Artificial Incubation Applied to Small Numbers of Altricial Bird Eggs

Mark Hagen, M.Ag.
Review Performed at: Department of Animal and Poultry Science University of Guelph
Guelph, Ontario, Canada
N1G 2K0

Artificial incubation goes back thousands of years when the ancient Chinese and Egyptians operated large hatcheries that were quite successful. Up until ten years ago most of the scientific information concerning artificial incubation applied to precocial species important to the poultry industry. Presently large commercial poultry incubators fit tens of thousands of eggs at a time and, due to selection, most hatch.

The incubation of exotic bird eggs, usually in small numbers, has recently become a popular way to try and increase production but unfortunately often leads to failure. There is a desire to improve artificial incubation techniques as diets to hand-feed altricial birds right from hatch are becoming available and more breeders are confident that they can raise a baby themselves.

The topic of incubation could fill a book with many different techniques leading to a successfully hatched egg. Having the right equipment is as important as knowing the process. Temperature, humidity, ventilation, egg turning and sanitation are all important factors in the proper incubation of eggs (Brown, 1979). This paper will discuss these factors as well as some characteristics of parrot eggs, their proper collection and assistance techniques for dried out eggs.

Van Der Heyden (1987) claims that artificially incubating to increase egg production is risky and that many aviculturists have lost more than they've gained by it. This may be due to improper techniques, poor parental nutrition and other factors that can be corrected.

Surrogate/foster parents have been successfully used to incubate and raise eggs (Gee, 1983; Harrison, 1987; Stoodley, 1984) with the same benefits as artificial incubation. Some species, such as the Monk Parakeet, make better foster parents than others. Possible disease spread, unacceptance by the foster pair and the cost (space) of maintaining them are factors which may make fostering less desirable.

HARI raised 12 babies from one of our Blue & Gold Macaw pairs which produced 18 eggs in 14 months. The first two clutches were pulled for artificial incubation within a week of being laid. Then, twice they laid again a month after we pulled three week old babies from them. Unfortunately the demand for unrelated, parent raised, captive bred breeding stock is rather small. As a result, we have to incubate (or pull at a very young age) and hand rear most of our babies for pet stock.

The contents of fresh psittacine eggs contain slightly more solids, 19.4% (Bucher, 1983) than is typical for altricial, or semi-altricial species, which contain 17% solids (Ar and Rahn, 1980). When compared on the basis of maturity at hatching, the water fraction is significantly different between fresh altricial and precocial eggs which contain 28% solids (Ar and Rahn, 1980).

In six parrot species studied by Bucher (1983) the average incubation period was 40% longer than that of birds in general, when compared on the basis of egg mass using the data compiled by Ar and Rahn (1978), and because of the prolonged incubation periods the total embryonic energy metabolism is greater than predicted for altricial species. Bucher (1983) found that pre-piping and hatching levels of oxygen consumption are lower than in the same size eggs of precocial species.

Clutch size within the psittacines varies from one egg up to six, with two or three being average for most species (Saunders et al. 1984; Smith and Saunders, 1986;

Saunders et al. (1984) found that amoung the graminivore-frugivores, the hole-nesting psittacines produce larger clutches, have longer incubation and nestling periods than the open-nesting Columbiformes.

When an egg is pulled, it is labelled with a code representing the species, pair (A,B,C,...) and egg number. For instance the eighth egg from our second pair of Blue & Gold Macaws to breed is labelled BGM-B-8. The seventh egg from our third pair of Medium Sulphur-Crested Cockatoos MSC-C-7, etc. By using a soft carbon pencil every egg is identified along with approximate date of lay. Eggs left with the parent pair are not labelled but are recorded.

Rowe (1986) describes a portable incubator used to transport eggs collected in the wild and brought into captivity.

Eggs which have been soiled by feces can be carefully dry cleaned with fine sand paper or steel wool. Gently flick away the feces and minimize scratching the cuticle or pressing the dirt through the pores and into the egg.
Older egg submersion washing systems used by the poultry industry often served to spread and multiply bacterial contamination if wash water was too cold or re-circulated too often inactivating the disinfectant. When the wash water has a lower temperature than that of the eggs, the result is a cooling and contraction of the egg contents, which serves to draw wash water and associated bacteria through the shell pores contaminating the egg.

This temperature-differential effect has been used to introduce into eggs both water, if they have lost excessive weight (Gee, 1983), and antibiotics to control certain egg-transmitted bacterial infections (Ekperigin and McCapes, 1977). Eggs are preheated in a disinfectant solution and then immersed in a cold antibiotic solution for 2.5 minutes with no adverse effect on hatchability (Ekperigin and McCapes, 1978).

When the goal is to remove the surface contamination, all eggs should be dipped in a disinfectant solution which is always warmer than the egg, carefully wiped with a paper towel (which is dipped often to warm it up and clean it) and then quickly dried. New automated washing systems use a warm pressure wash spray containing a detergent, a hot water rinse containing a disinfectant and air blow drying (Kuhl, 1988).

Mandl et al. (1987) studied the efficacy of various disinfectants on broiler breeder eggs contaminated with salmonella. No adverse effects on hatchability were obtained when fresh eggs were soaked in 2 % solutions of aldehydes, phenols or quaternary ammonium compounds for five minutes but were significantly reduced by a 5 % solution of an iodophor compound.

Fumigation of eggs has been a common method to kill shell surface micro-organisms. Fumigation should only be done with fresh eggs, older eggs can be killed. Incubators made out of porous wood or polystyrene and others with hard to reach areas can only be effectively disinfected by fumigation. Researchers at the University of California, Davis fumigate using 1.22 ml formalin (37% formaldehyde) and 0.6 g potassium permanganate per cu ft of incubator for 20 minutes (Cutler et.al., 1985). However, egg fumigation is dangerous to the breeder who can not exhaust it directly outside after fumigation. The gas is poisonous and smells horrible. It is also inconvenient for the average breeder who has small numbers of eggs over a longer period of time.

Hatching eggs can be stored under appropriate conditions for up to a week prior to incubation without a significant loss in hatchability. Pre-incubation storage of cockatiel eggs at a temperature of 13°C (55°F) and relative humidity of 60% does not reduce hatchability until after four days of storage (Cutler et. al., 1985). Cutler et. al. (1985) demonstrated that bagging cockatiel eggs during the storage period appeared to increase the storage time and improve viability. Storage of the eggs in plastic bags appears to reduce the rate of dehydration and pH change due to CO2 loss from the egg.

It is recommended to gradually warm cooled eggs from storage up to room and then incubation temperatures (Haigh, 1984).

For most exotic bird breeders working with small numbers of rare and valuable eggs, the risk associated with storage is unwarranted and the technique is not really needed.

Turning prevents the embryo from fusing with the eggshell membranes. If this happens the embryo will stick to the shell and development can be fatally distorted or the chick may be malpositioned for proper hatching.

Cheaper incubators are available with manual or hand turning but the savings are questionable for several reasons. Eggs should be turned at least three times a day or better still once every two hours for the first 75% of the incubation period. Manual turning may simply require turning or pulling a knob but forgetting to this will reduce hatchability. Turning eggs directly by hand has many risks including; contaminating the eggs with micro-organisms, damaging the eggs by careless turning, or twisting the embryo by turning in the same direction and forgetting to turn them.

The turning of chicken eggs can be stopped at 16 days (normal incubation period 21 days) without adversely affecting hatchability (Wilson, 1988).