Small Eggs Research Articles

Environmental change mediates plasticity in offspring traits through maternal effects in a coral reef fish

Wild populations are continuously challenged by natural environmental variation as well as threatened by anthropogenically-induced habitat loss and fragmentation. Non-genetic parental effects may be a key mechanism across taxa to cope with such environmental challenges and threats. However, the way in which environmental change modulates parental and offspring traits remains poorly studied in marine fish, especially in the wild. We empirically test whether environmental change directly affects monthly reproductive output and offspring phenotypes, including egg size, larval size and larval swimming abilities, in a wild population of anemonefish. In addition, we test whether environmentally induced parental physiology (hormones) modify parental traits, as well as offspring traits intergenerationally. First, we demonstrate plasticity in parental reproductive output when habitat size (anemone surface area) was experimentally manipulated. Second, we show intergenerational plasticity in wild anemonefish offspring traits. When habitat size increased, offspring traits were unchanged, but reproductive output was increased. Maternal reproductive hormones, such as 17ß-estradiol, showed a trend to increase when habitat size increased and 17ß-estradiol correlates positively with reproductive output. When habitat size decreased, reproductive output decreased, and smaller eggs and larvae were produced, however, these larvae swam faster. Our results provide evidence for marine fish plasticity in both reproductive output and offspring traits. In addition, the maternal reproductive hormone 17ß-estradiol plays a role in determining reproductive output and larval phenotypic traits. Through our study conducted in the wild, we show how changes in habitat size affect fitness of both parents and offspring in different ways. We highlight how parental and offspring plasticity, via intergenerational maternal effects, may ensure population persistence under environmental change.

The smallest known complete dinosaur fossil eggs from the Upper Cretaceous of South China

ABSTRACT The Upper Cretaceous Ganzhou Basin of Jiangxi Province, South China is among one of the richest egg fossil sites in the world and yields abundant exquisite egg clutches and embryonic eggs, especially in oviraptorosaurs. Hadrosaurian, troodontid, and potential dromaeosaurid egg fossils were also reported, though they were rare. All these reported eggs vary in morphology but have relatively large sizes. Here, we report a partial egg clutch with six complete small eggs from the Upper Cretaceous Tangbian Formation of Ganzhou City, Southeast China. The microstructure of the eggshell indicates that it can be assigned to Ovaloolithidae. Hence, we established a new ootaxon, Minioolithus ganzhouensis oogen. et oosp. nov. based on a unique combination of characters, including a small egg size, irregular egg arrangement, worm-like and nodular ornamentation, and a gradual boundary between two structural layers. The egg morphology and eggshell microstructure support it to be the smallest known non-avian theropod egg up to date. This discovery increases the diversity of dinosaur eggs in the Late Cretaceous and is significant for our understanding of the evolution of theropods in the Late Cretaceous.

Ultrasonography for non-invasive sex identification and reproductive assessment in Nile tilapia (Oreochromis niloticus).

Sex identification and the selection of monosex male tilapia are crucial for tilapia aquaculture. In this study, we evaluated the application of ultrasonography as an alternative procedure for sex identification and reproductive assessment in Nile tilapia (Oreochromis niloticus). Ultrasonography was performed on 23 fish weighing 232-1,281 g to capture longitudinal and transverse images of the ovaries and testes. Female tilapia were identified by the presence of numerous small egg granules and gray or light gray ovarian tissue and male tilapia by the homogeneous echogenicity and uniform gray tubular appearance of the testes. These distinct echogenic patterns allowed for accurate differentiation between the female and male fish. Ultrasonography achieved a 95% accuracy in sex identification, with minimal stress to the fish during the procedure, compared to manual sex sorting, which demonstrated an accuracy of 87%. Furthermore, the method facilitated the assessment of the reproductive status of the fish, including the maturation stages and fecundity potential. The use of ultrasonography offers significant advantages over traditional methods, such as animal welfare enhancements and improved breeding program efficiency. Our findings support the integration of ultrasonography into aquaculture practices and will promote sustainable and humane fish farming while optimizing reproductive management and productivity.

A new species of the genus Notodoma Lacordaire, 1854 (Coleoptera, Histeridae, Exosternini) from Korea, with a revised key to species of the genus.

A new species of the genus Notodoma Lacordaire, 1854 (Coleoptera, Histeridae, Exosternini), Notodoma koreanum sp. nov., is described from Korea. Most of them recognized from various fungi colonies, feeding on small insect eggs or larvae, as well as fungi. We present the descriptions and images of diagnostic characters for Korean Notodoma species, including Notodoma fungorum Lewis, 1884. Additionally, a revised key to all seven species of the genus Notodoma worldwide, including the newly described species, is provided.

Influence of the Weight of the Eggs of Flesh Roux and Kuroiler Breeding Hens on Their Hatching in an Incubator

To contribute to the development of poultry farming in Ivory Coast, a study was carried out in the Lakes Region, precisely in Yamoussoukro. The aim of this study was to determine the influence of egg weight on their hatching. To do this, Kuroiler (29 females and 6 males) and Chair Roux (29 females and 6 males) breeders aged 6 to 7 months were used. After rearing, 483 eggs including 230 Chair Roux eggs and 253 Kuroiler eggs were collected over twenty-one days. After identification and determination of their weight, the eggs were classified into three categories (Small eggs from 35 to 45g), Medium eggs from 46 to 55g) and Large eggs from 56 to 65g) and incubated in three incubators (Incubator 1, Incubator 2 and Incubator 3). In each incubator, the incubation performance was determined. The results showed that the average egg rate was higher (66.52% for Chair Roux eggs and 66.79% for Kuroiler eggs). Large eggs showed the highest fertility rate (95.92% for Chair Roux strain eggs, and 97.44% for Kuroiler strain eggs), followed by medium eggs (90.85% for eggs of the Chair Roux strain and 91.72% for eggs of the Kuroiler strain). In terms of the embryonic mortality rate, it was the small eggs which presented the highest rates with 17.85% for eggs of the Chair Roux strain and 26.66% for those of the Kuroiler strain. As for the actual hatching rate, large eggs recorded the highest rates (82.97% for Chair Roux eggs and 76.31% for Kuroiler strain eggs) followed by medium eggs (77.85% for Chair Roux strain eggs and 76.28% for Kuroiler strain eggs). Apart from Incubator 3 which recorded a higher embryonic mortality rate for large eggs (15.38%), Incubator 1 and Incubator 2 recorded higher rates for small eggs with respectively 11. 76% and 37.5%. In terms of the actual hatching rate, large eggs recorded the highest rates with 87.5% at Incubator 1 and 83.33%. Thus, it appears that large eggs and medium eggs are indicated to obtain a better hatching rate.

Reproductive ecology and egg parasitism of the Samoan swallowtail butterfly

AbstractWe investigated the reproductive ecology and effects of egg parasitism on the Samoan swallowtail butterfly (Papilio godeffroyi), which survives only on Tutuila Island, American Samoa, after having disappeared from the much larger islands of Upolu and Savai‘i in independent Samoa. During monthly surveys of its only known host plant, Micromelum minutum, across eight sites in 2013 and 2014, we collected eggs, eggshells, larvae, pupae, and pupal exuviae. Live specimens were reared under laboratory conditions to determine reproductive outcomes, developmental rates, and sex ratios, as well as parasitoid attack frequencies, brood sizes, and sex ratios. Sixty‐six of 448 (14.7%) eggs produced larvae, 47 of which became adults. The sex ratio was approximately even overall and within each developmental stage. Eggs were slightly larger on individual host trees and in host tree stands that yielded more eggs per unit of foliage, indicating that ovipositing females responded to some features of host trees and stands. Eggs hatching female or male larvae were similar in size, and the sexes developed at similar rates. A newly described species of parasitoid wasp, Ooencyrtus pitosina (Encyrtidae), emerged from 73.6% of 382 butterfly eggs that failed to hatch in the laboratory (62.7% of 448 eggs overall). Forty‐one other eggs contained dead parasitoid larvae. An additional, unidentified Ooencyrtus wasp species emerged from a single P. godeffroyi egg. No parasitoids were reared from P. godeffroyi larvae or pupae. Of 656 P. godeffroyi eggshells collected in the field and examined in the laboratory, 62.2% showed signs of having been parasitized by O. pitosina. There was no evidence that parasitism rates were density‐dependent. O. pitosina brood sizes ranged from 1 to 5, with the sex ratio skewed toward females (2.40 F:1.00 M). Larger parasitoid broods were associated with slightly larger host eggs, indicating that female wasps may adjust brood size according to host egg size or that fewer wasp larvae are able to complete development in smaller eggs. Techniques used to rear both P. godeffroyi and O. pitosina in the laboratory could be applied to a captive‐rear, wild‐release program, which may facilitate reestablishment of the species in Samoa.

Eucarid and Peracarid Fauna of the Valencia Seamount, a Deep-Isolated Seamount of the Western Mediterranean: Colonisation Capacity and Historical Changes

Seamounts can have a strong influence on the distribution and diversity of species, creating an oasis effect that may favour diversification. In order to assess how and to what extent supra- and epibenthic crustaceans can colonise these environments, the eucarid and peracarid fauna collected from the summit of the Valencia Seamount (VS), a small deep seamount (summit depth: 1056 m), rising from a depth of ca. 1850 m, in the oligotrophic Balearic Basin, was analysed. Based on a first sampling (beam trawls, plankton nets and stomach contents), and a faunal reconstruction from a sediment core (MC2, at 1151 m), the supra(epi)benthic crustaceans at the VS summit (to 1300 m) were composed of nine Eucarida and 25 Peracarida. Polycheles typhlops, Munida tenuimana, and Aristeus antennatus were the dominant species among eucarids. Among Peracarida the most abundant species were the Mysida Boreomysis arctica, the Amphipoda Rhachtropis caeca, and the Isopoda Munnopsurus atlanticus. Among Decapoda, a species with a wide amplitude in their depth distribution and small eggs (i.e., with planktotrophic larvae), showed a higher colonisation capacity. In the absence of larvae, the colonisation of peracarids depends on the amplitude of their depth distribution and only those species that reach the highest depths in the entire Balearic Basin, at least 1600–1800 m, were able to colonise the summit of VS. The natatory capacity of the species also has some influence and whole groups with low natatory capacity, such as the Desmosomatidae, were completely absent on the VS summit; however, they are distributed throughout the Balearic Basin to depths (up to about 1500 m) exceeding the depth of the seamount summit. Therefore, colonisation by peracarids must not have occurred by swimming through the entire water column, but by swimming along or just above the bottom. Remains of some suprabenthic species (mainly the isopod M. atlanticus) in MC2 and another core collected in NW Mallorca (MC3, 1114 m), i.e., out of the VS, showed how isopod diversity and size distribution changed historically. Also, after the 1960s, a decrease in primary production due to a decrease in rainfall and river runoff associated with river damming could have reduced the abundance of M. atlanticus. These types of historical studies can be useful in interpreting long-term changes in deep-sea communities and optimising the management of these vulnerable areas.

Reintroduction of spring‐run Chinook salmon in the San Joaquin River: Evaluating genetic and phenotypic effects of captive breeding

AbstractCaptive‐breeding programs are increasingly implemented to curb population declines but can have unintended negative effects on genetic diversity and phenotypes. Through an analysis of ~10 years of genetic monitoring, pedigree information, and phenotypic data, we evaluated a captive‐breeding program that uses adaptive management to reduce inbreeding and improve captive broodstock performance. A captive‐breeding program was established in 2012 to reintroduce spring‐run Chinook salmon to the southern edge of their range in California's San Joaquin River (SJR), using fish produced each year at the nearby Feather River Hatchery (FRH). We found that the SJR program adequately captured the genetic diversity of the FRH source population and that mate pairings guided by genetic relatedness reduced inbreeding. However, the SJR broodstock reared in captivity had smaller body size at maturity in comparison to the FRH source broodstock which matures at sea, but this effect disappeared when SJR juveniles were released from captivity to mature at sea. Phenotypic traits of SJR female parents also influenced reproductive performance; older mothers and those with smaller eggs had offspring with lower survival. These findings demonstrate that adaptive genetic monitoring and pedigree information can be powerful tools for reducing risks of captive breeding and evaluating program effectiveness.

Galactosomum nagasakiense n. sp. (Digenea: Heterophyidae) from the black-tailed gull, Larus crassirostris, with a description of metacercariae from some marine fishes developing trematode whirling disease

Galactosomum nagasakiense n. sp. (Digenea: Heterophyidae), the causative parasite of trematode whirling disease of marine fish, is described, based on the specimens collected from the black-tailed gull, Larus crassirostris in Nagasaki Prefecture, Japan. The new species belongs to the cochleariformum group, and is different from the three species in the group: G. cochleare (Diesing, 1850) in the larger oral sucker and phaynx and smaller eggs, G. cochleariformum (Rudolphi, 1819) in the smaller oral sucker and pharynx and smaller eggs, and G. spinetum (Braun, 1901) in the uterus which extends anterior to the ventrogenital sac. Metacercariae collected from the brain of several marine fish developing trematode whirling disease are also described. Considering low host specificity of the second intermediate hosts, the endemic nature of the trematode whirling disease may be attributed to the infection of a particular population of the final host and/or a limited geographical distribution of the first intermediate host.

Consuming royal jelly alters several phenotypes associated with overwintering dormancy in mosquitoes.

Females of the Northern house mosquito, Culex pipiens, enter an overwintering dormancy, or diapause, in response to short day lengths and low environmental temperatures that is characterized by small egg follicles and high starvation resistance. During diapause, Culex pipiens Major Royal Jelly Protein 1 ortholog (CpMRJP1) is upregulated in females of Cx. pipiens. This protein is highly abundant in royal jelly, a substance produced by honey bees (Apis mellifera), that is fed to future queens throughout larval development and induces the queen phenotype (e.g., high reproductive activity and longer lifespan). However, the role of CpMRJP1 in Cx. pipiens is unknown. We first conducted a phylogenetic analysis to determine how the sequence of CpMRJP1 compares with other species. We then investigated how supplementing the diets of both diapausing and nondiapausing females of Cx. pipiens with royal jelly affects egg follicle length, fat content, protein content, starvation resistance, and metabolic profile. We found that feeding royal jelly to females reared in long-day, diapause-averting conditions significantly reduced the egg follicle lengths and switched their metabolic profiles to be similar to diapausing females. In contrast, feeding royal jelly to females reared in short-day, diapause-inducing conditions significantly reduced lifespan and switched their metabolic profile to be similar nondiapausing mosquitoes. Moreover, RNAi directed against CpMRJPI significantly increased egg follicle length of short-day reared females, suggesting that these females averted diapause. Taken together, our data show that consuming royal jelly reverses several key seasonal phenotypes of Cx. pipiens and that these responses are likely mediated in part by CpMRJP1.

Evo‐devo in the ophiuroid family Ophiocomidae

AbstractThe Ophiuroidea, the most diverse echinoderm class, exhibits an array of life history patterns and larval forms, the evolution of which is poorly understood. With a robust phylogeny available for the major family, the Ophiocomidae, we undertook an assessment of the evolution of development in these ophiuroids. We spawned 15 species and documented larval development in 14 of these. In total, data on egg size or larval development were available for 27 species across the four recognized genera (Breviturma, Ophiocoma, Ophiocomella, and Ophiomastix). Ophiocomids have a bimodal egg size distribution. Species with small eggs (x̄ = 82 μm diameter, range 55–100 μm diameter) and large eggs (x̄ = 424 μm diameter, range 335–550 μm diameter) have planktotrophic ophioplutei and lecithotrophic vitellariae, respectively. The advanced ophiopluteus transforms into an armless vitellaria prior to metamorphosis through resorption of the larval arms and rearrangement of the ciliary tracts into series of transverse bands. Thus, the Type II pattern of development (which includes both the ophiopluteus and vitellaria) may be characteristic of the Ophiocomidae. This is not seen in other ophiuroid families. Evolution of nonfeeding (lecithotrophic) development through a vitellaria larva appears to have occurred only once in this family, in the genus Ophiomastix. Several traits appear to be specific to some species or genera, including an ornate fertilization envelope (Ophiocoma species), the presence of an early barrel‐shaped larva (Breviturma species), and the presence of vibratile lobes in advanced ophioplutei (Breviturma, Ophiocomella). In species with lecithotrophic development, the vitellaria is distinct, with prominent ciliated lobes around the developing juvenile rudiment. Larval form may assist with identification of ophiocomid larvae in plankton samples.

Evolution of Maternal Provisioning and Development in the Ophiuroidea: Egg Size, Larval Form and Parental Care.

The Ophiuroidea is the most speciose class of echinoderms and has the greatest diversity of larval forms, but we know less about the evolution of development (evo-devo) in this group than for the other echinoderm classes. As is typical of echinoderms, evo-devo in the Ophiuroidea resulted in the switch from production of small eggs and feeding (planktotrophic) larvae to large eggs and non-feeding (lecithotrophic) larvae. Parental care (ovoviviparity or viviparity/matrotrophy) is the most derived life history. Analysis of egg data for 140 species (excluding viviparity and facultative planktotrophy) indicated a bimodal distribution in egg volume corresponding to planktotrophy and lecithotrophy+ovoviviparity, with three significant egg size groups due to the very large eggs of the ovoviviparous species. The marked reduction in fecundity in species with extremely large eggs is exemplified by the ovoviviparous species. Egg size in the two species with facultative planktotrophy were intermediate with respect to the two modes. Identifying the ancestral larval life history pattern and the pathways in the switch from feeding to non-feeding larvae is complicated by the two patterns of metamorphosis seen in species with planktotrophic development: Type I (ophiopluteus only) and Type II (ophiopluteus+vitellaria larva). The variability in arm resorption at metamorphosis across ophiuroid families indicates that the Type I and II patterns may be two ends of a morphological continuum. This variability indicates ancestral morphological plasticity at metamorphosis followed by canalization in some taxa to the vitellaria as the metamorphic larva. Vestigial ophiopluteal traits in lecithotrophic ophioplutei and vitellaria indicate evolution from the ancestral (feeding larva) state. Parental care has evolved many times from an ancestor that had a planktonic ophiopluteus or vitellaria and is often associated with hermaphroditism and paedomorphosis. A secondary reduction in egg size occurred in the viviparous species.

Quality of hatching eggs and young quails of different breeds depending on the age of the birds

The most important link in the production technology of poultry products is the production of high-quality hatching eggs. Assessing egg quality is the fi rst necessary step for successful brooding. In order to realize the maximum genetic productivity potential of any breed, it is necessary to obtain high-quality young stock for rearing. In order to do this, it is also necessary to have information about the quality of hatching eggs, the characteristics of the embryonic development of quails and the requirements for the quality of day-old quails, both in general and separately for each breed. These issues have been little studied in quail breeds of meat and meat-egg productivity. The purpose of the research was to study the brooding traits of eggs and the quality of day-old young quails of meat and meat-egg breeds at the beginning, middle and end of the productive period. Research was carried out at the Siberian Poultry Research Institute on eggs and young quails of Omsk and Radonezh breeds of meat-egg and meat productivity. It has been established that the age of the quails aff ected the quality of hatching quail eggs, and accordingly the results of brooding the quality of day-old young quails, and further productivity. In order to improve the quality of the herd and the economic effi ciency of production, eggs obtained from laying quails aged 126–238 days should be used for brooding. The hatchability of eggs at this age was higher in Omsk breed by 2,56–8,14 abs.%, in the Radonezh breed by 2,39–8,73 abs.%. The hatching was also higher for breeds Omsk by 3,55–8,43 abs.%, Radonezh by 2,74–8,89 abs.%. Quails from small eggs obtained from a young laying quails grow more intensively. The livability of young quails was higher among breeds Omsk by 2–4 abs.%, Radonezh by 4 abs.%

Maternal Care under Large Clutches with Small Eggs: The Evolution of Life History Traits in Shield Bugs

Maternal Care under Large Clutches with Small Eggs: The Evolution of Life History Traits in Shield Bugs

Reproductive traits of the deep-sea shrimp Plesionika williamsi (decapoda: Pandalidae) from the eastern-central atlantic

The reproductive aspects of all Plesionika species are relatively well known worldwide, except for the deepest species of the genus, Plesionika williamsi, for which little information is available throughout its range. The ovarian maturity, sex ratio, brood size, and size-depth distribution of the deep-sea shrimp Plesionika williamsi (Pandalidae) in the Canary Islands (eastern-central Atlantic) were analysed. Ovigerous females were observed all year round, with the highest number of ovigerous females recorded between July and October. The presence of a greater number of ovigerous females during the summer may reflect a high local availability of food or the optimal abiotic conditions, which are factors with a strong influence on reproduction. The presence of non-ovigerous mature females throughout the year indicates that their resting period in the reproductive cycle occurs asynchronously. The physiological size at first sexual maturity was 19.24 mm in carapace length (CL) and the length at first sexual maturity was estimated at 23.15 mm CL. Estimates of size at first sexual maturity based on ovigerous females describe the result of the reproduction process, whereas size at first sexual maturity based on ovarian maturity deals with physiological preparation for reproduction. The modal size class of egg production was 24–30 mm CL, which yielded 83.22% of the population egg production. Plesionika williamsi is an iteroparous species that can produce small eggs during egg extrusion. The mean number of external embryos carried by females was 3048 and can be considered a true approximation of the number of larvae released in each batch, which depend on the conditions existing in each system. The shallower individuals are associated with a depth stratum that represents the boundary between two water masses present in the Canary Islands. The increase in size with depth is related to the presence of submarine volcanic canyons, which constitutes a flow channel of surface organic matter to depth.

Reproductive Characteristics and Suitability of Sterile dead end Knockout Nibe Croaker as a Recipient for Intraperitoneal Germ Cell Transplantation.

The use of sterile recipients is crucial for efficiently producing donor-derived offspring through surrogate broodstock technology for practical aquaculture applications. Although knockout (KO) of the dead end (dnd) gene has been used in previous studies as a sterilization method, it has not been reported in marine fish. In this study, nibe croaker was utilized as a model for marine teleosts that produce small pelagic eggs, and the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system was utilized to produce dnd KO fish. The F1 generation, which carried a nonsense mutation in the dnd gene, was produced by mating founder individuals with wild-type counterparts. Subsequently, the F2 generation was produced by mating the resulting males and females. Among the F2 generations, 24.0% consisted of homozygous KO individuals. Histological analysis revealed that primordial germ cells (PGCs) were present in homozygous KO individuals at 10days post-hatching (dph), similar to wild-type individuals. However, by 20 dph, PGCs were absent in KO individuals. Furthermore, no germ cells were observed in the gonads of both sexes of homozygous KO individuals at 6months old, which is the typical maturity age for wild-type individuals of both sexes. In addition, when cryopreserved donor nibe croaker testicular cells were transplanted, only donor-derived offspring were successfully obtained through the spontaneous mating of homozygous KO recipient parents. Results indicate that dnd KO nibe croaker lacks germ cells and can serve as promising recipients, producing only donor-derived gametes as surrogate broodstock.

The Relationship between Mean Length at Maturity and Maximum Length in Coral Reef Fish

This article proposes a mechanism that triggers first maturation and spawning in coral reef (bony) fish, which allows for predicting their length at first maturity. Thus, mean lengths at first maturity (Lm) and the corresponding maximum lengths (Lmax) in 207 populations of 131 species of coral reef fish were assembled and used to test the hypotheses that (a) there is, in coral reef fish, a single value of a size-related parameter acting as a trigger for their maturation and eventual spawning, and (b) that this single value is statistically the same as that published previously for other bony fish. The results, based on the assembled Lm and Lmax data and on estimates of the parameter D, which link the length of fish with the relative surface of their gills, covered 44 families and Lmax values ranging from 1.8 to 181.6 cm and confirmed that the threshold in (a) exists. Also, we assessed (in b) that this threshold value, i.e., LmaxD/LmD = 1.35 (±0.02), is not statistically different from similar estimates for other groups of teleosts, notably semelparous salmonids, cichlids, sturgeons and Chinese and Turkish freshwater and marine fish. One implication is that given ocean warming and deoxygenation, coral reef fish will not only be smaller than they currently are, but also mature and spawn at smaller sizes, and thus produce fewer, smaller eggs.

Влияние смещения половых циклов на репродуктивные характеристики самок сибирского осетра и рыбоводно-биологические характеристики молоди

Modern industrial fish farms have specialised fish-breeding equipment that allows them to artificially regulate fish rearing, such as getting spawners into a pre-spawning stage at the time required by fish farmers. In this context, there has been some interest in determining the effect of rearing conditions and husbandry of Siberian sturgeon spawners on the progeny. Various abiotic and biotic environmental factors were modelled using the test sites of the Branch for Freshwater Fisheries of the Russian Federal Research Institute of Fisheries and Oceanography (RFRIFO). Female Siberian sturgeons of the sixth domestication generation of 2008 were used in the experiments. Weight gain has a positive effect on relative and individual fecundity in females. Relative fecundity decreases after resorption. Female eggs get larger with age, however the difference in body weight of juveniles produced from smaller eggs after growing is only 13%. Throughout the rearing period, the condition factor in juveniles ranges from 0.088 to 0.094, representing 46.3-49.4% of the maximum value. When comparing the rearing conditions in all groups of females, no correlation was found between the duration of interspawning interval (285 or 600 days) and the thermal constant during this period (4.970-5.124 and 10.095 degree days) and relative fecundity. According to the studies, a shift in the timing of gametogenesis caused by a force majeure has no effect on reproductive product quality and the ensuing progeny.

Research on duck egg recognition algorithm based on improved YOLOv4

ABSTRACT 1. The following study addressed the problem of small duck eggs as challenging to detect and identify for pick up in complex free-range duck farm environments. It introduces improvements to the YOLOv4 convolutional neural network target detection algorithm, based on the working conditions of egg-picking robots. 2. Specifically, one scale of anchor boxes was removed from the prediction network, and a duck egg labelling dataset was established to make the improved algorithm YOLOv4-ours better match the working state of egg-picking robots and enhance detection performance. 3. Through multiple comparative experiments, the YOLOv4-ours object detection algorithm exhibited superior overall performance, achieving a precision of 98.85%, recall of 96.67%, and an average precision of 98.60% and F1 score increased to 97%. Compared to the original YOLOv4 model, these improvements represented increases of 1.89%, 3.41%, 1.32%, and 1.04%, respectively. Furthermore, detection time was reduced from 0.26 seconds per image to 0.20 seconds. 4. The enhanced model accurately detected duck eggs in free-range duck housing, effectively meeting the real-time egg identification and picking requirements.

Physical and chemical characteristics of eggs from eight Italian chicken breeds

Specific characteristics of the eggs from nucleus populations of Ancona (AN), Bianca di Saluzzo (BS), Bionda Piemontese (BP), Livorno, Mericanel della Brianza (MB), Mugellese (MU), Siciliana (SI) and Valdarnese (VA) chicken breeds kept in University Research Centres across Italy were evaluated. The physical characteristics considered were whole egg weight and shell, yolk and albumen proportion. The chemical characteristics considered were dry matter (DM), ash and protein content of the yolk and albumen, and the yolk fat. Among the breed groups evaluated in this study, BS and BP produce large eggs that are rich in total crude protein and lipids, with abundant egg whites. MB and MU produce small eggs with a high yolk percentage. AN and SI hens produce medium-small-sized eggs. The heaviest yolks were observed in AN eggs, and the highest shell percentage was found in SI eggs. LB and VA produce medium-large-sized eggs with low yolk lipid content.