Live food and supplements Part 2
Gary Fitt, Brisbane
We owe it to our birds to provide the best possible range and quality of nutrition. This includes the basic staple items such as dry seeds, half ripe seeding grasses, sprouted seeds, water and various types of greens, plus an assortment of supplements that collectively provide a complete and balanced diet to support successful breeding. In Part 1 of this article (Finch News, August 2010) I covered the various forms of livefood available for finches. In this part I discuss a range of other supplements, such as grits and minerals, particularly calcium in various forms, and vitamin supplements.
There are an enormous range of commercially available additives and supplements for birds. If you Google “supplements for birds” on the internet you will get 1.45 million hits, so there is plenty of information and advertising of bird supplements out there. The trick is to wade through all the hype and identify what your birds really need. It is also important to realise that for many key nutrients eg. calcium, there is a range of concentrations where the supply is adequate, but above or below that range can be detrimental. In fact it is very easy to go overboard with some additives and supplements. Nutrition is about balance, not excess, and the best judge of what is needed is your bird. Hence it is important that birds can select what they need from a varied diet and not be forced to consume nutrients by having no choice as for example might happen if vitamins are routinely provided in water.
Grits and Minerals
We will start with grits. Beyond seeds and water a good quality fine grit is essential for finches. Grits come in two forms – insoluble and soluble. Insoluble hard grit can assist the action of the gizzard in grinding seeds, although it is not clear that this really occurs in finches. Soluble grits are largely calcium carbonate and come in several forms – crushed oyster shell, canunda shells, other crushed shells, cuttle fish bone, crushed coral, limestone and of course egg shells. Being made of calcium carbonate these all dissolve in the acid digestive tract to provide a useful source of calcium and other minerals. Egg shells, which have been dried and then oven baked or “cooked” in a microwave for 5 minutes, are a great source of calcium. They can be fed whole or in large chunks or crushed into small pieces and incorporated into a grit mix. Soluble grits should be available to your birds at all times and can form a useful matrix for providing other minerals and vitamins since birds will only consume what they need.
“Picking stones” and mineral bells are also a very useful source of minerals which finches can access as they need them. Picking stones are made of multiple grits set in a mineral matrix while most mineral bells have a bentonite clay matrix.
Some prepared mineral powders are also useful and can be mixed with grit. An example is PVM Powder (available from the Australian Pigeon Company), which contains all the minerals necessary for a balanced diet, in particular calcium, iron and iodine, and also vitamins A, B, D, E and K. BioCal, also from APC, is another useful product. It contains for different calcium sources – ground shell grit, ground cuttle fish bone, ground sea coral and calcite. It is naturally rich in calcium and iodine and also includes PVM. Marcus Pollard has developed some excellent recipes for fortified
grits using these products (see www.cliftonaviaries.org/cfa/shellgrit/grit.htm ), while Peter James’ new book “The Finch Keeper’s Recipe Book” [available from QFS] also contains some useful mineral grit blends. A blend that I use contains 1 part PVM powder, 1 part Biocal powder, to 8 parts fine shell grit. When feeding this out I add a small quantity of crushed mineral block (Australian Pigeon Company), plus crushed charcoal and crushed eggshells in separate dishes.
Charcoal is another highly beneficial supplement. In powder form or crushed to small pieces charcoal is readily eaten by many finches and is also placed in nests by some species. Masked finches have a legendary attraction to charcoal pieces. Charcoal acts in the intestine as a natural astringent and can deactivate a range of toxins which may be present. Powdered charcoal is easily produced by pulverising chunks of charcoal collected from charred trees or by putting chunks through a mincer. Charred pieces of timber can also be put into the aviary where the birds will pick at it with relish. It is critically important that the charcoal comes from timber which has not been treated with potentially toxic preservatives. Despite the above there are some information sources which claim that charcoal should not be fed because it may interfere with the absorption of certain vitamins such as A, B2, and K, resulting in deficiencies. On balance however, almost every article I have seen on charcoal indicates that it is highly beneficial.
Calcium, Phosphorus and Vitamin D3
This trio is worth discussing together since they interact greatly.
Calcium is the most abundant mineral in a bird’s body. Obviously it is a key component of bones (about one third of their weight is calcium phosphate) and is used in egg shells (in the form of calcium carbonate). However calcium is also important for muscle and nerve function, blood clotting and other enzymatic functions in the body.
Calcium is available in some foods, or in the soluble calcium grits and other forms already mentioned. Seeds, the staple component of most finch diets, and many vegetables, fruits and livefoods are usually calcium deficient and unbalanced in relation to other minerals (Mark Shephard – Aviculture in Australia). For example millets have a calcium/phosphorus ratio of 1:6, a long way off the 2:1 needed. More about that shortly. Table 1 shows the value of different sources of calcium, phosphorus and Vitamin D3 while Table 2 shows a range of plant sources of Ca and P and their ratio.
Phosphorus is perhaps more critical to biological systems than any other element. It is important in many body functions including bone formation, metabolism of fat and carbohydrates, egg formation and in the metabolism of proteins, carbohydrates and lipids (fats) used throughout the body.
Phosphorus in the diet is not always readily available to birds. While phosphorus derived from animal products or inorganic supplements is almost completely usable, only about 30% of phosphorus from plant sources is available. Plant derived phosphorus is often bound with phytin, and birds lack the enzyme phytase necessary to break the P-phytin complex and make the phosphorus available. Nonetheless phosphorus is so readily available in bird diets that it is unlikely to be limiting.
Vitamin D plays a critical role in maintaining health by regulating absorption and excretion of calcium and phosphorus. This is especially important when the ratios of calcium and phosphorus in the diet are unbalanced. For bone health, an adequate intake of vitamin D is no less important than calcium.
Vitamin D comes in two forms. Vitamin D2 comes mainly from plants. Vitamin D3 is produced exclusively in a bird’s body when the UV rays present in sunlight or an artificial UV light source react with Vitamin D precursors in the skin. Vitamin D3 is 30-40 times more potent than D2, and plant sources are generally considered insignificant as a source of Vitamin D for birds. As Table 1 shows cod liver oil is an excellent source and the use of oil fortified seed has been practiced for decades. Studies with poultry show that sufficient Vitamin D3 can be produced for growth of chicks with 11-45 minutes of direct sunshine each day. So any birds with direct access to sunshine will not suffer Vitamin D deficiency.
Too much calcium or phosphorus!!!
Table 1. Sources of key nutrients relevant for birds
(over 20 times requirement)
(over 2 times requirement)
(0.5-2 times requirement)
|Fish & meat meals
|Dried milk powder
|Fish & meat meals
Wheat Germ Meal
Most oil seeds
|Vitamin D3||Cod liver oil
|Dried milk powder|
Table 2. Good Plant Sources of Ca and P
|Food||CA (mg)||P (mg)||
(2 : 1 optimal)
|Beet Greens||188||80||2 : 0.8|
|Broccoli Leaves||349||89||2 : 0.5|
|Broccoli Stem||111||47||2 : 0.8|
|Cabbage (outside green leaves)||429||72||2 : 0.3|
|Celery||44||32||2 : 1.4|
|Chinese Cabbage||400||72||2 : 0.4|
|Dandelion Greens||168||70||2 : 0.8|
|Endive||104||39||2 : 0.8|
Source: The Midwest Bird & Exotic Animal Hospital, Westchester, Illinois. Calcium and Phosphorus contents are for 1 cup of food.
Similarly too high levels of phosphorus will interfere with absorption of calcium. Consequently much nutritional work (done essentially with poultry) indicate that diets with a ratio of 2:1 calcium to available phosphorus are optimal. As Table 2 shows many greens are close to this.
Birds which live in arid climates and eat mainly lower nutrient, seed diets (such as many of our finches) have evolved to efficiently conserve nutrients and water and thus they may be more sensitive to excessively high levels of calcium in their diets, as might arise when they have no choice but to consume calcium supplements in food. Once again allowing birds to make their own selection according to their varying needs is a better strategy. By contrast birds of tropical forests, with access to abundant, varied foods, have not needed to conserve nutrients in their body and may have higher daily dietary needs for calcium. Many softbills kept in other parts of the world fall into this category. Calcium supplements are important for them.
Vitamins are nutrients that are required at only very low concentrations. Vitamin A, C, E and most of the B group vitamins are readily available in fruits, vegetables, greens and grains. Birds with access to a diverse high quality diet including seed, half ripe seeds, various greens and livefood when they need it should not suffer from vitamin deficiencies (Dr. David Shultz – Everybird). However for birds held in less than ideal conditions or with a poor diet a vitamin supplement will often be beneficial. There is a huge literature on vitamin supplements and many recommendations to provide vitamins in the water on a regular basis. As noted above with mineral supplements it is much better not to force birds to consume vitamins through the water, but to provide them in a varied and balanced diet. As Dr David Shultz says in the classic book on avian health, Everybird, “The practice of providing vitamins (on a routine basis) in the drinking water can be dangerous ….”. In part this is because overdosing of vitamins like Vitamin A can be detrimental, but also because such water provides an ideal environment for bacterial growth.
We have come a long way with finch nutrition and have a better understanding of how to provide a balanced diet to sustain growth and reproduction. There is still much to learn however. The key words with nutrition are variety, balance and choice. Balance and variety in what we provide across the spectrum of food types and supplements and choice in the opportunity for our birds to regulate their own intake through choice rather than be force fed with a plethora of superfluous additives.