Hatchery Management
By James S. Stewart, DVM

The artificial incubation and hatching of ostrich eggs for commercial production has been an ongoing practice since Arthur Douglass of Albany, South Africa, patented the Eclipse brand of incubator for ostrich eggs in 1867. The techniques that he developed were followed with little change for over a century. Only since 1980, concurrent with the international expansion of commercial ostrich production, have more modern methods been used. Although the basic principles of commercial poultry incubation technology form the foundation for modern improvements, there are important differences in the specific parameters that apply to ostrich egg management.

Hatchery management is evaluated by the hatchability obtained (i.e., the percentage of fertile eggs incubated that successfully hatch). A hatchability rate of over 90 percent is achieved by well-managed commercial ostrich operations. This section reviews the factors that affect hatchability, provides recommendations, and discusses incubation problems in commercial ostrich production.

Hatching Egg Quality

Genetics

Egg quality has a significant genetic component. In commercial poultry production, laying hens have been intensively selected so that eggs produced are uniform in conformation and content. Egg uniformity is not yet achievable in commercial ostrich production. The relatively small numbers of birds involved and the long generation time required make selection a difficult undertaking. Selection to date has emphasized the quality of such commercial products as feathers and the quantity of eggs rather than the quality. Consequently, hatchery management conditions must be directed toward an acceptable average. Hatchery parameters are of necessity a compromise, and wide variation in ostrich egg quality yields wide variation in the measured results.

Egg Size

Ostrich eggs may vary from 350 to over 2200 g. Average egg size varies with the subspecies and conditions of domestication, but typically falls between 1300 and 1700 g. Oversized eggs have a proportionately small surface area for gas and water vapor exchange and are likely to produce weak, edematous chicks. Conversely, undersized eggs may lose excessive water during the course of incubation, which results in weak, dehydrated chicks. Small eggs usually are produced early in the season or by young birds and are frequently infertile. Very small eggs may have excessively thick shells and often contain no yolk.

Shell Quality

The shell acts as a selective barrier that allows the appropriate exchange of oxygen, carbon dioxide, and water vapor yet inhibits the entry of infectious agents. Shell thickness is variable among ostriches, and may range from 1.4 to 2.4 mm, with an average between 1.7 and 2.0 mm. Thick shells inhibit water loss in particular, resulting in weak, edematous chicks. Thin shells allow excessive water loss, and are significantly more subject to bacterial or fungal penetration. Shells with cracks, chips, ridges, piping, chalkiness, or other irregular textures have a loss of structural integrity that makes them more prone to invasion by infectious agents.

Breeder Nutrition

An egg is a pre-formed package that, with the exception of oxygen, must contain all the essential ingredients necessary to produce a healthy chick. In general, if a hen is deficient in proteins, carbohydrates, or fats, eggs produced are nutritionally balanced but smaller than normal in size or fewer in number. However, deficiencies in vitamins or minerals may result in a nutrient-deficient egg. The effects of single nutrient deficiencies on embryonic morphology and mortality have been well described for poultry, and must at present serve as the basis for the analysis of nutrition-related hatchability problems in ostriches. For example, ostrich hens fed heavily on grains have produced eggs with a high incidence of edematous chicks with subcutaneous hemorrhage at midembryonic mortality. This is suggestive of pantothenic acid deficiency but has been corrected with multivitamin supplementation that obscures a specific diagnosis. Clinical evidence has correlated certain skeletal anomalies of the head of ostrich embryos from hens fed manganese-deficient diets. Manganese supplementation to the hens has corrected the problem.

Breeder nutrition also has an effect on shell quality. Dietary calcium, phosphorus, and vitamin D must be balanced. In current small-scale operations, oversupplementation with limestone or shell grit is a more frequent problem than calcium deficiency. An excess of chloride, copper, and other mineral salts is detrimental to shell formation in poultry and should be assumed to have similar effects in ostriches.

Disease

Infectious agents within the reproductive tract may be transmitted to the egg during formation of either the yolk or albumen, resulting in embryonic mortality, poor hatch, and unthrifty chicks. Escherichia coli and Salmonella sp, are commonly transmitted through ostrich eggs. Active infections of the reproductive tract or anatomical and physiological abnormalities resulting from previous disease may affect formation and integrity of egg contents, membranes, or shell and are a common occurrence in ostriches. Generalized infections, such as gastrointestinal disease, may reduce vitamin or mineral utilization by the hen and result in nutrient-deficient eggs even from hens fed a routinely adequate ration.

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