How Do Rhea Lay Eggs?
Ratite management is similar to both livestock and poultry management. Adults are hardy and are able to withstand most of Oregon’s weather challenges as long as they are protected from extremes.
Egg incubation often creates problems because most growers have little or no general knowledge of poultry and even less knowledge of incubation.
Like chicken, turkey, and other bird eggs, ratite eggs require constant incubation conditions for maximum hatchability.
Even minor variations can be detrimental. However, there has been little scientific research concerning the incubation and hatching of ratite eggs, so most current knowledge is from growers.
Length of incubation, temperature, and humidity suggestions vary greatly, so use the suggestions below only as guidelines.
Hatching time varies from 36–45 days for ostrich eggs, 46–56 days for emu eggs, and 36–44 days for rhea eggs.
Requirements for relative humidity during incubation also vary with species: 10–40 percent (usually around 20 percent) for ostrich eggs, 35–55 percent (usually around 40 percent) for emu eggs, and 40–55 percent (usually around 45 percent) for rhea eggs.
Virtually no standard exists for minimum acceptable level of fertility or hatchability in ratite eggs. Therefore, the determination of good versus poor fertility and hatchability is unknown. In most cases, if you obtain at least 50 percent hatchability of all eggs set, you probably are doing well.
Unless you intend to contract incubation and hatching with another producer, you’ll need a forced-draft incubator able to maintain a constant temperature of between 96 and 99.5°F. Temperature for incubating ratite eggs is around 96.5°F.
Incubators vary in cost and capacity. Some cost only about $500, while others cost more than $9,000. The incubators of choice seem to be on the extreme ends of the cost spectrum. Any incubator is adequate as long as optimal temperature, humidity, ventilation, turning, etc. can be maintained.
During incubation, most ostrich and rhea growers set eggs vertically in the incubator trays, with the blunt end up. Emu growers set eggs on their sides. Eggs must be turned at least 3 to 5 times per day and up to 12 to 24 times per day.
There is no conclusive evidence of the best position or turning times for ratite eggs. We have used poultry information here and modified it to provide a starting point for these species.
Three to 5 days before eggs are expected to hatch, transfer them to a separate incubator used only for hatching. Do not turn the eggs after transfer. A slight lowering of temperature (1°F) and an increase in relative humidity (5 to 10 percent) may be beneficial.
Ratite eggs need to lose between 10 and 18 percent of their weight (in moisture loss) to hatch properly. Most growers weigh eggs weekly to monitor water loss.
If the eggs are not losing the proper amount of moisture, you may need to change the relative humidity. Many producers maintain several incubators at different humidity levels and move eggs as needed. Others cover parts of the shell with tape or fingernail polish to reduce water loss, or sand away part of the shell to increase water loss.
These practices are easy with a few eggs, but become impractical when more eggs are produced. Their effectiveness is unproven. Many growers routinely wash eggs with water and sanitizers.
However, it is best not to wash eggs. Instead, set only nest clean eggs. If washing eggs is necessary, use only warm water (110–120°F) and approved hatching egg sanitizers.
Fumigation of eggs with formaldehyde gas is becoming rare due to health risks and government requirements, and, therefore, probably should not be used. Many growers use disinfectants prior to incubating.
It is important to follow instructions that come with these products to avoid potential disaster.
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