Resistance to Taenia pisiformis larvea in rabbits: Immunisation using live organism followed by chemotherapy therapy

Viable eggs or activated oncospheres of Taenia pisiformis were inoculated subcutaneously into rabbits. At various intervals the developing larvae were killed by treatment with Mebendazole. Most rabbits receiving oncospheres were protected against challenge infection if they were treated with Mebendazole 1 day after injection and absolute immunity was established in all rabbits if larvae were allowed to develop for 14 days before being killed. In rabbits receiving eggs, 21 days from injection to Mebendazole treatment was required before absolute immunity developed. Eggs appear to require a period of 1–2 weeks for hatching and oncosphere activation in a subcutaneous site. The data also indicate that production of functionally protective antigens occurs early during larval developement.     

The effect of temperature and relative humidity on survival of eggs of the cestode, Monieza expansa (Rudolphi, 1810)]

The survival of Moniezia expansa eggs in the droppings of lambs was investigated at various temperatures in laboratory conditions and on test plots outdoors. The optimum temperature of the livability of M. expansa eggs in laboratory conditions is 5 degrees C; at this temperature 10% of oncospheres survived after 161 days. At the temperatures of 10, 25, 35 degrees C the oncospheres survived 105, 28, 46 days respectively, at -12 degrees C it was 28 days. It was for 21 and 35 days that on the test grassy plots the eggs of M. expansa survived in the droppings of lambs in the summer months of July and August at the average air temperatures of 15.7-18.2 degrees C and relative humidity of 67.7-74.3%. In autumn in September and October, at the average temperatures of 5.8-14.6 degrees C and relative humidity of 65.3-76.7% the oncospheres survived for 49 to 91 days. The M. expansa eggs in the droppings of lambs were able to survive on the test plot. The living oncospheres were demonstrated for 119 days from November 1987 to March 1988, and for 175 days till May by means of experimental infection of intermediate hosts.     

Passive transfer of immunity to neonatal calves against the metacestodes of Taenia saginata

Passive transfer of immunity to neonatal calves against Taenia saginata was examined. Immune serum immunoglobulins were obtained from cattle inoculated orally with eggs of T. saginata, and from an animal which had been injected intramuscularly with eggs and activated oncospheres of the parasite. Immune colostral immunoglobulins were obtained by local injection of the mammary gland of a preparturient cow using activated oncospheres of T. saginata as antigen.Newborn calves fed the immune serum or colostral immunoglobulins were significantly protected against infection with T. saginata. In addition, more than 80% of the metacestodes in the protected calves showed evidence of degeneration, while only 34 and 27% of the metacestodes showed evidence of degeneration in those animals receiving “normal” control serum and “normal” control colostral immunoglobulins, respectively.     

Effect of egg composition on hatchability and on growth and slaughter characteristics of meat-type chicks

1.?Using the so-called TOBEC (Total Body Electrical Conductivity) method, which allows the determination of egg composition in vivo, correlations between egg composition, hatchability and hatched chicks’ development were studied.

2.?A total of 1500 hen eggs (Ross-308) were measured by TOBEC, and eggs with extremely high (10%, n = 150), extremely low (10%, n = 150) and average (10%, n = 150) electrical conductivity values were chosen for further investigation.

3.?During the incubation period, it was observed that eggs with high electrical conductivity had a significantly higher mortality than eggs with low electrical conductivity.

4.?It was observed that both the increase in electrical conductivity at the same egg weight, and the increase in egg weight at the same electrical conductivity resulted in an increase in the hatching weight.

5.?It was found that the dry matter, protein and fat content of the chicks hatched from eggs with low electrical conductivity was higher at hatching than that of the chicks hatched from eggs with high electrical conductivity.

6.?At 42 d of age the liveweight of cocks and pullets hatched from eggs with low electrical conductivity was 3·2 and 8·2% higher than the liveweight of cocks and pullets hatched from eggs with high electrical conductivity.

7.?Because of the higher liveweight at slaughter, there was a significant superiority of the chicks hatched from eggs with low electrical conductivity in the case of the examined carcase traits at slaughter.

8.?Similar tendencies were found also in the ratios of carcase variables to liveweight, but the between group differences were not statistically significant in this case.

9.?Based on the results it was concluded that TOBEC seems to be a useful method for separating eggs with different composition.

10.?This could be a good starting point for further in vivo investigations in order to clarify the effect of egg composition on hatchability and further development.     

Optimum incubation conditions of the domestic guinea fowl egg

1. During artificial incubation of 8000 guinea fowl eggs, the effects of temperature, relative humidity, rate of inflowing air and age of the laying flocks were determined.

2. Total duration of incubation was divided into setter (0 to 24 days) and hatcher (25 to 28 days) periods. Eggs transferred at the end of the setter period, (ET, % of fertile eggs) and hatching rate (HR, % of transferred eggs) were calculated, as well as the total hatching rate expressed as percentage of fertile eggs.

3. In the range 36 to 39°C, temperature affected significantly (P< 0.001) ET and HR, with optima at 37.2 and 37.0°C ± 0.1°C respectively.

4. During incubating period, relative humidity in the range 40 to 64% (water vapour partial pressure, Ph₂o ⁼ 17 to 34 Torr at 36 to 39°C), significantly (P< 0.001) affected the total diffusive water loss and hatchling mass, both expressed as percentage of fresh egg mass. ET was significantly affected by water loss, the highest ET being for water loss of 13.3 ± 0.5%. Optimal relative humidity was calculated to be 48 to 52% (Ph₂o = 23 to 25 Torr at 37.2°G).

5. The rate of inflowing air significantly (P< 0.001) affected HR, with an optimum at 3.1 Lstpd/(h . egg).

6. The age of the laying flock significantly (P< 0.001) increased water loss; this was explained by a parallel increase of the mass specific shell conductance to water vapour.

7. Finally optimum incubation conditions were deduced, giving total hatching rates of 78 to 81% of fertile eggs, improving by 5 to 8% the best results obtained routinely in commercial practice.     

Developmental competence of eggs produced by rainbow trout Doubled Haploids (DHs) and generation of the clonal lines

Poor quality eggs produced by the fully homozygous doubled haploids (DHs) may impair generation of clonal lines in fish species. In the present research, gynogenetic development of rainbow trout (Oncorhynchus mykiss) was induced in eggs originated from the DH females. Eggs were activated with the UV‐irradiated grayling (Thymallus thymallus) spermatozoa and subjected to the high hydrostatic pressure (HHP) shock to provide diploid clonal individuals. Only two of four DH females produced eggs that were successfully activated by the irradiated spermatozoa and subsequently developed into the gynogenetic embryos. Survival rates of rainbow trout from the clonal lines equalled 21.5% and 19.8% during embryogenesis and decreased after hatching to 18.6% and 14.9%, respectively. Some of the dead rainbow trout clones collected between hatching and swim‐up stage were emaciated and exhibited spinal deformities including scoliosis. Provided results confirmed limited developmental competences of eggs produced by rainbow trout DH females. Clonal rainbow trout developing in such eggs exhibited reduced survival and increased frequency of the body abnormalities.     

Bacterial contamination on eggs during incubation and hatching,and of fluffs of newly‐hatched chicks

1. Average numbers of bacteria on clean and dirty eggs produced from a specified‐pathogen‐free chicken flock were 10^3.0 and 10^4.5, respectively. When the eggs were washed with running tap water at about 40°C, the respective bacterial counts were reduced to 10^2.0 and 10^2.7, the latter difference being not significant.

2. After fumigation with formaldehyde from 40 ml formalin (372 g formaldehyde/1) and 20 g potassium permanganate/m³ for 1 h, no bacteria were recovered from clean eggs by agar plate culture, while a small number of bacteria were detected in three out of five dirty eggs.

3. Average numbers of bacteria detected in clean fumigated eggs were 10^0.8 to 10^1.1 during the first 19 d of incubation and 10^1.2 and 10^1.4 were recovered on days 20 and 21 of incubation, respectively. At the end of hatching, eggs containing dead embryos were highly contaminated with 10^3.8 organisms on average.

4. Fluffs of newly‐hatched chicks scattered inside the hatcher were contaminated with bacteria at 10^4.0 to 10^8.4 organisms/g. Water in the basin placed in the hatcher and floating fluffs in water were highly contaminated with bacteria.     

Attempted infection of calves with Taenia crocutae cysticerci and their subsequent serological response

The susceptibility of naive cattle to infection with cysticerci of Taenia crocutae was tested using three six- to nine-month-old Ayrshire bull calves, previously unexposed to infection with taeniid eggs. One calf was given 10,000 T crocutae eggs orally, another 5000 hatched unactivated oncospheres orally and the third 5000 hatched and activated oncospheres by intravenous injection. None of the calves contained viable cysticerci at post mortem examination 15 to 17 weeks later. All three calves contained small numbers of lesions in the liver and lesions were also present in the lungs of the calf which received oncospheres intravenously. All the calves developed an antibody response which was most pronounced in the calf given hatched unactivated oncospheres orally.     

Effective,appropriate and simple culture,egg hatching and cryopreserving of the nematode Cheilospirura hamulosa

1. Successful invasion by nematode parasites is associated with several factors including egg hatching at the right time in their hosts. To determine a simple and appropriate medium for culture and egg hatching of the highly pathogenic species of the Acuariidae family, Cheilospirura hamulosa were cultured in three different media. In addition the viability of C. hamulosa eggs was determined after storage in frozen infected gizzards.

2. Eggs removed from the uteri of the female worms in infected gizzards were pooled and washed in distilled water and screened under a stereo dissecting microscope. Eggs were counted and cultured in three different media, nutrient agar, normal saline 0.9% and Bearman, at room temperature. Additionally, 10 infected gizzards were kept at ?20°C for 2 and 8 months.

3. After 4–5 d there had been no growth in the nutrient agar medium, whereas 11% of the cultured eggs in the Bearman medium contained larvae 2–3 d after culturing. In 0.9% normal saline medium the two polar knobs appeared on the two poles of the eggs at 2 d post cultivation, and 74% of the eggs contained a larva on the third day. Mature larvae gradually exited from the eggs.

4. Eggs collected from female worms in gizzards frozen at ?20°C were cultured in the same three culture media at room temperature. Larvae were visible in the eggs after 2–3 d in the Bearman and 0.9% normal saline media and hatched thereafter.

5. The 0.9% normal saline medium is recommended for egg hatching and cultivation of C. hamulosa due for simplicity, efficacy and cost effectiveness. Moreover, freezing of the infected gizzards at ?20°C is proposed for long-term storage of the eggs.     

Bacterial Analysis of Fertilized Eggs of Atlantic Salmon from the Penobscot,Naraguagus, and Machias Rivers,Maine

Serious losses have occurred at the U.S. Fish and Wildlife Service, Craig Brook National Fish Hatchery, East Orland, Maine, among eggs that were taken from Atlantic Salmon Salmo salar, which were held as captive broodfish during their returns to the Penobscot River, Naraguagus River, and Machias River to spawn. Bacterial isolations were attempted from external surfaces and the internal contents of individual eggs. Externally and in all cases, Pseudomonas fluorescens was the predominant bacterium associated with the surface of all eggs. These bacteria were resistant to a surface treatment of 1,667 ppm formalin for 15 min and, therefore, the monoclonal nature of P. fluorescens on egg surfaces was considered to result from its ability to resist the germicidal activity of formalin administered for antifungal treatments. Flavobacterium psychrophilum, the cause of bacterial coldwater disease, was isolated from the interior of 23.6, 18.1, and 29.2% of the dead Atlantic Salmon eggs from Penobscot River egg lots A-98, A-100, and A-101, respectively, and concentrations of this pathogen ranged from 1.0 × 10³ to >5 × 10⁸ CFU per gram of dead egg. Flavobacterium psychrophilum was also isolated from 8.3, 26.7, and 10.0% of the dead eggs from Naraguagus River egg lots N-158, N-161, and N-163, respectively, in which concentrations of this organism ranged from 1.0 × 10³ to 7.5 × 10⁸ CFU per gram of egg. This bacterium was also isolated from within 18.3% and 3.3% of the dead eggs from Machias River egg lots M-128 and M-142, respectively, and its concentrations ranged from 1.0 × 10³ to 1.5 × 10⁸ CFU per gram of egg. The finding of F. psychrophilum from within these eggs is indicative of this pathogen's widespread and persistent prevalence in Atlantic Salmon in New England.

Received December 19, 2014; accepted May 4, 2015     

Effects of external stimulation on the onset of lung ventilation and the time of hatching in the fowl,duck and goose

Effects of naturally occurring and artificial stimulation on foetal development and the time of hatching were investigated in the fowl, duck and goose.

With respect to natural stimulation, it was shown in the fowl, that the time of hatching is advanced by contact with an egg given 24 h more incubation. Also in the fowl, it was found that contact with other eggs given the same amount of incubation reduces the spread of hatching, although without affecting the mean hatching time. In the Khaki Campbell duck, however, eggs kept in contact hatched earlier than isolates, as well as hatching within a shorter period of time.

The artificial stimulation used was that known to have an accelerating effect in the quail, and the developmental stage of the foetus was assessed by recording pressure changes within the air space of the egg, a method which reveals the time of onset of lung ventilation. When eggs were stimulated artificially it was found in the fowl, duck and goose that the stimulated eggs not only hatched earlier, but began to breathe earlier than did their unstimulated controls. In all three species also, the duration of breathing was shorter in the stimulated than in the unstimulated foetuses.     

Taenia taeniaeformis: effectiveness of staining oncospheres is related to both temperature of treatment and molecular weight of dyes utilized

Methods to determine viability of taeniid oncospheres following treatments with potential lethality have practical application in efforts to control transmission. Here we investigated several methods, in lieu of infectivity studies, to assess oncosphere viability and determine lethal temperature treatment regimens. In the first experiment, a standard treatment to exshell oncospheres with 0.5% hypochlorite was assessed for influence on oncosphere recovery of Taenia taeniaeformis eggs. Recovery of eggs and exshelled oncospheres decreased with increasing time in hypochlorite, which indicated that hypochlorite can damage eggs and oncospheres, translating into potential overestimation of lethality of experimental treatments. Losses in hypochlorite were accentuated when eggs were pretreated at 75 degrees C, but not lower temperatures, including 65 degrees C, indicating a sharp threshhold between 65 degrees C and 75 degrees C where eggs and oncospheres became hypersensitive to subsequent hypochlorite treatment. To further investigate this change in relation to temperature, non-vital (acridine orange, AO) and vital (propidium iodide, PI; trypan blue, TB) dyes were used to assess staining of oncospheres (exshelled or not) under conditions ranging from room temperature up to 95 degrees C. The behaviors of dyes as related to internal staining of oncospheres were described using non-linear regression and a sigmoid four-parametric model to determine the inflection point (T50). Each of the dyes differed significantly in T50 estimates, e.g. AO (69.22+/-0.53), PI (73.89+/-0.52) and TB (79.43+/-0.45). For these dyes, the T50 increased in relation to the increasing molecular weight of the dyes. Collectively, the results suggested that barriers to chemical permeability exist in eggs that breakdown incrementally with increasing temperatures above 65 degrees C. This staining behavior and the likelihood that the temperatures involved are above a lethal threshhold clarify a basic limitation in the use of vital dyes to assess oncosphere viability. The results may be relevant to other Taenia spp.     

Variance and covariance of hatchability and some of its components in the chickens

Samples of 20 hatching eggs from each of 2004 individual pedigreed pullets were incubated and hatchability recorded. Unhatched eggs were examined for evidence of embryo development and classified as infertile, early embryonic death (died 0–10 d) or late embryonic death (died 11–22 d). Variance analysis yielded a mean heritability value for hatch of all eggs of approximately 0.30. Heritability values for early and late embryo mortality were subject to larger errors but there was a tendency among the estimates of h ² ₈ for late embryo mortality to be higher than those for early embryo mortality.

The genetic correlations between hatchability and both early and late embryonic mortality were high and negative as was to be expected from part × whole correlations. However the genetic correlation between early and late embryonic mortality was also consistently positive indicating common genetic determination of these two independent traits.     

In ovo injection of branched‐chain amino acids: Embryonic development,hatchability and hatching quality of turkey poults

In this study, the influence of a branched‐chain amino acid blend (BCAA composed of 3 l ‐leucine:1 l ‐valine:2 l ‐isoleucine) injected into the amniotic fluid was evaluated for embryonic growth, yolk‐sac (YS) utilization and development of gastrointestinal tract (GIT) and skeletal muscles of turkey embryos from day 24 of incubation (24E) to hatching, together with hatchability, poult quality and liver L* (lightness), a* (redness) and b* (yellowness) values at hatch. At day 22 of incubation, embryonated eggs (n = 240) were assigned to three treatments, that is, eggs were not injected (control, NC) or injected with 1.5 ml sterile solution with 0.9% salt (SA) or 0.2% BCAA blend (BCAAb). These solutions were injected manually into the amniotic fluid of the embryonated eggs. To determine weights and lengths (where appropriate) of the studied organs and tissues, four embryonated eggs and poults per treatment were selected at 24E and at hatch. While the BCAAb decreased the YS and embryo weight, hatchability and the liver L* value, it increased the weight and quality of poults and the weights of breast and thigh muscles at hatch. In conclusion, the in ovo feeding of the BCAA blend negatively affected hatchability but positively affected hatching weight and poult quality by improving development of skeletal muscles and by regulating energy metabolism.     

Effects of Temperature on In Vitro Short‐Term Storage of Sterlet Sturgeon (Acipenser Ruthenus) Ova

Artificial propagation of sturgeons is becoming increasingly important for recovery efforts as well as for commercial production. Sterlet Acipenser ruthenus is a common Eurasian sturgeon with a small body size and one of the fastest reproductive cycles among the sturgeons. The practical question being addressed in this study was how long fertilization of ovulated eggs can be delayed without substantially reducing the hatching rate, and an ancillary question is under what' temperature conditions do eggs retain good quality. Broodstock were injected with homogenized carp pituitary extract (CPE); ovulated eggs from three females were allocated to various treatment groups for temperature storage (control, 7°C, 11°C, 15°C and 19°C) until fertilized. Storage times at the regulated temperatures prior to fertilization were for 2.5, 5.0, 7.5 and 10.0 h. After the selected storage times in ovarian fluid, eggs were fertilized and transferred to incubation cages and then they were counted. Three replicates were allocated to each storage period and temperature. Hatched larvae were counted at 7‐day post‐fertilization. We found that sterlet eggs do not need to be fertilized immediately after collection. Reasonably good quality was retained for several hours if temperature conditions are fairly cool and stable. Eggs retained good quality when stored at 7°C and 11°C for up to 10 h with 54.1 ± 2.9 to 69.9 ± 7.9% hatching success, but egg quality was significantly reduced after 5‐h storage at 19°C (p < 0.01) and 7.5‐h storage at 15°C (p < 0.05) compared to cooler temperatures. Uniform temperatures between 7°C and 11°C can be considered as appropriate for storage of eggs in ovarian fluid for up to 10 h. This information can have practical application to routine hatchery practice for acipenserids, as well as for certain research protocols.     

A comparison of two proteolytic techniques for hatching Hymenolepis diminuta eggs

Two techniques for hatching taeniid eggs, based on enzymic proteolysis and disaggregation of the embryophore, were evaluated using Hymenolepis diminuta. Both techniques proved ineffective on H. diminuta in their original form, achieving only a hatching rate of 1-2%. However, a gradual increase in pepsin concentration up to 3 mg ml-1 in the pretreatment solution enhanced hatching significantly (P less than 0.05). Normal or immune rat serum had no appreciable effect on the hatching process.     

Divergent selection for shape of growth curve in Japanese quail. 6. Hatching time,hatchability and embryo mortality

1. Hatching time, hatchability of fertile eggs and embryo mortality under standard egg storage (1 or 5 days at 12?±?1°C and 55% relative humidity) and incubation conditions (37·5?±?0·2°C and 50% relative humidity) were analysed in lines long-term selected for high (HG) and low (LG) relative weight gain between 11 and 28?d of age, respectively, and constant body weight at 49?d of age.

2. Egg storage duration did not have an effect on average hatching time. LG quail, characterised by a fast postnatal growth rate immediately after hatching, hatched earlier than HG quail with a low early growth rate (about 391 vs. 406?h after egg setting, respectively).

3. In contrast to hatching time, the hatchability of fertile eggs was influenced by line as well as egg storage duration. Extended storage decreased hatching success in both lines. However, LG eggs exhibited a higher hatchability than HG eggs (1?d storage: 96·0 vs. 82·5%; 5?d storage: 88·7 vs. 72·7%, respectively).

4. Lower hatchability resulted mostly from a higher frequency of embryo death during early (up to d 7) and late (d 14 and later) phases of incubation.

5. An inadequate nutrient supply to embryos in consequence of developmental delay seems to be a key factor decreasing viability of embryos during incubation.     

Survivability of Infectious Hematopoietic Necrosis Virus in Fertilized Eggs of Masu and Chum Salmon

Abstract

The possibility of vertical transmission of infectious hematopoietic necrosis virus (IHNV) was studied with the eggs of masu (cherry) salmon Oncorhynchus masou and chum salmon O. keta. The surfaces of eggs and sperm were contaminated with IHNV (10^3.8-10^4.8 50% tissue culture infective dose [TCID50]/egg) and then the eggs were fertilized. Eggs just after fertilization and embryonated eggs also were infected by injection with IHNV (10^3.8 TCID50/egg) directly into the yolk. During incubation, eggs were held in running water at 10°C. Mortality of the eggs or hatched progeny was determined and isolation of IHNV on the surface or inside of the eggs was determined during the incubation period. No mortality occurred and no virus was detected in fertile eggs from contaminated gametes. For injected eggs, IHNV was not detected on the surface of masu and chum salmon eggs after 1 d of incubation. Infectivity of IHNV inside the eggs decreased gradually and could not be detected after 1 month of incubation. This rate of IHNV reduction in the fertilized egg was similar to that found in a mixture of IHNV and homogenized yolk contents. Several individual yolk components also showed anti-IHNV activity. When eyed eggs were injected with IHNV, the embryos of both masu and chum salmon became infected, and the concentration of virus increased rapidly and reached more than 10^6.5 TCID50/fish. The cumulative mortality of eggs injected at the eyed stage for both masu and chum salmon was 90%. The susceptibilities of hatched-out larvae of masu and chum salmon to IHNV were different; cumulative mortality was more than 90% in masu salmon and 20–30% in chum salmon artificially infected with the virus. We concluded that vertical transmission of IHNV is doubtful because the virus is apparently unable to survive in eggs before the eyed stage.     

Bactericidal Effect of Several Chemicals on Hatching Eggs Inoculated with Salmonella serovar Typhimurium

Breeder flocks and commercial hatcheries represent an early contamination point for Salmonella entry into commercial integrated poultry operations. Utilizing effective antimicrobial treatments for hatching eggs is a critical part of reducing the incidence of Salmonella-colonized chicks on the farm. The objective of this study was to evaluate the bactericidal effect of several chemicals on Salmonella-contaminated hatching eggs. Four replications (n = 10/treatment per replicate) were conducted to determine the efficacy of 7 commercially available compounds. The compounds tested were as follows: 1) hydrogen peroxide, 2) water-oil emulsion droplets stabilized by detergent, 3) peroxyacetic acid, 4) 4 quaternary ammonium compounds attached to a polymer, 5) 2 quaternary ammonium compounds, 1 biguanide compound and bronopol attached to a polymer, 6) N-alkyl dimethyl benzyl ammonium chloride and stabilized urea, and 7) polyhexamethylenebiguanide hydrochloride. A naladixic acid-resistant Salmonella serovar Typhimurium was inoculated (10³ cfu/mL) onto fertile hatching eggs by drip-inoculation. Controls included a positive control (no spray application) and a water control (spray containing water to take into account rinsing effects). Compounds 5 and 7 had a 100% reduction, and both of these chemicals included a biguanide. Compounds 4 and 3 were also effective with a 95 and 93.5% reduction, respectively. Compounds 6 and 2 were the least effective of all chemicals, with a reduction of 47.5 and 40%, respectively. Hydrogen peroxide (compound 1), which has been used by the poultry industry, had a 70% reduction, and the water control produced a 10% reduction due to the rinsing effect. Several antimicrobials tested were more effective than hydrogen peroxide. More detailed studies will be required to adequately evaluate these antimicrobials.     

Effects of ethylnitrosourea on the hatchability and survival of chicks

1. Two experiments were carried out to study the effects of the mutagen ethylnitrosourea (ENU) at concentrations of 1.4 to 3 500 μg in 0.3 ml of saline (experiment 1) and 585 to 1 170 μg in 0.1 ml of saline (experiment 2) on hatching eggs of two breeds of fowls. Hatchability (experiment 1) and survival up to 7 d of age without food (experiment 2) were assessed. In experiment 1 the hens were fed on different diets prior to providing the hatching eggs.

2. The mutagen showed a non‐linear effect upon the hatchability, higher doses being less effective than small doses.

3. In the majority of cases, female embryos were more sensitive to the effect of ENU then male.

4. The mortality after hatching was also affected by ENU; the chicks from treated eggs surviving without food better than controls.