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. Dietary rapeseed had no effect on the onset of lay when fed from 17 weeks of age but caused a delay when fed from 10 weeks of age: changing to a control soyabean diet for the laying period resulted in normal egg production.
3. Diets containing B. napus but not B. campestris consistently depressed egg production and reduced egg weight in one experiment. Mustard seed meal did not affect performance.
4. Significant number of eggs with a “fishy” taint were laid by brown‐egged birds fed on a diet containing rapeseed.
5. Thyroids of birds fed on rapeseed meal diets during the laying period were significantly heavier than those of birds fed on diets containing mustard seed or soyabean.
6. The enlargement of the thyroid gland is probably related to the oxazolidinethione content of the rapeseed. 相似文献
2. Storage of eggs caused shrinkage of the blastoderm. The amount of shrinkage tended to decrease with parental age.
3. The developmental age of embryos after 42‐h incubation increased with parental age but was reduced by storage, with embryos in eggs from middle‐aged birds (35 to 40 weeks of age) being least retarded.
4. The rate of development in fresh eggs increased with parental age. Storage reduced the rate of development equally at all flock ages.
5. The number of malformed embryos increased with storage time. After 14‐d storage there were fewer abnormalities in eggs from birds between 31 and 49 weeks of age than in younger or older birds. 相似文献
2. At 10 weeks of age the birds exposed to “dawn” and “dusk” were significantly heavier than those exposed to 12 h uniform illumination and these were heavier than those in continuous light.
3. From 15 to 25 weeks of age the birds in continuous light showed a marked diurnal rhythm in food intake, eating most in the period corresponding to normal daytime, while all birds subjected to 12‐h photo‐periods ate most at the end of the day, apparently having learnt to anticipate when their day would end.
4. When the birds subjected to continuous light were given one of the two 12‐h photoperiods, those given 12 h of uniform light intensity started by eating most food in the mornings, but later ate more towards the end of the day, while those with the “dawn” and “dusk”, ate more food at the end of the day during most of the 20‐d experimental period.
5. It is concluded that the birds preferred to eat most at the end of the day, probably to ensure adequate stores of food in the crop during the night. However, it was necessary for them to learn when their day would end, and this they did much sooner with the presence of a “dusk” than without it.
6. It is suggested that the difference in growth rate among the three treatments can be accounted for by differences in the efficiency of food conversion and also by differences in food intake. 相似文献
2. The decrease in hatchability that occurred on the high protein (27.0 g CP), low energy (1.52 MJ AME) allowance from 26 to 36 weeks of age was due to an increase in the percentage of dead embryos in the second week of incubation and an increase in the number of “pipped” eggs at the end of incubation.
3. The low hatchability of eggs from birds on the 1.88 MJ AME allowance from 37 to 64 weeks could be related to the incidence of deaths in the first 5 d of the incubation period.
4. Malformations and malpositions of the embryo were not affected by maternal energy or protein allowance. 相似文献
2. The experimental diets, containing two concentrations (50 or 100 g/kg) of high‐ or low‐glucosinolate rapeseed meal and a diet, devoid of rapeseed meal, all supplemented with 0.3 mg I/kg were given to laying hens for 6 weeks before oral administration of 125I daily for 11d.
3. The percentage of 125I transferred to egg yolk was significantly reduced by the inclusion of high‐glucosinolate rapeseed meal but not by low‐glucosinolate meal.
4. Determination of the total iodine content of egg yolk indicated that there was some reduction in the transfer of dietary iodine to eggs even with the low glucosinolate rapeseed meal. 相似文献
The mustard seed meal and rapeseed meals D and E caused large and significant mortalities among laying birds. Macroscopic observations suggested that the main cause of death was probably liver haemorrhage.
Egg production, after correction for mortality, was significantly decreased by rapeseed meals D and E, and egg weight by the mustard seed meal. There were no significant treatment effects on food intake and therefore the weight of food needed for each egg produced followed fairly closely the pattern of egg production.
Overall egg production was depressed by mustard seed meal and by rapeseed meals D and E. Rapeseed meal C decreased production but not significantly.
Liver weights were not influenced by treatment, but thyroid weights of groups given rapeseed meals were significantly increased.
Broiler production was not significantly influenced either by mustard seed meal or by any of the rapeseed meals. 相似文献
2. The taint was due to the inclusion of either 25 or 70 g Icelandic capelin fishmeal/kg of the diet.
3. Babcock hens produced significantly more (17%) tainted eggs than Warrens (1.2%).
4. Tainted eggs were significantly reduced to a very low proportion (1.3%) by the third day of feeding a fishmeal‐free diet.
5. The taint was due to the presence of up to 17 mg/trimethylamine kg in affected eggs. 相似文献
2. All treatments that can be characterised as being less optimal for embryo survival than the control treatment affected the hatchability of fertile eggs more in the case of eggs produced by older birds.
3. A higher temperature in the nest box, longer storage periods, higher storage temperature, especially at longer storage periods, and higher pre‐setting temperature significantly reduced the hatchability of fertile eggs from the older birds.
4. For the younger birds, a significant reduction of hatchability was found only for the longest storage period. 相似文献
2. Genetic tests have demonstrated that tainting in these circumstances is conditional on the presence in the hen, in the heterozygous or homozygous state, of an autosomal semi‐dominant mutant gene that has variable expression, depending on environmental factors (including the rate of ingestion of rapeseed meal).
3. No simple test for the presence of this gene, applicable to either sex, can be anticipated at present. 相似文献
2. Hatchability was only 37.2% and the result of high rates of infertility and contamination (22.2% and 22.8% respectively); it varied between eggs from different farms.
3. Embryonic mortality was high at the start and end of incubation, a pattern similar to that of other domestic birds.
4. Mortality of late stage embryos was related to percentage water loss and mass specific water vapour conductance of the shell, with extremes of the ranges causing the highest mortality.
5. Microbial contamination of the eggs was a significant problem and varied in eggs from different farms indicating that more attention is needed in both breeder bird and nest management. 相似文献
2. Food intake restriction ranged from 22% in birds fed only in the morning to 13% in birds fed twice daily. However, egg production of birds fed twice daily was only marginally reduced compared with control birds. Giving free access to food from 69 to 84 weeks increased the total 20 to 84‐week egg production of the latter birds to greater than that of controls.
3. Birds fed only in the evening ate more and laid more and heavier eggs than birds fed only in the morning. However, a high proportion of the eggs from these former birds were laid in the evening.
4. The only anatomical adaptation to meal feeding was the larger crops observed in both groups of birds given one meal daily. 相似文献
2. Hens under continuous illumination lay eggs at quite regular intervals. With highly productive pullets and a limited period of observation (e.g. 10 weeks), many birds lay unbroken sequences (i.e. intervals between consecutive ovipositions do not exceed 33 h).
3. Some birds under continuous light lay eggs in clutches (i.e. one observes characteristic inter‐clutch intervals of 35 to 41 h between ovipositions). However, the first egg of a new clutch has a high probability of being laid between 05.00 h and 16.00 h and this is taken as evidence that the timing of clutches is dependent on diurnal environmental influences which persist in spite of attempts to provide a non‐varying environment.
4. The evidence available neither supports nor refutes the hypothesis that under constant environmental conditions an internal “ clock “ with a fixed period is responsible for timing the open periods during which release of luteinising hormone may occur.
5. Further experiments are needed with hens having a lower rate of lay, and therefore more likely to lay in clutches, maintained in a better‐controlled constant environment. 相似文献
2. The volume of water taken up by eggs that had been sanitised was significantly (P < 0.001) greater than that taken up by the control eggs. The volume of water taken up by the sanitised eggs increased as the flock age increased, whereas water uptake was maximal for the control eggs at 42 weeks of age.
3. There was no correlation between water uptake values and shell thickness or egg weight for either the sanitised or control eggs.
4. Sanitised eggs tended to dominate the “poor cuticle quality” category at all flock ages, when a subjective assessment of cuticle quality was made using the stain Edicol Supra Pea Green.
5. Egg sanitising did not affect shell reflectance values, shell thickness or the percentage of cracked shells.
6. When flock age reached 49 weeks of age, the sanitising process significantly (P < 0.001) reduced hatchability. 相似文献
2. A and B malformations are those seen in, respectively, an egg that is held in the shell gland for an abnormally long period and one that reaches the shell gland while an A‐egg is still there; many of the eggs recorded as rough‐shelled were probably A‐eggs for which the corresponding B‐eggs had been lost.
3. The birds were of three strains: a medium‐body‐weight brown‐egg‐laying strain and a White Leghorn strain, both of commercial origin, and a laboratory strain of Brown Leghorns.
4. The incidences of egg malformation in the three strains were 8.3, 9.2 and 0.5%.
5. A‐, B‐ and rough‐shelled eggs constituted more than two‐thirds of all malformed eggs.
6. Evidence from two generations suggests that these malformations have a high heritability. 相似文献
2. In the first experiment the diets contained 0, 8 (with and without supplementary methionine, lysine, or methionine and lysine) or 16% lupin meal: addition of the lupin meal required a concomitant addition of 5 % rapeseed meal (by computer selection).
3. The diets were fed from 38 to 65 d and did not affect live‐weight but the efficiency of food utilisation was significantly worse on the 16 % lupin, 5% rapeseed meal diet than it was on the control diet.
4. The second experiment was designed as a 2 x 4 factorial to separate any effect due to rapeseed meal from that due to lupin meal, the treatments, which were applied from 1 to 62 d, being 0, 8, 16 and 24% lupin meal with and without 5 % rapeseed meal.
5. Birds gained more rapidly in the second experiment on diets containing 16 or 24% lupin meal whereas live‐weight was depressed when 5% rapeseed meal was included in the diets containing 0 or 8% lupin.
6. The 16 and 24% lupin treatments also had added dietary fat from 6 to 9 weeks of age and this may have ameliorated the adverse effect of rapeseed meal.
7. Up to 16% lupin meal and 5% rapeseed meal had no detectable effect on the colour, appearance, flavour or texture of roasted chicken meat when evaluated by a trained taste panel. 相似文献
2. A similar diet containing rapeseed meal (200 g/kg) prepared from the new Canadian variety Tower did not depress egg production when compared with the soyabean meal diet. Compared with the diet containing the British meal, that containing Tower meal caused fewer deaths from liver haemorrhage and it caused enlarged thyroid glands, but to a much smaller degree. However, it did cause the production of as many tainted eggs as did the diet containing the British meal. 相似文献
2. The daily heat production of fed birds was significantly increased if feathers were removed from the entire neck plus breast region but not if the neck only or breast only were denuded.
3. Removal of feathers from the neck plus breast led to a 10% increase in food consumption.
4. The partially‐defeathered birds laid more eggs. 相似文献
2. The application of the 28‐h cycle did not affect mean rate of lay but increased mean egg weight and egg output.
3. Grouping the birds according to their preliminary sequence length yielded an interesting outcome. In both rooms, birds with short sequences (≤ 6 eggs) produced significantly more eggs under the 28‐h cycle, while those with long sequences (> 6 eggs) produced marginally fewer eggs. The same trend was also evident with egg output.
4. Changing from 24‐h to 28‐h increased yolk and albumen weights as well as shell quality. However, relative to egg weight, no measurable effect was detected due to light cycle, age or sequence length on yolk and albumen weights.
5. The paper provides new evidence suggesting that long ahemeral cycles could be used to improve egg production as well as shell thickness in flocks with modest rates of lay. 相似文献
2. Eggs with extremely low, average and extremely high yolk ratio were chosen for further investigation (n = 350 in each group in both genotypes). After incubating the selected eggs, hatched birds were reared and slaughtered at 11 weeks of age.
3. The yolk ratio of eggs significantly affected the body composition of the chickens at hatching and during rearing to 8–9 weeks of age.
4. Chickens of a genotype selected partly for weight gain had significantly higher live weight from hatching to the end of the rearing period and had better slaughter characteristics than those of the dual purpose TETRA-H genotype.
5. At hatching, only the dry matter content of the body was affected by the gender of the birds. The effect of gender on the live weight and body composition of chickens was evident from the 5th week of age to the time of slaughter.
6. It was concluded that eggs with a low yolk ratio were most beneficial for broiler production, because chickens hatched from these eggs had the highest slaughter weight and muscle index and the lowest fat index for their body mass. 相似文献