United States Egg-Grading Manual

1 AUnited StatesDepartment ofAgricultureAgriculturalMarketingServic eAgricultural Handbook Number 75 Egg-GradingManualiContentsI. Production and Maintenance of Egg and ..3 Feeding ..3 Care of Eggs on the Farm ..4 Egg-processing Facilities ..4 Buildings and Premises ..5 Washing, Grading, and Packing Operations and Equipment ..6 Cooling Facilities ..9 Health and Cleanliness of Employees ..10 Distribution ..10 III. Structure, Composition, and Formation of the Egg ..11 Physical Structure ..11 Composition .. of the of the of the Shell of the of Quality of Exterior Quality Shape and of of Interior Quality.

2 20 Interior Quality ..22 White (Albumen)..24 Loss Standards, Grades, and Weight Classes for Shell Standards for Quality of Individual Shell Consumer Grades and Weight Classes for Shell Nest Run Grade and Weight Classes for Shell Grades and Weight Determining Interior Quality by Hand Candling Candling Candling Determining Interior Quality by the Breakout Control Egg Grading and Certification Grading of Official Grade Labeling and Certification to Specific Purchase Shell Plant Sanitation and Good Manufacturing Practices (PSGMP) Legislation Affecting Grading and Marketing of Egg Quality Schools and Training Resource Materials IntroductionThis Manual is an aid in teaching both beginning andexperienced egg graders the correct interpretation andapplication of the standards, grades, and weightclasses for eggs.

3 It can serve as a guide in short courses orgrading schools when supplemented with lectures, groupdiscussions, and demonstrations. This Manual should alsoprove useful to those teaching or working in the produc-tion, processing, and marketing of some of the material in this Manual is notdirectly related to the actual grading function, knowledgeof it will help graders do a better job in handling eggs andin maintaining egg quality. Such information will givegraders a better understanding of their job, and will aidthem in acquiring the knowledge necessary to do theirjobs Manual provides graders with an understanding ofegg marketing, the purpose of grading, production andprocessing practices, and Federal-State grading in-depth description of USDA s egg grading and certi-fication programs is provided for use by processors, mar-keters, volume food buyers, and retailers to enhance theirprocurement and quality control is also included about the formation, structure, and composition of the egg.

4 The egg is a bio-logical structure used in nature for the reproduction ofthe chicken. It protects the developing chick embryo,provides it a complete diet, and serves as the principalsource of nutrition for the first few days of the chick slife. The egg also serves as one of the most nutritiousand versatile of human foods. Chickens produce eggs in abundance, making this source of food extremelyimportant throughout the world, nutritionally as well as modern trend in production is toward large, highlyspecialized flocks. The high-quality egg produced underthis system lends itself very well to the use of machine-flash candling equipment or mass electronic scanningdevices to detect checks, irregular shells, dirts, meat andblood spots, and loss eggs.

5 For this reason, it is highlydesirable for graders to have a working knowledge ofthese of the various qualities of individual eggsshould assist the student grader in understanding eggquality. However, it is imperative that the descriptions ofthe different qualities be compared with eggs before thecandling light, and that the quality interpretations bechecked by experienced importance of practice in candling cannot be stressedenough. It is essential that student graders become thor-oughly familiar with the descriptions of the different qual-ities because the final measure of their ability is the accu-racy by which they interpret quality before the candlinglight.

6 Occasional comparisons of broken-out appearancewith candled appearance are also essential in developinggrading quality and grading procedures are the what and how of the job. Coupled with reasonably good judg-ment, practice, and guidance, graders should acquire thenecessary skills to rapidly determine the proper classifica-tion of shell eggs based on official standards of Production and Maintenanceof Egg QualityEgg production has been, and continues to be, a majoragricultural industry in the United States . In 1999, totalegg production was almost 7 billion dozen. The northcentral area continues to lead the Nation in production,followed by the west and the middle Atlantic and marketing this volume of quality eggshave been accompanied by specialization in the areas ofbreeding, hatching chicks, raising chickens, producingeggs, and producing poultry meat.

7 Large vertically inte-grated firms that perform several or all of these functionshave become most prominent. The average flock size foran operation often exceeds 75,000 layers, with manyover 1 is either off-line or in-line. Off-line pro-duction refers to processing operations that are not inte-grated with the laying facility. Off-line eggs are gatheredand shipped in from laying facilities at other locations. In-line production refers to processing operations whereeggs are laid, processed, packed, and shipped from onelocation. Most production facilities today are large inte-grated in-line operations.

8 An understanding of egg pro-duction practices will help processors and quality controlpersonnel contend with product quality White Leghorn is the predominant breed of layerbeing raised, in part because it lays white-shell eggs are available in some parts of the coun-try, but white-shell eggs are more widely demanded byconsumers. Shell color and thickness, egg size, qualityand quantity of thick white, quantity of eggs produced,and, to some extent, freedom from blood spots arehereditary factors that affect overall egg quality. Forexample, broken and cracked egg shells are directly relat-ed to shell thickness and strength, and have great eco-nomic impact on the industry.

9 Also, a reduction in shellquality is a direct result of increased egg time, improvements in these hereditary factorshave been bred into the White Leghorn. Chicks or pul-lets for the initial flock or flock replacement should beprocured from a source that can give reasonable assur-ance that these factors have been carefully considered inthe breeding promote improved breeding and production qualitiesin poultry and to reduce losses from pullorum disease,the industry established the National PoultryImprovement Plan (NPIP) in , NPIP is administered jointly by USDA s AgriculturalResearch Service and an official State agency in each ofthe cooperating States .

10 It operates according to regula-tions and standards developed to provide assistance tobreeders and hatcheries in producing birds free from egg-transmitted diseases. Procurement of chicks from plan hatcheries assists the producer in the selection of desir-able young stock. In 1989, NPIP developed a Salmonellaenteritidis (Se) control program to reduce the incidence ofSein hatching eggs and chicks. Participants in this pro-gram follow designated control procedures and practicesat breeder farms and and RaisingSome operators brood chicks and raise them to layingage, while others purchase 16- to 20-week-old birds fromspecialists in the pullet-raising field.