Chop Mix: Perfect Nutritional Supplement or Popular Nutritional Disaster?

I often choose blog topics because of something I’ve recently seen or heard that troubles me. This one is no exception. After talking to a few clients recently and reading comments online, I’ve grown concerned about how Chop Mix is being prepared and fed to companion parrots.

What is Chop Mix, you ask?chop  Chop is a mixture of finely chopped vegetables with cooked grains, cooked legumes and/or beans, and other ingredients. It has been described as an “everything but the kitchen sink” approach to preparing supplemental food for birds.

I and others have used some form of the chop mix concept for a couple of decades.  However, in the past several years, this form of feeding parrots has gained huge popularity, mostly thanks to the efforts of Patricia Sund and others who have written so widely about it.

I love the concept and recommend it to others. Feeding Chop, in addition to high quality formulated foods, is a great way to get healthy variety into our birds’ diets. It makes conversion to new foods (pellets and vegetables) easier. It is relatively simple to prepare and serve, since it is typically frozen for storage, eliminating the need to prepare fresh food every morning.

So, why my recent concern?  I think there are a couple of problems with how Chop is being prepared. First of all, people seem to have gotten the idea that the sky’s the limit – that you can put anything into Chop and the resulting mix be a valuable thing to feed their birds. This is not the case.veggies  The nutritional value of Chop is only as good as the ingredients you put into it. Some individuals are adding ingredients that really should not be offered in any quantity to companion parrots on a daily basis.

When I searched for the term “chop mix” as I prepared to write this, I immediately found 21 different websites that all offered recipes for Chop. I stopped counting after two minutes. I found chop mix for cockatiels, chop mix for Eclectus, chop mix for African greys…and the list goes on. The “recipes” were all quite different from each other, as was the advice directed at owners.

On those 21 different websites, I found a lot of strongly-worded, very confusing advice. Some recommend including uncooked grains, which is definitely not a good idea. Grains should always be at least soaked and sprouted, if not cooked, in order to make them more digestible and eliminate the enzyme-inhibitors present. download (6)Some people advise adding raw yams or sweet potatoes; others say these must be cooked. Others include vegetable or whole wheat pasta, while their counterparts recommend no pasta at all. Some sites advise the addition of fruit; others warn against this, since it creates a wetter mix. How is anyone to understand that Chop must be prepared conscientiously with all of this different advice floating around?

I see two main problematic strategies being used when preparing Chop Mix. The first recommends the addition of high quantities of carbohydrates to prevent the mix from being too wet. The second involves adding too many “goodies” in the desire to create a mix the parrot will eat.

The creation of a truly great Chop poses one distinct challenge.  When you chop up a bunch of vegetables and then freeze them in a plastic bag, the cell membranes of those vegetables rupture, releasing all the moisture that was inside of them.  Thus, you can wind up with a very wet mess that your birds won’t eat.

Those dedicated to the Chop concept have gotten quite creative over the years as they have attempted to deal with this inconvenient problem. Some individuals recommend making large batches in the bathtub, advising that this way all the juice will go down the drain, thereby solving the problem.  Ahem.

I don’t care how much bleach you might have used, it’s not a good idea to prepare food in your bathroom, no matter who you intend to feed it to. Take it from one who has spent years staring at microbes through a microscope lens. If you need to make a large batch, you can always use large plastic storage tubs reserved just for that purpose.

Second, “all the juice” contains many valuable nutrients. You don’t want that going down the drain. You want to preserve as much of it as possible, hopefully getting it into your bird at some point.  So, the second option to which people resort is the addition of dry ingredients that will soak up the moisture.download (7)  Suggestions for this include pasta, rolled grains, certain seeds and others.

Consider this photo, which I lifted off of the internet. Please ignore the fact that there seems to be a parrot taking a bath in the middle of a bowl of Chop. I want you to look at the ingredients. Can you see how much pasta is in there?!?

That is a problem. You simply can’t add that amount of refined carbohydrates to a mixture and believe that it’s going to be a healthy thing to feed your birds. I have written previously about the dangers of unbalancing your parrot’s diet by feeding high levels of fatty foods and simple carbohydrates in the diet. If you rely on dry carbohydrates to soak up excess moisture, you will have a parrot eating too many carbs in his diet.

I also see folks getting a little crazy with “additions.” I once watched a speaker at a conference prepare a large beautiful batch of Chop.  I then watched as she ruined it by dumping in whole bags of nuts, pumpkin seeds, and dried sweetened coconut. “Egads,” I thought. Any parrot eating that mix will be able to load up on goodies and ignore the grains and vegetables.Iggy.Chop.FB

Chop can be a wonderful supplemental food for parrots…or a nutritional disaster. If we strive for the former, we must embrace the fact that a good Chop Mix must be prepared carefully according to certain guidelines.

First, it should conform roughly to the same percentages of protein and fats as balanced formulated diets contain. This can be estimated by simply looking at it, if you have a fundamental knowledge of the different categories of nutrients (protein, fat, etc) and which ingredients contain them.

Second, the overall percentages of “ingredient types” matters. A good Chop Mix should contain roughly 40% grains, 50% vegetables, and 10% other ingredients. By using that formula you stand a better chance of approximating the protein and fat percentages in formulated foods. You also will avoid creating a mix that allows your parrot the opportunity to fill up on things like coconut, nuts and pasta due to their too-high percentage in the mix.

whole grainsThird, the quality of your ingredients matters. The grains used should be in their most natural form, as close to their harvested state as possible. White rice and other refined grains should not be used.

Nor should you include white or vegetable pasta. Cooked and/or sprouted whole grains are best. Vegetables must be in their freshest state and washed carefully.no pasta Additions to control moisture or create greater interest must be chosen very carefully and used sparingly.

I am not going to provide a complete description here of how to make Chop.  You too can Google “chop mix” and find 21 recipes in two minutes.  But I do have some tips for dealing with the excess moisture. I will share with you what works for me. I am able to create a mix my parrots love without sacrificing their nutritional status to the carbohydrate gods.

First, do not include:

  • Vegetables high in water content, such as cucumber, chayote squash, jicama, celery. These can always be added right before serving, once the base mix has been defrosted.
  • Fruit, unless this is freeze dried. Fruit has too much moisture to be included and should be limited in the diet anyway. A few pieces of fruit can be added to a Chop serving right before feeding.

Second, when creating your base mix that you will freeze:

  • Slightly undercook your grains, which will allow them to absorb a bit more moisture once mixed with the vegetables. Sample them yourself to determine doneness. The grains should be tender, but still a bit firm. Do not include mushy grains – these will support more bacterial growth and only contribute to your moisture problem.
  • Allow the grains to thoroughly cool before adding the finely chopped vegetables.
  • Add dry, uncooked pasta that is made from legumes, quinoa, or brown rice. If you’re going to do so, add in a small quantity only. Do not use pasta made from white flour, which includes most “veggie” pastas.TJs mix
  • Add a bag of Trader Joe’s Super Seed & Ancient Grains Blend – this works as well as pasta or better to absorb moisture and adds better nutrition.
  • Add raw, uncooked oat groats or a small amount of rolled grains.

After defrosting and before serving:

  • Cut a tiny corner off of the bottom of the defrosted bag of Chop. Allow the liquid to drain from the bag into a large measuring cup. Store this in the freezer for adding to birdie bread.
  • Add raw hulled hemp seed.
  • Add sprouts – these will continue growing slowly in the food dish or refrigerator, absorbing some moisture.

This is the last Chop Mix that I prepared. It is dry, with individual pieces easily separated from each other.Chop Mix The ingredients I used this time included: kamut (cooked with cinnamon), broccoli, cauliflower, carrots, lightly cooked winter squash, sugar snap peas, green beans, red bell peppers, jalapeno peppers, parsnips, yellow squash, zucchini squash, sprouted white winter wheat, sprouted rye berries, sprouted sunflower seed, sprouted mung beans, sprouted lentils, sprouted millet, sprouted poppy seed, sprouted fenugreek, sprouted buckwheat, sprouted sesame seed, sprouted purple barley, corn kernels, 100% lentil pasta, garbanzo beans (canned and rinsed), raw oat groats and raw hulled hemp seed. IMG_20180829_070837831_LL

Greens and fruit are added right before serving, directly into the dish. This works best since they are such fragile foods.

A final tip: it’s important to limit the size of your servings. You will see that the portion of Chop I provide to my greys, Amazon and Moluccan is relatively small. They each get ¼ level cup of the mix each morning. By limiting the amount served, I further avoid the problem of any bird picking out only what he wants. They are encouraged to eat it all and they still have room for pellets, which they also enjoy. For more information on Chop, please go to Life from Scratch. This article is the best I have ever read about making Chop Mix.

I would love to hear from readers. I’m sure that many of you have better ideas than I do. If we collaborate, I’m sure that the quality of Parrot Chop will only improve for all parrots! Please add a comment to share your thoughts.

Thank you for reading my blog. I am Pamela Clark, an IAABC Certified Parrot Behavior Consultant and licensed veterinary technician. My passion is helping people with parrots. For more information and to access many free resources, please visit me at http://www.pamelaclarkonline.com. Until next time!

Pellets: To Feed or Not to Feed

Parrot nutrition is a special area of interest for me and one about which I am fairly passionate. The foods that a parrot eats will literally determine his experience, physically and emotionally, throughout his life. photo-1436902799100-7eb776a61f79

What we are doing as a population of bird owners is not working. Too many parrots are diagnosed daily with malnutrition and the often fatal illnesses that result. As a veterinary technician, I have seen it too often.

I also know how hard bird owners work at feeding a healthy diet. But it’s not an easy task. Information found on the internet results in both confusion and frustration. Too many websites voice strong opinions without citing sources or even acknowledging authorship in some cases.

And, parrots offer their own set of challenges. Adult parrots often don’t accept new foods readily. Second, they are biologically “programmed” to consume high energy (high fat) foods before consuming others that may offer better nutrition and more fiber. This can make them resistant to eating lower fat foods if both are offered in plenty. (Molukwu, M. 2011)

I will tell you up front that I am a strong advocate of feeding pellets – not as 100% of the diet, but as a wholesome and beneficial staple in the diet. downloadIf you are staunchly opposed to feeding pellets, then please do not read on. This is written for those with an open mind. On the other hand, if you are undecided or wish you could get your parrot to eat pellets and can’t…then this blog is for you.

Nutrient Requirements for Parrots

I once again just recently researched published scientific information about parrot diets. It is still true that the best minds don’t know for certain what the best diet is for any parrot. They readily admit this. “Few nutrient requirements have been derived scientifically for companion birds, so nutrient requirements are based on the best guess from galliforms [chickens, ducks, turkeys, Japanese quail]”. (Orosz, S. 2006)Photo by Kris Porter

“Companion bird nutrition has virtually no tradition. In the last fifteen years progress has been made in the area of pet avian nutrition. As companion bird popularity increases, interest into researching nutritional needs has surfaced. There is still a relative lack of research information due to lack of funding, need to research “natural” diets, and the difficulty in duplicating nutritional needs in captivity.” (Ritzman, T. 2008) It is now ten years after that was written, and progress in growing our knowledge has been slow.

In the face of such a lack of knowledge, why would anyone adhere so strongly to their own prejudices that pellets aren’t important to a balanced diet when most veterinarians advocate their use so strongly? Significant advances in parrot health have been seen since they were introduced. Yet many do.

Let’s take a look at the many aspects of feeding pellets, so that you can make up your own mind about the correct choice: Should I feed my parrot pellets, or not?

The Default Diet

First, I contend that we all need a “default” diet. By this I mean a diet that our parrots will eat that we can pour out of a bag. Serving other foods can be good for adding variety into the diet to ensure nutritional balance. However, the day may come when some problem prevents you from following through with your usual parrot food preparation plans. In times of disaster, we need a food that we can serve quickly that will support good health.

This “default diet” is going to be either a seed mix or a formulated diet. If we want to protect our parrots’ health, we can’t feed seed as the main dietary staple. Not only does daily consumption of a seed mix lead to malnutrition, it sets the parrot up to develop diseases like obesity, lipoma development, atherosclerosis and fatty liver disease.

Problems with Seed Mixes

Seed mixes are deficient in 32 essential nutrients. They are very low vitamin A, which is essential  if the  immune system is to function correctly. If it does not, illness results. Seed mixes also lead to calcium deficiencies, which can put a bird’s life in peril. Many egg-bound birds who lay soft shell eggs do so because of the seed mix they eat.images (7)

Feeding a high-fat diet can also contribute to behavior problems. Dr. Jamie Lindstrom explains: “As we provide these high carb, high lipid diets, we’re also providing these birds with high energy. If the parrot has insufficient opportunities to expend this energy, it leads to some of the aberrant behaviors, such as screaming and biting, that we see in these birds.”  (Lindstrom, J. 2010)

Fatty foods give the parrot more energy, which may be channeled into biting or screaming. With one client years ago, I improved a screaming problem simply by converting a Scarlet Macaw from a seed mix to pellets and vegetables. That wasn’t the sole solution of course, but that change was crucial to long-term success. It is also thought by many that high fat diets contribute to increased “hormonal” behaviors, such as cavity seeking, intense bonding with one person in the family, paper shredding on the bottom of the case, and territorial aggression. (Hoppes, S. 2018)

In Defense of Seed Mixes

Some defend seed mixes by pointing out that pellets have been mixed with the seed or that vitamins have been sprayed on the outside of the seeds to create a “balanced” diet. However, whether a diet is deemed balanced or not depends upon what that bird actually eats. When given the option of seeds vs. pellets, parrots usually only eat the seed. When vitamins are sprayed on the outside of seeds, this also does nothing to balance the diet. Parrots hull all of the seeds they consume. Thus, the added vitamins wind up on the floor of the cage with the shells. “For the supplement to be effective, it must be consumed in proportion to its presence in the mix.” (Brilling Hill, Inc. 1996)

Even if the attempt is made to balance a seed mix by feeding table food, the fact still remains that seed mixes contain too much fat for the average parrot. Adding table food can make this worse, as most Americans do not eat a low-fat diet. There really is no valid argument in favor of feeding a seed mix as the chosen dietary staple. That leaves us with the option of feeding pellets  (formulated diets).

Types of Formulated Diets

Formulated diets come in three types. Two of the types are typically lumped together, being described as “pellets.”  The third type is manufactured by combining seeds and pellets into one product. An example would be the Lafeber Nutriberries and Avicakes.

 Pelleted or Extruded Diets

Not all pellets are created equal. There are two methods for manufacturing a “pelleted” diet. The first creates an extruded nugget.  An example of this type would be Zupreem or Pretty Bird. Some extruded products contain sugar, which makes them a favorite among many parrots. Some say that it is easier to convert a parrot to an extruded nugget, but I have not found this to be true.images (8)

Extruded diets are manufactured by forcing a mixture of dry, ground ingredients and water through a die under high pressure and high temperature. The higher temperatures required to produce extruded diets may cause more nutrient depletion than happens with pelleted foods. In either case, nutrients that break down under higher temperatures are then added back into the product to ensure that nutrient levels are met. (Brilling Hill. 1996)

Extruded diets often, but not always, contain chemical dyes that are made from petroleum. It has not been substantiated definitively that food dyes cause behavior problems or allergies in children. However, many swear that this is the case. Choose a product without artificial coloring if this is a concern of yours.

True pellets, on the other hand, are produced by adding steam to a mixture of dry, ground ingredients and then forcing this through a die to create the shape. Generally, they are produced under lower temperatures than are extruded nuggets. Some pellet brands are organic and non-GMO. Ingredients may be less finely ground and there may be more whole-food ingredients listed on the label. Harrison’s is an example of a pelleted diet.

A word of caution: You can’t choose a pellet simply by reading the ingredient list. Organic, non-GMO, and a variety of ingredients are all good claims. However, you must also ask yourself what person or body is behind the product.

Who formulated the product? Do they have a degree in nutrition or other pertinent education? Was any research done during the formulation? Any feeding trials performed?  Do they claim that the pellet is a complete diet? If the company cannot willingly and happily provide you with this information, you should consider another choice.

Arguments Against Feeding Pellets

Let’s look at some of the arguments often given for not feeding pellets:

Argument: Pellets are too dry and can contribute to a “dry crop mix” if the parrot doesn’t drink enough water.

Answer: I have never seen or heard of such a case. Parrots in the wild consume many foods, including soil, that vary widely in moisture content. It is likely that they readily adjust their water intake to account for this. If a parrot is ill or is prevented access to water, this could be an issue. However, consuming pellets poses no risk to a healthy parrot.

Argument: Pellets are boring.

Answer: They are to us. We can’t know how our parrots regard them. In any case, I’m not sure that parrots expect their food to be exciting. That said, this is why it’s a good idea to offer a variety of vegetables, limited fruit, whole grains, and legumes.

Argument: Pellets do not allow for natural foraging behavior.

Answer: They do if you include them in foraging toys and other foraging opportunities.

Argument: Pellets cannot possibly meet the nutritional needs of all species of parrots kept in captivity.

Answer: This is probably true, especially for those species who forage from a huge selection of plant materials and invertebrates in the wild. However, it’s no reason not to feed them. They offer balanced nutrition. It’s up to us to supplement the pellets with enough healthy variety as described above to make sure that we get as close as possible to offering a balanced diet.

Argument: Pellets are not palatable so parrots don’t like them.

Answer: Not true. This argument is the result of incorrectly interpreting behavior. Many people conclude this after offering pellets and finding that the parrot won’t eat them. Introducing pellets has to be done correctly to ensure acceptance. You can’t offer a choice between seeds and pellets and then conclude that the parrot doesn’t like pellets. This is like offering a two-year-old a choice between broccoli and ice cream. Further, if a parrot hasn’t seen pellets before, it may take several weeks of offering them before he accepts them.  

Argument: Eating pellets leads to iron storage disease (hemochromatosis).

Answer: True… IF your parrot consumes moderate quantities of both pellets and citrus fruits or juice. Parrots do not need dietary iron and too much iron absorbed from the diet can cause a health risk. The ascorbic acid in citrus fruit causes increased absorption of iron from the diet. There is no need to feed citrus fruits and they are best avoided in a pellet-eating parrot.

Argument: Veterinarians only recommend pellets because they make money off of them.

Answer: This is so ludicrous it doesn’t even merit a response.

Argument: Eclectus parrots develop toe-tapping and wing flipping if you feed them pellets.

Answer: Actually, these behaviors cannot be blamed solely on pellets or vitamin supplementation.  (Desborough, L. 2014)

Argument:: Converting my parrot to pellets is just too hard; he never eats them.

Answer: He will if you introduce them in the right way. Read on…the next section is for you.

But first, an additional argument is often presented. Why feed pellets at all?  Why not just offer a healthy variety and allow the parrot to choose which foods he needs? GreyIn theory, this should work. In practice, it does not. I can assure you of that from my own personal experience. In addition, “a self-selected diet in African grey parrots (Psittacus erithacus) resulted in a diet that was deficient in a total of 12 dietary components consisting of vitamins, minerals and amino acids. (Orosz, S. Lafeber.com)” For most species a combination of a formulated diet (50-80%) is ideal along with fresh vegetables, fruits, legumes, and other appropriate fresh foods.” (Ritzman, T. 2008)

 Converting the Seed-Eating Parrot to Pellets

 Let me reassure you about two things. First, I have never been unsuccessful in converting a parrot from seed to pellets. Second, I have never found it necessary to make the parrot hungry in order to accomplish this goal. If pellets are introduced correctly, your parrot will choose to eat them. The following is a foolproof method for getting your parrot to eat pellets:

First, make a chop mix for your bird. You may already have heard of “chop.” (While some lay claim to this idea, some version of it has been around for a long time.) Chop.FBWhole grains are cooked, then mixed with finely chopped vegetables and other items. The mix is frozen and then defrosted for feeding. It’s a good way to get a lot of variety into a parrot’s diet and offer a foraging experience. Here is an excellent article about making chop.

The only way you can screw this idea up is by including too many “goodies” (nuts, wheat-based pasta, dried fruit, etc.) into your mix. It should include only grains as close to nature as possible and a wide variety of vegetables. Other healthful additions might include flax seed, pasta made from legumes, sprouts, etc.  Using the chop mix to convert the parrot to eating pellets works extremely well for birds who are used to being offered variety.

Once you have created your chop mix:

  • Measure the amount of seed mix consumed each day.
  • Mix this into an equal quantity of chop mix; offer this on a daily basis. (Your parrot will need to forage through the chop in order to eat his seeds. If he won’t go near the dish, then you will need initially to offer a small quantity of seed in a separate dish so that he doesn’t go hungry.)
  • At the same time, begin to offer in a separate dish a good-quality pellet. Don’t worry if he doesn’t eat them at this time. Feed fresh pellets daily in a small quantity (two or three) until he starts to eat them.
  • When you observe that he is eating some of the grains and vegetables, start reducing the amount of seed you mix into his chop. (You can reduce the overall quantity of seed by as little as one teaspoon a week if he is slow to eat the chop. Or, you can reduce it more quickly if he eats the chop mix readily. Take your cues from your parrot. Go as slowly or as quickly as he needs, but continue to steadily reduce weekly the amount of seed you put into the chop.)
  • Drumroll: At some point (once the quantity of seed mix offered gets to the point where he can no longer rely on it to meet his nutritional need for dietary fat) he will begin to eat the pellets. You won’t have to do anything else to encourage him to eat pellets.
  • Once he is eating the pellets well, completely eliminate the seed mix from the daily diet. Give it to the wild birds or use it to reward different behaviors that you ask him to perform.

Please note that this method is intended for species other than budgerigars and cockatiels. Generally, veterinarians recommend feeding these species fewer pellets. I convert these birds first from seed to Labefer Nutriberries and Avicakes, then add in a smaller quantity of pellets. This method has been most successful.

There are other ways, of course, to successfully introduce pellets to parrots. However, if I make this blog any longer, no one will read it!

Feeding Other Foods

If you do offer other foods in addition to the pelleted or extruded diet, you may change the nutrient balance of the diet as a whole, which could be problematic. This only becomes a serious problem if you are adding in seeds or nuts. As previously stated, parrots will eat high fat foods in preference to formulated foods. The best practice is to reserve any treats, whether seeds or nuts or cheese, for use in reinforcing behaviors that you have asked the parrot to do.

If you supplement with fruits and vegetables, you are less likely to upset the total nutrient balance of the diet. These foods are high in water content, so even if they make up a high proportion of dietary weight, they have a relatively small influence on the balance of nutrients supplied by dry pellets or extrusions that contain much less water.  (Brilling Hill, Inc. 1996)

Veterinarians generally recommend that formulated foods make up between 50% and 80% of what is consumed. My best advice is to consult your own veterinarian as to what brand and amount to feed.

A Few Cautions

If pursuing a diet change, please weigh your parrot regularly to guard against weight loss. This is easier than trying to figure out what the parrot is actually eating. (An exception to this would be if your veterinarian has recommended weight loss for your parrot and is monitoring your progress with this.) Otherwise, weigh your parrot once or twice a week. You can use a good-quality kitchen scale. Alternatively there are many websites that sell scales with perches.

You should also be monitoring the droppings as an added precaution. What goes in must come out. If you have more than one bird in the cage, please also increase the number of food dishes. You should eliminate any competition for food as the diet conversion is completed.

Sources:

Brue, R. (1997) Nutrition. In: D. Zantop, abridged edition, Avian Medicine: Principles and Application. Lake Worth: Wingers Publishing, Pages 23-46.

Brilling Hill, Inc. for Veterinary Practice Publishing Company. 1996. Nutrition of Psittacines (Parrot Family.) [online] Available at: https://www.marionzoological.com/docs/NutritionPsittacines-1009.pdf

Dr. Sharman M. Hoppes, DVM, Dipl ABVP. (2018) Reproductive Diseases of Pet Birds. Merck Veterinary Manual. [online] Available at: https://www.merckvetmanual.com/exotic-and-laboratory-animals/pet-birds/reproductive-diseases-of-pet-birds.

Clark, P. Dr. Jamie Lindstrom (2010) Telephone interview: The Link Between Diet and Behavior.

 Desborough, L.  (2014) Toe-tapping in Eclectus Parrots. [online] Available at: https://eclectusparrotcentre.com/contact/toe-tapping

Molokwu, M and Nilsson, J and Olsson, O. (2011) Diet Selection in Birds: trade-off between energetic content and digestibility of seeds. Oxford University Press for the International Society for Behavioral Ecology. [online] Available at: https://academic.oup.com/beheco/article/22/3/639/269921

Nijboer, J. (2018) Nutrition in Psittacines. In: Merck Veterinary Manual. [online] Available at: https://www.merckvetmanual.com/management-and-nutrition/nutrition-exotic-and-zoo-animals/nutrition-in-psittacines

Dr. Susan Orosz, DVM, DABVP, DECAMS. (2006) Avian Nutrition Demystified. In: North American Veterinary Conference Proceedings, Volume 20. [online] Orlando: IVIS. Available at: http://www.ivis.org/proceedings/navc/2006/SAE/565.pdf?LA=1.

Dr. Susan Orosz, DVM, DABVP, DECAMS. Date unknown. Avian Nutrition Revisited: Clinical Perspectives. Pet Birds by Lafeber Co. [online] Available at: https://lafeber.com/pet-birds/avian-nutrition-revisited-clinical-perspectives

Dr. Tracey Ritzman, DVM, DABVP. (2008) Practical Avian Nutrition (Proceedings). CVC In San Diego. [online] Lenexa: UBM Animal Care. Available at: http://veterinarycalendar.dvm360.com/practical-avian-nutrition-proceedings