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Submitted to: National Egg Quality School Proceedings
Publication Type: Proceedings Publication Acceptance Date: 10/6/2004 Publication Date: 10/11/2004 Citation: Jones, D.R. 2004. Shell egg quality. National Egg Products School Proceedings. Meeting Abstract. p. 11-15. Interpretive Summary: The goal of all producers is to produce a better product. In the shell egg industry, this translates to producing a higher quality egg. Egg quality can be defined in many ways. The American consumer demands a clean and sound egg that looks appealing when cracked into a skillet. The shell egg producer could define egg quality in terms of being relatively free of defects which would result in a downgrade. There are many factors, both interior and exterior, that determine the grade of a shell egg at the point of retail. In the US, eggs can be marketed as grades AA, A, or B. Most shell eggs in the US market are sold as 'Grade A'. The USDA Agricultural Marketing Service (USDA-AMS) is responsible for determining what factors contribute to the down-grading of a shell egg. Currently, all regulations governing shell egg grades are based on physical quality attributes. A complete description of these factors can be found in the USDA Egg Grading Manual (USDA, 2000). Egg grades are determined by either hand candling or breaking out the egg. During hand candling, a light is shown through the egg shell to allow the grader to examine the clarity and quality of the albumen and yolk. The size of the air cell can also be estimated. All these factors, along with other exterior factors are combined for a grade assignment. Defects which would render the egg inedible can also be detected during hand candling. A more precise measurement of egg interior quality is the Haugh unit (Haugh, 1937). During this examination, the egg is broken out onto a flat surface, usually a break-out table, and the height of the thick albumen is measured with a micrometer. The Haugh unit is a correlation between egg weight and albumen height. While the Haugh unit is a more precise measurement of egg quality, it destroys the egg during analysis, so hand candling is the more common form of egg quality determination for grade. The USDA-AMS has also established guidelines for consumer weight classes of shell eggs. These weight classes exist to ensure the consumer is receiving a full dozen of appropriately sized eggs and not a mixed grab-bag. Table 1 is a summary of the required weight classes for commercial shell eggs. The six allowable egg sizes and the corresponding minimum weights of individual eggs within a dozen, dozens, and 30 dozen cases are presented. There are many factors that can affect egg quality. These can include nutrition, breed, management, egg temperature, and processing methods. Therefore, when attempting to enhance egg quality, a producer must consider both production and processing factors. Table 1. Weight class requirements for shell eggs. Size Minimum net weight for individual eggs in a dozen (ounces) Minimum net weight per dozen (ounces) Minimum net weight for a 30 dozen case (pounds) Jumbo 29 30 56 Extra large 26 27 50.5 Large 23 24 45 Medium 20 21 39.5 Small 17 18 34 Peewee -- 15 28 Hen nutrition can have a direct effect on egg quality. When a hen is nutritionally compromised, the body begins to shut down unnecessary processes. Reproduction is greatly diminished, and the bird becomes immunologically compromised which can lead to increased incidence of disease. If a layer diet is complete except for a lack in the appropriate level of the amino acid lysine, a laying hen will not efficiently produce eggs and the eggs laid will be of inferior quality. A lack of calcium and phosphorus in the layer diet will result in the hen leaching these minerals from the bones in order to lay sound eggs. As this condition progresses, the hen will reach a point where it will no longer removed minerals from the bones. After this, a hen will produce soft shell or even shell-less eggs. A layer diet should be formulated by a trained nutritionist to ensure all nutrient requirements are met. Minimizing physiological stress within the hen Technical Abstract: The goal of all producers is to produce a better product. In the shell egg industry, this translates to producing a higher quality egg. Egg quality can be defined in many ways. The American consumer demands a clean and sound egg that looks appealing when cracked into a skillet. The shell egg producer could define egg quality in terms of being relatively free of defects which would result in a downgrade. There are many factors, both interior and exterior, that determine the grade of a shell egg at the point of retail. In the US, eggs can be marketed as grades AA, A, or B. Most shell eggs in the US market are sold as 'Grade A'. The USDA Agricultural Marketing Service (USDA-AMS) is responsible for determining what factors contribute to the down-grading of a shell egg. Currently, all regulations governing shell egg grades are based on physical quality attributes. A complete description of these factors can be found in the USDA Egg Grading Manual (USDA, 2000). Egg grades are determined by either hand candling or breaking out the egg. During hand candling, a light is shown through the egg shell to allow the grader to examine the clarity and quality of the albumen and yolk. The size of the air cell can also be estimated. All these factors, along with other exterior factors are combined for a grade assignment. Defects which would render the egg inedible can also be detected during hand candling. A more precise measurement of egg interior quality is the Haugh unit (Haugh, 1937). During this examination, the egg is broken out onto a flat surface, usually a break-out table, and the height of the thick albumen is measured with a micrometer. The Haugh unit is a correlation between egg weight and albumen height. While the Haugh unit is a more precise measurement of egg quality, it destroys the egg during analysis, so hand candling is the more common form of egg quality determination for grade. The USDA-AMS has also established guidelines for consumer weight classes of shell eggs. These weight classes exist to ensure the consumer is receiving a full dozen of appropriately sized eggs and not a mixed grab-bag. Table 1 is a summary of the required weight classes for commercial shell eggs. The six allowable egg sizes and the corresponding minimum weights of individual eggs within a dozen, dozens, and 30 dozen cases are presented. There are many factors that can affect egg quality. These can include nutrition, breed, management, egg temperature, and processing methods. Therefore, when attempting to enhance egg quality, a producer must consider both production and processing factors. Table 1. Weight class requirements for shell eggs. Size Minimum net weight for individual eggs in a dozen (ounces) Minimum net weight per dozen (ounces) Minimum net weight for a 30 dozen case (pounds) Jumbo 29 30 56 Extra large 26 27 50.5 Large 23 24 45 Medium 20 21 39.5 Small 17 18 34 Peewee -- 15 28 Hen nutrition can have a direct effect on egg quality. When a hen is nutritionally compromised, the body begins to shut down unnecessary processes. Reproduction is greatly diminished, and the bird becomes immunologically compromised which can lead to increased incidence of disease. If a layer diet is complete except for a lack in the appropriate level of the amino acid lysine, a laying hen will not efficiently produce eggs and the eggs laid will be of inferior quality. A lack of calcium and phosphorus in the layer diet will result in the hen leaching these minerals from the bones in order to lay sound eggs. As this condition progresses, the hen will reach a point where it will no longer removed minerals from the bones. After this, a hen will produce soft shell or even shell-less eggs. A layer diet should be formulated by a trained nutritionist to ensure all nutrient requirements are met. Minimizing physiological stress within the hen |
