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
2. Based on the variance of the full‐sib family means, the heritability estimates for pure‐bred, cross‐bred and for the combined data were 0.lb186 ± 0.lb105, 0.lb065 + 0.lb021 and 0.lb088 + 0.lb005, respectively: the results showed absence of non‐additive genetic variance for hatchability.
3. Fertility was influenced more by sire strain than by the dam while hatchability was primarily influenced by the dam strain.
4. The sire x dam interaction effect was significant for fertility but not for hatchability.
5. Fertility was influenced by crossing two divergent strains. 相似文献
2. 18% to 21% of eggs in each batch were contaminated with bacteria and fungi, with the latter being found more often in eggs which contained more advanced embryos.
3. Although infertility and prolonged storage reduced hatchability, the high inci dence of microbial contamination in ostrich eggs is deemed to be a significant problem.
4. Improving nest hygiene is considered to be the simplest way to reduce microbial spoilage. 相似文献
The aim of this experiment was to determine the profit returned at 12 weeks by broiler chickens hatched from eggs ranging in weight from 44 g. to 58 g. at one gram intervals and to determine how competitive and separate rearing might modify the relationship.
A total of 6000 eggs were collected during 10 days from a 28‐week‐old, broiler breeding flock and graded into the above mentioned egg weight classes. From these, a total of 3480 day‐old broilers were housed. Each egg weight class was equally represented and balanced for sex.
Hatchability and fertility showed no consistent trend with egg weight for eggs above 46 g., but below the 47 g. level there was a trend of declining fertility and hatchability.
A strong positive relationship was found between the weight of the chick at 1 day of age and egg weight for both males and females with no significant difference overall in body weight between the two sexes.
Body weight to 12 weeks was found to be strongly related to egg weight, in a linear fashion, though this influence declined with age.
There was a greater influence of egg weight on body weight at all ages in the separate rearing treatment compared with competitive rearing but this was not significant after 10 weeks.
Egg weight had an important bearing on body weight and profit at 12 weeks, but no effect on food conversion or mortality.
The increased profit over food costs per 100 day‐old chicks was found to be 52.75 cents for the separately reared birds respectively for each 3 g. increase in egg weight. 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. Also, in an aseptic laboratory trial, eggs from Large White turkey hens were injected with 0.2 ml of saline solution and 0.2 ml of saline solution containing 600 μg of pyridoxine hydrocholoride.
3. In field trials, hatchability of pyridoxine‐injected eggs was 4.6% higher (P<0.05) than the control (non‐injected) eggs.
4. In the aseptic laboratory trial, hatchability of pyridoxine‐injected eggs was 4.2% higher (P<0.05) than saline‐injected and control (non‐injected) eggs. 相似文献
2. Using one of these methods a survey was conducted on eggs which had failed to hatch from commercial hatcheries.
3. An assessment of the level of contamination in the eggs examined indicated an average level of contamination of 12.7%.
4. The contaminating flora was composed mainly of Micrococcus sp. and Enterobacteriaceae, with Streptococcus sp., Staphylococcus sp., Bacillus sp. and Pseudomonas sp. present at lower levels.
5. Various interrelationships between contamination and hatchability are discussed. 相似文献
2. There were no significant differences between egg types in terms of egg shape index, eggshell strength and thickness, albumen height, Haugh unit, yolk colour, weight of the eggshell with or without membranes, calcium, phosphorus, copper and manganese contents in the eggshell (with the inner and outer membranes or without the inner membrane), albumen weight, dry matter of albumen, crude protein (CP) of thick albumen and pH of the thick albumen.
3. The weight of eggshells with membranes, weight of thick albumen and CP of thin albumen in striped eggs were lower than those in normal eggs.
4. The thin albumen in striped eggs was heavier than that in normal eggs. The pH of the thin albumin in striped egg was significantly higher than that in normal eggs.
5. There were no significant differences in EW loss during incubation or duckling weight between striped and normal eggs. However, the hatchability of striped eggs was lower.
6. The lower weight of the eggshell inner membrane and thick albumen, lower CP content and higher pH in the thin albumen of striped eggs might contribute to lower hatchability. 相似文献
2. These eggs were stored at room temperature (27°C‐31°C) or in an air‐conditioned room (20°C‐23°C), for two, three, six or seven days and incubated in four replicate hatches.
3. Eggs kept SEU improved hatchability even for short‐term storage when temperatures were high.
4. Simple air‐conditioning can reduce the temperature sufficiently for the viability of the embryo to be preserved for up to a week. 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. Eggs were collected over 21 d and the collected eggs were stored at 10° to 12°C and relative humidity of 70 to 80% until they were set together on d 21. Fertility and hatchability of fertile eggs were calculated for each d of collection to study their relationships with age of eggs (length of storage).
3. The hatchability of fertile eggs was considerably different between the two lines in the average over 21 d and, more importantly, in the pattern of decline with length of storage.
4. In the first 3 to 4 d of storage, hatchability was very similar between the lines. However, it decreased linearly at a rate of 1.9% per day of storage over the 21‐d period in the ASS line (average 65.9%), whereas in the AS line (average 78.6%), it stayed at around 84% up to 12 d of storage, when it started to decline at a similar rate as in the ASS line.
5. Fertility was 2.6% higher in the AS line than in the ASS line, but in each line showed no significant trend with age of eggs. 相似文献
2. Mass specific eggshell water vapour conductance, Gsp, increased by approximately 50% over about 13 weeks during the winter breeding cycle. A similar increase occurred over 8 weeks during summer.
3. Constant setting of humidity in goose incubators and changes in mean Gsp may cause sub‐optimal egg water loss which increases late mortality.
4. Mean Gsp was measured for every batch from each flock. Humidity was changed accordingly in order to reach optimal water loss. A significant improvement of 6% in hatchability and of 8% in Class‐A goslings was noted during 14 successive weeks compared with the previous 11 weeks.
5. Dynamic humidity control for optimising water loss according to mean batch Gsp thus increases hatchability. 相似文献
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. 相似文献
2. Oiling slowed the decline in albumen height (Haugh units) to that which occurred in unoiled eggs stored at 12 °C.
3. Oiling slowed the increase in albumen pH equally at 28 and 12 °C.
4. Oiling markedly decreased the weight loss of eggs stored at either temperature.
5. Oiling and temperature of storage were without effect on the whipping volumes of either albumen or unseparated albumen and yolk. 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. Cooling to 22°C for 24 h on days 14, 15, 16, 17 or 18 yielded similar results but cooling on day 13 increased late embryonic mortality.
3. When eggs were cooled to 22°C on day 16 of incubation there were no major differences in hatchability up to 48 h of cooling but chick quality deteriorated rapidly after 30 h and the limit for embryonic survival at this temperature was about 72 h.
4. There were no significant differences when eggs were cooled on day 16 and held for 24 h at 21.1, 23.9 or 26.7°C but hatchability and late deaths were significantly affected by cooling to 18.3°C. 相似文献
2. No significant differences were found between genetic groups in hatchability.
3. Groups containing the fast‐hatching line genotypes were significantly smaller in egg weight than those not containing this line.
4. Significant differences in hatching time existed between male lines and between female lines within pure and cross‐line parent types while no differences were observed between the female parent types and no interactions of male by female lines occurred.
5. It was concluded that inbreeding in the pure lines (10%) did not affect any of the variables measured.
6. The results on hatching time support the conclusion that little genetic variance other than additive variance is involved for this trait. 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. Eggs laid between 05.00 and 11.00 h had higher fertility than eggs laid between 11.00 and 17.00 h.
3. Hatchability of fertile eggs was highest in eggs laid between 05.00 and 08.00 h. Hatchability decreased progressively for eggs laid later in the day.
4. It may be more economic to use eggs laid from 14.00 to 17.00 h as table eggs rather than hatching eggs. 相似文献