Free range egg production problems

This article was taken from the Ranger magazine. A monthly magazine sent to members of the British Free Range Egg producers Association. For more details about receiving the Ranger visit www.theranger.co.uk
Egg production problems are one of the most frustrating and worrying concerns for the free range egg producer, never more so than at present with worries over high feed prices, low egg prices and general financial uncertainty.

Even worse, production problems are often accompanied by shell quality defects and continued loss of production , poor shell quality and internal quality problems can result in severe financial loss to the producer.

It is imperative therefore that producers as far as possible take preventive action to reduce the risk of egg production and shell quality problems occurring. If such problems arise, they should be investigated at the earliest possible opportunity to try and resolve the problem as quickly as possible and reduce the financial impact.

Causes of egg production problems and shell quality problems fall broadly into three categories as discussed below:

DISEASE
1. Virus infections
Many of the viral infections of poultry can lead to production problems, sometimes coupled with shell quality problems and, in some cases with increased mortality in laying birds. These include Infectious Bronchitis (IB) and associated variant viruses, Egg Drop Syndrome (EDS), Epidemic Tremor (AE), and Avian Pneumovirus (APV) , Newcastle Disease virus (NDV) and Avian Influenza(AI)

As discussed in a previous Ranger article, pullet flocks in the UK receive a very robust and comprehensive vaccination programme in the rearing period which is designed to protect birds against viral challenges on the laying site.

Virus infections which are most likely to cause problems with egg production and/or shell quality problems on the laying site are IB and associated variant viruses as well as Avian Pneumovirus.

Producers in some areas of the country may find it of benefit to give additional "top up" live vaccination to flocks on the laying site to provide protection against these viruses.

Such vaccination programmes should be based on knowledge of the local disease challenge and knowledge of the particular site involved. Any "top up" vaccination programme must always be discussed in detail with your veterinary surgeon to ensure that the optimum programme is in place for your birds. Producers should be aware that live vaccines are not licensed for use in birds in lay so should only be used on veterinary advice.

Producers should take blood samples from their birds shortly after delivery to the laying site. Blood samples can then be tested to check the level of immunity to respiratory viruses and a programme of additional top up vaccination planned if required.

If your flock suffers a production drop or shows shell quality problems, it is important to investigate this with your veterinary surgeon to determine if there is any evidence of viral challenge – this will enable you to plan a protective vaccination programme for the next flock on your site. You may need to request changes or additions to your rearing vaccination programme to provide protection for your next laying flock.

2. Bacterial infection
One of the most common bacterial infections to cause egg production problems and shell quality problems in laying flocks is Mycoplasma, both Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS). Mycoplasma infection can cause drops in production and sometimes loss of shell colour. Usually uncomplicated Mycoplasma infection in adult layers does not cause clinical signs in the birds but in some cases, particularly where Mycoplasma infection is present with other infections or stresses, increased mortality may also be seen in the flock.

Birds can be vaccinated in rear to give some protection against Mycoplasma gallisepticum (MG) challenge. If problems are seen with Mycoplasma in lay, antibiotic treatment can be given, for example, with Tiamulin (Denagard), Tylosin (Tylan) or Tetracyclines (Aureomycin Soluble)via drinking water. These three antibiotics currently have a nil egg withdrawal period in the UK.

Other bacterial infections such as E.coli, Pasteurella and Erysipelas which have been discussed in previous Ranger articles may cause mortality in laying flocks but in themselves seldom cause egg production or shell quality problems.

Bacterial infection with Brachyspira has been identified as a problem in laying flocks more frequently in the last few years. Some Brachyspira are relatively harmless and may be present in the intestine without causing problems but other strains are more pathogenic and can cause gut disturbance. Birds with intestinal problems then lose condition and become unthrifty resulting in problems with loss of production, reduced egg size and sometimes shell quality problems.

If flocks are showing abnormal droppings, often yellow or caramel coloured droppings, and are underweight or with unexplained production problems, this could suggest Brachyspira infection.

If Brachyspira problems are present, birds can be treated with Tiamulin (Denagard) or Tylosin(Tylan) via drinking water. Your veterinary surgeon will be able to advise you on an appropriate course of treatment and on other preventative management measures to reduce the risk of further problems.
3. Parasitic disease.
External parasites:
Heavy red mite infestation can cause drops in production of anything up to 5-8%. Problems may also be seen with loss of shell colour and loss of yolk colour. Flocks with high red mite infestation often show increased mortality with many birds showing pale combs due to anaemia. Red mite has been discussed in more detail in previous Ranger articles. It is important to take a proactive approach and monitor for red mite and to treat regularly to stop the mite level becoming a problem.

In large commercial flocks, it is very rare to see lice as a problem but in smaller flocks, particularly multi age flocks, lice may become established and can lead to a general unthriftiness and disappointing production.

Internal parasites:
The very damp weather we have experienced in the UK this year has provided favourable conditions for parasites to thrive. Both Ascarid worms (roundworms) and Capillaria worms (hairworms) when present in significant numbers can result production problems, shell quality problems and loss of yolk colour. Heavy worm burdens can also predispose birds to develop secondary bacterial gut infections and problems such as "spotty liver" syndrome.

As with red mite, a proactive, preventive approach to worm control is the best policy as once birds have shown a drop in production associated with a heavy worm burden, they may have suffered significant gut damage and weight loss and it may be difficult for them to recover to full production even if the worms are treated and removed.

Producers should monitor flocks regularly for worms either by regular screening of faecal samples or preferably screening of dead/cull birds for worms and discuss with their veterinary surgeon an appropriate worming strategy for their site. Alternatively producers may routinely worm flocks every 6-8 weeks to prevent worms becoming a problem

Worming control regimes can vary considerably from site to site depending on the level of worm challenge present but it is important to get this right for your site.
There are various options available for worming, either the use of Flubenvet in feed or Solubenol in water.

Pasture management is also important in worm control - ensuring well drained pasture and proper pasture rotation should reduce the risk of worm challenge to your flocks.

Nutrition
Appropriate nutrition is a key part of good egg production and shell quality in the free range flock. An appropriate nutritional programme should be discussed and agreed with your nutritionist prior to the arrival of your new flock on farm. Increasingly different breeds of layer may require a slightly different approach to feeding regime particularly in the period from housing up to peak production. It is crucial, as discussed in previous Ranger articles, to monitor body weights closely and to monitor egg size and egg mass to determine the most appropriate time to change rations, so that the ration can be tailored to best suit the requirements of the bird.

Very occasionally errors may happen in the feed mill and there may be problems with the balance of nutrients in the ration or with inclusion of particular raw materials. This is uncommon but obviously mistakes can happen.

It is important for the free range producer to keep labelled samples of each ration stored in a cool dark place for at least 3 months in case they are required for investigation of a feed problem.

If any problem with feed is suspected, then the farmer should contact the feed supplier immediately so the problem can be investigated and, if necessary, resolved.

It goes without saying that the modern free range layer requires easy access to supply of fresh water ( avoid birds drinking from poached muddy areas!) and palatable feed to sustain egg production. If there are any interruptions in feed or water supply, then this can have a disastrous effect on egg production so it is important to check daily at each visit to your birds that feed and water is easily available and to ensure that you order food on time so that birds do not run short.

Management/environmental issues
It is always important to remember that problems with egg production may not always be associated with infectious disease but can be influenced by management and environmental factors. As mentioned above, if there is an interruption in feed or water intake, this can have a dramatic effect on egg production.

Other stresses to the birds such as extremes of temperature, disturbances, for example, by predators, hot air balloons may frighten and unsettle the birds and lead to drops in production or shell quality issues.
Any sudden changes in lighting either in the photoperiod or light intensity due for example to time clock problems,can also adversely affect production.

As discussed in previous Ranger articles, air quality can also be a problem, particularly in Winter months, very high ammonia levels may impair bird health and lead to reduced production.

Of vital importance is good record keeping. Accurate daily records of egg production should be kept, preferably with production set out on a graph so that any problems/trends can be quickly identified and investigated.

Regular checking of egg weights and bird weights are also important management tools.

What to Do?
What should the producer do if there is an egg production or shell quality problem?

First of all, double check that the figures have been calculated correctly.

Are eggs being lost to the system in any way, for example increased floor eggs, egg eating or egg stealing. Are the numbers of birds in the shed correct?

If nothing is found to suggest a disease problem, all aspects of the environment,light programme, feed quality and presentation and water quality and presentation should be assessed.

If you establish that there is a problem, this should be investigated in a systematic way.

First of all, look at the flock for any obvious signs of disease. If the flock look sick, contact your veterinary surgeon who may suggest a visit to the site or post mortem examination, blood sampling or faecal examination to investigate whether there is an infectious or parasitic disease problem.

If the flock look well and there is no excessive mortality, post mortem examination may not be of benefit in investigating a problem but this should be discussed with your veterinary surgeon.

If there is any loss of shell colour or abnormal shells, this may suggest viral challenge or in some cases parasitic disease or a stress problem.

Blood sampling may be useful to determine if there is any evidence of viral or Mycoplasma involvement.

It is important to remember that in many cases egg production and/or shell quality problems may be due to a combination of factors and not due to one single cause.

Egg production problems are often a very confusing and frustrating problem to resolve but a structured and systematic approach to investigating any such problem should help to pinpoint the most likely causes . Lessons learned from problems in one flock should help you to prevent problems next time around.


Claire Knott, Philip Hammond and Stephen Lister.
Crowshall Veterinary Services