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Contrary to what one might think from reading some of the veterinary articles in The Ranger, free range layers are generally very healthy and seldom require any treatment during their laying life.

However, there are occasions if flocks are affected by infectious or parasitic disease when treatment of the flock may be recommended by your veterinary surgeon. Even in healthy flocks, producers may wish to give birds a bit of a boost by adding vitamins to drinking water.

If your dog or cat is poorly you can go to your vet and your pet may receive treatment with an injection or tablets. If you have 10,000 poorly chickens, then the treatment approach, by necessity, has to be a little different but the principles involved are the same.

Why might I treat my flocks?

Where medication is required for free range layer flocks, this would most commonly be either antibiotics or wormer.

Antibiotic treatment
Antibiotics may be prescribed by your veterinary surgeon for your laying flock if a bacterial disease is diagnosed in the flock. This could be an acute bacterial infection causing high mortality such as Erysipelas or Pasteurella or might be a more chronic infection, perhaps causing little mortality but resulting in unthriftiness and/or egg production problems such as Brachyspira or other bacterial enteritis. Mycoplasma infection in a laying flock may also require antibiotic treatment.

There are only a limited number of antibiotics available to treat free range layers which have a nil egg withdrawal period. Your veterinary surgeon will recommend the most appropriate antibiotic for the condition diagnosed in your flock. In making this decision, your vet will take into account such factors as the clinical history of the flock, mortality, bacteriological findings and antibiotic sensitivity testing and the previous history of the site.

Having decided that your birds will need treatment, it is then very important to calculate the dose required and to make sure that the treatment product is added to drinking water so that each bird receives the correct daily dose.

Your veterinarian may work out the dosage required based on amount of antibiotic per kg bodyweight of the birds so the dose of antibiotic required daily will be calculated based on the total body weight of the birds in the shed and this amount is then added to the drinking water on each treatment day.

Sometimes the amount of medication required is calculated based on expected water consumption with a recommendation of a particular volume of medication to a known volume of water to supply the correct dose to the birds.

In order to make accurate calculation of dosage, it is very important that your veterinary surgeon is provided with the correct bird numbers, up to date average body weight figures and daily water consumption figures so that the amount of treatment can be calculated accurately.

Depending on the antibiotic used and the nature of the problem being treated, the length of time birds require treatment may vary. In some cases, treatment may be given for a short 3 day course, in other cases birds may require 10-14 days of treatment and, in some cases, repeat treatments may be required.

Having calculated the daily dose required, the producer then has to make sure that this is correctly administered and that, as far as possible, the medication reaches the birds. On farms with a header tank, treatment products can be added to a known volume of water in the header tank and the birds treated in this way. If the product used for treatment is a liquid, then it is easy to add the calculated amount to the header tank and mix it in. If the product being used is a powder, then it is important to dissolve this first in a smaller volume of water before adding to the header tank.

Some powder antibiotic formulations, particularly in hard water areas, have a tendency to settle out and thus it is important to either keep agitating the water in the header tank from time to time to keep the product suspended or to use, for example, a small aquarium pump to try and keep the product suspended. It goes without saying, as discussed in previous Ranger articles, that header tanks should be kept clean. If the header tank and water system are generally dirty with accumulations of biofilm and scale, then success of any treatment through the drinking water system is likely to be reduced.

Alternatively, water medication can be given through a water proportioner system. In this case, a stock solution is made up with the treatment to be used and the main water system is dosed from this stock solution. When dosing in this way, again it is important, particularly with powder medications, that you keep the product well suspended in the stock solution. The use of an aquarium pump or a device such as a "spin stir" may be useful.

Some antibiotic treatments will require that the birds are treated continually through the drinking water over a 24 hour period. With other antibiotics, the treatment period during the day may be shorter, for example, birds may only require medicated water over a period of 6-8 hours. Your veterinary surgeon will advise you on the amount required for daily treatment and the duration of treatment each day and the length of the total treatment period.

If you are in any doubt about the instructions you have been given by your vet of how to physically mix or add the product to the water system, then do not hesitate to ring your veterinary surgeon for clarification.

You should keep in contact with your vet during the treatment period. If you feel that the flock are not responding as expected or that the disease problem is escalating, then you should contact your veterinary surgeon as soon as possible for advice as a change in treatment or possibly a change in dosage rate may be required.

Your veterinary surgeon should be able to give you an indication of when the birds might be expected to respond to the treatment.

You should note down details of the treatment including the name of the product, the batch number, the expiry date and the amount used in the medicines record sheet on farm and keep with this a copy of the prescription given to you by your veterinary surgeon.

Worming via drinking water
Wormer products are given in a similar way to antibiotics with the total daily dose calculated based on bird body weight and treatment administered usually daily over a 7 day period. As discussed in the previous Ranger article, your veterinary surgeon will be able to give you guidance as to the frequency of worming treatments required on your farm and will be able to discuss with you whether it is preferable to give wormer via feed or drinking water.
Other water treatments
Other water treatments which may be used include vitamins, electrolytes, herbal extracts and water sanitisers.

With all of these products, it is very important to read the instructions supplied with the products and to use correctly.

When treating the birds via drinking water with any product, it is very important to monitor water consumption closely. If there is any drop in water consumption, this may indicate that there is a problem with palatability and it may be necessary to put birds back onto plain drinking water to maintain water intake.
Summary

Water medication can be a useful tool in treating flocks when required to maintain health and welfare. For successful results, it is crucial that products are administered correctly.




C.I.F.Knott, BVM & S, MRCVS
S.A.Lister, BSc, B.Vet.Med, CertPMP, MRCVS
Philip Hammond, BVetMed, MRCVS