broken eggs effect
Egg Shell Quality: its Impact on Production, Processing and Marketing Economics
Published: December 14, 2007
By: DON BELL - University of California, Riverside, USA (Courtesy of Alltech Inc.)
A number of excellent research papers and reviews of the subject have been published (Petersen, 1965; Carter, 1969; Hunton, 1969; Bezpa, 1972; Creger et al., 1976; Parsons, 1982; Bell, 1982; 1984a, b; 1985, 1986; Gomez- Basauri, 1997).
This paper will discuss the factors associated with egg breakage with primary emphasis on the ‘insult’ factors with secondary emphasis on the egg’s ability to withstand such ‘insults’. The economic impact of various factors will be stressed.
NATURE OF PROBLEM
Egg shell defects range from those of scientific interest, which require electron microscopy to identify, to the leaking egg in the consumer’s carton. Defects include eggs with no shells that are rarely seen and never counted because they drop through the cage to the manure storage area, and eggs which break inside the hen’s body during formation with subsequent repair (partial or complete) prior to oviposition. Shell defects also include misshapen eggs, eggs with thin shell areas, and eggs with very rough shells. Shells also vary between different strains or breeds of chickens, age of the flock, seasonally, and from bird to bird within a given flock.
Consumers, producers, regulation enforcement officials, and scientists may have completely different opinions about the importance of various shell characteristics. Most would be relatively unconcerned about egg shell problems which do not include a clear break in the shell. On the other hand, the scientist may associate an unseen fracture in the shell with a food safety issue. The egg inspector may reject eggs for egg breakage that can be seen only with the use of a candling light, while the consumer would be perfectly happy with what appears to be a sound shelled egg. Everyone would be concerned with eggs with broken membranes that exude their contents.
WHY DO EGGS CRACK?
From what first might appear to be a ridiculous question, it must be understood that “An egg shell cracks if the strength of the shell is less than the strength of the ‘environmental insult’ to which it is exposed”. “Crack incidence does not depend on shell strength alone, but on both shell strength and the strength of the insult” (Carter, 1969). Figure 1 illustrates this principle. The regression line illustrates that combination of impact and the shell’s resistance to impact that will result in a broken egg shell.
Once it is recognized that all eggs will break if handling procedures are excessively harsh and that practically all eggs can be protected if enough attention is given to the issue; the amount of breakage experienced can be kept within reasonable limits. The strength of the shell is a product of the strain and breed of the flock, its age, the nutrient balance and intake levels of the ration, environmental conditions, the flock’s general health and previous health history along with other factors. Considerable latitude exists to correct each of these contributors to shell strength. On the other hand, the strength of the insult must also be controlled or damage will still occur – even with the strongest shelled eggs.
Finally, the person responsible for determining egg shell damage must be well-versed and experienced in differentiating ‘real’ cracks from those that only appear to be cracks. This may sound simplistic, but high speed equipment and the candler’s inability to separate windowed and body checked eggs from actual cracks can be an expensive problem in the egg grading plant. Grading plant employees must be fully conversant with the regulations under which they are operating – both local and federal.
Figure 1.Egg breakage: effects of impact and the shell’s resistance to the impact.
WHERE DOES SHELL DAMAGE OCCUR?
Various studies show that eggs are broken in locations ranging from within the hen to the consumer’s kitchen. Everywhere the egg passes, new breakage problems can be measured. The hen herself produces eggs with varying levels of shell strength. She produces soft shells, thin shells, rough shells and irregularly shaped eggs. From time to time she produces two eggs within a 24 hour period – one being soft shelled or with an ultra-thin shell. As she gets older, the shell strength of her eggs is reduced and the number of cracks increases.
During oviposition, the hen may break her own egg due to her inherent posture. Hens lay their eggs from a sitting or standing position with a high incidence of breakage associated with the standing position. Other birds will step on their own or their penmate’s eggs before the egg has an opportunity to exit the cage. This is why it is of critical importance that activity in the lay house is minimized during the egg-laying hours. Eggs may be ‘kicked’ out of the cage often causing damage to two or more eggs in the roll-out or on the egg gathering belt.
Egg handling, by hand or mechanized gathering systems, is a major contributor to breakage. The more components (elevators, accumulators, washers, packers), the more the total breakage. It is not uncommon to see 4 to 6% egg breakage in this process alone with extremely poor handling procedures resulting in 10 to 20% breakage.
HOW MUCH VALUE IS LOST AS A RESULT OF DEFECTIVE SHELLS?
The eggs that are found in the manure are comprised of eggs that would never have been salable (soft and ultra-thin shelled eggs). Oftentimes they represent the second egg produced in a day. Hard shelled remnants of eggs can reflect eggs trampled through the cage bottom by the hens or leakers thrown there by egg gatherers. In either case, the loss should be considered. Production of a portion of these may be preventable by adjusting egg collection times and(or) periods of activity within the house.
Body checks are eggs that have been broken during the formation process and then repaired by the hen prior to oviposition. Such eggs are broken as a result of excessive activity during the 20+ hours of shell deposition. It may occur in the initial, intermediate or late stages. The quality of the repair is dependent upon the severity and timing of the incident. Technically, it would be accepted in a AA or A grade if the shell is ‘practically normal’ as defined by egg grading regulations. Individual eggs may lose from 0 to 50% of their value depending upon the severity of the damage.
Non-leaking cracks (checks, blind checks, hairline cracks, toe holes, thermal checks, etc.) are determined by candling and their value may vary from 25 to 50% of the value of a sound shelled egg. Flocks will vary from 2 to 12% incidence with problem flocks sometimes exceeding 20%. Eggs with ruptured shell membranes are considered ‘losses’ and are rejected for human use in the US. As a result, they have zero value. This category (in the candling booth) usually also includes bloods, missing and dirty eggs as well. Some of the eggs in this category are discarded in the chicken house and are not recorded. Typical losses reported in the processing plant range from 0.5 to 2.0% with an effect on the average egg price of 0.5 cents per dozen for each 1% of losses. This is equivalent to $0.11 per hen.
THE ESTRUCTURE OF THE EGG SHELL
To the human eye, the shell of the egg appears to be a homogeneous structure with uniform composition throughout, but when observed under high magnification it becomes readily apparent that the structure is extraordinarily complex. Within its typical thickness of 0.015 inches lie at least six significantly different layers beginning with two shell membranes between the albumen and the interior surface of the shell followed by three regions of calcified materials, and completed with a thin organic material on the outer surface called the cuticle.
Within the different layers are crystalline interfaces, hundreds of hidden fault lines, and thousands of pores (tiny tunnels which travel from outer to inner surfaces of the shell). It is this complexity of structure which gives rise to unexplainable differences in breakage between two samples of eggs from what appear to be identical conditions. The crack severity, shape and length are results of variations in the structure with fractures occurring at the points of least resistance.
METHODS OF MEASURING SHELL STRENGTH
Numerous techniques have been used by scientists to estimate the ‘likelihood’ of an egg to break. This is an indirect way of establishing a ‘standard’ of what we would expect to occur. As stated earlier, the event of breakage is the result of the combination of the strength of the insult with the shell’s ability to withstand that insult. Theoretically, a regression curve could be developed comparing one of the many shell strength measuring techniques with a known force to produce breakage.
For example, shell thickness could be plotted on one axis and crushing strength on the other. The plot would show what combinations of shell thickness (shell strength) and crushing strength (insult) would result in egg breakage. The degree that the data fit the curve is an indication of the accuracy of each of the two components and the possible involvement of other factors.
Many researchers have explored the correlation between two or more techniques and have determined the optimum procedures for their own work.
Various techniques include: candled egg breakage, specific gravity, shell deformation, quasi-static compression, impact, puncture, shaker, ß-backscatter and shell thickness tests.
The data discussed in this chapter are primarily limited to specific gravity and shell thickness procedures, two of the most common methods used in the field. Kansas State University researchers studied the relationship between these two measurements in 1963 and found an R2 of 0.62. This is interpreted to mean that 62% of the variation in specific gravity is related to changes in shell thickness (Fry et al., 1963). Their regression analysis associated a shell thickness of 0.013 inches with a specific gravity of 1.082. In practice, most researchers would probably consider these two measurements to represent‘poor’ shell quality.
The choice of procedure is dependent upon whether or not the egg is to be destroyed in the process (e.g. shell thickness vs. shell deformation), the reliability of the system relative to elapsed time from gathering (e.g. specific gravity vs. shell thickness), expense (e.g. quasi-static compression vs. shell thickness), portability (e.g. quasi-static compression unit vs. shell thickness gauge), and other factors.
Figure 2 illustrates the relationship between the specific gravity of individual eggs and whether or not they were broken in a 24 week experiment conducted with 9-month-old pullets (Wells, 1967b). These eggs were produced by chickens in individual cages and were candled shortly after oviposition. Interestingly, all eggs with a specific gravity less than 1.043 were cracked and none were cracked with specific gravities of 1.087.
More recently researchers have simplified the specific gravity system to one that requires only one solution (1.08) (Figure 3). Every egg that sinks is considered to have a thick shell and every egg that floats is considered to be a thin shelled egg (Bennett, 1993).
As with any type of testing, sampling must be representative and consistent. University of Georgia researchers have shown that specific gravity measurements for a given flock may vary as much as 0.005 points throughout the day (Washburn and Potts, 1975). For this reason it is essential that the eggs measured are done at the same time each day and that they do not include eggs from another time period. British researchers illustrated the importance of first day measuring for specific gravity (Wells, 1967a). A loss of 0.00156 units per day was observed over a 16 day storage period.
Within any sample, variation is expected and the extremes within a sample are usually the source of most of the problems. Figure 4 depicts the percentage of eggs within shell thickness categories in a 1995 University of California experiment. In this example, 29% of the eggs had shells less than 0.014 inches in thickness – potentially problem eggs.
Figure 2.Effect of egg specific gravity upon percentage cracks (9 month-old pullets) (Wells, 1967a).
Figure 3.The effect of flock age on the proportion of thin-shelled eggs (< 1.080 specific gravity) (Bennett, 1993).
EGG BREAKAGE
A MODEL FOR ESTIMATING ECONOMIC LOSSES DUE TO EGG BREAKAGE
The economic losses from egg breakage are dependent upon the prices for good, cracked and loss eggs. For this analysis, good eggs were valued at $0.55/dozen, cracked eggs at $0.20/dozen and loss eggs at zero value.Atwo cycle flock model was constructed representing flocks molted at 65 weeks of age and sold at 105 weeks. Total eggs produced per hen housed was 363 eggs. Two different cracked egg percentages were used: 5.6 and 6.6%. Comparison of results indicated:
Figure 4.Distribution of shell thicknesses at 65 weeks (Babcock B300, DeKalb Delta, Hyline W-36) (University of California, 1995).
1% added cracks reduced income by 0.3 cents/dozen or $0.08/hen/year
1% added loss eggs reduced income by 0.5 cents/dozen or $0.11 hen/year
EGG BREAKAGE PROBLEMS AT DIFFERENT LOCATIONS WITHIN THE SYSTEM
Some researchers have concentrated their studies to different locations within the normal flow of eggs from production to the retail outlet. Each study was done at a different time, in a different region of the country and under varying circumstances. Only a few studied the same eggs throughout the entire process.
Uncollected eggs
Two basic types of eggs are found below the cages in the manure – eggs that were never going to be a salable product and eggs that had sound shells but were trampled through the cage bottom thus becoming a loss (Table 1). The first type should not be assigned value as they are not considered part of production. They are associated with a cost and they can be associated with specific problems. Researchers at Auburn University have shown that these are produced in increasing numbers as the flock ages and they have been observed at rates of 7.5 defective shelled eggs for every 100 hard shelled eggs gathered (Roland, 1997; Roland et al., 1977).
Earlier work by researchers at Texas A & M University studied the issue of sound shelled remnants in the manure and estimated that there were 3.9 of these eggs for every 100 hard shelled eggs collected (Table 2). If this is still applicable today, it represents the largest single contributor for economic losses because these eggs have zero value (Miller and Mellor, 1971).
Table 1. Uncollected eggs due to inadequate shells (not including sound shelled eggs in the manure).
Table 2. Broken eggs in the manure (soft shells and partial shells excluded).
Table 3. Body checked eggs (cracked in the hen and subsequently repaired).
Body checked eggs
Body checked eggs (and windowed eggs) are usually not downgraded in value except for the more serious body checks which result in distorted banding of the egg or if they are incompletely sealed (Table 3). Both types, however, cause considerable confusion to candlers and are commonly rejected in the haste of making candling booth decisions. For this reason, management should do everything possible to minimize their number and the risk of economic losses. Their incidence is closely associated with flock age, periods of activity in the layer house and cage density (Roland, 1984).
TYPICAL BREAKAGE ON THE EGG ROLL-OUT
The data in Figure 5 were collected in 1984 and represent several thousand weekly flock samples. Each sample (200 eggs) was hand-candled by the quality control supervisor for a major US company. The results parallel similar studies of the author and others and illustrate the increasing crack problem as flocks age and in successive flocks (molted). The incidence of breakage triples from the beginning of the first cycle to the end and is 50% higher in the second cycle compared to the first (Bell, 1984a).
These data parallel every study of the relationship of age to the shell quality problem (Figure 6). University of California research in 1982 found an average of 4.35% cracks in 117 flocks. Individual samples exceeded 10%.
WHY DO EGGS BREAK IN THE CAGE?
UK researchers in 1971 found that different chickens have different laying postures and as a result, egg breakage was directly correlated with the height of the egg drop to the floor of the cage. Chickens were observed laying their eggs with a drop of 1.5 inches resulting in 14.5% breakage; others laid their eggs with a 2.9 inch drop with 73.5% broken eggs. Interestingly, chickens can be genetically selected by their laying posture to correct this problem (Carter, 1971).
Other researchers in the UK studied the slope of the cage floor and found positive correlations with increasing slope associated with increasing breakage. With 32-week-old flocks, breakage increased from 3.4 to 10.0% between slopes of 7.4 and 11.5 degrees, respectively. In 72-week-old flocks, breakage increased from 12.4 to 26.3% over the same range of floor slopes (Elson and Overfield, 1976). It should be pointed out, however, that slopes of less than 7.4% may also increase egg breakage as the egg may not exit the cage before it is trampled or otherwise abused.
University of California research in 1978 with 17 different cage types measured 2.4% less egg breakage in shallow cages compared to traditional cages (12 inches deep vs. 18 inches deep). With today’s prices, this would be equal to $0.19 per hen. The theory behind this improvement was that the shallow cages provided 50% more space for eggs to leave the cage and the length of the roll was only two-thirds of the distance (Bell, 1985).
The more often eggs are gathered, the fewer eggs for collisions. An experiment in 1985 in California compared once vs. twice per day hand collection and found a 1.6% reduction in egg breakage. This is equivalent to $0.13 per hen per year minus added labor costs for the second gathering.
Figure 5.Cracked eggs associated with age and cycle of egg production (Bell, 1984a).
Figure 6.Egg shell damage in the cage and during collection (University of California, 1982).
Egg breakage through processing and carton packing
In 1972, the USDA Agricultural Research Service studied the issue of egg breakage in five California egg packaging plants with nine 1,000+ egg samples. Eggs were candled for breakage in the receiving cooler immediately after washing and drying and after having been packed in cartons into shipping containers. Egg breakage and costs are shown in Table 4.
Egg breakage during mechanical collection and processing
A national survey of technology usage in the US indicated that by the year 2000, 91.8% of the eggs produced would be gathered by belt conveyors either to a farm packer or directly in-line to a processing plant (Bell, 1993). The use of mechanical egg gathering systems in conjunction with the processing plant equipment represents a major opportunity for egg shell damage. An early California study in 1977 of 17 mechanized collection systems found 3.1% of the eggs were cracked between the egg roll-out and the filler flat (no eggs were packed in cartons in this study) (Ernst and Johnston, 1977).
As was observed in the UK work (Figure 2), eggs broke within the system in direct proportion to their shell strength as expressed in shell thickness (Figure 7). Eggs with shells thinner than 0.013 inches had a probability of from 0.30 to 0.77 of breaking while eggs with shells thicker than 0.013 inches had a probability of 0.02 to 0.08. This, once again, demonstrates the relationship between shell strength, environmental insult (mechanical egg collection) and egg breakage. Table 5 illustrates the contribution of each of the egg collection components.
Table 4. Egg breakage during processing and associated losses.
Figure 7.Relationship of shell thickness to the probability of eggs breaking during mechanical egg collection (University of California, 1977).
In the 1977 study, it was observed that egg washers contributed 1.47% of the cracks. Today this would represent economic losses of almost $0.12 per hen. A second study in 1982 examined the question of shell damage in the egg washer using 117 different egg washers in California. Washer damage ranged from none to 7.8% with an average of 1.2% of all eggs tested. This represented a loss of 0.44 cents per dozen or $0.09 per hen per year (Bell et al., 1978). Figure 8 illustrates the number of washers and the amount of breakage in each.
Figure 9 shows the egg breakage in the washer associated with eggs with shells of differing thickness for young vs. older flocks. Figure 10 illustrates the total breakage (from nest through washing) observed relative to egg weight and shell thickness. As eggs get bigger, they experience more breakage – most of this appears to be related to the corresponding age of the flocks as opposed to weight per se.Within weight categories, decreasing shell thickness increases breakage.
Table 5. Egg breakage due to mechanical egg collection.*
Figure 8.Frequency distribution of eggs broken in the egg washer (University of California, 1978).
Washers exert considerable pressure on eggs during the brushing procedures. In addition, water to egg temperature differences of 50wF have been observed to increase the production of ‘thermal checked’ eggs.With 110wF wash water, eggs should be at least 60wF at time of washing. Removal of all cracked eggs prior to washing will also reduce their chances of becoming losses. It was observed in these studies that 8.3% of the cracked eggs became losses during washing resulting in loss in value as well as adding egg material to the wash water and to the conveyor spools.
Figure 9.Eggs broken in the egg washer associated with flock age and shell thickness (University of California, 1978).
Figure 10. The effect of egg weight and shell thickness on egg breakage (total measured after the egg washer) (University of California, 1982).
The procedures used to measure breakage in research can also be adapted as monitoring programs for the commercial industry. Any mechanical component of a collection or processing system can be ‘tested’ by carefully pre-candling a representative sample of eggs (500 eggs suggested) and carefully inserting these eggs into the system to be tested. Remove them after the component and re-candle. This is an excellent way to monitor your equipment.
OTHER ISSUES TO CONSIDER
All egg shell problems are not associated with shell breakage even though these are of the highest economic significance. The roughness of the egg shell increases with age (Figure 11); and when serious enough may result in some downgrading under the definition of being ‘abnormal’. Molting corrects the problem to a degree, but when flocks are kept in lay beyond 30–40 weeks, many eggs become very rough and consumers may find this displeasing.
A major problem in the 1990s has been the Salmonella enteritidis (SE) association with shell eggs. All trace-backs to the assumed source can only be to the farm or possibly a single flock. The cause can only be speculated with blame placed on the rodent population, the egg handling procedures, general sanitation or the source of stock. The incriminated eggs are collectively defined as ‘Grade A’ eggs and assumed to be sound of shell. With the recognition that up to 5% of so-called Grade A eggs are also cracked, it might be an important item to investigate in more detail.
Is the organism associated with sound shelled eggs or might it have a greater prevalence in cracked eggs? A1996 experiment at the University of California by R.A. Ernst studied the effects of sweating on SE penetration of shell eggs and found that 75% of the cracked eggs were contaminated by surface application of the organism compared to only 4% for sound shelled eggs. If cracked eggs are a significant source of the problem, a greater effort must be taken to assure that these eggs find their way to pasteurization rather than into the carton.
Figure 11.Effect of age and cycle of egg production on shell roughness score (University of California, 1965).
ERRORS IN MEASURING EGG SHELL BREAKAGE
As faster egg grading equipment is developed, the time allowed for individual egg examination decreases. A 200 case per hour machine with two candlers represents individual egg decisions at the rate of 10 per second (400 case per hour machines are in use). The decision must also include the type of defect (cracks, bloods, dirts, etc.) and the physical removal of leakers. Obviously, mistakes happen and defective eggs are missed and good eggs are mistakenly rejected. Tolerances within the grading laws are there to allow for mistakes.
Research at the University of California (Bokhari et al., 1995) showed that 17.3% of the rejects from 12 processing plants were found to be perfectly good eggs by regulatory definition. Figure 12 illustrates the error range from 1.5 to 47.9% in individual plants. This represents a loss of income from 0.6 cents to $0.18 per case.
The apparent reasons for these errors (Figure 13) were rejections due to translucent markings on the shell (wire marks windows, shell mottling), 42.5%; shell deformities, 11.9%; body checks, 11.7%; and perfectly good eggs, 30.6%. Translucent markings on the shell are commonly interpreted as cracks and are often mistakenly rejected by inexperienced candlers. Eggs with shell deformities and body checks are in the ‘gray area’ of definition associated with the term ‘practically normal’. To reject or keep these eggs requires a rapid decision and many plant managers chose to reject when in doubt. The 30.6% of the eggs that are rejected without any known reason are the ones which definitely have to be eliminated.
Figure 12. Good eggs as a percent of rejected eggs in 12 California plants (Bokhari et al., 1995).
Figure 13.Apparent reasons for rejecting good eggs (17.3% total) (University of California, 1995).
The net economic impact of these rejections by error is estimated to be $0.07 per hen per year. The economic losses associated with windows is $0.0294 per hen per year and with perfectly good eggs is $0.0212 per hen per year.
Recently, a new technology has entered the scene with potential to correct this important problem. The electronic check detector is now being used in many of the country’s major shell egg processing plants. The equipment has the potential of removing any or all of the cracks it identifies. Through multiple evaluations per single egg, the equipment can remove or retain all gradations of the problem. The choice of removal now becomes a decision of management. All defects and some errors can be removed or removal can be limited to only the most severe with no errors.
A study of eight of these systems was done in California plants in 1995 and the error rate in the reject pack was found to be 12% compared to the 17.3% in the older systems. The error rate ranged from 0.6 to 30%. The range is due to the differences among plant managers in policies to ‘remove all cracks and suspected cracks’ or ‘work to the maximum of the tolerance’ (5%). Within the tolerance of 5% at origin lies the potential of gaining up to $0.40 per hen per year. As sensitive as these systems are, a more practical level of crack retention may be more like 3% at origin thereby removing all of the more serious cracks without rejecting perfectly good eggs.With these systems, attempting to remove 100% of the cracks will lead to the rejection of sound shelled eggs as well which is unacceptable. As with human candling systems, the new technology also requires constant management and maintenance of the system.
EGG SHELL DAMAGE AFTER PROCESSING
Egg shell damage in transport
An extensive study in the Northeastern area of the US in 1975 evaluated the change in shell damage between the egg processing plant storage room to the retail store and display case (Johndrew et al., 1975). The study involved eight different farm packing plants and 11 retail stores. It was found that prior to shipment, 5.2% of the eggs packed in cartons were cracked. This number increased to 6.9% in the retail store holding room, to 7.5% in the display case after stocking and to 9.2% when they were re-candled 2–10 hours later.
Today, the average condition described above would make the eggs subject to rejection at each level – the processing plant for exceeding 5% and at destination for exceeding 7%. From an economic viewpoint, none of these eggs would affect the producer, processor or retailer as long as eggs were not rejected. Customers may not like the product and switch to another store and retail buyers may change to another supplier, but if the eggs are sold, no losses in income are experienced.
A second study by the USDA in 1978 showed an increase in egg breakage of 1.45% between the egg processing plant and the supermarket storage room. This study involved 28 truckloads of eggs shipped 105 to 330 miles. Half of the eggs were packed in cartons and wire baskets, the other half in cartons and cardboard cases. In this study, the average preshipment breakage was 2.4% compared to post-shipment breakage of 3.9%. Eggs from younger flocks (less than 40 weeks of age) increased by 0.29% compared to eggs from older flocks (over 60 weeks of age) which increased to 2.02%. Eggs shipped during the summer broke at a rate three times the winter rate (Lederer, 1978).
Egg shell damage in the supermarket
In 1996, a national study of retail egg quality was made in six states of the US (Bell et al., 1997). The study included 38 cities, 115 stores and 771 dozen large eggs packed in standard one-dozen cartons. Cracks in white shelled eggs, determined by hand candling, averaged 5.9% with a range from 4.0 to 7.4% by state. Brown shelled eggs averaged 6.9%. Fifty-five percent of the cartons examined had no cracks, 29% had one crack, 11% had two cracks and 5% had three or more cracks (Figure 14).
PLACING EGG BREAKAGE LOSSES IN PERSPECTIVE
Throughout this discussion, we have assumed that a 1% increase in cracks would represent a loss of $0.08 per hen for one year. A 1% rate of loss (at zero value) would represent a loss of $0.11 per hen for one year. This may or may not sound to be of economic significance, but when compared to a conservative estimate of annual profits for the egg industry, it becomes a very significant economic issue. If it were assumed that annual profits per hen were $1.00, a 1% increase in breakage would represent an 8% loss in profits; a 1% increase in losses would represent an 11% reduction in profits. These are certainly significant effects. When all the factors affecting egg breakage are put together, the issue becomes a major concern for all producers. Control of the problem can be the difference between a successful operation and one that could easily go bankrupt.
Figure 14. Cartons with cracked eggs: results of a six state study (Bell et al., 1997).
COSTS TO THE US INDUSTRY
The emphasis in this article is the economic effects on the individual company. It is the company that can remedy the problem; and it is the company that suffers if it is not remedied. The effect on the industry as a whole is of interest only because of its magnitude compared to other issues of importance in the industry. Table 6 summarizes our estimates of losses to the industry based upon the assumptions stated. It is suggested that the direct costs (losses) are $247.5 million per year.
In addition, there are associated costs for the cost of candling and the purchase of equipment to detect breakage, labor and packaging costs for re-working rejected eggs, customer dissatisfaction with our products, clean-up costs, and possible human health risks associated with eating cracked eggs. Numerous methods have been listed which can reduce the incidence of egg breakage at various levels of production, processing and marketing. The important message is the significant economic impact of 1% egg breakage to over-all profits in the egg industry.
Table 6. Summary of economic losses to the US egg industry due to breakage from production through grading.
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