Hatching Characteristics Research Articles

Incubabilidade e Qualidade de Pintos de Ovos Matrizes de Frangos de Corte Submetidos a Estresse de Temperatura

O experimento foi conduzido para avaliar o efeito do estresse de temperatura sobre as características de incubabilidade e qualidade dos pintos nascidos. Trezentos ovos, obtidos de um lote de matrizes de frangos de corte com 42 semanas, foram distribuídos em três incubadoras, reguladas para manter uma temperatura de 37,8ºC, umidade relativa de 60% e viragem mecânica a cada duas horas. Aos 16 dias de incubação (D16), aplicou-se uma variação de temperatura de calor (40ºC) ou frio (32ºC) durante cinco horas em duas máquinas. Os embriões da terceira máquina foram usados como controle. Os dados obtidos foram analisados estatisticamente, obedecendo-se a um delineamento inteiramente casualizado, com 3 tratamentos. A eclodibilidade e a qualidade dos pintainhos, avaliados pelo peso ao nascer e qualidade de pernas e umbigo não foram significativamente diferentes entre o grupo controle e os grupos estressados. Os resultados revelaram que os ovos exposto ao estresse pelo frio ou calor tiveram um período de incubação maiores - 506,5h e 504,2h, respectivamente - do que aqueles expostos a temperatura normal - 496,3h - como conseqüência no atraso de bicagem interna (7 e 6 h) e externa (13 e 14 h). Concluiu-se que a alteração da temperatura normal de incubação, com resfriamento ou aquecimento por 5 h no D16, não foi suficiente para prejudicar a eclodibilidade e a qualidade dos pintainhos, mas causou uma dilatação do período total de incubação, indicando que mesmo um breve período de variação da temperatura normal de incubação em um período crítico de desenvolvimento é suficiente para determinar estresse nos embriões de frangos de corte.

Egg size manipulation: a technique for investigating maternal effects on the hatching characteristics of herring

Egg size manipulation: a technique for investigating maternal effects on the hatching characteristics of herring

Egg size manipulation: a technique for investigating maternal effects on the hatching characteristics of herring

A technique was developed for manipulating egg size of recently fertilized Atlantic herring Clupea harengus embryos. Larvae hatching from eggs with reduced yolk volume were shorter than predicted for the volume of yolk removed. The reduction in both body and yolk mass of hatchlings was less than predicted, partly because larval yolk‐sac mass was unaffected by yolk removal.

Nestling cuckoos, Cuculus canorus, exploit hosts with begging calls that mimic a brood

Nestling cuckoos, Cuculus canorus , eject host eggs or young from the nest and are then raised alone by the hosts. Using reed warblers, Acrocephalus scirpaceus , as hosts, we investigated how the single cuckoo chick can command the same provisioning rate as a whole brood of host young. Large size alone is not sufficient to stimulate adequate provisioning because single blackbird, Turdus merula , or song thrush, T. philomelos , chicks of the same mass as a cuckoo were fed at a lower rate. Our experiments show that the key stimulus is the cuckoo chick9s rapid begging call (‘si, si, si, si ...’), which sounds remarkably like a whole brood of host chicks, and which it matched in calling rate. When single blackbird or song thrush chicks were accompanied by loudspeakers that broadcast either cuckoo begging calls or calls of a brood of reed warblers, the hosts increased their provisioning rate to that for a cuckoo chick. We suggest that the cuckoo needs vocal trickery to stimulate adequate care to compensate for the fact that it presents a visual stimulus of just one gape.

Production, disinfection and evaluation for aquaculture applications of rotifer resting eggs from Bohai Bay, P.R. of China

The dynamics of resting egg production of the rotifer Brachionus plicatilis originating from a wild population in the Tanggu Saltworks (P.R. China) was investigated. In the natural environment as well as in semi-controlled rearing conditions an increased resting egg production was noticed with declining food availability. Processed resting eggs had a hatching efficiency of 3 x 10 6 rotifers per gramme irrespective of their origin. Hatching started 22 h after the initiation of incubation and was completed after 36 h. Rotifers obtained from resting eggs could be further cultured on Culture Selco® and enriched with Super Selco®. The fatty acid profile of these rotifers were not divergent from reference rotifers (originating from the Laboratory of Aquaculture and Artemia Reference Centre) demonstrating that this strain was not catabolizing essential fatty acids and could be used for enrichment purposes. Storage of resting eggs at 4°C resulted in a 50% lower hatching after 1 year but remained stable during the next 2 years. The resting eggs used for storage could easily be disinfected without affecting their hatching characteristics. These results indicate that this material could be used as inocula for mass cultures of live food for commercial hatcheries.

International study on Artemia. LVI. Characterization of two Artemia populations from Namibia and Madagascar: cytogenetics, biometry, hatching characteristics and fatty acid profiles

Two parthenogenetic Artemia populations from southern Africa, one from Swakopmund saltworks (Namibia) and another from Ankiembe saltworks (Madagascar) have been studied. The population from Namibia is mainly diploid (2n=42) with few tetraploid individuals (4n=84), while the one from Madagascar was found to be triploid (3n=63). No chromocenters have been observed in either of the two populations. The Namibian population has smaller cysts and nauplii compared to those of the Madagascar population. Discriminant analysis revealed significant differences in the biometry of the adults from the two populations. The two populations exhibited very good hatching characteristics. The study of fatty acid methyl esters revealed that the Namibian population belongs to the ‘fresh water’ type of Artemia showing low levels of eicosapentaenoic acid, whereas the population from Madagascar displayed exceptionally high levels of eicosapentaenoic acid, belonging to the ‘marine water’ type.

Characterization of two newArtemia populations from two solar saltworks of Lesbos Island (Greece): biometry, hatching characteristics and fatty acid profile

Cysts of two parthenogeneticArtemia strains from the Kalloni and Polychnitos saltworks on Lesbos Island were evaluated for their potential use in aquaculture. The characterizations performed were: cyst and naupliar biometrics, cyst hatching characteristics, and fatty acid profile of instar-I nauplii. Deactivation of diapause after treatment with H2O2 and/or decapsulation were applied in order to improve cyst hatchability. The evaluation revealed that the strains studied exhibit acceptable hatching characteristics for parthenogeneticArtemia and that the fatty acid profile of the Kalloni strain is excellent for use in culturing marine fishes and crustaceans. Statistical analyses on cyst and naupliar biometrics showed that the two populations characterized are almost identical and very similar to other Greek parthenogenetic strains.

Further characterization of two Artemia populations from Northern Greece: biometry, hatching characteristics, caloric content and fatty acid profiles

Cysts of parthenogenetic Artemia strains collected from the Citros and M. Embolon saltworks in Northern Greece are evaluated for their potential use in aquaculture. The following characterizations were performed: cyst and naupliar biometrics, cyst hatching characteristics, fatty acid profile of the nauplii, caloric content of nauplii stored at 25 °C and in a refrigerator (4–8 °C). The above evaluation reveals that the two Artemia strains studied exhibit good qualities for use in aquaculture, especially in culturing fresh-water species. The biometrical analysis of cysts, nauplii and adults shows a high degree of similarity with other parthenogenetic strains from various geographical sources, but especially with tetraploid Artemia from Spain. The Greek Artemia strains cannot be considered as ‘sources’ for aquacultural uses unless proper management of the saltworks is assured.

Variability in timing of egg hatch of Triaenophorus crassus Forel (Cestoda: Pseudophyllidea) as a mechanism increasing temporal dispersion of coracidia

Eggs collected from 174 Triaenophorus crassus Forel over 3 years were maintained under a 12-h photocycle at 15 °C to quantify variability in three egg hatching characteristics. The percentage of eggs hatching to release coracidia varied from 20 to 90% (mean 82%). The median hatch time (time from egg release to hatch) varied from 4.3 to 14.2 days (mean 8.3 days). The duration of the egg hatching period (the time between hatch of 10 and 90% of eggs) varied from 1 to 17 days (mean 4.6 days). These three characteristics varied among years, among worms from different hosts, and among worms from the same host. Variability in egg hatching characteristics was not correlated with egg size or fecundity of the parent, but a consideration of this variability within the context of the hierarchical nature of parasite populations suggested that this variability resulted from genotypic and environmental contributions to parasite phenotype. Results of a simulation study suggested that naturally occurring levels of variability in egg hatching characteristics could increase temporal dispersion of coracidia beyond that resulting solely from temporal variation in egg release from adult worms. The time at which peak densities of coracidia occurred was affected little by variability in egg hatching characteristics. However, peak densities of coracidia were reduced because the period of egg hatching began earlier and ended later compared with expectations in the absence of variability in egg hatching characteristics.

DIFFERENCES IN POST-DIAPAUSE THERMAL REQUIREMENTS FOR EGGS OF TWO RANGELAND GRASSHOPPERS

AbstractA study was conducted to examine the springtime hatching characteristics of Melanoplus sanguinipes (F.) and Aulocara elliotti (Thomas) eggs on rangeland. Laboratory experiments showed that eggs of M. sanguinipes required fewer accumulated degree days (DD) to complete post-diapause development than those of A. elliotti at a constant temperature of 23.3°C. Springtime field observations revealed that A. elliotti nymphs emerged prior to or concurrent with M. sanguinipes. Additionally, results suggest that A. elliotti nymphs emerge over a shorter interval than M. sanguinipes. Much of the variation in springtime emergence could be attributed to species-specific oviposition sites, pod depth, and pod orientation that resulted in A. elliotti eggs accumulating heat more rapidly than M. sanguinipes eggs. Results help explain some of the variation found in egg hatching of these two grasshopper species on rangeland.

Taeniidae: Modification to the life span of the egg and the regulation of tapeworm populations

The hatching characteristics of the eggs of Taenia hydatigena, T. ovis, T. multiceps, and Echinococcus granulosus were examined in vitro. These characteristics varied with the eggs from different segments and different tapeworms, suggesting that the eggs from each segment, although morphologically similar, consisted of populations at different phases of their life span. The absence of surface moisture and or high temperatures during storage prevented hatching. Washed eggs survived longer than unwashed eggs. The survival as manifested by changes in the hatching characteristics in vitro was temperature-dependent. Survival of some organisms was less than 10 days at 38 C but more than 200 days at 7 C. Some embryos of T. hydatigena stored in water at 7 C for 90 days completed their reorganization into cysts when fed to sheep. Some stored at −9 C for 90 days or at 7 C for 273 days, were invasive, but failed to complete their reorganization in sheep. Temperatures between 7 and 38 C accelerated the degeneration process and also appeared to stimulate a proportion of juveniles to reach a phase of development when activation and invasion could be accomplished. At −9 C this latter process was limited without extending the survival time. Some epidemiological implications of egg survival in the regulation of tapeworm populations are discussed.

Egg Hatching and Life History of a Fairy Shrimp Branchinecta Mackini Dexter (Crustacea: Anostraca) in a Mohave Desert Playa (Rabbit Dry Lake)

Observations on populations of Branchinecta mackini in temporary ponds, which last for as little as 3 days to as long as 4 months, on a desert playa showed that hatching of dehydrated cysts (eggs) follows initial entry of water into the basin if salinity remains low. Salinity ranges from an initial 0.5% to as much as 34% as the pond evaporates. Hatching is continuous at constant low salinity, but since salinity general increases rapidly, initial hatch is usually of short duration. Additional periods of hatching follow further inflows of water or after meeting of ice, that is, after reductions in salinity. The duration of hatching is inversely proportional to rate on increase in salinity. When salinity of small—volume summer ponds increases at rates above 500 ppm (1,000 (mu)mhos) per day, three in virtual inhibition of hatching. Laboratory studies showed that egg hatching was controlled by both salinity and oxygen operating in various combinations to inhibit or stimulate hatch. The hatching characteristics obtained from laboratory cultures after ejection from ovisacs of living females. The finding that a salinity—oxygen complex regulates hatching in a desert pond permits tentative explanation of a difference between branchiopods of humid and arid regions. In both cases the branchiopods are characteristic of astatic waters, and stimulation of the egg to hatch must be by some factor that changes at the time or origin of the temporary pond. In humid regions the factors of concern are temperature and oxygen. If the water undergoes significant changes in salinity, as it does in arid regions, control of egg hatch may be by both salinity and oxygen, with temperature limited to control of rate of development.

Experimental Hatching of the Eggs of Ascaris suum

Summary1. Infective Ascaris eggs treated in “Clorox”-sodium hydroxide solution, hatched and produced viable larvae when they were subsequently:(a) incubated in physiological saline at 37.5° and 40°C. Hatching occurred up to 100% in 4 weeks.(b) dried, rewet and incubated in saline at 37.5°C. Hatching occurred up to 100% in 2 days.(c) centrifuged at speeds from 2000 to 3000 R.P.M. Hatching occurred up to 99.1% during 10 minutes of centrifugation at 3000 R.P.M. with a starting temperature of 40°C.2. Batches of eggs from different worms showed different hatching characteristics depending on the treatment strength and time, and influenced by subsequent procedure.