Trainers’ Manual – Unit 6– Commercial Egg Production

There are several choices that can be made about management and housing of laying hens.

Hybrid layer of large brown-shelled eggs.

They can be kept in group (3-5) battery cages; this has a high capital cost unless the cages are constructed from local material. They can be kept indoors on the floor (barn hens) or they can be kept out -of – doors (free range).

There is another system where they are kept in large groups in colony cages, and allowed more space than in battery cages (see later). Hybrids give more eggs when in cages and dual purpose birds perform well under free-range conditions. Black Australorps are ideal for free range as they have a good temperament.

There are two options

1. The farmer can purchase hybrid day old female chicks. These are currently expensive

2. The farmer can hatch his or her own with a broody hen or in a small incubator if she/he has suitable heating. In this case she/he will have equal numbers of male and female chicks. Later she/he may then be able to separate them by feather growth but not until 6-8 weeks of age. If they are dual purpose, the males can be grown for meat production, or sold. They grow quite slowly.

Hatching chickens

If the farmer has a laying flock, she/he will need one rooster for about 8 hens. The hens’ eggs will be fertile after the cock runs with them for 7days. The fertile eggs should be kept in a cool, dry place for no more than 8 days before incubating. This may be in a small incubator or in nest boxes, in a secure house. These boxes should be located in a quiet space. The broody hens will need special litter, and a layer of sand to keep the eggs moist is placed below the litter. Water and feed should be placed close to the broody hen.

Pullets

These are immature hens and usually raised indoors on litter in the same way as broiler chicks except that they grow much more slowly. They stay in the brooder for up to 4 – 6 weeks on a starter diet that is of high quality. Floor space is 25 pullets up to 20 weeks of age per 6-7 m2. The grower diet is of lower nutrient specifications until about 17 weeks when they are then given a layer diet. This is high (3%) in calcium. The pullets are then transferred into the layer house and should be at a predetermined or target body weight at point of lay. If too light (thin) and immature, they will start to lay later than normal and produce fewer eggs. If too heavy, egg production will suffer and they will have over-consumed costly feed during the rearing period.

 

Hen Housing

 

Battery cages

In intensive layer systems, 2 to 5 hens are normally kept in battery cages in various configurations (i.e. flat deck or in tiers) but there is increasing criticism of these cages on welfare grounds. Floor space is 400cm2/hen or 2000 cm2 for five hens (50 x 40 cm). Expensive, ‘furnished’ cages are being introduced in some European countries. Although maximum egg production occurs from hens in cages, the hens should have their beaks trimmed as pecking one another particularly around the vent can result in high mortality.

 

Cages constructed out of local material

 

 

Mortality is normally 1%/month although it can be much higher and depends on the breed and numbers per cage. Sharp claws can damage the backs of hens in cages and at the end of lay they have few feathers left around the neck and breast. An advantage of cages is that individual hens can be observed. Those not in lay have flat, pale, scaly combs instead of large, shiny, waxy, red combs. Also the vent is dry instead of being moist and enlarged. These hens still eat feed and if they continue to be out of lay they should be culled (removed).

Small-scale cage system

Twelve hen cage system

A sustainable, household cage system has been designed in South Africa which is a single cage (120 cm long x 50 cm wide x 45 cm high) and divided into three compartments holding 12 hens (total). It can be constructed from bamboo with a thatched or other type of roof and is on poles or a stand about 1 m above the ground. Each compartment holds 4 layers. The cage is portable and can be moved out of the sun and rain and to a secure place at night if necessary.

A bamboo or metal feeder is located on the outside of the cage and various kinds of drinkers can be used; some made from large, soft-drink bottles. Hens must be given a good-quality layer diet but household food scraps can be added. The system should be self-sustaining in that 12 hens should lay 9 – 10 eggs/day from about 23 weeks of age. The farmer sells 5 eggs to neighbours to buy more feed, and keeps 4 – 5 eggs for his/her family to eat. At the end of 12 months the 8-9 surviving hens are sold and some of the income saved from the sale of 5 eggs/day is used to replace the 12 hens (either raised or purchased as point-of-lay pullets). The manure from under the cage is a valuable fertiliser for the household garden.

Colony cages

An interesting modification of the cage system has been developed in Vietnam. These are large colony cages on stilts/legs and made from bamboo with external feeders and drinkers. They hold about 12 or more layers. The eggs roll out of the cages as in battery cages as the floor is on a slope of about 1 cm in 8 cm. The manure can be collected underneath the raised split-bamboo floor. The large cages are in a barn or house. Such a system may be successful in other countries and is a good compromise between the barn and the battery cage system.

Barn hens

These are kept indoors and run on litter at 50 hens /10m2 . There is a need to provide nest boxes at about 18 nests /100 layers. Clean litter should be placed in the nest box (35 cm x 35 cm x 35 cm) and replaced every month. The boxes can be on a stand or on the floor. Eggs should be collected twice each day. Feeders and drinkers are similar to those for broilers except that the height is fixed at about 30 cm above the floor. A free-choice system of feeding can be introduced, and a source of calcium in a separate feeder. Ideally there should be perches (25 cm/hen) on which the hens will roost and this concentrates the manure below. The advantage of this system is that it has lower capital costs than cages but feed consumption will be a bit higher, and egg production lower than for the same hens in cages. Some eggs will be laid on the floor so there will be some dirty eggs. However there is likely to be lower mortality with reduced vent pecking. There is also the need for floor litter which may have to be added to during the laying cycle to keep it. Green feed should be given to keep the birds occupied and provide them with essential nutrients especially vitamins.


Free range

Hens are allowed access to pasture during the day time. The area needs to be enclosed (hen proof) and good green feed should be available. The hens should be given adequate space to range (5-6 m2/hen). Ideally there should be two fenced areas to free range so that one may be rested to prevent disease build up and the pasture or other green feed to re-establish. The hens will return to the deep-litter house (similar to barn hens) in the evening where they should be safe from theft and predators. This may be an ongoing problem.

Floor space in the deep-litter house can be less than the barn system by about 20%. The great advantage of free range poultry is that they are less likely to get a nutrient deficiency than if indoors all the time. The disadvantage is that they are more likely to pick up disease especially internal parasites. Medication can be added to the water. Again egg production will be lower and feed intake higher than in caged birds. The system is more appropriate to docile breeds such as the Black Australorp and dual purpose breeds than often flighty hybrids. They are likely to be able to give reasonable production on diets of only moderate quality.

Trainer should have access to these systems for demonstration purposes. These, together with photographs and illustrations, will be important in discussing advantages of the different housing systems giving details of cost of materials and other costs

Force moulting

Replacement pullets can be expensive so that it may be worth while putting hens through a second laying cycle. Production normally starts to drop, and shell quality declines at 40 – 50 weeks of lay (60 – 70 weeks old). Before this happens, hens are given a low-quality feed (just grain) for about 3 – 4 weeks which will put them out of production within 7 – 10 days and will slowly lose all their feathers. They are then gradually introduced to the layer diet and will start to lay again after a total elapsed time of 5 – 6 weeks. Egg production will go much higher than that at 40 – 50 weeks of lay and egg shell quality will greatly improve. Although unlikely to reach the previous peak production, they will lay a large egg and at an acceptable rate until about 90 – 100 weeks old. The decision to moult will depend on (a) pullet replacement costs and (b) the price of eggs of different weights. Eggs are sold either graded (weight) or mixed grades and usually by the dozen or half dozen.

Unit VI. Trainer will go through the pros and cons, and the steps in force moulting hens and illustrations will be shown in the Trainee’s Manual

Internal egg quality

Not everyone is aware of egg quality. It is related to both the outside (shell) and inside (contents) of the egg. This relates to the appearance, the cooking quality and the eating quality of the egg, some of which can be controlled by management.

Yolk colour

In some countries an egg with a pale, yellow yolk is preferred to a deep yellow-orange yolk. Natural yolk colour depends on the feed. Maize (corn) contains a pigment which gives the yolk a rich orange colour but wheat does not. Green feed darkens the yolk so that free-range hens on good pasture will lay eggs that have yellow yolks. In some countries consumers think that eggs with pale yellow yolks are not up to standard or are from hens who are sick. This is not correct.

A pigment or colouring agent can be added to the feed. Marigold petals, capsicum and chilli are an excellent source of natural pigments; others are synthetic (manufactured). Yolk colour does not alter the taste of the egg.

 

Staleness

As an egg ages in storage, it starts to lose weight. It will eventually float in water when very stale. In warm weather, this happens very quickly due mainly to loss of moisture, but other changes also occur. The result is that as the egg ages the yolk becomes watery when you break it out. The height of the white layer surrounding the yolk can be measured using a micrometer. This, and the weight of the egg, can be used to calculate Haugh Units (110 to 0). A new laid egg has a Haugh Unit of about 90 but declines quickly so that it reaches below 60 in less than 4 days at room temperature of >25oC but only 80 at a cool 10oC. When eggs reach a Haugh Unit of < 60, they are becoming stale; the white then spreads out and the yolk mixes with the white in a frying pan. A stale egg may taste no different from a fresh egg but looks to be inferior.

Stale egg

A fresh yolk with compact white and yolk colour score 12-13.


Other factors that affect Haugh Units are, breed of hen, age of bird (Haugh Units decline with age), and some diseases. Eggs should always be stored in a cool place and in a refrigerator if there is one. Oiling eggs by spraying them with an approved, light mineral oil seals the shell pores and reduces moisture loss. This is sometimes practised in warm climates to stop early deterioration. Blood spots may occasionally appear in eggs; the exact cause is not known although it may be related to breed.

External quality

This is a serious problem in the egg industry and at least 10 -15% of all eggs are rejected (seconds). Breakages are high due to thin shells. As mentioned, shell quality deteriorates as a flock ages. Shell is thin and the eggs cracks easily. Blemishes, rough surfaces and misshapen eggs can be caused by poor diet (low calcium and phosphorus), high salt water, and some diseases. Dirt marks due to fly droppings, fungus, blood stains and cage wire marks are all causes of down-grading of eggs. Some aspects of shell quality can therefore be improved by management. Nutrition is sometimes a factor, especially insufficient calcium and available phosphorus in the feed (plant phosphorus is poorly available). Some diseases can affect shell quality.

  1. Shell has rough textured areas, may be due to double ovulation with one egg without a shell  followed by one with a ‘sand paper shell’
  2. Shell is partly flattened and wrinkled seen during early lay
  3. Shell becomes stained with blood (usually in pullets) or faeces (laid on ground)

Egg with a sand paper shell

 

Egg with a sand paper shell

Soft shell egg

Soft shell egg

Blood stained egg

Unit VI. Trainer will have visual material available and eggs with defects will be collected and demonstrated. Eggs will be kept for several weeks and when stale will be broken out on a frying pan and compared with a fresh egg

CONCLUSION

Poultry production is a slow process based on both knowledge and experience. Poultry keeping is not attractive to everyone, nor does everyone have the natural skills to manage poultry. It requires dedication and kindness to the flock if the birds are to respond. There is a need to examine all aspects of the production system before a farmer decides to set up a poultry enterprise. Recently, some farmers in some low -income countries have seen broiler production as opportunistic but this short-term approach does not form a solid or sustainable foundation for a broiler business. The producer not only needs to be dedicated but must be able to survive the good and the inevitable bad times associated with any livestock industry.