Getting pullet flocks to the correct, uniform weight, with a robust immune system before laying starts is fundamental to achieving higher egg numbers and better shell quality,
“Looking at the previous flock’s health record as it comes to depopulating, will focus attention on what the growth profile for chicks or egg production for layers, has been,” he says. With this knowledge, and identification of any other issues which have been problematic, better preparation can be made for the new flock.
Cleaning and disinfection
This task should be viewed, not as the last phase of the previous flock, but as preparation for the next one, the cleaning and disinfection regime can then be devised to ensure the main problems are tackled and there is no carry over to the next flock.
It is essential to get advice on how various products work to meet a unit’s specific needs.
For example if coccidiosis has been a problem it is important to use a coccidiocidal product that will help penetrate the tough oocyst and break it down.
Water
The downtime between flocks can also be used to assess water quality. Pipelines should be tested for bacteria-harbouring biofilms and cleaned.
Water which is acidic can help to reduce harmful bacteria populations in the hen’s gut. Setting up a system that introduces organic acids to create a pH level of between 3.5-4 can improve gut health and overall performance.
However, organic acids and other water sanitisers can make water bitter if they are included at too high a dose rate and hens doesn’t like bitterness and this could depress consumption.
Another issue that could reduce intake is water temperature. Hens prefer water to be cooler than their body temperature. Colder water also helps to reduce biofilm development. It may be possible to introduce a cooling system or insulation particularly if the house is new.
Selecting Stock
Bird choice, whether for a brand new unit or an established set up, should be matched to the specific conditions of the farm and the system it operates.
It is worth talking to several genetic companies and comparing types before making the final choice. Some breeds are hardier while others are known for outright yield.
And, as outdoor units have grown, demand has increased for calmer strains that are less likely to show aggressive characteristics in larger groups.
Restocking
If buying pullets of 14 and 18 weeks, the housing temperature should be between 21°C to 25°C. Depending on the empty house temperature there may be a need to provide extra heating to minimise any stress. However, this should be monitored closely, particularly during the summer because the introduction of a large body mass will cause the temperature to rise and it could quickly exceed a safe level.
For day-old chicks the house temperature should be at 36-37°C on the day of arrival. After that the temperature should be reduced by daily increments to reach 21°C at about 7 to 8 weeks.
“The chicks should distribute themselves evenly throughout the house. If they are huddled, they are too cold and if they are at the edges they are too warm,”
Temperature should be adjusted accordingly and monitored. Any other distribution may indicate draughts and this should be addressed or the birds will become stressed.
Cleaning and Disinfection
Before C&D remove all manure, feed and litter;
Pressure wash from ceiling down using detergent to remove all organic matter;
Allow drying period;
Spray or foam with disinfectant advised by consultant, vet or supplier;
Apply formalin through fogger;
Use tests (hygiene audit) to establish cleanliness of surfaces.
Ventilation
Relative humidity during the first week of the chick’s life should be about 40% to prevent dehydration and drying of mucus membranes.
Ammonia build up from the litter (floor rearing) must be dissipated with effective ventilation. If it accumulates the caustic action can damage the pullet’s eyes and upper respiratory tract, leaving it susceptible to infection as it grows. In free-range units, it is more difficult to control humidity and temperature.
Lighting
Lighting is controlled to encourage the bird to assume it is approaching spring as it matures towards point-of-lay. The intensity is stepped down from the introduction of the chicks from 25lux for 20 hours a day to about 15lux and 10 hours a day between weeks 12 and 14. Thereafter intensity is increased to 25lux and, from 16 weeks old, the daylight hours are gradually raised to mimic spring.
House Temperature for chicks
Day Temp (°C)
1 36-37
7 33-34
14 31-32
21 29-30
28 27-28
35 25-26
42 23-24
49 21-22
Growth
Development of the digestive tract and immune system is rapid in the first 6 weeks of life. Poor nutrition or other stressors at this stage can have a permanent negative effect on the bird’s ability to digest and absorb nutrients. Likewise, there may be a long-term impact on the immune system, making it more susceptible to disease.
Bone calcification accelerates in the first few weeks of life and continues beyond the start of lay. Any deficiency in growth or skeletal development may limit the potential calcium reservoir needed for egg shell strength later on.
Monitoring Growth
Ensuring birds reach the optimum weights throughout the first few months of life is fundamental to both laying performance and to health and welfare.
There are suggested times to weigh at 6, 12, 18, 24, and 30 weeks old.
But it is better to get into a routine of weighing once a week from arrival through to point-of-lay at 22 weeks and beyond 30 weeks. At each weighing, about 100 birds in every 4,000-batch should be taken from areas across the house to provide a representative sample.
Average target weights vary according to the breed or strain of bird but general averages would be about:
- 1.3-4kg at 14-16 weeks
- 1.6kg at 22 weeks (point-of-lay)
- 1.8kg at full mature bodyweight
Equally important as an indicator of good management is the weight distribution across the flock. A large variation can be due to factors such as the feed regime, disease and overcrowding. Ideally more than 90% of the flock should be within 10% of the target weight for their age.
Frequent weighing will help determine at what point a flock has started to deviate, allowing staff to identify factors and act accordingly.
If the flock is not sufficiently uniform as the critical point-of-lay approaches it is advisable to stall egg laying by reducing light hours.
Holding back the flock and forgoing egg production for about two weeks, so underweight birds can reach target weights, will ultimately pay dividends.
A hen which has failed to reach the body mass will produce fewer eggs overall during her lifetime so the two-week catch-up is well worth it.
Weighing is also a useful opportunity to examine crop fill and breast composition. Assessing these will give a further indication of how well the flock is developing and whether the feed regime is correct.
Conventional disease vaccine schedule
- Marek’s Disease
- Coccidiosis
- Salmonellosis
- Gumboro Disease
- Newcastle disease
- Avian Encephalomyelitis (Epidemic Tremors)
- Infectious bronchitis
- Infectious Laryngotracheitis
- E.coli (specific strain if isolated)
Nutrition
“If the pullets have missed target weight it is not necessarily because of a lack of food, and, therefore, it is not usually necessary to provide more but to increase the number of feeds per day,” More frequent feeds will reduce the dominant birds gorging on food and give weaker birds more opportunity to feed.
The food consistency is also important. A meal or mash overcomes the likelihood of the hens picking out grains or larger pieces and provides better distribution of the micronutrients calcium and phosphorous.
Calcium
As the hen progresses beyond peak lay, ensuring calcium is available for egg shell production is vital.
Many flock managers now split-feed with a higher calcium mix offered in the afternoon. The theory is that calcium provision is matched to the peak demand on reserves while the egg is forming overnight.
Without this, the bone reservoir will be quickly depleted causing layer fatigue or osteoporosis later in their lives.
Fibre
Dietary fibre is also key to the pullet’s development and should be offered at an inclusion rate of about 4-5% to maintain gut function and health.
Water
Arguably, water is the forgotten element of nutrition. Eggs comprise 70% water, so there is a high metabolic demand that must be met as the pullet approaches point-of-lay.
Good quality, clean water is also a route that can be used to provide additional micronutrients.
Disease prevention
About 16 vaccines are delivered in the first 16 weeks of life. These are delivered via aerosol or in drinking water as a live virus to stimulate the young hen’s antibody response. To boost those levels a killed, inactivated vaccine booster is provided at the end of the rearing stage.
To assess the level of protection gained from the live viruses, it is a good idea to take blood samples at 12 weeks old. Any shortfall in response can then be investigated.
Dr William Garton
