grit

.
INTRODUCTION: Grit seems to be such a simple subject to be talking about to aviculturists yet there needs to be a great need to pay attention to the grit our birds receive. From my observations of many aviaries over the years and despite the amount that has been written on dirt in the past, there are a lot of aviculturists who do not understand the principle involved. Many aviculturists state that they give their birds plenty of shell grit or cuttlefish bone which the birds like, so that will do instead of grit. This comes from people you would expect to know better.

Cuttlefish bone certainly is great and beneficial for the birds, but it performs a totally different function to that of grit. I am not so sure about the benefits of shell grit. There are just too may iffs and buts about shell grit which would require another article to explain fully. Shell grit and cuttlefish bone are fine for the supply of calcium but useless for the hard tack of grinding up seed. The seed kernels that end up in the gizzard are quite hard and will certainly need more than small pieces of cuttlefish bone or even shell grit to break them down to tiny pieces.

Some aviculturists believe grit is grit and any sort is as good as any other. They fail to see what use 'hard' stones are. Why hard stones? The answer is simply that the birds have no teeth. After looking into a great many gizzards the muscular organ that grinds the birds' food into an acceptable product for them to use) I believe it is better to think of the gizzard as a "tumbler" or breaking down machine similar to the tumblers used at brickworks to knock sharp corners off certain varieties of bricks.

Another aspect to be considered is the size of the grit used, and this depends on the variety of birds kept. Finches tend to have stones of 1-2 millimetres diameter in their crops; whereas in the crop of King Parrots I have found stones of 2-5 millimetres diameter. These are the sizes of the stones selected by birds that have had free access to gravel or coarse sand. In aviaries I have seen King Parrots and larger birds on concrete floors with trays of beach sand as the only source of grit, or worse still, nothing more than cuttlefish. Beach sand is too fine even for finches. What is needed is some clean creek sand with a high percentage of quartz. Quartz is often the clear mineral you will find in almost all varieties of sand.

Birds on free range with access to all varieties of grit will almost always have the greatest percentage of grit consisting of quartz in their gizzards. On the scale of hardness in minerals, quartz rates a hardness of 7 as compared to diamond with a score of 10. Obviously the birds favour the harder grit as it does a better and more efficient job of crushing up the seeds.

The sharpness of the stone doesn't seem to worry the birds either. In fact, when dressing chickens, I have often found freshly swallowed jagged pieces of glass along with smooth well-worn pieces of glass in their gizzard with no sign of injury or cuts to the gizzard wall.

CONCLUSION: So my advice to aviculturists is to consider the type and size of the grit you supply your birds and if possible, with a high quartz content. You will need to renew your grit as the birds have to renew the supply to their gizzard. As the stones in their gizzards are worn down smooth and to a size that is of no further use in seed crushing, they are passed out through the bird's droppings. This means renewing or adding fresh grit to ensure the birds continue to have access to a wide range of sizes.©