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By Ioannis Mavromichalis , International Consulting Nutritionist, Madrid, Spain
The quality of egg shell is important not only for the fresh-egg industry, but also for the hatchery sector. A clean, well formed egg, without visible cracks, spots, or other deformities ensure high acceptance by consumers. In addition, a high quality shell enhances the chances of producing a healthy chick from each egg. Thus, when it comes to eggs, first looks do count for more than one good reason.There are many factors affecting shell quality, including genetics, health status of the animal, environmental stress, management issues, facilities, handling and of course, nutrition. If certain principles in diet formulation are not followed, nutrition can be the causing factor for some egg shell quality issues. But, in most cases, proper nutritional intervention can ameliorate egg shell quality problems caused by other stress factors, unrelated to nutrition. We shall next examine the two major areas of egg shell quality issues as affected by nutrition.
Dirty eggs not acceptable
Obviously dirty eggs, contaminated with bird excreta, are not acceptable by consumers, as they pose a health risk. In addition, a dirty egg harbours enough bacteria on its surface to impair the health of a hatching chick, reducing thus hatching rate success.
Obviously dirty eggs, contaminated with bird excreta, are not acceptable by consumers, as they pose a health risk. In addition, a dirty egg harbours enough bacteria on its surface to impair the health of a hatching chick, reducing thus hatching rate success.
Dirty eggs are usually caused by digestive issues that lead to sticky droppings. This is a result of dietary composition choices. For example, certain cereals, with rye being the most offensive in this aspect, contain high levels of non-starch polysaccharides that increase digesta viscosity. This invariably leads to sticky excreta that contaminates eggs. This issue can be easily resolved by reverting to less offensive cereals, such as maize or wheat, or by reducing the amount of ‘offensive’ cereals. In addition, there is some evidence suggesting a reduction in sticky droppings when certain non-starch polysaccharide enzymes are added in diets containing these offensive cereals (Table 1).
High water concentration
Another reason for dirty eggs is the problem of having wet droppings (a kind of diarrhoea). This is mostly caused by disease or environmental stress, but certain nutritional factors can aggravate the situation.
Another reason for dirty eggs is the problem of having wet droppings (a kind of diarrhoea). This is mostly caused by disease or environmental stress, but certain nutritional factors can aggravate the situation.
For example, feed or water high in mineral salts, and particularly sulphur salts, can cause excessive water secretion in the gut resulting in a high water concentration in the excreta. Conversely, factors leading to high water intake, including high dietary protein levels and salt, may also lead to wet droppings. When certain ingredients high in simple sugars are used in formulation (for example, bakery meal can have up to 25% sucrose), then this can also lead to this problem. Quite often, knowing the causative factor is enough for professionals to remedy the situation.
In other cases, an intervention strategy is needed (for example, when there is no way to alter the source of drinking water!). Here, certain additives can play a strong role. There are two types of additives suitable for this problem: absorbents that trap water inside the gastrointestinal track and thus reduce the amount of free water, and osmoregulators that cause reversal of excessive water secretion from the gastrointestinal epithelial cells. As usual, a combination works better than any ingredient alone. Fortunately, such ingredients are not expensive and they can be used with relatively good results.
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Source: World Poultry, Vol. 27, No. 7, 2011
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