Use of medications in free range laying birds
Although it may be necessary to use products such as antibiotics to help combat certain infections, we should not lose sight of the fact that this is very much a last line of defence. Consideration of the basic biosecurity of the site, management of the birds and also the previous vaccination history is vital if we are going to try to prevent disease challenges from having an effect on both the health and welfare of the birds as well as an effect on the economic viability of the flock. When we also consider the reduced number of products which are licensed in the UK for use in laying birds compared to a number of years ago, it also puts pressure on the poultry vet to make the correct decision in terms of product selection and application.
The veterinary industry is coming under ever increasing pressure from customers such as supermarkets to reduce antibiotic use in all types of livestock. The laying sector is no different in this respect.
Excellence in practice in the area of administration of medicines in livestock has long been championed by RUMA. Their website states the following: “The Responsible Use of Medicines in Agriculture Alliance (RUMA) was established in November 1997 to promote the highest standards of food safety, animal health and animal welfare in British livestock farming.
RUMA is a unique initiative involving organisations representing every stage of the food chain, facilitating transparency and traceability in the process.
A unique initiative involving organisations representing every stage of the "farm to fork" process, RUMA aims to promote a co-ordinated and integrated approach to best practice in the use of medicines.”
It has produced documents for each livestock sector which detail the best practice for antimicrobial administration. This is a very good summary of how medicines should be used in all types of livestock, including poultry. It is supported by The British Veterinary Poultry Association (BVPA) a branch of the British Veterinary Association of which most practising poultry veterinary surgeons in the UK are members. Some of the important parts of this document are detailed as follows:
Veterinary surgeon responsibilities:
Antimicrobials may only be prescribed and used under the direction of a veterinary surgeon when:
a. the veterinary surgeon has been given responsibility for the health of the flock in question by the owner or the owner’s agent; and
b. the care of the flock by the veterinary surgeon is real and not merely nominal
In general, a veterinary surgeon is expected to see the affected animal prior to prescribing medication. However, in poultry medicine, best practice in the control of infectious disease (biosecurity rules) often dictates alternative approaches.
The veterinary surgeon involved should perform a health audit (e.g. post-mortem examinations including bacterial culture and antimicrobial sensitivity data where possible, serology, farm visits and other relevant laboratory investigation) and have a sound knowledge of the production and management systems employed. The veterinary surgeon must visit the farm prior to treatment if he/she does not have this knowledge. This information will form part of a health plan for the site in question.
It is the responsibility of the farmer to clearly give their veterinary surgeon responsibility for the health of the animals and to co-operate in ensuring that such responsibility is real.
Specifically, the farmer should:
a. Regard therapeutic antimicrobial products as complementing good management, vaccination, and site hygiene.
b. Initiate medication only with formal veterinary approval, provided either by prescription, a verbal direction or an approved treatment programme or protocol. In the case of in-feed medication, this will be provided by a “Medicated Feedingstuff Prescription” (MFSP or MFS prescription).
c. Ensure that accurate information is given to the veterinary surgeon in order that the correct dosage can be calculated for the birds concerned, and ensure that clear instructions for dosage and administration are obtained and passed on where necessary to the staff responsible.
d. Always complete the course of treatment at the correct dosage. Ensure that the dosage is carefully administered in an effective manner.
e. Accurately record the identity of the flock of birds medicated, the batch number, amount and expiry of the medicine used, the withdrawal period required and the date and time the medication was completed.
f. For in-feed or in-water medication ensure that the end of medication is accurately determined by cleaning the feed-bin or header tank as appropriate.
g. For any medicines used, appropriate information should be kept on file - for example, the package inserts, product data sheets, or the safety data sheets as available.
h. Report to their veterinary surgeon any suspicion of an adverse reaction to the medicine in either the treated animals or farm staff having contact with the medicine. This should include any unusual failure to respond to medication. Such reports may also, if desired, be made directly to the Veterinary Medicines Directorate at Woodham Lane, New Haw, Addlestone, Surrey KT15 3BR.
i. Ensure that the appropriate withdrawal period is complied with prior to the sale or collection of the treated birds or eggs for human consumption. In general the withdrawal time required is specified on the MFSP or prescription, or the label of the medicine. Note that if in the professional judgement of the veterinary surgeon, it is necessary for a product to be prescribed for a species for which it is not authorised or at a dosage higher than the authorised dosage, then an appropriate withdrawal period should be specified to ensure that food produced from the treated animals does not contain residues harmful to consumers. In general this should be not less than the following:
Eggs: 7 days
Meat from poultry: 28 days
Medications can be dispensed either via the drinking water route or some can be delivered via the feed (an example would be the wormer Flubenvet – Elanco which is licensed for use in laying birds). In general terms products delivered via the drinking water are absorbed more quickly and can be controlled in terms of the treatment period fairly easily.
Delivery systems vary and products are either put into the header tank of the house and left to run through the drinker lines or are delivered via a proportioner system. The advantage of the proportioner method is that a constant concentration can be delivered to the drinker lines without the need to switch off the supply to the header tank. Indeed in houses with no header tanks, this is the only way to apply the medication. Proportioners should be regularly serviced so that an accurate concentration of product is included. The constant addition of both antimicrobials and also products such as multivitamins or electrolytes over a 24 hour period is best applied via a proportioner system.
Attention should also be given to the drinker system. Any build up of biofilm within the drinker line or around the nipples and valves can lead to a disturbance in the flow of water through the system and even cause blockages of the nipples themselves. In addition, biofilm can harbour contamination including bacteria which can adversely affect the health of the birds. Unfortunately the inclusion of products containing carriers such as glucose can also lead to a dramatic increase in bacterial levels in a system which already has biofilm build up along the line. Therefore attention should be paid to flushing of water lines and the use of products to remove biofilm following the application of some antimicrobials and nutritional support products.
Some products can be difficult to dissolve in water, often depending on the pH of the mains or borehole supply and the hardness of the water. Certain products are best left to dissolve for a 20 minute period without agitation (Tylosin ). It may be worthwhile investing in an automatic magnetic stirrer which can help to keep products mixed and in solution whilst in the container used to deliver via a proportioner system. Keeping products mixed in a header tank can be challenging – especially when they tend to be placed at inaccessible parts of the poultry house. Premixing products with warm water initially can help to dissolve them and aid dispersal.
As previously mentioned there are very few licensed antimicrobial products for use in laying hens with a nil egg withdrawal. This puts extra pressure on the veterinary surgeon to ensure that the correct diagnosis is reached. There are some antibiotics which cannot be used in laying birds at all (Fluoroquinolones for example) under the current licensing system. Please contact your veterinary surgeon if you have any doubts concerning medicating your birds. There are fewer restrictions in the use of nutritional products such as multivitamins, electrolytes and competitive exclusion products in laying birds. These can be very useful in combating periods of stress, including vaccination, pre and post movement or even when birds are at peak lay. These can be included in your health planning and help to prevent some of the egg production and shell quality problems encountered by producers in recent years.
Alastair Johnston BVMS, MRCVS
Minster Veterinary Practice Ltd
North West (Garstang and Wrexham)
Tel 01995 604061
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