2. Broiler chickens were electrically stunned with 81 mA per bird and then allocated to three treatments. About 67% experienced a VF at stunning and half of these birds were bled out before processing while the other half were processed without being bled out. The birds which did not experience a VF at stunning were bled out before being processed. The carcases were subjectively graded for haemorrhagic conditions.
3. Inducing a VF at stunning caused increases in the incidence of red wingtips and haemorrhaging at the humerus‐radius joint in the birds which were bled out. There were no other obvious effects of inducing a VF on carcase downgrading.
4. Failure to bleed the chickens which had a VF at stunning resulted in high incidences of red wingtips, red necks, haemorrhaging at the humerus‐radius joint and red sternal feather tracts. It was concluded that bleeding efficiency was important in influencing the expression of these characteristics when a VF occurred at stunning. 相似文献
2. On average the duration of apparent insensibility lasted between 53 and 59 s, and at 105 mA per bird it was as short as 22 s in the bird which showed the quickest recovery.
3. Increasing the stunning current had no effect on the duration of insensibility. 相似文献
2. Two replicates of broilers (age 54 and 59 d respectively) were stunned in carbon dioxide, in argon or by electric current, and the carcases were plucked either by a mechanical plucker or by hand.
3. Carcase and meat quality were evaluated to determine the effect of these stunning treatments and plucking methods. The quality factors measured included pH at 20 min post‐mortem, ultimate pH, texture and colour of the pectoralis major muscle, and the incidence of carcase appearance defects, cooking loss, broken bones and bruises in the breast and leg muscles.
4. Stunning method had a significant effect on pH at 20 min, ultimate pH, texture and colour of breast meat. Plucking method had a significant effect on the cooking loss and texture.
5. Argon stunning resulted in fewer muscle haemorrhages, a more rapid early post‐mortem fall in pH and more tender breast meat than in the electrically stunned broilers; carbon dioxide stunned broilers had intermediate values for pH decline and meat tenderness but were not significantly different from argon stunning regarding muscle haemorrhages.
6. Appearance defects occurred to a similar extent in all the stunning methods and mechanical plucking resulted in 4 times as many defects compared with hand plucking; the incidence of broken bones was higher in mechanically plucked broilers than in hand plucked carcases.
7. Gaseous stunning of broilers produced relatively better quality carcases and meat than electrical stunning, and therefore may have commercial advantages. 相似文献
2. High frequency stunning (1500 Hz) caused a reduction in the incidence of broken bones compared with 50 Hz.
3. Battery birds had a higher incidence of recently broken bones in comparison with perchery and free range birds. However, there were more old breaks in the perchery and free range systems than in the battery system.
4. Breed of bird, age at sexual maturity and age at culling had no effect on the incidence of broken bones. 相似文献
2. An additional 40 broilers were stunned either by anoxia or by constant current electrical stunning (107 mA 50Hz) and their eviscerated carcases held overnight at 1°C prior to filleting at 24 h postmortem.
3. All the breast muscles (pectoralis major) were cooked at 24 h postmortem and their texture measured. The results indicated that the mean texture of breasts from the different stunning and filleting time treatments were similar, and there were no significant differences between them.
4. It is concluded that stunning with anoxia followed by a rapid chilling would enable the broiler carcases to be filleted at 1 h postmortem with no adverse effect on the texture of the meat. 相似文献
2. Hens of the population with the high incidence of whitening appeared to be more fearful than hens of the population with the low incidence of whitening.
3. Brown colouration of the egg shell and the incidence and degree of shell whitening declined as the hens aged.
4. Brown colouration and egg shell whitening were most pronounced on the blunt ends of the eggs.
5. A large part of the variation in egg shell whitening was attributable to the individual (hen) component of variance.
6. Differences in egg shell whitening, between the two populations, were detectable throughout the 26 weeks of the experiment.
7. Oviposition intervals were similar for normal and coated eggs when birds were not exposed to disturbance.
8. Disturbance of hens increased oviposition intervals and the incidence and degree of shell whitening, to a similar extent, in both populations.
9. It is concluded that stress‐related egg retention is not the sole factor responsible for abnormal egg shell whitening. Shell whitening may occur as a consequence of the premature termination of shell pigmentation as well as a consequence of the retardation of oviposition which occurs when hens are disturbed. 相似文献
2. Over 95% of the frozen broilers from the supermarket company had broken bones and there were between 3 and 4 breaks per carcase. Only 3% of live birds had broken bones so most of the carcase damage must have been caused by processing.
3. The effect of 100, 200 and 300 V electrical stunning on the incidence of broken bones was investigated: increasing voltage resulted in an increase in the incidence of broken bones in the collar region. 相似文献
2. The meat samples were frozen at — 40° C and stored at — 20°C until they were thawed at 1°C and cooked at 85°C. They were subjected to sensory evaluation by 10 experienced assessors and instrumental texture measurements were made.
3. Only stunning method had significant effects on the sensory profile and instrumental texture. Breast meat from anoxia‐stunned turkeys was less firm on cutting, more tender and had a more powdery residue on eating than that from electrically‐stunned turkeys. The instrumental texture values confirmed that breast meat from anoxia‐stunned turkeys was more tender than that from the electrically‐stunned turkeys.
4. There was no significant correlation between the subjective tenderness rating and the instrumental texture value.
5. Principal components analysis showed that 59% of total variation was explained by the first two dimensions, the first being a contrast between turkeys that were tender and powdery and those that were firmer and fibrous. When values from individuals were plotted, this dimension was related to the differences between anoxia and electrical stunning, with anoxia‐stunned turkeys at the tender end of the first dimension. 相似文献
2. The production of double‐yolked eggs/100 hen d, high during the initial weeks of lay, rapidly declined and disappeared by 30 weeks of age.
3. The frequencies of broken, membranous and soft‐shelled eggs were significantly correlated with each other and with the frequency of multiple daily ovulations indicating a common aetiology for these defective egg types.
4. Double‐yolked eggs were produced by the heavier, earlier‐maturing pullets in the population.
5. Normal egg production in dwarf White Leghorns may be enhanced by reducing the incidence of defective eggs. 相似文献
2. Breast muscles (pectoralis major) were filleted at either 2, 3, 5 or 18 h post‐mortem, and pH and muscle temperature were measured at the time of filleting for the medium and large stags. The breast fillets removed soon after killing were stored at 3°C until transported to the laboratory.
3. All the breast fillets were cooked to an internal muscle temperature of 85°C and their texture was measured instrumentally. The fillets were weighed before and after cooking to determine the proportional cooking loss.
4. The results showed that, for electrical stunning, the rate of pH fall soon after killing differed between the bird types, and it resulted in a variable texture in the breast meat when filleting was performed soon after killing. The medium stags had a relatively slower rate of pH fall and filleting them soon after killing resulted in tougher breast meat.
5. By contrast, in all the three bird types, gas stunning resulted in a rapid pH fall soon after killing and produced tender breast meat at all the filleting times tested.
6. The cooking loss was higher in the large stags than in the medium stags or hens.
7. Stunning turkeys by anoxia or 30% carbon dioxide in argon would enable filleting to be performed soon after killing, and produce less variable‐and more tender breast meat. 相似文献
2. The shells of such eggs were thinner than those of intact eggs in seven of the populations.
3. The number of defective eggs, the specific gravity of the eggs, and the percentage hen‐day egg production of normal eggs were significantly correlated within populations with the incidence of broken eggs.
4. No significant correlations were found within populations between the incidence of egg breakage and either egg weight, body weight, or shank length. 相似文献
2. Higher rates of fertility and hatchability of Japanese quail eggs were observed from parents of 10 to 19 weeks of age, with peak fertility and hatchability at 14 and 12 weeks of age, respectively.
3. Sex ratios of 1:2 to 1:5 gave comparable fertility and hatchability results.
4. The hatching performance of quail eggs from cage and deep litter reared breeders was comparable.
5. Fertility and hatchability were directly proportional to the egg weight.
6. Quail egg shell colour, tints and blotches were found to influence hatching performance.
7. Storing quail eggs at 16 ± 2°C and 75 ± 5% relative humidity for more than 4 d reduced hatchability.
8. Hatchability of eggs stored at room temperature was improved if they were sealed in polyethylene bags.
9. Provision of light during the first 14 d of incubation resulted in a photo‐acceleration of about 3.2 h. 相似文献
2. Hyperphagia, amounting to twice the intake of control birds early in the experiment, occurred on the repletion day.
3. Final body weight attained 80% of that of the controls.
4. Body fat concentration decreased at first but returned to that of controls after 3 weeks.
5. A consistent hyperlipaemia was observed after food deprivation or restoration.
6. There was a marked increase in the digestive enzymes found in the small intestine, but not in the pancreas during the repletion day.
7. These responses may be considered as mechanisms to reduce the physiological manifestations of starvation. 相似文献
2. Salmonellae were not isolated from the empty, cleaned and fumigated houses and only on one occasion from the foodstuffs.
3. Salmonellae were isolated from the environment of the chicks and spasmodically from the litter, water troughs and dust.
4. The incidence of infection of the chicks did not influence the number of isolations of salmonellae from the environment of the birds during rearing.
5. Water in the water troughs rather than foodstuffs appeared to be the major oral route of infection or re‐infection of birds during rearing. 相似文献
2. Despite the absence of a control flock, this programme has demonstrated that selection in a broiler population can rapidly increase the incidence of TD.
3. There was consistent circumstantial evidence of the presence of a major sex‐linked gene, the recessive allele of which is associated with an increased incidence of TD.
4. The realised heritability estimates (obtained in the absence of a control flock) consistently exceeded 1.00, suggesting the presence of an environmental trend favourable to the onset of TD over the four generations of this investigation.
5. There was a high maternal component or dominance genetic component, or both, for the inheritance of TD in the final generation, suggesting that environmental factors associated with the female parent line may influence the incidence of TD in broilers. 相似文献
2. During the second and third weeks the incidence of tainted eggs exceeded 20% but fell to 11.4% during the final week.
3. Omission of the rapeseed meal from the diets halted the production of tainted eggs.
4. Neither egg production nor the health of the birds was adversely affected by the treatments.
5. The taint was described as “ fishy ” or “ crabby ” and was distinctive, but the source was not identified. 相似文献
2. Birds were housed either in hypobaric chambers simulating 1000, 1500 or 2200 m altitude or in pens at ambient atmospheric pressure and fed on diets containing 100 g/kg added fat as either an animal/vegetable (A/V) blend or flax oil.
3. Birds raised under hypobaric conditions had a decreased growth rate and increased mortality, blood haemoglobin content, and incidence of pulmonary hypertension and ascites compared to the groups at normal atmospheric pressure.
4. Broilers fed on the diet containing flax oil snowed no difference in growth rate or blood haemoglobin content compared to birds fed on the A/V fat diet raised at the same altitude.
5. Inclusion of flax oil in the diet decreased mortality and the incidence of ascites at 2200 m and pulmonary hypertension at 1500 m.
6. Flax oil may be an effective method of reducing ascites and pulmonary hypertension in broilers without affecting performance. 相似文献
2. Growth of both embryo and wing length during 42 d of incubation was comparable and approximately linear, with a more or less weekly doubling in size up to 35 d of incubation.
3. The embryo eye size increased more rapidly than beak length and reached a maximum of ~16.2 mm by 28 d of incubation, whereas beak length increased continuously until hatching at 42 d.
4. Linear regression equations were derived from morphometric measurements of embryos between 7 and 42 d.
5. Information stemming from these results can be used to estimate the age of dead-in-shell embryos in an attempt to identify timing of incubation problems that potentially result in low hatchability of fertile eggs. 相似文献
2. The inclusion of AA improved egg production, food intake and efficiency of utilisation, and decreased the cost of food per kg egg. The addition of 400 mg AA/kg diet gave the most efficient performance.
3. Palm oil inclusion reduced the effect of heat stress and increased egg production, egg weight, food intake and efficiency of utilisation.
4. When 200 mg AA and 50 g palm oil/kg were used, additive responses were obtained with further improvements in egg production, food cost and efficiency.
5. Ascorbic acid and palm oil when fed alone or in combination reduced the incidence of cracked eggs.
6. Thus, 400 mg ascorbic acid/kg of diet, 50 g palm oil or 200 mg AA plus 50 g palm oil/kg diet ameliorated the effects of heat stress in laying hens. 相似文献
2. The total number of yolks laid to 40 weeks was comparable with that of a control line selected for high egg number.
3. At peak production an F1 cross of the two inbred lines laid 140 yolks per hundred hens per day.
4. Double‐yolk selected lines when crossed produced hens with a 20% increased body weight.
5. By the 10th and 11th generations the incidence of eggs with three or four yolks was increasing. 相似文献