Question 1.

 

I have read somewhere that mealworms that are fed on wheat bran contain a substance called phytic acid which the author stated could leach calcium from the birds that consume them. Is this really the case??. Would feeding my mealworms on oat bran (as this author of that article suggests) lessen this effect.??

 

Answer 1.

The information is partly correct and I will endeavour to explain why.

Phytic acid or cereal phytates are concentrated in the aleurone layer of the seed coat of all cereal grains. This is third outermost layer of the seed coat (2nd is the testa, 1st is the pericarp). These three layer are what makes up the product we know as bran once processed. Cereal phytates have the property of being able to immobilise dietary calcium and magnesium i.e  the phytates bind to calcium and magnesium and form insoluble complexes that are not readily absorbed. Calcium is therefore not removed from the birds body BUT it is prevented from entering the birds body in the first place. When we consider that mealworms are very low in calcium in the first place it is safe to consider that virtually none of this will be available to the bird if the mealworm also has a gutful of phytate rich cereal bran when it is fed to your birds.  Not all cereal grains have the same level of phytates in their aleurone. The highest levels are found in oats, followed by barley, rye, wheat and lastly millets. This means that oat bran is actually a far poorer choice than wheat bran.  Incidentally, when a bird dehusks its seed, the aleurone, testa and pericarp are peeled off. In sprouted seed, the germination process results in up to 70% of phytates being deactivated.

In order to feed our mealworms (and maggot cultures) on a substrate that has reduced phytate levels is to therefore prudent to use a cereal based product not made from the seed coat. Two products are recommended. Pollard (or wheat fines) are processed from the endosperm (the starchy central part of wheat) and therefore have significantly reduced phytate level. The disadvantage of pollard is that many manufacturers produce it very fine which makes it (in my hands) too “gluggy” for maggot substrate BUT excellent for mealworms as it is easier to sieve. In addition, on a personal note, I do not suffer from hayfever when working with pollard but I  most certainly do with bran. Some manufacturers produc a coarse pollard with is excellent for both purposes. Mill Run is an alternative product which has a coarseness suitable for both maggots and mealworms. It is made up of coarser pollard with remnants of bran. I use is by preference as its texture is always ideal for maggots, it has about 6% more protein than bran (which is essential protein for use by the mealworms or maggots) and it doesn’t flare up my hayfever.  I hope this helps.

 

 

Question 2

Is there a connection between the term “going light” and “avian tuberculosis”?. Is there a test for the latter??.

 

Answer 2

The answer is “Yes and No”.

“Going light” may occur with tuberculosis but is not specific to that disease.

“Going light” is a widely used term with very little relevance from a diagnostic point of view. Most birds are a food item for something else. The first bird within any flock to be eaten is the bird that appears the weakest. Birds therefore will mask their illness as long as they physically can by surviving entirely on the energy stored in their ample breast musculature. By the time we are vigilant enough to see a really ill bird, most of this muscle is already been broken down (catabolised) and the bird now appears thin and is reduced in weight, hence the term “Going light”. Any disease or trauma that reduces a birds ability to go about its normal daily duties (e.g. infections, parasites, poor nutrition, reproductive problems) will result in the bird using these muscle reserves. A bird will lose weight as soon as the energy usage exceeds the energy intake. A bird can therefore appear “light” in as little as 48 hours.

Tuberculosis can cause “going light” but it is realistically a relatively uncommon disease in most  countries.

Tuberculosis is a group of diseases caused by bacterial organisms in the family Mycobacteria. Within birds most infections are caused by Mycobacterium avium.

There are several different types of this species, some affect only birds, others infect birds and mammals including humans. Clinically, tuberculosis in passerine birds is seen mostly in canaries and Gouldian finches but can occur in any species. It may be more related to hygiene and closeness in these birds than their specific breeds. Sick birds show non specific gastrointestinal and respiratory signs and will often “go light” with chronic disease. Realistically there are probably 20 more common diseases that will also cause these exact same set of signs in the same birds. Diagnosis in the live bird is unreliable at best. Mycobacterial organisms are only identified by special stains caused acid fast stains. Acid fast staining of faeces may detect Mycobacteria if they are present in the faecal sample but are just as likely to miss light infections. To properly diagnose Mycobacteria infection requires acid fast staining of finely sectioned post mortem samples of liver, lung, spleen and intestines. Not all birds within a flock will be infected. Mycobacteria is a zoonotic disease in some cases (i.e. it may infect humans) and correct diagnosis is therefore important. The different species can be identified with other special laboratory techniques such as fluorescent staining. Humans with poor immune systems (e.g. the very young, very old, and immunosuppressed individuals (chemotherapy, HIV)) are most at risk.

Within birds, the disease cannot be treated and culling of infected stock is recommended.

 

 

Question 3

It has always amazed me that when finches are diagnosed with worms by a vet that they seems to respond to treatment fairly rapidly. What is the actual time span for recovery and what helpful hints would you have for helping with full recovery? In severe cases would you recommend holding the bird back from breeding for 12 months or more?.

 

Answer 3

Most gastrointestinal worms are just nutritional free-loaders. They don’t usually do a lot of physical damage to the bird. Mostly they just hang their by their mouthparts and sponge up the nutritional soup that they hang in. When we get rid of them with an effect parasiticide what we have done for the birds has been to rapidly improve their nutrition. Obviously there is a small amount of irritation that needs to be healed but otherwise the birds other organ systems have not been overtly affected so it often recovers quite rapidly as long as it is not reinfected. The exception to this is from a finch perspective is Acuaria (the gizzard worm) and Synhimantus (the proventricular worm) which are both invasive and induce considerable pathological changes in their respective organs of preference. Although the worms may be killed, the damage may take a long time to being reversed or in many cases may be permanent. This is why a parrot finch with tapeworm will recover faster and be healthier then the same species of bird recovering from gizzard worm even though all worms may have been eradicated.

In terms of actual time that the bird should be rested I usually recommend three negative faecal results each 2 weeks apart and  then until the  droppings return to normal i.e as little as 6 weeks for a simple tapeworm infection or potentially much longer for a gizzardworm  infection. Helping the birds through this period  with the use of probiotics to restore normal gut function (minimum 10 days)  and good quality soft foods for easy digestion and higher protein for tissue repair. For heavy infections I suppose 3-6 months rest will do a world of good. For lighter infections, a few weeks may be all that is needed particularly in a flock situation. Many birds will however not miss a beat and will just get on with what the were doing before but with greater dietary efficiency.

 

 

 

Question 4

I have heard that in cases where Cochlosoma is diagnosed there is a need to not only treat the free organisms in the gut but also to treat those burrowed into the walls of the intestines as well? Does this make them harder to fully remove??.

 

 

Answer 4

Cochlosoma is a species of single celled protozoan  in the family called flagellates. This group also includes Giardia, Hexamita and Trichomonas. All of these organisms behave in similar ways. They are not necessarily burrowers as such. It would be safer to say they they inhabit the surface of the gut rather intimately and the reaction of the gut engulfs them in thickened mucosal folds. Most of the successful treatments that we use such as Ronidazole and Metronidazole are systemic medications i.e although they are taken orally the drug is metabolised and spread throughout all of the bodies tissues. This means that “deep” parasites are equally as accessible as those within the gut lumen. What does change success rates is how much the intestinal wall has reacted to the parasite and it’s subsequent effect on digestion. Some areas of gut may permanently thickened (hypertrophy) in response to the parasite and these areas may remain permanently inefficient with regards to digestive ability.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Question 5

Some finch breeders in my local club are recommending that I use certain wormers at half the recommended dose rate for safety purposes. Would this be a better way to go? Does this increase the risk of parasite resistance?

 

 

Answer 5

 Firstly, if you have concerns that a drug is not safe at normal dosage then I would be selecting a safer drug in the first place. Within a population of worms there will be whimpy ones that die with just a sniff of medication, average ones that require a minimum therapeutic dose and the real toughies that sit there and laugh until the dose reaches near toxic levels. It is this last population that are our problem and using lower dose rates will encourage the selection of these strains as the primary worms within our collections. A nightmare waiting to happen!.

The only time I would use a lower dose is in severely infected individual (as indicated by massive faecal worm egg numbers). There are two scenarios where I would consider this prudent. (a) a bird with severe gizzard worm infestation where is assumed that the gizzard no longer contains normal tissue and that a sudden die off of all worms will induce such a immunological reaction to further compromise function within the gizzard.

                                   (b) a bird with very heavy tapeworm or roundworm (more likely in a parrot but occasionally in some softbills) where a sudden die off of all worms will cause a gastrointestinal blockage due to the huge bulk of the dead parasites.

In both of these cases a follow up with normal dosage would occur 5-10 days after the initial treatment. This is done with the assumption that  the parasites populations do actually contain individuals with weaker, average and stronger tolerances to that medication.

For routine treatment, rely on faecal testing to identify the target and then choose the most efficient yet safest drug for the job.

 

 

Question 6

I have noticed that some insectivorous finches, especially the pytilia family, appear to suffer from some ailment that is reflected in large cheesy yellow coloured droppings.

These birds don’t appear to be too ill at the onset but continue to produce these droppings. They are however very thin and eventually die after 7-14 days. Does this sound familiar??. When the droppings are tested they usually return a negative result for parasites.

 

 

Answer 6 

This is unfortunately a very common presentation with a great many diagnostic challenges. The droppings that you describe are indicative of maldigestion so what we are seeing is basically part digested seed pulp coming straight through. Closer examination may also reveal whole seeds in the mix. There are a great many causes for this problem so it is not uncommon that parasites are not seen on faecal exam as they may not be involved. The commonest causes, in order of most common first, are :-

Yeast (Candida infection) – these common environmental and food spoilage yeasts will colonise the gastrointestinal tract at any point from the mouth to the large intestine and cause severe thickening and damage to the lining which reduces access of the food to the digestive surfaces.

 

Avian Gastric Yeast (Megabacteria) – this giant yeast is thought to block physical access of the food to the enzymatic digestive surfaces of the true stomach (proventriculus) and may affect pH resulting in poorer food breakdown that cannot be compensated for further down the gut.

 

Gizzardworm (Acuaria sp.) – These destroy the gizzard (ventriculus) lining so that food cannot be ground up efficientl and therefore cannot be processed properly further down the gut.

 

Bacterial infection (particularly Campylobacter sp.) – these simply damage the gut wall so that it no longer performs it normal role. Other bacterial organisms such as E.coli do very little damage but interfere with fluid control resulting in undigested food being simply flushed out without being digested properly.

 

Cochlosoma ( and other flagellate protozoan parasite) – these physically impede the access of food to digestive surfaces or cause the lining to thicken and become inefficient. These will normally only be diagnosed in a fresh steaming warm dropping.

 

Tapeworm – if numbers are significant enough then all that remains in the gut after the tapeworm have eaten is undigestible pulp. They may also irritate the gut lining.

 

Viral Diseases (particularly Polyomavirus) – any systemic damage done by viruses to any digestive surface or any organ that assists the gut (such as the liver and pancreas) will reduce digestion.

 

As you can see , it would be nice to be able to blame just one bug and use one drug to fix this problem, but you can’t. Correct diagnosis is essential and in many cases sacrifice of a chronically ill bird for fresh post mortem and microscopic histopatholgy is the ultimate diagnostic tool.