2. A simple technique for chicken manipulation is eggshell windowing, without or with seal, the latter having demonstrated some improvement in hatching rates.

3. Likewise, a surrogate eggshell system provides an accessible model for manipulation during chicken and quail development, with a higher hatchability compared to the simple windowing method.

4. The development of the chicken ex ovo culture systems in a synthetic environment as an efficient technique for imaging and microsurgery applications has enabled the study of important events of live chicken embryos at a specific time point.

5. This short review illustrates recent applications of well-designed whole embryo culture systems as a robust model for research into numerous biological mechanism, drug discovery, gene manipulating and production of functional proteins.  相似文献   

2. By 2004, however, residues of the side-chain metabolite, 3-amino-2-oxazolidinone (AOZ) of furazolidone, were detected in chicken meat produced in Northern Ireland.

3. With the random spread of positive results across farms of a single integrated organisation, including organically reared flocks, it seemed unlikely that the source of residues was due to illegal use of the drug, but more likely caused by a source of contamination.

4. Potential sources investigated were as follows: furazolidone contamination of feedstuffs, a “hot spot” of furazolidone in poultry houses, contamination occurring within breeding stocks and transferred with the birds to broiler growing houses, and furazolidone contamination of the water supply.

5. Furazolidone contamination was associated with birds reared in houses more than 10 years old.

6. Contamination was traced to the water supply of poultry houses, where un-dissolved furazolidone, legally administered prior to 1997, had settled to the bottom of water storage tanks. It remained un-disturbed until 2004 when the integrator changed the procedure for cleaning water tanks between crops of birds.

7. The use of Proxitane, a hydrogen peroxide disinfectant, caused effervescence within the tank such that small quantities of furazolidone were dissolved, delivered to birds via drinkers and subsequently caused residues in the broiler meat.

8. The environmental impact of the contamination was investigated by testing soil and grass from land adjacent to an organic poultry house to which birds had access.

9. Mechanisms of contamination and how residues may be spread throughout a large integrated poultry system are not restricted to furazolidone. Incidents of contamination are even more likely when using licensed drugs where the drugs may be present on-farm in large quantities.  相似文献   

2. Eighty broilers were randomly divided into two groups. Birds in the control group were fed on maize–soybean-based diets. Birds in the treatment group were provided the same diet supplemented with 2 g/kg BA encapsulated in a vegetable oil matrix.

3. At the end of the trial (d 35), pH, bacterial composition and metabolites were determined in the crop, jejunum, ileum and caecum.

4. Growth performance variables and pH were not significantly different.

5. BA concentration decreased rapidly in the proximal gut. However, the treatment diet showed higher BA in the crop, jejunum, ileum and caecum.

6. Total lactate in the crop and D-lactate in the jejunum was higher in the BA treated group. Caecal total and branched chain fatty acids were decreased due to the treatment.

7. Lactobacilli populations were significantly altered by BA supplementation. A trend for increased lactobacilli was observed in the crop, while it became significant in the jejunum and ileum. Lactobacillus species responded differently to the treatment. Four of 5 measured Lactobacillus species, particularly in the ileum, followed the course observed for total lactobacilli; only Lactobacillus salivarius was not modified.

8. Correlation analysis showed that BA modified the intestinal microbiota. Lactobacilli correlated negatively to all studied clostridial clusters and enterobacteria. Clostridial clusters IV and XIVa were significantly increased in the jejunum, whereas only clostridial cluster XIVa was increased in the caecum.

9. Encapsulated BA modified the intestinal microbiota which can lead to the conclusion, that the main beneficial mode of action of BA in the gut appears to be the enhancement of lactic acid bacteria, which in turn may act as a vanguard against pathogens.  相似文献   

2. A total of 160 Hy-Line Brown layers (45 weeks old) were randomly assigned into 4 treatments on the basis of laying performance. Each treatment had 4 replicates with 10 birds each.

3. Dietary treatments were basal diet supplemented with 0 (control), 2.5, 5.0 and 7.5 g/kg diet G. procumbens during 56-d feeding period.

4. Serum (d 21, 42 and 56) and egg yolk (d 28, 42 and 56) cholesterol and triglycerides concentrations were linearly reduced with increasing dietary concentrations of G. procumbens.

5. Increasing dietary concentrations of G. procumbens linearly reduced the excreta total anaerobic bacteria (d 28), Clostridium sp. and Escherichia coli (d 28 and 56) populations.

6. Overall egg production and egg mass were linearly increased, and overall feed efficiency was linearly improved with increase in dietary G. procumbens.

7. Dietary increasing concentrations of G. procumbens linearly improved egg yolk colour (d 28 and 56) and breaking strength of eggs (d 56).

8. The results obtained in the present experiment indicate that dietary supplementation with G. procumbens could reduce the egg yolk cholesterol, suppresses harmful excreta microflora and improves layers performance.  相似文献   

2. A circadian system was postulated to control the restriction of ovulation to an 8‐h period of the day under conventional 14 h light: 10 h dark regimes.

3. The final phase of follicular maturation was postulated to commence after ovulation of the preceding ovum in the hierarchy.

4. Ovulation was postulated to occur when a mature follicle was present in the ovary during the appropriate phase of the circadian‐linked system.

5. The predicted times of oviposition were within the standard error of the observed times of oviposition under 21‐, 24‐ and 28‐h photoschedules.

6. It was concluded that this hypothesis for the control of the ovulatory cycle of the hen is consistent with current knowledge.  相似文献   

2. Restricted birds were lighter throughout the experiment.

3. Relative adrenal weight tended to be greater in restricted birds but the difference decreased with time.

4. There was no depletion of adrenal cholesterol: from week 5 there was a significantly greater amount in the adrenals of restricted birds.

5. After 1 week of restriction plasma corticosterone concentration was 73% greater than in controls. It decreased progressively, falling within the normal range at 5 weeks.

6. Restricted birds were hypoglycaemic from weeks 2 to 7 and hyper‐lipacidaemic throughout. A negative correlation between plasma glucose and free fatty acids was found.  相似文献   

2. Resonances from adenosine triphosphate, phosphocreatine, inorganic phosphate and phosphorous storage protein were observed. These changed in relative intensity as the embryo developed.

3. No ill effects due to exposure to radiofrequency radiation or magnetic fields were observed.

4. It is concluded that topical magnetic resonance can make a useful contribution to the study of embryonic development in avian eggs.  相似文献   

2. Storage of uneviscerated Wrolstad turkeys at 4 °C for 10 days caused no statistically significant changes in meat flavour or texture.

3. During further storage at —2 °C, however, there was a slight but significant change in flavour, which became more marked with time in birds which had been eviscerated after the initial period at 4 °C.

4. Both eviscerated and uneviscerated birds became slightly tougher during storage.

5. Initial holding at 4 °C increased the numbers of psychrotrophic bacteria on the skin by about 10³ but subsequent changes at — 2 °C were slight for uneviscerated birds.

6. Eviscerated carcases had higher counts than uneviscerated birds after storage at — 2 °C and, although ‘off’ odours were not detected, spoilage appeared to be imminent at the end of the 20‐d period.  相似文献   

2. Addition of 10 g ascorbic acid/kg to the control diet (without excess tyrosine) produced no beneficial effects on performance. Excess dietary tyrosine caused depressions in all measures of performance.

3. Adding 0.1, 1, 10 or 20 g ascorbic acid/kg to the diet containing excess tyrosine tended to improve performance.

4. Subcutaneous injection of 50 mg ascorbic acid/bird d to chicks receiving excess tyrosine brought about a significant improvement in body‐weight gain.

5. The elevation of plasma free tyrosine caused by excess dietary tyrosine decreased as dietary ascorbic acid increased.

6. Ascorbic acid can alleviate, though not completely counteract, the adverse effect of excess dietary tyrosine.  相似文献   

2. In 4 consecutive trials, 4752 hens were recorded for keel bone status. Evaluation of plumage condition was made for 1440 hens and bone breaking strength was recorded for 1200 hens. A total of 4962 eggs were analysed for internal and external egg quality traits. Analyses involved 30 small group compartments per trial.

3. The layer line had a much more pronounced influence on humerus breaking strength than on tibia breaking strength.

4. Plumage condition, particularly on the neck, was positively correlated with humerus breaking strength in both layer lines.

5. An average of 34% of LB and 23% of LSL hens showed keel bone deformities, with higher proportions of slight deformities.

6. Slight keel bone deformities, rather than moderate to severe, increased significantly during the laying period.

7. Stocking density had no influence on bone breaking strength, keel bone status and egg quality traits.

8. LB layers had a 1.4-fold higher humerus, but only a 1.06-fold higher tibia breaking strength compared to LSL layers.

9. Tibia breaking strength was significantly affected by the interaction of group size and layer line. LSL layers in small groups had lower tibia breaking strengths than those of the large groups.  相似文献   

2. Dry plucking increased weight loss due to plucking and eviscerating, and reduced chilled carcass yield.

3. Dry eviscerating increased carcass water uptake during chilling.

4. Pre‐chilling with running water increased carcass water uptake compared with chilling in ice and water alone.

5. Water uptake during chilling appeared to be increased by longer eviscerating time.  相似文献   

2. Preparations from leg weakness cases displayed neither accelerated muscle fatigue nor decreased nerve conduction velocities as compared with control preparations.

3. The muscles of the TA‐treated turkeys but not of those with naturally occurring leg weakness were hyperexcitable relative to those of controls.

4. Post‐tetanic potentiation of preparations from both naturally occurring and experimentally‐induced cases of leg weakness was less than that of control preparations, both before and after partial neuromuscular blockade, significantly so at the lower pulse frequencies used.

5. It is tentatively suggested that the last finding might be of significance in explaining the clinical signs of leg weakness and might be associated with a disordered calcium metabolism.  相似文献   

2. During the rapid‐growth phase (yolk deposition) of the oocyte, i.e. an increase in size from about 9 mm diameter to 35 mm diameter, there is about a 15‐fold increase in its surface area. During this time the number of granulosa cells adjacent to the oocyte increases by about 5‐fold.

3. The granulosa cells become flatter during the growth period of the follicle, consequently increasing their surface area adjacent to the oocyte by about 3‐fold.

4. Together the change in shape of the granulosa cells and the increase in their number account for the increase in area of the granulosa layer during follicular growth.

5. Measurement of the DNA content of the granulosa layer indicated a progressive decrease in the cellular content of DNA as the follicle matures.  相似文献   

2. Increased mortality, perosis and other pathological changes involving a number of tissues were observed in birds fed on a low‐choline diet.

3. Methionine replaced part of the dietary requirement for choline at low dietary choline concentrations.

4. High dietary concentrations of choline (> 1 750 mg/kg) increased the requirement for dietary TSAA.

5. Increasing the dietary choline while maintaining the TSAA at an inadequate level may decrease performance.  相似文献   

2. Growth rate, food intake, food utilisation and proportion of dietary nitrogen retained were much poorer in chicks receiving salseed meal.

3. The chicks receiving salseed meal developed pathological lesions in liver and kidney.

4. The red blood cell count, white blood cell count, haemoglobin concentration and packed cell volume of the chicks receiving salseed meal were lower than those of chicks receiving maize.

5. The apparent metabolisable energy value of salseed meal was determined as 6.83 MJ/kg.  相似文献   

2. The different varieties of wheat investigated contained different proportions of water‐soluble to water‐insoluble hemicelluloses.

3. By comparison of the arabinose to xylose ratios it was concluded that water‐soluble and insoluble arabinoxylans of wheat were branched to the same degree.

4. Starch from six wheat varieties grown in the U.K. was very well digested by adult cockerels and true metabolisable energy values of the wheats were high.

5. Small amounts of cell wall carbohydrates were digested by adult cockerels.  相似文献   

2. The two experimental diets were maize or sorghum-based. In addition to the total bacteria, bacterial groups belonging to the Enterobacteriaceae (Enterococcus and Lactobacillus) were quantified by real-time PCR.

3. There were no differences in body weight gain and feed intake, but feed conversion ratio increased for sorghum-fed broilers at 21 and 42 d of age.

4. The Enterococcus group decreased in all gut segments from 7 to 42 d, while the Lactobacillus group increased in both ecosystems. In the ileal mucosa, the enterobacterial counts decreased from 7 to 42 d in the maize-based diet, but remained stable in the sorghum-based diet.

5. The results shed light on the spatial and temporal distribution of bacterial groups that play important physiological roles in the small intestine of chickens. Specifically, the increased Enterobacteria population in the ileum is consistent with the relatively poor feed conversion in sorghum-fed broilers.  相似文献   

2. Male and female day-old Ross 308 chicks were fed on a standard commercial diet containing 0, 2.5, 5 or 10 g/kg feed ground M. officinalis for 84 d before slaughter.

3. Weight gain and feed conversion ratio were significantly improved in the broilers receiving either 5 or 10 mg M. officinalis/kg feed.

4. Inclusion of M. officinalis did not affect muscle chemical and fatty acid composition.

5. On the basis of microbiological and sensory experimental data and subsequent extension of meat shelf life, M. officinalis did not reduce the microbial populations of the meat, but was effective in limiting lipid oxidation.  相似文献   

2. Protein content generally increased with age in all muscles and decreased in skin. Protein content in skin of males was always higher than that in females.

3. Moisture content in all muscles decreased with age. In the skin, moisture decreased with age considerably more in females than in males.

4. Fat content increased with age in all tissues, while ash content of breast, thigh and skin decreased with age.

5. Phosphorus, chloride, magnesium and potassium all decreased with age in all the tissues. Thigh and skin calcium content were affected by age, as was the sodium content of drumstick and skin.

6. The sex effect on the inorganic constituents was variable.  相似文献