POULTRY NOTES

Southland Times, Issue 24241, 26 September 1940, Page 12

POULTRY NOTES

By A. PEAT The supply of fresh air in the incubator is of great importance. No hatching egg will live or will continue to develop without fresh air. The hatching egg, like any living animal, in the process of its respiration uses oxygen and eliminates carbon dioxide. This process is continuous. A chicken egg of 60 grams, for example, during the entire period of its development in 21 days uses about one quarter of a cubic foot of oxygen and eliminates about the same amount of carbon dioxide.

When we hatch hundreds or thousands of eggs in one incubator the problem of a proper supply of fresh air in the incubator becomes very important. The chief problem is how much fresh air should we supply for normal development of the embryo without necessary waste of heat. Experimental observations show that the supply of fresh air in the incubator depends upon five factors. These are: (1) The size of the egg; (2) the stage of incubation; (3) the number of eggs to the capacity of the incubator; (4) the type of the incubator; and (5) the condition of air in the incubator room.

The size of the egg.—ln the process of respiration of the developing embryo the amounts of consumed oxygen and eliminated carbon dioxide are proportional to the size of the egg. A goose egg, which weighs about 180 grams—three times larger than a chicken egg—requires about three times more fresh air. On the other hand a quail egg, which weighs about 9 grams—over six times smaller than a chicken egg—requires about six times less fresh air. In other words the incubator filled with goose eggs would require much more fresh air than the same incubator filled with quail eggs.

EXCHANGE OF GASES The stage of incubation—The amounts of consumed oxygen and eliminated carbon dioxide are proportional to the live weight of the embryo. At the beginning of incubation the embryo is very small and the exchange of gases and the consumption of oxygen and elimination of carbon dioxide is insignificant. But when the embryo begins to gain in weight, especially during the later part of incubation, the exchange of the gases is very noticeable. A few days before hatching there is so great a consumption of oxygen and accumulation of carbon dioxide that the condition of the air in the incubator may easily become alarming, especially in a crowded incubator.

The number of eggs to the capacity of the incubator.—The rate of supply of fresh air in the incubator depends greatly upon the number of eggs in the incubator up to full capacity. The less crowded incubator requires less fresh air than the more crowded one. Moreover, we have found that during the early part of incubation the presence of a moderate amount of carbon dioxide in the incubator is desirable for normal development of the embryo. Therefore, during the first week of incubation it would be desirable to keep the ventilation holes closed as much as possible without interference with the control of temperature and humidity and in this way to concentrate in the incubator some carbon dioxide. The neglect to do so would lead to poor hatches. This is especially noticed with the hatching of the first set of eggs not up to full capacity in the forced draught type of incubators. The type of incubator.—The supply of fresh air also depends upon the type of the incubator. In the natural draught incubators as a rule there is inside proportionately more air space an egg than in forced draught incubators. Therefore at the beginning of incubation the natural incubators require relatively less ventilation than the force draught type. The natural draught incubator on account of its slow movement requires at hatching time plenty of ventilation to purify the air and to drive away excess of moisture. Since the forced draught incubators are always crowded with eggs, they require relatively more ventilation at all times than the natural draught incubators; but the amount of opening of ventilator holes in both types of incubators depends greatly upon the condition of the air in the incubator room.

AIR IN INCUBATOR Conditions of air in the incubatorroom.—lf the incubator room is well ventilated, there is need for a slower exchange of air in the incubator. On the othei- hand if the incubator room is poorly ventilated there is need for more rapid exchange of air in the incubator. With a natural draught incubator in a room which has a low temperature, for example 40-50 deg. F., less ventilation is required than in a room which has a high temperature of 70-80 deg, F.

On the whole the consideration of these five factors constitutes the control of the supply of fresh air in the incubator which plays an important part in the production of a complete and healthy hatch. In practice, however, it is one of the simplest problems of incubation in the hands of a thoughtful operator who remembers that incubated eggs are living creatures and they need fresh air as much as we do for health and comfort.

Most experienced poultry farmers have, no doubt, learned that late hatched chickens are not profitable, but there are many beginners, who in their desire to increase the numbers of their stock, may consider it necessary to continue hatching chickens after the end of October. It should be pointed out that unless the chickens are to be raised on new ground and under specially good conditions it is inadvisable to continue hatching after the end of next month. Where chickens have run on the same ground from the beginning of the season it is not advisable to hatch late. Exceptions may be made in the case of some old show or competition bird that has been a proved breeder and owing to advanced age was late in starting to lay, but these chickens must have clean, fresh ground and special care to give them a chance.

STUD COCKERELS Where it is desirable to retain cockerels for stud purposes next season the best birds from the early chickens should be selected rather than those hatched later in the season. In making a selection of the breeding cockerels it must be borne in mind that it is necessary to retain a much larger number than will be ultimately required. In fact when the selection is made at an early age it will be found that in most cases only about 25 per cent, will be really suitable by the time they reach maturity as many of the birds develop faults as they grow and they must be culled.