Hatchery Management
By James S. Stewart, DVM

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Hatching

Temperature and Humidity

Recommended protocols for hatcher temperature and humidity are controversial, even within the commercial poultry industry. It has been suggested that the temperature be decreased in the hatcher to compensate for the increase in metabolic heat generated at hatch. Conversely, it has been suggested that hatcher temperature be increased to compensate for the decrease in heat produced by the smaller number of eggs in the hatcher compared with those in the incubator. Likewise, some producers recommend an increase in hatcher humidity once most eggs have pipped to prevent membranes from drying and sticking to the chicks; others advocate a decrease in humidity in order to increase the partial pressure of oxygen at the time of greater demand.

The recommendation for ostrich production is that temperature and humidity in the hatcher be the same as those in the incubator. The suggested changes in protocol for poultry are not only slight and controversial but require that they be executed at a specific stage of development. The nonuniformity of ostrich eggs is such that the hatching period, even under the best of conditions, routinely lasts three to six days. The use of a different temperature and humidity in the hatcher would require that the eggs be individually monitored in the incubator and then transferred. This is not only inefficient but requires frequent entry and contamination of the incubator. If hatcher and incubator conditions are the same, transfer time is independent of the specific developmental stage, and eggs can be transferred as a batch. The recommended time of transfer is three days before average hatch time (day 39 or 40 in routine ostrich production).

Position and Turning

Eggs should not be turned while in the hatcher. During the last few days of development the embryos shift into position for hatching, and turning of the eggs can reduce hatchability. It is least disruptive to the embryos if the eggs continue to be positioned air cell upward in the hatcher. If the eggs are to be placed horizontally, the upward side should be marked with a pencil and the eggs returned to the same position after handling.

Assisted Hatch

The sequence of the average hatching process is for the chick to break into the air cell on day 40, to pip the shell during day 41, and to complete hatching by day 42. This, of course, is subject to normal biological variation. In addition, inferior chicks may fail to hatch because of infectious, nutritional, genetic, or other causes of weakness. However, otherwise normal chicks may also fail to hatch because of improper incubation and hatching conditions, or simply as a result of the lack of external stimuli. The social facilitation of hatching is well developed in the ostrich, and the absence of the stimulus from parents and other chicks to promote the hatching process may be a significant factor in reduced hatchability under artificial conditions.

The hatchability of ostrich eggs may be significantly increased if each egg receives individual attention after being placed in the hatcher. The weighing of eggs at collection and again at transfer is useful to identify eggs with inadequate or excessive evaporative water loss that may require special attention during hatching. Commercial production guidelines for an efficient and effective routine must also be established to accommodate for the variation in hatch time. Assisted hatching on a specified day is too early for some chicks and too late for others. Hatching progress can best be monitored by candling the air cells daily. Each day, the eggs in which the chicks have penetrated the air cell are identified with a pencil mark and become part of a hatching group. The majority of eggs should pip the shell by the following day and pipping is assisted for the remainder by creating a 2-cm opening in the shell at the air cell pole of the egg. By the second day, most chicks in the group should have completed the hatching process, and those that remain may be assisted by the gradual removal of shell to free the chick. Assistance to malpositioned or other abnormal chicks is a skill that develops best with experience.

Post-Hatch

The hatcher should provide a clean environment in which the new chick dries and begins to develop the strength to walk. The umbilicus of all chicks should routinely be treated with antiseptic ointment or spray. If the umbilicus is open, it should be protected with a clean wrap in order to prevent infection. The hatcher surface should not be injurious to the soft skin of the freshly hatched chick yet it must provide good traction to prevent spraddled legs. The hatching of ostriches in individual 20-cm cubicles reduces the potential for spraddled legs and provides a support against which the chicks may lean in the initial attempts to stand. The holding time for most chicks after hatch should be no more than 12 to 24 hours, after which they should be transferred to rearing facilities.

Editor’s note: Reprinted with permission from Dr. Stewart and Zoo & Wild Animal Medicine, pages 206-211; W.B. Saunders Company, publisher; Murray E. Fowler, DVM, editor; third edition; 1993.

References
1. Beer AE: A review of the effects of nutritional deficiencies on hatchability. In Carter TC, Freeman BM (eds): The fertility and hatchability of the hen’s egg. Edinburg, Scotland, Oliver and Boyd, 1969, p 93.
2. Bertram BCR, Burger AE: Aspects of incubation in ostriches. Ostrich 52:36 1981.
3. Hoyt DF, Vicck D, Vleck CM: Metabolism of avian embryos: Ontogeny and temperature effects in the ostrich. Condor 80:265, 1978.
4. Jarvis MJF, Keffin RH, Jarvis C: Some physical requirements for ostrich egg incubation. Ostrich 56:42, 1985.
5. North MO; Commercial chicken production manual. Westport, NY, AVI, 1985 p 710.
6. Stewart JS: Unpublished data, 1989.
7. Swart D, Rahn H, de Kock J: Nest microclimate and incubation water loss of eggs of the African ostrich (Struthio camelus var. domesticus). J Exper Zool Suppl 1:239, 1987.

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