Tools for Optimizing Egg Size in Commercial Layers

Tools for Optimizing Egg Size in Commercial Layers

Consumers tend to prefer and are willing to pay more for larger eggs, so knowing what may influence the size of egg produced may be beneficial for maximum return. A large egg is not always a good egg. The larger the egg is, the thinner the eggshell thickness is. A hen will only deposit 2 grams of calcium per egg, regardless of egg size. Numerous non-genetic factors will influence the ability of pullets or layers of the same variety to achieve the goals specified by the breeding company. These factors include body weight and frame development, nutrition, bird density in cages or floor housing systems, feeder and water space, lighting programs, housing and climate conditions, beak treatment procedures, vaccination schedules and diseases. Genetic and non-genetic factors influence egg weight of commercial layers and should be controlled by farm management before production of a flock starts: the genetic profile of a strain cross with regard to egg weigh and correlated traits, the light stimulation during rearing and the bodyweight or frame size development of the pullets. Once a flock is in production, the nutrient intake, especially the early feed intake, has a major effect on the egg weight curve. Modern layer nutrition is focused on meeting the demands of the birds at all times by adjusting the supply of nutrients according to daily egg mass production and daily feed intake. Precision supply of nutrients influencing egg size is a tool to adjust the egg weight on mid or short-term basis.

Each commercial variety has a genetically determined range of egg size, and within this range, environment plays an important role in the expression of egg size. Genetics, body weight management, nutrition, and lighting programs are the four pillars of egg size and are useful tools for the egg producer to change egg weight profiles to best supply the optimum egg size to a market.

The end users of table eggs today are looking for the best buy for their money. When it comes to groceries and a food staple like eggs, it’s Grade A Large Eggs that fit this scenario most of the time. To further drive this trend in Nova Scotia retail figures from last year show that for all size eggs sold Grade A Large Eggs had the lowest average retail price per dozen. The total nutritional value of a carton of Grade A Large Eggs (56-62 gm/egg) may be increased when the carton is supplemented with eggs that are Extra Large in size (63-69 gm/egg), which is allowable under egg regulations. This type of marketing using cost and nutritional value further drives up the demand for the Grade A Large Egg. Unless there is a special market, producing bigger size eggs is not economical for the table egg producer. It takes more nutrients to produce bigger size eggs, which increases the amount of feed eaten to produce the egg and therefore the cost per egg increases

The genetic make up of a layer variety determines its range of possible performance results. Within this genetically defined range, we can alter the production characteristics through our management systems to optimize these traits which are most profitable for our market. Based on International market levels eggs are sold on the basis of egg size. Much preference is given to egg size, whereas in Indian markets the eggs are not graded according to egg size. But still the consumer preference is towards large egg size. Hence poultry farmers have to give equal emphasis towards the production of large number of eggs with maximum egg size.

Size refers to the weight of an egg rather than the dimensions of the egg or how big it looks in appearance. For measuring the accurate egg size it is better to calculate the net weight per dozen eggs. In effect the factors affecting egg weight may be applied to egg size as well.

In the production cycle of the commercial layer, the hen will begin laying small eggs and in a matter of a few weeks will go to medium size and then to the desired large size egg. It is well known that the main factor that determines egg size is body weight, therefore the diet that supplies all nutrients can be used to manipulate and produce the preferred early egg size.

The four pillars of egg size

1. Genetics

Many Poultry Genetics company like Hy-Line is working at the genetic level to create commercial lines that have different egg size ranges. Egg weight is a heritable trait (~40%) that responds well to genetic selection. About 60% of egg size variation, however, is due to non-genetic factors (nutrition, management, etc.). These non-genetic factors can be manipulated by egg producers to achieve the desired egg size profile.

Hy-Line has been collecting egg weight data and selecting on egg weights for decades. Historically, egg weights have been collected periodically throughout a hen’s lifetime. Currently, Hy-Line weighs the first three eggs a hen lays, eggs laid mid cycle, and eggs laid late in the cycle. The Hy-Line Research department uses these egg weights to select for a more desirable shape to the egg weight curve. Specifically, they select to increase early egg weights, hold mid-cycle egg weights constant, and decrease late egg weights.

Egg numbers and breaking strength have a negative correlation with late egg weight. As Hy-Line varieties continue to improve late persistency and shell strength, the egg sizes at later ages will come down. To help adapt to this selection pressure, Hy-Line is relaxing the selection pressure to reduce late egg weight to ensure that sufficient egg size and egg mass is available in the genetic potential of the birds.

2. Body weight

An important factor in egg weight is the pullet‘s body weight at maturity. Heavier hens tend to lay more eggs throughout the production period and will have greater flexibility in adapting different egg size profiles. Body weight is affected by many factors, including beak trimming, vaccination program, transfer, disease challenges, pullet lighting program, space allotment, and nutrition. Due to the direct affect of body weight on egg weight, the achievement of flock target body weight with good flock uniformity is important for egg size management.

3. Nutrition

Nutrition during the rearing and laying period has a critically important role in egg weight. Proper rearing nutrition allows the hen to achieve or exceed the standard body weights. Changing the rearing diets based on attaining body weight standards (and not bird age) will best match the diet to the actual nutritional needs of the pullet.

During the laying period, the specification of diets can be used to manage egg size. Energy, methionine/cystine, other digestible amino acids, linoleic acid, and total fat can directly affect the egg size. These components can be specified in layer diets to influence egg size downwards or upwards.

The protein content of the diet should be balanced to ensure the amino acids are utilised efficiently by the bird. Unbalanced protein can result in poor utilisation of amino acids and suboptimal egg size.Breghendahl (2008) estimated the “ideal amino acid profile” and determined that the ratio of methionine to lysine should be a minimum of 47:100 to support maximum egg mass. All other amino acids should be balanced relative to lysine to ensure egg size is optimised as efficiently as possible.

To avoid excessively large egg size and weak egg shells later in the laying period, these nutrients are gradually reduced after peak egg production (30 weeks of age). Pushing nutritionally for greater egg size could result in thinner shells and more cracked eggs if mineral requirements of the bird are not adequately provided for.

Management for larger egg size should include nutritional considerations in rear for subsequent shell quality and bone strength (i.e. pre-lay diet).

Egg weight can be regulated through use of a phase feeding regime. Optimal egg weight will be easier to achieve when formulating feed according to egg weight or egg mass and constantly updating the formulas according to these parameters. This tool can be very helpful either to increase egg weight on earlier production, or to control egg weight on late production.

Be aware that not only nutritional levels, but all aspects of nutrition management can affect egg size. Feed particle size, water intake, water temperature, and feeding schedule can affect daily feed intake and nutrient intake as a consequence.

Heat stress can depress egg weight. High environmental temperature above the thermoneutral zone (> 33°C) has a depressing effect on the bird’s feed intake. The result can be a shortfall in nutrients like protein (amino acids) and energy, which will decrease egg weight. It is common to see decreased egg size as a consequence of heat stress. Appropriate adjustments in feed formulation to match the actual bird feed intake and mitigation of heat stress conditions can minimise this depression of egg size. In environmentally controlled houses, lowering the environmental temperature will increase feed intake and support egg weight.

4. Lighting programs

Chickens are responsive to changes in day length, and this has a significant effect on egg production and egg size (Figure 2). Slow step-down lighting programs (C and D) during the rearing period provide the pullet with more light hours to eat and grow. At the same time, these slow step-down lighting programs can also delay maturity and increase egg size.

Faster step-down lighting programs (A and B) provide fewer light hours and slower growth but earlier sexual maturity with smaller egg size.

Age of light stimulation and body weight are interacting factors that help determine the onset of egg production, as well as egg size. Light stimulation should be done based on the flock’s body weight and uniformity. Generally, early light stimulation at lighter body weights will accelerate maturity and decrease egg size; while later light stimulation at heavier body weights will delay maturity and increase egg size. Generally, the hen has the ability to produce a certain egg mass. As egg weight is changed, the egg number tends to change inversely to keep the egg mass constant.

Management tips to optimise egg size in a market

Management for larger egg size:

1. Select a commercial variety with a heavier egg weight profile.
2. Use a slower step-down lighting program in rear. (12 weeks)
3. Light stimulation at a heavier pullet body weights.
4. Make smaller gradual reductions in energy and methionine/cystine during the phase feeding program.
5. Use feed formulation that provides 10–15% higher digestible amino acid intake (mg of digestible amino acid per bird per day)  Increase the ratio of methionine + cystine to lysine to be >90%.
6. Linoleic acid has a positive impact on egg size. For increased egg size, use 1.5 g linoleic acid per bird per day. Use sources of supplemental oil which are higher in linoleic acid, like soybean oil or flaxseed.
7. Increase total and supplementary fat content in the diets. Studies have shown that at the same linoleic acid levels, birds consuming a higher amount of total fat will produce larger eggs.
8. Keep an optimal energy intake. In situations of deficient energy intake, laying hens will utilize protein and amino acids as an energy source, resulting in less amino acids available for optimal egg size. Many situations of low egg weight are due to low energy intake. Overfeeding energy above recommended amounts tends to depress egg weights, as a consequence of lower feed intake.

Management for smaller egg size:

1. Select a variety that has a regular egg weight profile.
2. Use a faster step-down lighting program in rear. (7 weeks)
3. Light stimulation at a lighter pullet weight.
4. Make larger gradual reductions in energy, methionine/cystine, and total digestible amino acids during the phase feeding program.
5. Nutritional management for controlling egg size is more complex and generates slower results than managing for increased egg weight.
6. Reduce methionine + cystine to lysine ratio (<84%). This reduction should be done gradually to avoid reduction of egg production as well.
7. Control total digestible amino acid intake. Studies have shown that a reduction of intake of all amino acids can be more effective in controlling egg weight than reducing only methionine and methionine + cystine.
8. Limit linoleic acid intake to 0.9 g/day per bird. Change to an oil source with lower linoleic acid content, such as palm oil.
9. Start to control egg weight with phase feeding at least 2–3 g before the desired egg weight. Provide clear objectives of the amount of cumulative amino acid intake per egg weight phase you desire.

 MANAGEMENT TIPS TO OPTIMIZE EGG SIZE IN A MARKET

Management for larger egg size:

1. Select a commercial variety with a heavier egg weight profile.
2. Use a slower step-down lighting program in rear. (12 weeks)
3. Light stimulation at a heavier pullet body weights.
4. Make smaller gradual reductions in energy and methionine/cystine during the phase feeding program.
5. Use feed formulation that provides 10–15% higher digestible amino acid intake (mg of digestible amino acid per bird per day. Increase the ratio of methionine + cystine to lysine to be >90%.
6. Linoleic acid has a positive impact on egg size. For increased egg size, use 1.5 g linoleic acid per bird per day. Use sources of supplemental oil which are higher in linoleic acid, like soybean oil or flaxseed.
7. Increase total and supplementary fat content in the diets. Studies have shown that at the same linoleic acid levels, birds consuming a higher amount of total fat will produce larger eggs.
8. Keep an optimal energy intake. In situations of deficient energy intake, laying hens will utilize protein and amino acids as an energy source, resulting in less amino acids available for optimal egg size. Many situations of low egg weight are due to low energy intake. Overfeeding energy above recommended amounts tends to depress egg weights, as a consequence of lower feed intake.

Management for smaller egg size:

1. Select a variety that has a regular egg weight profile.
2. Use a faster step-down lighting program in rear. (7 weeks)
3. Light stimulation at a lighter pullet weight.
4. Make larger gradual reductions in energy, methionine/cystine, and total digestible amino acids during the phase feeding program.
5. Nutritional management for controlling egg size is more complex and generates slower results than managing for increased egg weight.
6. Reduce methionine + cystine to lysine ratio less than 84%
7. Control total digestible amino acid intake.
8. Limit linoleic intake to 0.9 g/day/bird
9. Start to control egg weight with phase feeding at least 2-3 gram before the desired weight gain.

 Parameters Influencing Egg Shell Quality

Factors Affecting Egg Shell Quality
Role of Nutrients
Balancing the calcium and phosphorus in layer feed formulation is of utmost importance to maintain a better egg production and shell quality. A normal poultry egg contains almost two grams of calcium in their egg shell. To maintain a better egg shell quality, a daily dietary intake of four grams of calcium through the diet is essential. In general, 50-60% of dietary calcium is used for the egg shell formation. A normal layer ration containing 3.56 % or higher calcium level would ensure maintenance of 20-30mg/dl of calcium levels in their blood. When layer birds are fed with a calcium deficient diet (<2% dietary levels), the layer birds utilize 30-40% of its calcium from the bone for its normal egg shell formation.
Phosphorus absorption is optimal at a pH range of 5.5-6.0. The absorption of phosphorus decreases when pH is higher than 6.5. A high dietary calcium level increases the pH in gut leading to a reduced phosphorus absorption along with zinc and manganese. Correspondingly, a high plasma phosphorus level has a negative influence on the calcium absorption and mobilization. An increase free fatty acid levels in diet, decreases the pH and interferes with calcium and phosphorus absorption.
Mycotoxins
Aflatoxin B1 and cyclopiazonic acid are the most common mycotoxins implicated in egg shell quality. Aflatoxins were found to reduce the calcium content in egg shell of laying hens. Whereas, cyclopiazonic acid produces a marked deterioration in egg shell quality in laying hens. T2 toxin and deoxynivalenol elicit oral lesions leading to lower feed intake and resulting in reduced egg production and poor shell quality.
Age of Birds
Calcium and phosphorus level must be maintained in feed of laying hens as per the age. Normal egg contains about 2g of calcium regardless of the laying hen’s age and egg weight. As the hen’s age advances, eggs will become larger with thinner shell. The absorption of calcium from intestine will also be reduced. As age advances, calcium level in feed should be increased. In phase-1 (0.5% hen day production to 40 weeks of age), 4.2g/day calcium and 0.44g/day available phosphorus must be provided. In phase-2 (above 41 weeks of age), 4.35g/day calcium and 0.42g/day available phosphorus must be provided.
Physiological Changes
In early stage of laying period, the young layer birds commonly produce soft shelled eggs. This will be reduced with the maturity of reproductive system. Sometimes, stress or fright could also lead to the eggs laid without shell.
Disease Condition
Diseases like infectious bronchitis (IB), new castle disease (ND) and avian influenza (AI) affects the egg shell quality. In IB, occurrence of misshapen eggs with thin, soft, rough and pale shells were observed. While in ND, occurrence of misshapen eggs, rough or thin shelled eggs and reduced egg production could be observed. Mycoplasma gallisepticum affects the bird’s respiratory tract, responsible for salpingitis, reduced egg production and poor egg quality. Whereas, Mycoplasma synoviae affects the oviduct of layers resulting in egg production with shell abnormalities like roughened shell surface, shell thinning and increased translucency on apical side leaving a clear demarcation zone. The proportion of affected eggs can be as high as 25% with susceptibility to breakage and cracking of eggs resulting in economic losses.
Environmental Changes
Disturbance in the plasmatic acid-base balance results in soft shelled egg production. During exposure to warm environmental temperatures, hens reacts by increasing its rate of breathing to help cool itself. This physiological occurrence causes the lowering of CO2 in blood and produces a condition termed “respiratory alkalosis”. The pH of blood becomes alkaline reducing the availability of Ca++ needed for the formation of egg shell. This causes an increase in the production of soft-shelled eggs. Thus, egg shell quality is somewhat compromised during warm summer months.

• After forced moulting, the egg specific gravity, shell weight and shell thickness tend to improve or maintain same as prior to the forced moulting. Egg shell breaking strength is also improved in all strains of layer birds after forced moulting.
• Low dietary cationic-anionic balance, presence of non-starch polysaccharides (NSP) and mycotoxins results in poor egg shell quality.
• Old layer cages with rough edges and handling of eggs leads to egg breakage.
• Steps to Improve Egg Shell Quality

Trace Minerals
Trace minerals are essential in the biochemical processes necessary for growth and development, including bone and egg shell formation. Zinc plays a vital role in deposition of albumen and egg shell membranes production respectively in magnum and isthmus respectively. The carbonic anhydrase, a zinc dependent enzyme, stimulates calcium carbonate deposition for egg shell formation. Manganese is essential for egg shell formation and positively affect egg shell quality. Copper, an integral part of lysyl-oxidase enzyme is important in collagen formation present in egg shell membrane. In poultry nutrition, either inorganic or organic forms of trace minerals are commonly added as feed additives to diets in improving hen’s performance, production and quality of eggs. Compared to inorganic sources, organic mineral sources are reported to have several advantages including protection from undesired chemical reactions in gastrointestinal tract, easy passage intact through intestine wall and, possibly different absorption, metabolic pathway and mechanism.
Calcium, Phosphorus and Vitamin-D3
Crystalline layer of egg shell consists of more than 90% calcium in the form of calcium carbonate. The dietary calcium (3.8- 4.2%) uptake, deposition and excretion are regulated by Vitamin D3 and its metabolites. Vitamin-D3 is absorbed from intestine in association with fats and it requires the presence of bile salts for absorption.
Sodium Bicarbonate
Addition of sodium bicarbonate maintains the dietary electrolyte balance, thus positively influencing the egg shell quality through better calcium absorption. During summer, sodium bicarbonate must be added at the rate of 1kg per ton of feed to improve egg shell quality.
Chromium and Vitamin-C
Chromium improves the productive performance in poultry due to its important functions in metabolism, growth and reduction of lipid and protein peroxidation. Glucose tolerance factor (GTF), the biologically active form of chromium potentiates the action of insulin and thereby regulating the carbohydrate metabolism. Under heat stress conditions, chromium plays a crucial role in poultry nutrition, production, health and enhances the quality of eggs. Ascorbic acid improves the poultry performance during stress conditions by lowering of plasma corticosterone level and adrenocorticotropic hormone. When ascorbic acid was used at 100mg/kg of feed or less for commercial layers, an improvement in egg production, egg shell quality and livability was observed. Thus, a combination of chromium and vitamin-C will be more beneficial to combat the heat stress with an improvement in production and shell quality.
Management

• Analyze the raw materials for multi-toxins before the usage.
• In old layers, increase in egg size leads to thinning of egg shell. Hence, feed formulation should be optimized to maintain standard egg size and avoid egg breakage.
• A proper vaccination for infectious bronchitis and new castle diseases must be followed to sustain egg shell quality.
• Mycoplasma prevention program should be followed in chicks, growers and layers.
• A practice of minimum two or more egg collection schedules daily should be followed to avoid piling of eggs and egg breakage.

layer-management-Egg Size Control

Compiled  & Shared by- Team, LITD (Livestock Institute of Training & Development)

 Image-Courtesy-Google

 Reference-On Request.

TIPS FOR OPTIMIZING EGG SIZE IN COMMERCIAL LAYERS

Please follow and like us: