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At least 793 records · Page 44Linked to original sources
PubMed1982

Performance of laying hens subjected to intermittent lighting initiated at 24 weeks of age.

Leghorn pullets of a commercial strain were subjected to a conventional light program of constant photoperiod or an intermittent programming involving, during the house of conventional "lights-on", 45 min light (L): 15 min dark (D) from 24 to 27 weeks of age; 30 min L:30 min D from 28 to 35 weeks; and 14 min L:45 min D from 36 weeks to the duration of the trial. Each light treatment was tested with 12 replicate groups of 14 individually caged birds housed in adjacent rooms, with all birds fed a standard 15% crude protein, 2750 kcal ME/kg diet. Intermittent lighting resulted in a significant (P less than .05) reduction in feed intake and a consistent but nonsignificant (P less than .05) reduction in egg production. Egg size, egg shell quality, and albumen quality, as assessed by Haugh units, were not affected by light treatment. Due to the effect on egg production, it is concluded that intermittent lighting programs should not be initiated close to time of peak egg production.

Animals↗
PubMed1984

Assessment of viability of Schistosoma mansoni miracidia by Congo red staining.

The viability of Schistosoma mansoni miracidia, either hatched or unhatched, has been assessed by a staining technique using Congo red, a pH-sensitive dye (pH 3-5), under the light microscope. Hatched, free-swimming miracidia and live miracidia inside egg shells were stained light blue whereas dying miracidia altered the dye color from blue to orange and eventually to red. Immature eggs containing undeveloped miracidia were not stained by Congo red. This staining technique is simple, rapid and can be used as a method to assess both the viability of S. mansoni miracidia and the hatching process.

Cilia↗
PubMed2002

Influence of the microstructure on the shell strength of eggs laid by hens of different ages.

1. The eggshell is a bioceramic material constructed of columnar calcite crystals preferentially oriented with their c-axis perpendicular to the shell surface. 2. The influence of microstructure (crystal size, shape and crystallographic orientation of crystal grains) on the mechanical properties of eggshells (shell strength) was investigated using eggs from hens of different ages. 3. There was a strong correlation between crystallographic texture and the strength of the eggshell in the case of eggs laid by young hens. The strength of eggshells increased as the preferential orientation of the crystals constituting the eggshell decreased. 4. By comparing two age populations, the effect of hen age on eggshell properties was evaluated. In general, eggshells from aged hens had a lower breaking strength (less than half that of those laid by young hens) and showed a greater variability in their structural properties such as thickness, grain morphology and crystallographic texture. 5. Texture analysis revealed that shells from eggs laid by aged hens have two preferred crystal orientations, after (001) and (104), compared with mainly one, after (001), in eggs laid by young hens. 6. These observed changes in eggshell properties could be due to changes in the organic matrix of the eggshell associated with ageing of the hens.

Age Factors↗
PubMed1988

Egg mass and shell thickness in dippers Cinclus cinclus in relation to stream acidity in Wales and Scotland.

The shell thickness and mass of eggs of the dipper (Cinclus cinclus) collected on streams of different pH in Wales and Scotland were measured. The aluminium, phosphorus and calcium content of their invertebrate prey were also measured. In a regression analysis, significant at p<0.05, stream pH accounted for up to 7% of the variance in shell thickness, with shells decreasing by 2.5% of the overall mean with each unit of pH decline. In the Welsh sample, differences in shell thickness due to pH were small compared with differences between years across all sites. In data pooled between Scotland and Wales, pH accounted for 17% of the variance in egg mass, but a greater proportion (25%) in Scottish eggs alone. Aluminium concentrations in invertebrates showed no relationship with stream pH, but calcium levels in two insect orders increased significantly with pH. Calcium rich prey, such as Gammarus, were found only in circumneutral streams. The importance of calcium in the diet of dippers before and during egg formation is discussed. No evidence that aluminium in prey adversely affected dipper eggs was found.

Journal Article↗
PubMed1982

Serological examination and egg production of progeny of fowl experimentally infected with egg drop syndrome 1976 virus.

Following EDS'76 virus (BC14 virus) infection of breeder chickens by the conjunctival route, vertical transmission occurred in the first week after infection. In the progeny which had been infected with EDS'76 virus by the vertical route, increasing haemagglutination inhibiting (HI) titres to BC14 virus and increasing numbers of birds with HI titres were observed from 3 weeks to 15 weeks of age. Sixty-one per cent of the hens and 77 per cent of the cocks had 2 log HI BC14 virus titres exceeding 4 at an age of 15 weeks. Some birds which han been serologically negative throughout the rearing period, seroconverted between 25 and 28 weeks of age. This phenomenon occurred in hens as well as in cocks. Simulation of stress twice during the laying period by injection of corticosteroid hormone did not increase the number of birds serologically positive to EDS'76 virus. EDS'76 was observed in the group of hens that was vertically infected, since egg production was significantly depressed between 28 and 34 weeks of age. Probably this was mainly the results of a production drop in the hens showing serconversion at 27 or 28 weeks of age. In this group of fowl vertically infected with EDs'76 virus, serologically positive birds appeared to be protected for the greater part to BC14 virus challenge at 50 weeks of age, while negative birds seemed to be fully susceptible. Chicks hatched from eggs collected in the third and fourth week after infection of the dams had maternal antibodies. Fertility and hatchability of apparently normally shelled eggs seemed not to be affected after BC14 virus infection of the dams. Intensive contact with contaminated faeces is probably an indispensable condition for lateral transmission of the virus.

Adenoviridae Infections↗
PubMed1979

[Keeping quality of hard boiled eggs].

Only a few and contradictory results are available on the storage stability of hard boiled eggs which are of considerable importance for institutional feeding. Therefore four storage experiments on about 500 hard boiled eggs each were carried out and chemical and sensorial changes occurring during storage investigated. The one-day-old eggs of the same origin were boiled for 17 minutes under standard conditions and subsequently stored in air at a relative humidity between 73 and 85% at 4 degrees C (experiment No. 1), at 20 degrees C (experiments No. 2 and 3) and in pure carbon dioxide at 20 degrees C (experiment No. 4). Immediately after boiling, the eggs used for experiments No. 3 were dipped into coloured resin for egg shells (natural Manila-Kopa; dissolved in ethanol and stained with "Acillantechtgrün). Losses in weight during storages were distincly lower in the lacquered eggs than in the non-lacquered samples otherwise treated in the same manner. The weight decrease caused by the loss of water was extraordinarily high in pure CO2 and is due mainly the the decrease of the pH in the egg whites caused by the uptake of CO2. A few days after boiling the concentration of the free amino acids reached approximately the same level in albumen and yolk and remained practically constant over the following 3 weeks. For the breakdown of lecithine in yolk determined according to Grossfeld and Peter, a "deterioration quotient" of 6, like in unboiled eggs, was fixed as the limit value for unspoiled condition. Accordingly a possible storage time of 3 to 4 weeks resulted for the eggs stored at 4 degrees C and for the eggs treated with stained resin. The non-lacquered eggs stored in air or in CO2 at 20 degrees C reached the critical value in about 10 days. From the vitamins A, B1 and B2 only vitamin A showed considerable losses during storage. On the basis of the microbiological (3) and chemical findings and of the sensorial evaluation of colour, consistency, odour and taste of egg whites and yolks, the following storage times were determined for eggs in the quality class "saleable" requiring an overall rating not lower than 6 (satisfactory): 14 to 16 days, for non-lacquered eggs stored at 4 degrees C and for lacquered eggs at 20 degrees C whereas 5 days were found to be the maximum storage time for untreated eggs stored at 20 degrees C. If boiled eggs are stored in pure carbon dioxide at 20 degrees C, a distinct quality loss is observed already after a few days.

Animals↗
PubMed1987

Failure to turn eggs during incubation: effects on embryo weight, development of the chorioallantois and absorption of albumen.

Turning eggs during incubation is essential for good hatchability. In the present paper additional effects on the development of the chorioallantois, absorption of albumen and growth of the embryo are recorded. The ability of an unturned egg to hatch was not affected by egg weight, egg shell porosity or water loss during incubation. The ability of the chorioallantois to spread around the inner surface of the inner shell membrane and the degree of absorption of the residual albumen affected the growth of the embryo and its ability to hatch. Unturned eggs hatched later than eggs which were turned throughout incubation.

Allantois↗
PubMed1998

Effects of incubation temperature on the energetics of embryonic development and hatchling morphology in the Brisbane river turtle Emydura signata.

Incubation temperature and the amount of water taken up by eggs from the substrate during incubation affects hatchling size and morphology in many oviparous reptiles. The Brisbane river turtle Emydura signata lays hard-shelled eggs and hatchling mass was unaffected by the amount of water gained or lost during incubation. Constant temperature incubation of eggs at 24 degrees C, 26 degrees C, 28 degrees C and 31 degrees C had no effect on hatchling mass, yolk-free hatchling mass, residual yolk mass, carapace length, carapace width, plastron length or plastron width. However, hatchlings incubated at 26 degrees C and 28 degrees C had wider heads than hatchlings incubated at 24 degrees C and 31 degrees C. Incubation period varied inversely with incubation temperature, while the rate of increase in oxygen consumption during the first part of incubation and the peak rate of oxygen consumption varied directly with incubation temperature. The total amount of oxygen consumed during development and hatchling production cost was significantly greater at 24 degrees C than at 26 degrees C, 28 degrees C and 31 degrees C. Hatchling mass and dimensions and total embryonic energy expenditure was directly proportional to initial egg mass.

Animals↗
PubMed2006

Relationships between genetic, environmental and nutritional factors influencing osteoporosis in laying hens.

1. The effects upon bone quality of feeding limestone in flour or particulate form and housing type (cage or aviary) in lines of hens divergently selected for high (H) or low (L) bone strength over 7 generations were investigated. 2. As in previous generations, highly significant phenotypic differences between lines were observed in all measured bone traits at peak egg production (25 weeks) and towards the end of production (56 weeks) in both cage and aviary systems. 3. At 25 weeks there were no significant effects on bone variables of feeding particulate limestone although a significant reduction in osteoclast number was observed at this age. By 56 weeks osteoclast numbers were further reduced in hens fed particulate limestone and beneficial effects on some bone variables were observed in this treatment group. 4. The genotypic and dietary improvements upon bone quality were independent and additive at both ages. There were very few interactive effects. 5. Hens with the freedom to move in an aviary environment during the laying period had improved bone status compared to caged siblings. Environmental and genotypic effects were additive. 6. There were no effects of line on egg production although H line hens had slightly higher egg production by 56 weeks. Egg numbers were unaffected by diet. Eggshell thickness and strength were unaffected by line but hens fed particulate limestone had thicker- and stronger-shelled eggs over the production period as a whole. 7. We conclude that; (a) genetic selection is extremely effective in improving bone strength and resistance to osteoporosis; (b) allowing hens freedom to exercise can also improve bone strength but may increase the risk of keel damage if they do not have genetically-improved bone status; (c) feeding hens a particulate form of limestone from 15 weeks onwards can also increase bone strength and eggshell quality; (d) genetics, environment and nutrition all have independent and additive effects on bone status in laying hens but the relative effectiveness of these factors is genetics > environment > nutrition.

Animal Feed↗
PubMed2002

Freezing of sheep faeces invalidates Haemonchus contortus faecal egg counts by the McMaster technique.

Faecal pellets from a sheep that was artificially infected with a monoculture of Haemonchus contortus were collected over a 2-h period in the morning. In the laboratory the faeces were thoroughly mixed by hand and 48 by 1 g aliquots of the pellets were sealed in plastic bags, from which the air had gently been expressed. The faecal worm egg count of the sheep was about 14,000 g(-1). Varying numbers of the bags were either processed for faecal worm egg counting (FEC) by the McMaster technique on day 0, or were stored at one of the following temperatures: about 4 degrees C, -10 degrees C or -170 degrees C before processing. The faecal aliquots that were frozen were thawed at room temperature after having been frozen for either 2 h or 7 days, and processing of aliquots maintained at 4 degrees C proceeded shortly after the samples had been removed from the refrigerator. A dramatic reduction in egg numbers was found in all the aliquots that were frozen at -170 degrees C before faecal worm egg counts were done, as well as in those frozen for 7 days at about -10 degrees C. Numerous empty, or partially empty, egg shells were observed when performing the counts in faeces that had been frozen. In contrast, there was no significant reduction in the numbers of eggs in aliquots maintained for 7 days in a refrigerator at +/- 4 degrees C before examination, when compared with others examined shortly after collection of the faeces. Since H. contortus eggs in faeces are damaged by freezing, some methods that can be used for short term preservation are outlined. It is concluded that all nematode egg counts from cryopreserved faeces (whether in a freezer at -10 degrees C or in liquid nitrogen) should possibly be regarded as being inaccurate, unless the contrary can be demonstrated for different worm genera. However, exceptions are expected for the more rugged ova, such as those of the ascarids and Trichuris spp.

Animals↗
PubMed1984

The effect of cyclic and constant ambient temperatures on feed consumption, egg production, egg weight, and shell thickness of hens.

Groups of 18 hens, 230 days of age, were housed in each of three climatic chambers with light schedules of 14L:10D. One was maintained at a constant temperature of 23.9 C, the second was cycled between 15.6 and 37.7 C (mean, 26.7 C), and the third was cycled between 21.1 and 37.7 C (mean, 29.4 C). In Experiment 1, the high temperature peaked during the dark period at 0200 hr and in Experiment 2, the high temperature peak was at 1400 hr during the light period. The birds had free access to a commercial breeder feed in these two experiments. The results from three 2-week observation periods indicated no significant differences in percent hen-day production, grams of feed per gram of egg mass, or overall body weight change but feed intake per day, egg weight, and shell thickness were significantly reduced by mean temperatures of 26.7 and 29.4 C in cycling chambers. The pair-feeding of birds in the 23.9 C constant chamber compared with those in the cycling 29.4 C chamber resulted in production of significantly heavier eggs with thicker shells without significantly influencing any of the other parameters. The reductions in egg weight and shell thickness observed at cyclic temperatures were not simply a result of a reduction in nutrient intake at high temperatures but also the direct effect of heat stress on the hens. In the 23.9 C constant temperature chambers, a reduction in AME of the feed for the hens fed ad libitum was observed but not for hens pair-fed to hens in the 29.4 C cyclic chamber.

Animals↗
PubMed1995

Salmonella enteritidis: the egg and I.

The world-wide clinical incidence of Salmonella Enteritidis has increased markedly. The increase is associated with the enhanced ability of the bacterium to systemically colonise layer chickens. Subsequent contamination and consumption of intact shell eggs from colonised layer hens, either directly or in foods containing raw or lightly cooked eggs, causes human disease. Despite investigation, no change in the biology of the bacterium has been correlated with increased colonisation in chickens. To date, no method of control at the production level has proven effective; consumer education is the best means of minimising the public health risk.

Animals↗
PubMed1990

Identification of different radiolabelled antigens of the developmental stages of Onchocerca volvulus.

By using radioiodination methods which are thought to label preferentially the surface followed by SDS-PAGE and autoradiography, components of different developmental stages of O. volvulus have been identified. Between 2 and 10 polypeptide antigens were revealed on infective larvae (L3), females, males, eggs, nodular and skin microfilariae by using immunoblotting assays with human onchocerciasis sera. Antigen recognition did not vary with the density of skin microfilariae in the patients from whom the sera were obtained. Some of the antigens seemed to be stage specific; for example, antigens of 31 kDa which were detected only on skin microfilariae, or the 67.5 and 25 kDa components that occurred on the adult females, but were absent from adult males. Some of these antigens were also identified as glycoproteins. A 68 kDa glycoprotein was found in adult females, males and nodular microfilariae. Two glycoproteins of 74 and 45 kDa were found on egg shells, and a 18.5 kDa glycoprotein was recovered from L3. Type VI collagen was found with a specific antiserum on skin microfilariae, but not on eggs and females. Laminin was found on nodular mf. It is concluded that the changing antigenic profiles of the worm stages and the coating of these worms with connective tissue epitopes contribute to the evasion of host immunity.

Animals↗
PubMed2006

In situ characterisation of a microorganism surface by Raman microspectroscopy: the shell of Ascaris eggs.

Intestinal nematodes are very common human parasites and a single species, Ascaris lumbricoïdes, is estimated to infect a quarter of the world's population. A sticky external layer covers their eggs. This work shows that Raman vibrational confocal spectroscopy is able to give information on the biochemical composition of the shell of Ascaris eggs. The biochemical localised characterisation of Ascaris eggs was performed directly on the eggs in their aqueous environment. The studied parasites came from two origins: dissections of adult females and extractions from biosolid sludges. The presence of mucopolysaccharides, proteins and chitin in the shell was demonstrated. The presence of ascaroside compounds was shown particularly via the narrow and intense bands from the organised long CH2 chains. To the best of our knowledge, this is the first time that the latter have been observed in Raman vibrational spectra of microorganisms. Hydration of the shell was different depending on the intensity of the colour of the sludge eggs. Knowledge of the biochemical structural properties of egg surfaces would be useful to understand the egg adhesion phenomena on vegetables contaminated by reused wastewater.

Animals↗
PubMed1975

Toxicity of certain polychlorinated and polybrominated biphenyls on reproductive efficiency of caged chickens.

The biphenyls tested with caged White Leghorn pullets were polychlorinated biphenyl (PCBs) Aroclors 1232, 1242, 1248, 1254 and 1016 and polybrominated biphenyl (PBB) PBP-6 at the 5, 10 and 20 p.p.m. levels. These pollutants exerted no adverse effects on egg production, egg weight, egg shell thickness, feed consumption, adult body weight changes, livability and fertility after 8 weeks of biphenyl feeding, irrespective of biphenyl level or compound. Hatchability of fertile eggs as a result of biphenyl feeding was significantly affected by 10 or 20 p.p.m. and by three PCB compounds (Aroclors 1232, 1242, 1248). The hatchability (%) of eggs laid by pullets fed 10 and 20 p.p.m. declined to 78 and 45, respectively, for Aroclor 1232, 48 and 5 for Aroclor 1242 and 40 and 5 for Aroclor 1248 after 6 weeks of biphenyl feeding, as compared with 90 for the control group. The most common embryonic abnormality was edema in the neck and rump areas. Biphenyl supplementation in the maternal diet also caused a shift in the peak pattern of embryonic death. Progeny growth as a result of biphenyl in the maternal diet was significantly depressed by 10 or 20 p.p.m. and by Aroclors 1242 and 1248. The level of the three PCBs found to be toxic to chickens appears to lie somewhere between 5 and 10 p.p.m.

Animals↗
PubMed1999

Changes in yolk states of duck egg during long-term brining.

To elucidate the relationship between shyandan yolk formation and NaCl penetration degree, fresh duck eggs were brined in 26% NaCl and a prolonged brining test was conducted for up to 24 weeks. Shyandan yolk was obtained from brine-cured duck shell eggs in 26% NaCl for 4-6 weeks and subsequently heated at 85 degrees C for 90 min. Though NaCl contents for albumen and yolk increased to 14.8 and 8.9%, respectively, during the prolonged test for up to 24 weeks, the R values (NaCl/water x 100) were similar (increased from 0.6 to 21) throughout the brining process. The oil-off ratio of the yolk increased rapidly from 14 to 50% (0-6 weeks) and gradually decreased during the extended brining. Granulation and gelation of yolk appeared in the different stages of the brining process. This study demonstrates that the formation of shyandan yolk was determined by the degree of NaCl penetration.

Animals↗
PubMed1987

Gender-specifically expressed genes in Schistosoma mansoni.

Using a genomic gene bank in phage lambda and two cDNA banks in the expression vector lambda-gt11 we have cloned and characterized genes that are expressed preferentially or exclusively in females. One of these genes transcribes two predominant RNA molecules of 0.8 and 3.9 kb which comprise more than 5% of the mRNA population of adult female worms. Transcription of these two RNAs occurs in close proximity on the genome, probably in an overlapping fashion. Experiments are presently in progress to sequence the genes and to produce antibodies against their polypeptide products which will be used to determine in which tissue and at what time in development these genes are expressed. The gene products are probably used for egg shell formation. The final long-term perspective of this project is to interfere with the schistosome parasite's cycle and to reduce its pathogenicity by interrupting egg production.

Animals↗
PubMed2000

Intestinal parasites of baboons (Papio cynocephalus anubis) and chimpanzees (Pan troglodytes) in Gombe National Park.

A survey of gastrointestinal parasites of nonhuman primates in Gombe National Park, Tanzania, was conducted during July and August 1989. Fresh fecal samples collected from 35 baboons (Papio cynocephalus anubis) and 20 chimpanzees (Pan troglodytes) were analyzed for intestinal parasites. Parasite identifications were based upon the size and appearance of eggs and larvae on both direct and fecal flotation examinations. Seven species of helminths and three species of protozoa were noted in the chimpanzees, and seven species of helminths, two species of trematodes, and one species of protozoa were noted in baboons. An unidentified parasite, with a thick egg shell similar to that of ascarids, was noted in both the chimpanzee and baboon population. Unfortunately a definitive identification of this parasite could not be made based upon egg size and morphology alone and insufficient numbers of larva were present to aid identification. One previously unreported parasite, Schistosoma mansoni, was identified in the baboon population. This is the first report of a schistosome in Gombe's nonhuman primate population.

Animals↗