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 you
