B-6092 5-00 Incubating and Hatching Eggs Incubating and Hatching Eggs A. Lee Cartwright* ggs of exotic birds and common Most eggs are laid by mid-morning. Eggs Echickens require a standard measure should be collected several times a day to of care in storage and incubation to reduce the amount of time eggs remain in the ensure a successful hatch. Environmental nest. This practice decreases the number of conditions, handling, sanitation and record cracked and soiled eggs and also prevents keeping can impact the success of incubating premature incubation. Embryos begin to and hatching eggs. prematurely develop at temperatures above 72 degrees F. Starting and stopping embryo Fertile Egg Quality development by repeatedly changing tem- peratures increases embryo death. Frequent From the smallest canary eggs to the collection and proper storage delays embryo largest ostrich eggs, high quality fertile eggs development until egg incubation can begin. should always be considered rare and fragile. To successfully hatch eggs, begin with fresh, clean, fertile eggs. Storing Fertile Eggs Eggs can be produced “on site” or pur- Fertile eggs are alive. Each egg contains a chased from many sources. Commercial living cell mass that develops into an em- hatcheries will ensure good fertility, but often bryo, and finally into a chick. Each incidence will not ship small quantities of eggs. of improper handling reduces the probability of a successful hatch. Fertile eggs usually are Eggs easily transmit contagious diseases gathered over a period of time before an between flocks. Therefore, to ensure adequate number of eggs can accumulate for protection from such diseases, purchase incubation, or until the incubator is available eggs from only National Poultry Improve- for a new set of eggs. These normal situations ment Plan (NPIP) or equivalent surveyed require that, before incubation, eggs must be facilities. Every egg producer should be stored properly to ensure hatchability. NPIP tested; further information can be obtained from Texas A&M University NPIP Cleaning and culling—Cracked, poorly at (979) 845-4186. shaped, soiled and unusually large or small eggs should not be incubated. These eggs If eggs are purchased by mail order, it is rarely hatch and they increase the probability important to ensure that the eggs receive of introducing infection into the incubator. proper care in transit. Extremes of tempera- ture and poor handling can destroy prospects Eggs should not be washed. Washing or for a good hatch. wiping with a damp cloth removes a protec- tive layer that coats the egg. Soiled eggs If fertile eggs are produced “on site” at the should be cleaned by gently buffing the business location, the breeding stock must be soiled area with fine sandpaper. Washing maintained and supported for maximum eggs transfers disease infection agents from health and fertility. Basic egg production is the surface to the inside of the eggs. severely affected by day length and lighting control. Egg quality and embryo livability are If an egg is washed, it should be washed affected by hen and sire age, health, nutri- briefly in 110-degree F water that contains a tion, cock/hen ratio, breeder genetics, and commercial egg sanitizer. Washing an egg in other factors that can stress birds such as the water that is cooler than the egg itself causes weather. Keeping more than four females per egg contents to contract. Contraction of egg male can reduce fertility in some settings. contents draws water into the egg through Inbreeding, the mating of closely related pores in the shell. This water carries infecting males and females, might decrease fertility of microorganisms into the egg. eggs and increase embryo mortality. Hatch- General care—After clean and undam- ability of eggs is severely harmed by inbreed- aged eggs have been selected for incubation, ing, age and poor health. use great care to prevent damage or contami- nation of the eggshells. This includes using * Extension Poultry Specialist, The Texas A&M Univer- frequent hand washing as a barrier to micro- sity System. bial contamination. Storage time—Ideally, eggs should be set humidity in an incubator. Relative humidity in the incubator as soon after gathering as is expressed as a percentage while wet bulb possible to maintain egg quality. If eggs are temperature is expressed as degrees. to be stored before incubation, the best A wet bulb thermometer can be purchased hatchability occurs when eggs are stored for or made from a common dry thermometer. less than 7 days from the time they were laid. Knowing how to make a wet bulb thermom- However, some species are more sensitive to eter helps to understand how it works. A storage than other species. Hatchability thermometer, a shoelace (approximately a 6- decreases rapidly in eggs held in storage for inch long piece) and a short piece of dental more than 10 days. Storing eggs longer than floss are needed. First, stick the bulb end of 2 weeks also can extend the normal incuba- the thermometer about 1 inch into the hollow tion time as much as 1 day. of the shoelace. Next, tie a piece of dental Temperature and humidity during floss around both the shoelace and thermom- storage—Fertile eggs should be stored at a eter directly above the bulb. This is to keep dry bulb, normal temperature between 55 the shoelace from sliding off. Place the degrees F and 65 degrees F, or 13 degrees C opposite end of the shoelace directly in a pan and 18 degrees C. Embryos will begin to of water. If the water is the same temperature develop abnormally, weaken and die if the as the air temperature, the reading on the temperature is too high. A low temperature thermometer is the wet bulb temperature. also causes high embryo mortality. Storage The temperature reading of the wet bulb will temperature should never exceed 72 degrees be less than a dry thermometer because F (22 degrees C) and never go below 46 evaporation of water cools the thermometer. degrees F (8 degrees C). Egg storage at room However, the reading also will be influ- temperature or at normal refrigerator tem- enced by the relative humidity of the air. The peratures (32 degrees F to 40 degrees F) is not wet bulb reading is used as an index of acceptable because hatchability decreases. relative humidity but is not numerically A refrigerator can be used to store eggs if equal to the relative humidity value. The wet the temperature is properly adjusted to the bulb temperature will change at different dry recommended temperatures. Eggs should be bulb temperatures even as the relative stored in a refrigerator dedicated to egg humidity remains constant. So, the appropri- storage because these temperatures are not ate wet bulb temperature that is to be main- low enough to safely store food. Storage tained must be known for each dry bulb temperature should be reduced to 50 degrees temperature that occurs during storage. F or 55 degrees F if eggs must be stored more Relative humidity in the storage room than 2 weeks. should be approximately 70 percent to 80 Holding eggs for more than 10 days percent (wet bulb temperature of 50 degrees reduces hatchability. However, chukar and F to 60 degrees F). Condensation forms on turkey eggs are an exception. Chukar eggs eggshells exposed to excessive humidity. have been stored 3 weeks to 4 weeks without Condensation on the eggshell can clog pores appreciable loss in hatchability. and, like washing eggs, provides a vehicle for A good storage area also requires stable contamination. Suffocation or contamination humidity. Two methods, wet bulb tempera- of the embryo can result. Excessive amounts ture and relative humidity, are measures of of water evaporate from the egg if humidity humidity. These two methods should not be is too low, which also causes embryo death. confused; whenever humidity measures are To increase the humidity, a pan of water can discussed, know which method is referenced. be placed in the storage room. If the incuba- tor temperature is correct, the only factor Relative humidity is the water vapor in governing humidity is the surface area of the air expressed as a percentage of the water inside the incubator or storage unit. greatest amount of water vapor possible at Avoid drafts during storage that can dry eggs that temperature. The amounts of water even when humidity levels are within vapor that air can contain are different at appropriate levels. different temperatures. To measure relative humidity, expensive equipment or a compli- Hatchability is best maintained by storing cated procedure is required. However, the eggs with the small end down in sealed, wet bulb temperature is easily measured and airtight plastic bags. The bags help keep the is the method usually used to measure eggs clean and prevent moisture loss. 2 Positioning and turning eggs during storage—Eggs that will be stored for less Egg Storage Reminders than 10 days before incubation should be ✰ Store less than 10 days. placed on egg flats or in egg cartons with ✰ Maintain temperature between 55 degrees to 65 degrees F. the large end up. Eggs do not need to be ✰ Keep relative humidity at 75 percent (50 to 60 degrees F wet turned from side to side during storage if bulb temperature). they are incubated within the week the ✰ eggs are laid. If the eggs are not sealed in a Turn eggs stored more than a week. plastic bag, cover them with a loose fitting ✰ Handle the eggs with care! material to prevent debris or dust from soiling the eggs. Eggs stored for more than 10 days should Consider the differences between forced- be tilted from side to side over a 90-degree draft and still air incubators before choosing a angle once or twice a day to assure optimal system to use.