2. Four different rearing treatments with a subsequent constant 16‐h photoperiod during laying were used.
3. A 15‐h rearing photoperiod resulted in delayed sexual maturity, increased mature body weight and decreases in both total egg numbers and the proportion of smaller eggs, compared with a 6‐h photoperiod.
4. Continuous light to 56 d, although associated with a high incidence of subsequent blindness, resulted in satisfactory egg production.
5. Abrupt reduction in the photoperiod from 15 to 6 h for the 112 to 167 d period resulted in unsatisfactory subsequent performance, especially when the day‐length was only slowly increased to 16 h during laying.
6. In the two laying treatments, in which the photoperiod was increased gradually from 6 to 16 h during the 168 to 238‐d period, a decrease in the number of smaller eggs occurred, compared with the treatments in which a single abrupt increase in photoperiod was used. 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. Food consumption during the scotophase was negligible. Peak food consumption during the photoperiod occurred at the beginning of the photoperiod and in the late afternoon.
3. During the photoperiod, the crop and proventriculus/gizzard contained only small quantities of ingesta. However, at the beginning of the scotoperiod, dried ingesta content of crop and proventriculus/gizzard increased by 10.5‐ and 2.76‐fold respectively. This increase was followed by a gradual decrease towards the end of the scotoperiod.
4. Food transit time during the scotoperiod was significantly longer than that during the photoperiod.
5. The daily pattern of heat production closely followed the 14L:10D lighting schedule. Total heat production during darkness averaged 53% of total heat production during the photoperiod.
6. It was estimated that the storage of energy (as ingesta) in the crop and proventriculus/gizzard, followed by its gradual release and the increased food transit time during the night, contributed 75.5% of nocturnal energy needs. It must be recognised that these mechanisms play a major role in the energy balance of the growing chicken during periods without food intake. 相似文献
2. Mean oviposition time for both breeds was advanced relative to dusk by approximately 0.5 h for each 1 h extension of photoperiod.
3. Mean oviposition time for the brown egg hybrid was 1.2 to 1.4 h earlier than that of the white egg hybrid under each lighting regimen.
4. A genetic difference in phase setting of the Open Period for Luteinising Hormone (LH) release is the likely reason for the difference in mean time of lay of the two breeds. The difference is possibly one between brown and white hybrids generally, rather than between the particular varieties of hen used in this trial.
5. The proportion of the day in which eggs are laid is shorter under long photoperiods presumably because light at the end of the photoperiod inhibits the pre‐ovulatory surge of LH. 相似文献
2. Birds on the experimental lighting programme matured earlier than constant 8‐h controls, later than 11‐h controls but at the same age and body weight as constant 14‐h controls.
3. Weight of the first egg was correlated with age at first egg.
4. It is assumed that potential advances in maturity for the experimental birds from the 30 min increments in photoperiod were cancelled by the retarding influences of 6 h decreases in photoperiod, resulting in their maturity being similar to that of birds reared on a constant daylength equal to the longest photoperiod reached during the cycle. 相似文献
2. The data conformed to a mixed model and adjustments were made for the fixed effects sex, hatch date and location. Adjustment improved the precision of the estimates by reducing the error variances significantly.
3. Rearing equal numbers of birds from each family at different locations made the interactions negligible.
4. Weight gain was greater if illumination intensity up to 35 d was less.
5. Females were not heavier on the 1st day but were heavier on the 14th and 35th days than males.
6. Variance components and genetic parameters were estimated. 相似文献
2. Breeder hens fed ad libitum and subjected to either conventional or intermittent lighting ingested respectively, 25 g and 14 to 17 g more than hens restricted to 115 g/d.
3. Body weight was greater in hens fed ad libitum irrespective of the lighting pattern and of the amount of food intake.
4. Persistency of egg production was impaired by intermittent lighting.
5. Ad libitum feeding reduced egg fertility. The decrease was larger in breeder hens on intermittent lighting.
6. Hatchability was increased in hens submitted to the symmetrical lighting pattern (0.5L:3.5d).
7. Egg and chick weights were higher in hens fed ad libitum.
8. Shell index and shell breaking strength increased in restricted hens on the intermittent lighting pattern (0.5L:3.5d) × 6.
9. The best performance was obtained in restricted hens on the conventional lighting pattern. 相似文献
2. Rocking embryo cultures during the first half of incubation enhanced embryo growth.
3. Embryos explanted into ‘surrogate’ eggshells of either other individuals or other species have been successfully ‘hatched’.
4. A normal chorioallantois is formed in these surrogate eggshells. This enables a functional albumen sac to form and eggshell resorption to be achieved.
5. Embryos grown in ‘surrogate’ eggshells are slightly smaller than controls but otherwise normal.
6. The technique provides opportunities for genetic engineering experiments. 相似文献
2. Because the traditional method of determination of droppings digestibility coefficients of nitrogen may lead to systematic errors in estimating the feeding value of foodstuffs, a method is proposed to determine the ileal digestibility coefficients. The ileal method is compared with the droppings method for a mixed food and for two foodstuffs: wheat and solvent‐extracted soyabean meal.
3. Birds selected for efficient food conversion showed distinctly higher digestibility coefficients for all nutrients than birds selected for high growth potential or birds from a commercial strain.
4. The influence of age on digestibility coefficients was not consistent.
5. Female birds showed digestibility coefficients which were, in general, 3% higher than those of male chickens.
6. Interactions between genotype and sex and between genotype and age for energy metabolisability were the only interactions observed for digestibility measurements.
7. The method of determination influenced the amino acid digestibility coefficients of the mixed food and the relative feeding values of wheat and soyabean meal.
8. It is important to use well defined animals (genotype, sex, age) in evaluating foodstuffs.
9. The preferred method for determination of digestibility coefficients of nitrogen and amino acids is based on ileal sampling, although the differences in amino acid digestibility coefficients were small between methods. 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. Significant increases in plasma LH occurred following light stimulations at 6, 9 and 12 weeks of age.
3. Changes in LH concentration 7 d after a light increase from 8 h to 8, 10, 13, 16 h were highly correlated with photoperiod length at 9 and 12 weeks of age.
4. Changes in LH were generally poorly correlated with age at sexual maturity, although the reduced influence on age at first egg of a light increase given close to sexual maturity was reflected in minimal LH responses at 18 and 20.3 weeks. 相似文献
2. Replacing groundnut oil cake (GNC) by Niger oil cake (NC) on an isonitrogenous basis, did not affect egg production, egg weight or the amount of food required per dozen eggs.
3. The percentage retention of nitrogen from diets containing 30% GNC or 30% NC was similar.
4. The ME value of NC used was 3025 kcal/kg.
5. It is concluded that NC can replace GNC in layers’ diets. 相似文献
2. It was fed at 16 weeks of age to five separate groups (groups 2 to 6) each of 50 to 60 birds.
3. Group 2 was fed on a normal layers’ diet at 23 weeks of age, group 3 at 27 weeks, group 4 at 31 weeks, group 5 at 35 weeks and group 6 at 55 weeks while the control group (group 1) of similar size to groups 2 to 6 was subjected to a normal commercial treatment for laying stock.
4. In all the experimental groups the onset of sexual maturity occurred normally, but only one or two eggs were laid before laying ceased under the influence of the treatment.
5. Laying re‐started when the hens were fed on a normal diet and production rapidly rose to a high level.
6. Groups 1, 2 and 3 differed little in the total number of eggs produced up to 72 weeks of age.
7. In all experimental groups there were fewer very small, small and medium eggs than in the control group.
8. It is suggested that the use of a low‐calcium diet before the onset of lay may have advantages which could be exploited on a commercial scale. 相似文献
2. More eggs were produced per hen housed from 30 to 70 weeks in the shallow cages; the difference approached significance.
3. The pattern of feeding activity over the day was significantly more U‐shaped in the shallow cages; this pattern accords more closely with physiological requirements.
4. Feather damage caused by pecking was slightly but significantly more severe in the deep cages at 70 weeks.
5. The proportion of cracked eggs (collected from 60 to 70 weeks) was significantly lower in the shallow cages.
6. The arrangement of the hens was such that within the shallow cages a higher proportion of birds was present in the front half.
7. It is suggested that some of the advantages conferred by the shallow cage may be related to the greater accessibility of the food trough. 相似文献
2. The response in shell thickness to ahemeral lighting was more rapid (2.2 d) than for egg weight (4.2 d).
3. Differences between genotypes were evident in both the speed and magnitude of response.
4. Overall, egg weight and shell thickness on the 28‐h cycle were 7% and 8% greater than on 24 h.
5. The allometric increase indicates that the increase in shell weight was on average 14% more than the increase in egg weight. 相似文献
2. An Individual Poultry Weighing System (IPWS) was developed to record time, duration, location and body weight of visits of individual hens to 4 weighing scales.
3. The number of hens that visited the weighing scales per 3 h period varied from less than 10 during the dark‐period to more than 60 during the light‐period.
4. The average number of visits per individual hen was 1–4 and the average number of successful weighings per hen was 0–6 during the light‐period.
5. Body weight showed a diurnal rhythm: the difference between the maximum body weight at night and the minimum body weight in the morning was 63 g.
6. The location of the scales influenced number of visits, number of weighings, mean body weight, flock‐uniformity and duration of visits.
7. Body weight per 3 h period did not differ between hens which were individually recognised and those which were not.
8. Flock‐uniformity was 2–6% higher during the light‐period if it was based on weighings of identified hen visits.
9. The average duration of the visits to the scales in the middle of the feeding tier during the light‐period was 63 s.
10. Of all the hens that visited the scales during a 24 h period, 54% visited them only once.
11. Automatic weighing systems without individual hen recognition can deliver reliable management information on mean body weight and flock‐uniformity in aviary systems if the weighing scales are located on the feeding tier in the middle of the house and if they are used during the light‐period. 相似文献
2. Food intake and rate of consumption were two‐fold greater in broilers than in layers. The proportion of time spent feeding in the morning was lower in layers compared with broilers and was similar in the afternoon. Rate of consumption was higher in the morning than in the afternoon in both lines.
3. Overall, a similar proportion of time was spent feeding, standing and sitting in bodi lines. The birds were more likely to be sleeping (eyes closed) in the afternoon than in the morning.
4. The proportions of time spent on preening, pecking and stereotypic pacing were greater in layers than in broiler breeders. The proportion of time spent drinking tended to be higher in broiler breeders than layers.
5. Two measures of fearfulness, aversion to a looming human and a novel rod were respectively positively and negatively correlated to time drinking and stereotypic pacing.
6. The time spent in stereotypic pacing was negatively related to rate of consumption and time spent preening.
7. The results suggest that low food intake is associated with increased arousal, fear and frequent feeding and drinking. There was no evidence that beak related activity was related to fearfulness. 相似文献
2. Changes in plasma cholesterol were equivocal, though there was perhaps a trend towards hypercholesteraemia.
3. Birds became hypoglycaemic within an hour but were hyper‐glycaemic between 2 and 4 h. At 24 h they were normoglycaemic.
4. Plasma corticosterone was increased markedly at 1 h but was decreased compared with the control at 2 h (P<0.01). Thereafter the concentration was in the normal range.
5. There was an enhanced hyperlipacidaemia in the treated birds after 1 h.
6. Adrenal cholesterol stores were decreased by 10% at 4 h but were unaffected at all other times.
7. Colonic temperature decreased by 1–6 °C after 2 h but was normal by4h.
8. It is concluded that propranolol has mild stressor activity which is lost within 24 h. 相似文献
2. Very large egg batches are required to detect small improvements in the hatchability of good hatching strains.
3. Small‐scale laboratory studies on hatchability are best confined to strains and species of low hatchability in which larger between‐treatment differences may be expected.
4. The results of hatchability studies should always be subjected to tests of statistical significance.
5. There is a strong case for studying continuous variates in the laboratory before proceeding to large‐scale hatchability studies. 相似文献