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. As the bird aged, the percentage of cracked eggs increased (P <0.01) and the percentage of grade A eggs and WSM decreased (P <0.01). Cracks in dirty eggs (10.1%) were more than double those in all eggs laid (4.9%).
3. Seasonal effects on percentage cracked eggs and percentage grade A eggs were one‐third the magnitude of those due to age but were significant (P <0.05).
4. Variability in percentage cracked eggs, dirty eggs and WSM accounted for by the factors measured, were 72, 64 and 92% respectively.
5. The variability in WSM was significantly affected by percentage lay, food consumption and age but not by percentage cracked eggs, originally dirty and grade A eggs.
6. Flock management and climate inside the laying house each increased the amount of variability accounted for in the percentage cracked eggs and dirty eggs by at least 10%. 相似文献
2. A total of 200 Ross broiler breeder hens at 42 weeks of age were randomly divided into two groups: MS or control. Hens in the MS were fed 2 mg/hen/d CORT for 14 d. Eggs (648 and 635 eggs for MS and control, respectively) were collected from d 3 to 14 of dietary CORT supplementation and incubated. Weights of embryo, chicks and organs and body composition were determined during incubation and at hatch. Biochemical blood parameters were measured at internal pipping stage and day of hatch. Hatching performance and embryonic mortalities were recorded.
3. Hens fed a diet supplemented with CORT had lighter body weight and produced less eggs at the end of the 14-d treatment period. Although MS embryos were heavier than control from 12 to 18 d of incubation, chick weight was similar at the day of hatch. Lower relative weights for yolk sac and bursa were observed at 12 d of incubation for MS chicks compared to control. Chicks from both groups had similar body content in spite of higher fat content of MS embryos on d 18 of incubation.
4. MS had no effect on the duration of incubation or hatching performance but increased mortality at the pipping stage.
5. The results suggest that hormone-mediated MS might affect embryonic development during incubation without adverse effect on chick weight and body composition. 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
Only the growing ration containing 1.83 per cent magnesium significantly reduced growth, percentage bone ash and food utilisation during the growing phase (9–20 weeks). In the laying phase (20–40 weeks) significantly greater gains in body weight and percentage bone ash were produced by the birds which had received the growing ration containing 1.83 per cent magnesium.
The magnesium content of the growing rations had no effect on rate of lay, egg weight or egg shell thickness.
Hens fed the laying ration containing 1.96 per cent magnesium gained less body weight, laid fewer and lighter eggs and utilised their food less efficiently than those fed other levels of magnesium.
Egg production and food required per dozen eggs were poorer with the ration containing 1.20 per cent magnesium, but were not statistically different from the rations containing 0.48 or 0.70 per cent magnesium.
Eggs with thinner shells were produced by hens fed the 1.96 per cent magnesium ration at 34 weeks of age than were produced by those fed the 0.48 or 0.70 per cent magnesium rations. 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. Cracks were classified according to type (hole, star or straight) and the weight, shape, shell colour and specific gravity of all the eggs were measured. Shell thickness and dry shell weight were also recorded for a maximum of 10 intact and 10 cracked eggs from each sample.
3. The largest proportion of cracks were holes.
4. Differences in mean egg weight and shape of intact and cracked eggs within each sample were inconsistent. Mean shell colour was darker for the intact brown eggs than for the cracked ones. For all the samples, mean egg specific gravity, shell thickness and dry shell weight were higher for the intact eggs. The difference in egg specific gravity was significant (P<0.05) for all samples.
5. Holes occurred in eggs of lower mean weight but with better quality shells than those in which star or straight cracks occurred. 相似文献
2. Storage of eggs for 14 d caused a delay of 134 h in the mean total incubation period.
3. Female embryos hatched about 3 h earlier than males in the non‐stored eggs but there was no difference between the sexes in eggs stored for 14 d.
4. Rate of weight loss during incubation was similar in both non‐stored and stored eggs: there was no relationship between weight loss at 19 d incubation and total incubation period.
5. Hatchability of fertile eggs was 19.5% lower in eggs stored for 14 d and proportionately more embryos died between 4 d and 18 d incubation than in the non‐stored eggs. 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
2. In a subsequent experiment, hens of the 2 lines were inoculated with 0.1 ml of 2.50% suspension of SRBC, and eggs laid on days 10 to 13 after inoculation were incubated. Maternal antibody titres were determined in 15 and 18‐d embryos as well as in chicks at 0, 5, 10, 15, 20, and 25 d after hatch.
3. Dosage of SRBC had no effect on the antibody titres in line HA; however, the higher dosage elicited greater antibody titres than the lower dosage in line LA.
4. Maternal antibodies were detected earlier in chicks of line HA (eggs laid on days 7 to 9) than those of line LA (eggs laid on days 10 to 12) regardless of dosage administered to the hens.
5. In both lines, antibodies specific to SRBC were observed on day 15 of incubation, with the frequency of responders greatest at hatch. The high frequency of HA responders was maintained for 15 d after hatch, whereas there was an immediate decline with age in LA responders.
6. It was concluded that lines HA and LA have diverged in the pattern of maternal antibody levels as a result of the divergent selection for antibody response to SRBC. 相似文献
2. Each increase in the non‐productive period resulted in a gradual decrease in egg production but a gradual increase in the percentages of hatching eggs, fertility and hatchability.
3. There were no significant differences between hens fed on cracked grain for 2 or 3 weeks for any of the performance characteristics, except fertility and hatchability. The best fertility and hatchability were observed in hens fed on cracked grain for 3 weeks. 相似文献
2. The mutagen showed a non‐linear effect upon the hatchability, higher doses being less effective than small doses.
3. In the majority of cases, female embryos were more sensitive to the effect of ENU then male.
4. The mortality after hatching was also affected by ENU; the chicks from treated eggs surviving without food better than controls. 相似文献
2.?The ratio of chick to egg weight was 1·6% higher in the group given 30 mg threonine and at 28 d of age chicks receiving threonine were 29 to 79 g heavier than untreated controls.
3.?Food conversion ratio until 7 d after hatching was improved in those chicks receiving 10, 20 or 40 mg threonine but there was no significant effect on the activities of amylase, pepsin or trypsin.
4.?The humoral response to sheep red blood cells was significantly greater in those groups receiving 10, 20 or 30 mg threonine supplementation than in untreated controls.
5.?The response to phytohaemagglutinin-P, a measure of the cell-mediated immune response, was not affected, however.
6.?It is concluded that injections of 20 to 30 mg threonine into yolk sac can improve post-hatching growth and humoral responses of broiler chicks. 相似文献
2. The estimates of heritability for the frequency of cracked eggs ranged from 0.11 to 0.43, for egg number from 0.12 to 0.29 and for egg weight from 0.58 to 0.65.
3. The estimates of the genetic correlations between the traits were variable but in general showed no evidence of antagonism between a reduction in crack frequency and an increase in the production traits.
4. The efficiency of selection for reduction in the frequency of cracked eggs based on early measurements is briefly discussed. 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
There was a higher mortality in the pullets fed a ration containing 0.53 per cent lysine during the growing period. The mortality in the group fed the ration containing 0.42 per cent lysine from 7 to 22 weeks of age was the same as that of the control. There were no differences in mortality during the laying season that could be related to methods of rearing the pullets.
During the laying season, the highest rate of lay was obtained from hens which had been fed the ration containing 0.42 per cent lysine from 7 to 22 weeks of age. Hens fed on the ration containing 0.53 per cent lysine from o to 4, 8 or 12 weeks of age showed no improvement in rate of lay as compared with controls.
Hens fed the ration containing 0.42 per cent lysine from 7 to 22 weeks laid fewer small eggs at the beginning of the laying season than did hens receiving adequate amounts of lysine throughout or fed the ration containing 0.53 per cent lysine from o to 4, 8 or 12 weeks. The hens fed the latter ration laid smaller eggs throughout the laying season.
No differences were found between the fertility, hatchability or embryonic mortality of eggs obtained from hens fed on lysine deficient diets during growth and those fed on diets adequate in lysine. 相似文献
2. Villus height and perimeter increased 9 to 11 fold from day 14 of incubation until 7 d after hatching. Arbor Acres chicks had values which were consistently higher than Lohmann chicks.
3. DNA concentration of duodenal tissue increased with age in parallel to the increase in the number of enterocytes per villus. In the pre‐hatch period tissue activity as indicated by RNA/DNA, and ribosomal capacity as shown by the RNA/protein ratios, were high for both strains; values for Arbor Acres embryos and chicks were greater than for Lohmann.
4. DNA concentrations, RNA/DNA, RNA/protein and protein/DNA ratios correlate with morphological measurements and can be used as additional criteria for evaluating development in chick intestine.
5. In the last week of incubation and immediately after hatching, intestinal growth appears to arise mainly from cellular hyperplasia and not from cellular hypertrophy. Intestinal development patterns were similar for both strains but growth was more rapid in Arbor Acres chicks. 相似文献
2. Candling showed that there was a progressive increase in dark shadowing within the egg but fine details were not easily seen. Nevertheless candling is considered to be an important method of assessing development of ostrich eggs during incubation.
3. The ostrich embryo adopts a hatching position and follows a hatching sequence different from that of the fowl. During internal pipping, the air space is pulled towards the beak in the former but the beak moves to the air space in the latter. The right foot has an important role in breaking the shell during hatching.
4. The hatching process is considered to reflect an adaptation to the egg having a hard, brittle shell.
5. Malpositions in the ostrich may have been misinterpreted in the past because of the unusual hatching position. The commonest malposition described here was head‐in‐the‐small‐end. 相似文献
2. Chick diets had no significant effects on rearing or subsequent laying performance.
3. Food‐regulated pullets were 7% lighter than pullets given the DPM diet ad libitum at 18 weeks but consumed 12.5% less food; growing treatments had no significant effect on subsequent egg production.
4. Hens housed in shallow cages laid 10.3 eggs/bird‐housed more than those in deep cages, produced 3.8% greater egg mass, consumed 2.7% less food and produced fewer damaged (cracked, broken and hair‐cracked) eggs (P< 0.001).
5. DPM‐containing layer diets had no adverse effects on egg production, or mortality; with 100 g DPM/kg efficiency of food conversion (EFC) was better than with 0 or 200 g/kg (P< 0.001).
6. Reduction of the energy intake of L110R and L220R hens with diets containing 110 and 220 g DPM/kg by 8.2 and 9.0% respectively, reduced the number of eggs laid/hen‐housed by 6 and 10.7 but improved the EFG (P< 0.001); there was no significant interaction between cage shape and energy regulation. 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