Layers in Household Poultry Flock Need Two Types of Grit

New Zealand Journal of Agriculture, Volume 91, Issue 6, 15 December 1955, Page 551

Layers in Household Poultry Flock Need Two Types of Grit

THOUGH most household poultry keepers appear to realise that their laying birds . require grit, many are somewhat hazy about the best kind of grit to feed and about the reason for which grit is fed. The two types of grit required and why they are needed are described in this article by the Animal Industry Division.

ANIMALS have teeth with which to masticate food before it enters the stomach to be further acted on by digestive juices. Birds have no teeth and have other means by which their food is “masticated” before passing on for the normal digestive processes. “Mastication” in a bird takes place in the organ known as the gizzard, which forms an important part of a bird’s digestive system. Approximately round, and flattened on either side, the gizzard is largely constructed of powerful muscles. The interior is lined with a thick, leathery material covered in ridges. This saclike lining can be • readily removed from the interior, as it is when the gizzard is used for cooking. In a properly fed or healthy bird the gizzard contains pebbles or stones which are retained there for the grinding or disintegrating of food passing through. The grinding by the stones is effected by contraction and expansion of the enveloping powerful muscles of the gizzard.

Birds, including poultry, which feed on hard foods such as seeds or grain look. for stones or other hard substances of a size that can easily be swallowed, as they need to keep a supply of hard. material in . their gizzards. With the continuous grinding process these stones become rounded and smaller, ultimately passing down the digestive tract to be voided with the droppings. Grit for Laying Birds Many laying birds are kept inside a house and have no access to the ground outside where stones are to

be found. Consequently it is highly desirable to have a small box of poultry grit, as it is usually termed, in the laying house open to the birds at all times. They will not eat a lot of this pebble grit, as the rate at which it is used up in the gizzard is slow. If no metal grit is supplied, gizzards gradually become devoid of any grinding material. Fibrous food is then not broken up or adequately disintegrated in the gizzard and ultimately the gizzard muscles soften, as they have no hard material on which to work. This state leads to faulty or inefficient digestion of food. There can therefore be no question about the desirability of supplying grit to laying birds; it should always be available in the laying house.

Kind of Grit From the description of the gizzard and its function a hard grit is obviously needed. In fact the harder the grit the better it is. In England poultry are given flint grit, which is extremely hard and consequently lasts a long time in the gizzard. If possible, the grit should be angular or irregular in shape, as this makes it more efficient as a grinding agent in the gizzard. Smooth, rounded pebbles are less effective and tend to pass out of the gizzard more readily than angular chips. Such is the powerful action of the g iz z a r d that pieces of glass have been smoothed and rounded inside it. The lining is so tough that no rough or sharp edge will injure it.

Any hard, metal grit, preferably irregularly shaped, is suitable for poultry. The box of grit should be placed on a wall well above the litter. Unless this is done the box is soon filled to the top with litter from the floor when the birds scratch for their grain and the birds are unable to get at the grit. If birds are without grit for a considerable period and then are given an ample supply, they will tend to glut themselves with it for a short time and a considerable amount of grit may be passed with the droppings. This may worry poultry owners, but the phase will rapidly pass and the birds will not be injured.

Reminders for January fa T this time of year adult birds begin to drop in production and non-producers should be culled. Light breeds such as White Leghorns should be suspected of going off lay when combs show indications of becoming dry and shrivelled. Heavy breeds- such as Australorps, Rhode Island Reds, and crossbreds do not show such obvious signs of falling production and they, as well as the light breeds, should be checked by handling. The. birds should be caught and held and the palm of one hand placed over the pelvic and keel bones at the rear of the bird. These bones are triangular with the two pelvic bones uppermost. If there is less than two fingers' width between the pelvic bones and less than three between the pelvic and keel bones, the bird is not paying its way and should be removed and used for table purposes. New season's pullets should receive all the mash and grain they can eat without wasting it. Adequate supplies of fresh, cool water should be given daily in containers left out of direct sunshine. Nov/ is a suitable time to treat growing stock against roundworm infestation. ■ Birds over 8 weeks old and under 12 weeks may be given a I c.c. carbon tetrachloride capsule. Birds over 12 weeks old may receive a 2 c.c. capsule. Birds should be inspected for body lice at the bases of the feathers next to the skin, particularly in the fluffy feathers near the vent. Birds infested with lice should be treated without delay. A drop or two of nicotine sulphate or a louse powder should be applied into the feathers round the vent and under the wings. A further application 10 days later will destroy new lice which hatch from the eggs or nits. Red mites under the perches or in the fittings of the fowl house can be controlled by painting affected parts with a solution of kerosene and used sump oil.

Metal and Shell Grits Confusion sometimes occurs between the uses of metal grits and shell grits. Laying birds require a substantial quantity of lime; a relatively small proportion is needed for their bodies and a large amount for forming shells on their eggs. A small percentage of ground limestone is commonly incorporated in laying mashes to give birds a steady supply of lime. A bird’s requirement of lime will vary considerably, however, according to the rate at which she is laying. The more eggs she lays the more lime will be required. A box of “grit” rich in lime in addition to a metal grit should therefore be available always to laying birds. Birds appear to regulate their intake of lime grits according to their needs. Crushed oyster shells or pipi shells are commonly used. Shell grits are not hard enough to be really efficient for grinding food in the gizzard. If shell grits were as hard as metal grits, they would not serve their particular purpose of affording a ready supply of lime. From time to time hard limestone grits that are claimed to serve the double purpose of being hard enough to grind food in the gizzard and at the same time break down sufficiently to release lime for shell formation are put on the market. It is doubtful whether the claim has been either satisfactorily established or refuted. However, . most commercial poultry producers still, prefer a shell grit and a metal grit for their birds.

INSTRUCTION OR RESEARCH? GRADUATES in science or agriculture and holders of agricultural diplomas are needed to fill vacancies in the Department of Agriculture. Positions are available for extension work in the field or research work at the Department's research stations. Commencing salaries are good: Holders of B.Sc., £575; M.Sc., £615; M.Sc. with Ist class honours, £705. Holders of B.Ag.Sc., £615; M.Ag.Sc., £665. Promotion prospects are good. Staff are given the opportunity to attend Departmental courses and conferences of professional societies. Inquire at any office of the Department of Agriculture or write to the Staff Training Officer, P.O. Box 2298, Wellington.

Temporary Docking Yards of Jute Nets

COR the construction of temporary docking yards jute nets rather than wire netting • are worth consideration because of their ease of transport and speed of erection. The material is about the same weight as that in sugar bags. Ewes from which lambs have been taken are easily held in a yard of this nature, because they will usually stand back at a distance rather than try to break out. The netting can be fastened to wooden stakes by staples driven lightly over a reinforcing rope running full length through a hem on either edge.. If iron standards are used, eyelets may be inserted in the net hem at regular intervals to allow the use of baling twine, which can be cut when docking .is finished. A finished height of 39in. by 25yds. long is a useful size for handling. The nets may also be used to extend a wing to the yard opening for gathering in ewes and lambs; if the yard is erected on an existing fence, the netting may be used to secure the part of the fence left uncovered to facilitate filling.

—C. R. M. JONES,

Livestock Instructor,

Department of Agriculture, Wairoa

Tussock Grassland j Improvement