Air velocities in the incubators varied from 0.08 to 3 m/s, depending on the location of the anemometer between the eggs, the turning position of the drum and the speed of the air stirrer. The air velocities were not affected by opening or closing the ventilation ports.
A direct effect of the air velocity on the hatchability could not be shown. When stirrer speeds of 60 and 120 rev/min (experiment A) and 120 and 180 rev/min (experiment B) were employed, the best hatching results were always obtained in the incubator with the highest stirrer speed. These differences were explained by the results of a number of temperature measurements which showed more accumulation of heat between the eggs when a lower stirrer speed was employed.
At 60 rev/min a significantly higher loss of weight was found between 5th and 18th day of hatching than at 120 rev/min. This difference was also explained by the presence of higher temperatures between the eggs at lower stirrer speeds. 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. 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. 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. Collecting eggs hourly rather than five hours after lay slightly reduced hatchability (P<0.10). Pre‐storage fumigation of almost un‐contaminated eggs had no effect on hatchability even after storage for 8 d. Storing eggs in unsealed polythene bags did not affect hatchability of eggs stored for 5 or 8 d.
3. Eggs stored for 2 d hatched better when held at 18 °C than at 15 °C (P<0.05). Eggs stored for 8 d at 15 °C hatched better than eggs stored for 8 d at 18 °C (P< 0.01). Best hatchability was in eggs stored in unsealed polythene bags at a room temperature of 15 °C. When older eggs were allowed 30 to 40 min more in the setter for each day of storage, the decline in hatchability was 0.5 to 0.6 percentage units per day in storage as compared with a decline of 1.2 percentage units per day when eggs of different storage times, up to 8 d, were set simultaneously.
4. Those eggs which showed a weight loss during incubation of near average for their relative humidity (RH) treatment tended to hatch better than others except under conditions of very low RH (0.36), when best hatchability was associated with lower than average weight loss.
5. In eggs from a young flock (28 to 44 weeks of age) hatchability of fertile eggs was depressed by 1 percentage unit with an increase in RH of 0.17, and by 1 percentage unit with each decrease of 0.06 in RH from a control RH of 0.53. In eggs from the same flock between 48 and 60 weeks of age hatchability was depressed by 1 percentage unit with each 0.037 increase in RH from 0.44 to 0.70.
6. Eggs from a young flock (34–49 weeks) hatched significantly better when maintained at 0.82 rather than at 0.66 (P<0.05) or 0.95 (P<0.10) RH during the hatching period from 19 to 21 d of incubation. Eggs from an older flock (51–61 weeks) hatched better at 0.82 and at 0.‐92 than at 0.72 RH during the same period, but the differences were not significant. 相似文献
2. A linear relationship was found between the area of a hole drilled and the apparent increase in eggshell gas conductance (G). Drilling more than one hole increased apparent G 3.6 times more than one hole only, of the same total area.
3. Hole‐drilling did not increase egg contamination. The drilling of a 5 mm2 hole on day 17 of incubation increased hatchability both in laboratory tests and in commercial hatcheries (6.1% and 10.5% respectively).
4. Drilling holes on days 15 to 22 of incubation increased hatchability when the predicted mean water loss was lower than 14%. Drilling on day 25 did not have a significant effect, and drilling on day 11 of incubation was too early.
5. Drilling a hole into the aircell (during the second half of incubation) may increase hatchability of low conductance eggs, although oxygen pressure under the eggshell should then be checked in order to evaluate oxygen availability to the embryo. 相似文献
2. The improvement in hatchability declined if the warming was carried out less often than every 3 d. 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