09-C in chicken embryos. Here, five trypsin-like proteases that activated NDV in chicken embryos were identified. The F protein with 3B-FCS was sensitive to the proteases Tmprss4, Tmprss9, and F7, was present in fewer tissue cells of chicken embryos, which limited the viral tropism, and was responsible for the attenuation of NDV with 3B-FCS, while the F protein with FCS containing two basic amino acids could be cleaved not only by Tmprss4, Tmprss9, and F7 but also by Prss23 and Cfd, was present in most tissue cells, and thereby was responsible for broad tissue tropism and high pathogenicity of virus in chicken embryos. Furthermore, when mixed with the protease inhibitors aprotinin and camostat, NDV with 2B-FCS exhibited greatly weakened pathogenicity in chicken embryos. Thus, our results extend the understanding of the molecular mechanism of NDV pathogenicity in chicken embryos and provide a novel molecular target for the rational design of in ovo vaccines, ensuring uniform and effective vaccine delivery and earlier induction of immune protection by the time of hatching. IMPORTANCE As an attractive immunization approach for chickens, in ovo vaccination can induce a considerable degree of protection by the time of hatching, provide support in closing the window in which birds are susceptible to infection, facilitate fast and uniform vaccine delivery, and reduce labor costs by the use of mechanized injectors. The commercial live Newcastle disease virus (NDV) vaccine strains are not safe for in ovo vaccination and cause the death of chicken embryos. The mechanism for viral pathogenicity in chicken embryos is poorly understood. In the present study, we identified five trypsin-like proteases that activate NDV in chicken embryos and elucidated their roles in the tissue tropism and pathogenicity of NDV used as in ovo vaccine. Finally, we revealed the molecular basis for the pathogenicity of NDV in chicken embryos and provided a novel strategy for the rational design of in ovo ND vaccines.

Embryonic development of the skull in a parthenogenetic lizard, the mourning gecko (Lepidodactylus lugubris).

Gekkotans are one of the major clades of squamate reptiles. As one of the earliest-diverging lineages, they are crucial in studying deep-level squamate phylogeny and evolution. Developmental studies can shed light on the origin of many important morphological characters, yet our knowledge of cranial development in gekkotans is very incomplete. Here, we describe the embryonic development of the skull in a parthenogenetic gekkonid, the mourning gecko (Lepidodactylus lugubris), studied using non-acidic double staining and histological sectioning. Our analysis indicates that the pterygoid is the first ossifying bone in the skull, as in almost all other studied squamates, followed closely by the surangular and prearticular. The next to appear are the dentary, frontal, parietal and squamosal. The tooth-bearing upper jaw bones, the premaxilla and maxilla, develop relatively late. In contrast to previous reports, the premaxilla starts ossifying from two distinct centres, reminiscent of the condition observed in diplodactylids and eublepharids. Only a single ossification centre of the postorbitofrontal is observed. Some of the endochondral bones of the braincase (prootic, opisthotic, supraoccipital) and the dermal parasphenoid are the last bones to appear. The skull roof is relatively poorly ossified near the time of hatching, with a large frontoparietal fontanelle still present. Many bones begin ossifying relatively later in L. lugubris than in the phyllodactylid Tarentola annularis, which suggests that its ossification sequence is heterochronic with respect to T. annularis.