...the wounds will need to drain and so they need to be kept moist (the DE
ON the birds will do nothing to keep flies away (only work when dry)...I suggest you do as Terrie Lacy suggested and bring them in>fly strike is a real danger).....
...you are stating these are deep wounds which will need to be flushed (as explained earlier with a saline solution (daily>for the wounds by the vent area you will need to do this more than once a day?) and then you can apply a triple antibiotic cream (will also keep it moist)...
Here is some info on AVIAN wound management :
http://dlhunicorn.conforums.com/index.cgi?board=practical&action=display&num=1158141893
and specifically:
http://www.worldwidewounds.com/2003/august/Cousquer/Avian-Wound-Assessment.html
excerpt summary on TREATMENT measures:
First aid
Traumatised birds often have multiple injuries and may be further compromised by dehydration, malnutrition and other problems, especially if there has been a delay (hours or days) between injury and presentation [1]. Fluid and nutritional therapy and treatment for shock are critical in the early management of all traumatised birds. Overzealous wound and fracture treatment before stabilisation of the bird may prove fatal [1]. Some first aid of the wound, however, will inevitably be required.
Wound first aid will usually be performed at the time of the initial or subsequent clinical examination. It need not be high tech but should fulfil a number of basic objectives:
Cleaning - The wound should be cleaned quickly to remove as much contamination as possible. A more thorough cleaning should await veterinary examination of the wound. This is usually performed under general anaesthetic to help minimise stress . Sterile isotonic saline (0.9%) or a solution of 0.05% chlorhexidine may be used. Care should be taken not to wet the bird excessively as this is likely to increase the risks of hypothermia.
Haemostasis - veterinary attention should be requested if there is excessive bleeding. Bleeding from most small wounds will stop following the application of a wound dressing.
Protection from dehydration - the use of a hydrogel (e.g. Intrasite) will help protect a wound. This can be covered by a vapour permeable film dressing (e.g. Opsite) to provide further protection.
Immobilisation - certain wounds may benefit from immobilisation or splinting. A figure of eight dressing can be used to immobilise the lower wing, for example, or the limb can be strapped to the body.
Analgesia and antibiotics - broad spectrum antibiotics can be provided in the first instance: clavulanic acid potentiated amoxycillin (150mg/kg orally or subcutaneously) will provide cover against most aerobes and anaerobes. Analgesia can be provided with NSAIDs (e.g. carprofen (Rimadyl)) 5mg/kg subcutaneously or intravenously. Local anaesthetics should not be used in birds due to the suggested sensitivity of birds to drugs of the procaine group "."
http://www.ronsvetsupply.com/granulexv.html
supplier of a difficult to find component described in the wound management articles ):
A "must have" product for advanced wound care. This is an over the counter, veterinary version of a prescription human product that has been used for many years to treat bed sores, deep abrasions and thermal burns. The active ingredient, Trypsin, is an enzyme that digests necrotic (dead) tissue, enabling it to be removed while at the same time, stimulating healthy epithelial cells to develop so that they can cover open or slow healing wounds. Can be used with or without bandaging. Use twice daily, washing debris away between applications. Labeled for use on dogs, cats, horses and cattle. Manufactured by Bertek
(concerning the above product...there is also a product for HORSE wounds which contains this enzyme also...might have a look at your agristore to see if they have that one...)