Layer management and egg production
There is no secret to successful egg production. Carefully selected hens, well housed, fed and protected against disease reward poultry farmers with a continual supply of high quality, marketable eggs.
Welfare starts from day one when newly-hatched chicks are bought in and taken through the growing phase into laying hens. Then, a careful producer will provide warmth, space, dry litter, recommended vaccines, clean water and appropriate feed, over the next 18 weeks.
Higher protein (20 per cent) and lower crude fibre (5 per cent) feeds (containing coccidiostat) for chicks up to eight weeks old eventually make way for the lower protein (18 per cent), higher crude fibre (7.2 per cent) feeds for growers at 9-18 weeks. Grower rations are cheaper but producers should watch out for wastage by ensuring feed troughs are not overfilled and tube feeders not fully opened. Farmers can make or buy feed troughs custom designed for spillage reduction.
Failure to take these steps can result in feed wastage levels of up to 25 per cent and transform a potentially profitable egg production enterprise into a loss-making venture even before the first egg is laid. After the growth and development phase, birds are ready for their egg-laying environment at 18 weeks of age.
Successful management of laying flocks hinges on the following factors:
• Housing and light management
• Feed and water management
• Heat stress management.
Housing and light management
In the interests of disease management, layers’ quarters should be located at least 100 metres from houses where chicks and growers are raised. Choice of housing is wide and includes intensive (battery cages) and semi-intensive (Californian type battery house, slatted floor housing, deep litter housing and the aviary type house). Producers should be aware that the textbook economic advantages of housing layers in intensive battery houses can be outweighed by loss of production through stress. Where space is not restrictive, producers can opt for the half inside/half outside system that reduces heat stress on birds during the hot season months. Where land is plentiful and predators not a problem, they can use the field ark which is moved onto fresh and clean parts of the pasture every day. In countries with high rainfall, chickens can be kept on pebble yards, which are washed clean daily by rainfall.
Appropriate length of the artificial day used in the house can be manipulated to stimulate egg production. The artificial day may be lengthened in one step or by a series of steps until it reaches 16-18 hours, at which stage maximum number of eggs laid in the shortest possible time should be achieved. More usually and sensibly, the natural lighting of the open type housing traditionally used in the tropics is augmented two hours of artificial light, administered in two 1-hour periods, one in the early hours of the morning (03.30) and the other in the early evening (19.30). Comparative studies show this light regime is economical with electricity and compares favourably in production terms with the conventional programme of continuous lighting (natural and artificial) from 03.30 to 20.30.
Feed and Water Management
Feed and feeding advice for laying hens may seem contradictory. Feed restriction is essential, especially for heavier breeds, if hens are to start laying at the best time and in the best condition. At the same time, birds should never be deprived of feed, and feeders should never be empty i.e. feed should be provided ad lib.
Hens should start to lay no earlier than 22 weeks old and in the ideal condition (not too fat and not too young). If sexual maturity is attained too early, the length and quality of overall performance will suffer. Eggs will be fewer and smaller with more prolapses towards the end of the laying period. Such birds lack vitality, die early and are more likely to be culled. These problems can be avoided by carefully restricting feed at the right time and in the right way as advised for specific breeds by the farms that sell day-old chicks. Feed restriction should only be used under the following guidelines:
• Use expert advice from the breeding farm relating to the particular breed you have purchased
• Do not start before the birds (at grower stage) are at least 9 weeks old
• Supply feed in a restricted programme based on regular weighing of birds to obtain an accurate live-weight average for the flock:
1. Weigh birds weekly
2. Sample one in 10 of the flock; half from the front of the pen and half from the back
3. Take birds at random using a catching wire
4. Weigh at the same time each week just before feeding
5. Provide adequate feeding space so that all birds can feed at the same time
6. Make feed change periods gradual. When 10 per cent of egg production has been achieved (at about 23 weeks), the flock should be on layers’ mash
7. Stop restrictive feeding if birds become ill or show symptoms of stress; return to feeding ad libitum
The mechanics of restrictive feeding are varied. Farmers can adopt a once-a-day feeding method and, if automated, replenish the troughs at night. Others may prefer to use the ‘miss a day’ method but this carries the risk of increased cannibalism due to the combined effects of boredom and hunger. This is overcome by offering extra rations based on high fibre cereals such as millet or using ‘greens’ that keep the birds ‘happy’ without adding the calories. Feed restriction practices can save the farmer up to 15 per cent in feed costs although potential savings should not enter into the equation when deciding whether or not to embark on this course. Reducing feed wastage (up to 12 per cent in laying flocks) is a safer and more sensible way of saving money.
Layers’ rations must contain 3-4 per cent calcium, needed for extra strong bones (calcium phosphate) to cope with the stresses and strains of egg production and egg lay, and as a vital ingredient for production of the shell that is mostly of calcium carbonate. Feed lacking in calcium must be boosted with supplementary supplies in the form of grit (e.g. oyster-shell grit). Farmers must ensure that these high calcium levels are present in the diet at least two weeks before laying starts. This timing coincides with the hormonal changes that allow extra calcium to be laid down in the bones, especially the medullary bone tissue from which calcium is mobilised for egg-shell formation.
Poultry require the full range of vitamins, nutrients and amino acids, but Vitamin D in particular has a crucial role in the metabolism of laying hens. Hens lacking in Vitamin D are unable to utilise calcium and phosphorous with serious consequences for bone tissue and egg shells. Ample supplies of cool, clean fresh water are essential for laying hens, especially in the tropics where they will inevitably suffer problems with heat stress. Any lack of water results in loss of production and a higher mortality risk.
Heat stress management
Chickens are better adapted to keeping warm than keeping cool. Normal internal body temperature is 41.3ºC which is just a few degrees centigrade below the temperature at which enzyme inactivation and tissue death begins. The ideal environmental temperature for hens is 12.8ºC, a long way short of the typical daytime temperatures in tropical Asia where heat stress is a huge potential problem. Hens actively maintain their body temperature by:
• Reducing heat absorption by staying in the shade
• Reducing heat production by reducing feed intake and activity
• Increasing heat loss through evaporative cooling
Birds do not have sweat glands and therefore rely on panting (passing air over the moist surfaces of the respiratory tract) to dissipate heat. This causes excessive loss of carbon dioxide, needed to make calcium carbonate in the uterus. The net result is lower egg shell quality with soft shelled eggs a common occurrence. Failure to maintain body temperature leads to a general fall in egg production.
Farmers can help their layers to keep cool by:
• Locating hen houses in the shade
• Providing shade by planting fast growing trees and establishing grass in a 6-metre strip right around the building
• Using open-sided houses orientated east-west to avoid sun shining directly inside
• Constructing wide roof overhangs and placing the roof angle north and south to avoid the direct rays of the sun
• Providing air movement and evaporative cooling
Contributed by Dr Terry Mabett
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