Artificial incubation provides the basis for the commercial poultry industry. With the increasing interest in captive propagation of exotic species, artificial incubation is becoming more prevalent in the exotic bird industry as well.
One aspect of egg handling and incubation is egg storage. Hatching eggs can be stored under appropriate conditions for a week or more prior to incubation without a loss in hatchability. Advantages derived from storing hatching eggs are increased efficiency of handling of eggs and chicks, improved opportunities for sanitizing eggs and equipment to reduce disease losses and control over time of hatching. Most information concerning length of storage comes from precocial species important to the poultry and gamebird industries. Since little or no information is available on the storage time of hatching eggs from altricial species common to the cage bird industry, research on storage of cockatiel eggs was begun in the Department of Avian Sciences.
A preliminary study suggested that the maximum storage time for cockatiel eggs prior to incubation was about 3-4 days, after which hatchability declined to less than 50%. This current study was undertaken to evaluate the storage time of cockatiel eggs under several test conditions.
Eggs from the Department’s flock of cockatiels were collected daily and marked with a felt tip marker to indicate the date each egg was laid. All cracked eggs were discarded. Immediately after collection and prior to storage eggs were fumigated using 1.22 ml formalin (37% formaldehyde) and 0.6 grams potassium permanganate per cu ft for 20 minutes.
Properly timed fumigation is an effective method to control egg shell borne disease. Fumigation of eggs between 24-84 hours of incubation has been shown to cause increased embryo mortality; so eggs should be fumigated prior to incubation or immediately upon setting. After fumigation the eggs were distributed into three treatment groups.
All eggs were placed small end down on cardboard egg flats. Treatment 1 eggs were not turned during storage. Treatment 2 eggs were turned 450 fm the vertical once per day. Treatment 3 eggs were bagged in self-sealing freezer bags and turned 450 from vertical once per day. The three groups were stored at a temperature and relative humidity of 55°F and 60 percent, respectively for 0-10 days prior to incubation.
Incubation took place in a Jamesway 252 incubator at a dry bulb temperature of 99.5°F and a humidity of 87.0°F wet bulb. The eggs were set in chicken trays modified to accommodate the small cockatiel eggs. Eggs were turned automatically every two hours.
At seven days of incubation, eggs were candled and all infertile and early dead embryos were removed for break out examination. On day fifteen of incubation, eggs were candled and any additional dead embryos were removed and examined. All eggs remaining after the second candling were transferred to the hatcher; a Lyon’s glass top incubator was used for this purpose.
Optimal conditions for hatching often differ from conditions used earlier during incubation. Temperature and humidity often should be changed and egg turning is no longer required. The hatcher for these cockatiel eggs was maintained at temperatures of 98°F and 88-90°F wet bulb. Eggs that failed to hatch by the 19th day of incubation were removed and examined. Infertile eggs, age at death, and embryonic abnormalities were recorded.
Figure 1 shows the hatchability data by treatment groups relative to storage time. There are no differences in hatchability between the treatment groups, perhaps reflecting sample size. However, hatchability decreased within treatment groups as storage time increased. Hatchability declined in treatments 1 and 2 after four days of storage. This decline in hatchability continued, ultimately reaching 0 at nine and ten days of storage, respectively.
Hatchability remained high in treatment 3 until after the sixth day of storage and did not decline to 0 as was observed in treatments 1 and 2. This demonstrated that bagging eggs during the storage period can successfully increase the storage time. Storage of the eggs in plastic bags appears to reduce the rate of dehydration and pH change due to CO2 loss through the shell.
Figures 2 and 3 represent embryonic mortality after 1 and 7 days of preincubation storage. No morphological abnormalities were found among the treatment groups. Embryonic mortality is represented as percent mortality (number dead/number survivors on that day) at a given age (days) of embryonic development.
Figure 2 demonstrates that there were essentially no differences among the treatment groups in the early (days 1-4) and late (days 17-19) mortality peaks. The mid peak (days 7-8) mortality associated with treatment 1 is unexpected and was not observed in the other treatment groups. Mortality during mid incubation is often associated with nutritional deficiencies in the hen’s diet, exposure of eggs or the laying hen to toxic materials, inbreeding or disease.
Figure 3 shows an increase in both the early and late mortality periods of treatment groups 1 and 2, resulting in a decline in hatchability. Treatment group 3 had a lower mortality in both periods than treatments 1 and 2. Although this was not statistically significant because of sample sizes, bagging appears to improve viability during storage.
Hatchability of cockatiel eggs declines after 4 days of preincubation storage. Bagging eggs in self-sealing plastic bags can reduce the loss of viability during the preincubation storage period.