POULTRY NOTES

Northern Advocate, 2 July 1927, Page 9

POULTRY NOTES

(BY E. J. TERRY.)

INCUBATION.

I am going to make an- endeavour to enable my readers thoroughly to grasp a few facts re artificial incubation. I have previously said that there is no reason to worry re temperature in the modern makes of incubators. The amount of ventilation that .should be given seems to be the rock on, which many beginners wreck their prospects. It is a difficult matter to make them grasp the fact that eggs incubating require different treatment from chicks as regards ventilation. Most people have the mistaken idea that they are developing in the incubator something which breathes through its lungs even though it is in embryonic state. If that were the case they wo.uld be quite right in their oftrepcatcd statement that, like a man, a chick cannot breathe too much pure air. That is perfectly correct, but they make the mistake ;of calling an embryo a chick. In that way they show their want of close knowledge of embryology or the development of the fetus when they imagine, as they evidently do (there can be no other explanation of their statement) that the embryo breathes in the same manner —that is, through its lungs —as the chick does after it is hatched. It is this question of ventilation and to a lesser degree, moisture, that makes for the successful hatch. In testing eggs for fertility on the fifth or sixth day one can see through the shell of the egg when held in front of the light in a darkened room wffiat is termed the “spider,” which really is the eye of the chick, which shows up dark, .and that which looks like a web is really a system of blood vessels. All these who use incubators knew that in testing' eggs on the fifth day instead of finding wTiat is

termed the “spider" when you look through the shell in many cases there is an irregular ring of blood. It used to be, and is still, thought by many that this was duo to the eggs

having been shaken in transit, but if one fills up an incubator directly from the nest, and you carry them yourself so that you are certain that the eggs have not received the slightest concussion, you will find in certain makes of incubator, especially the old style machines, a number of eggs which show the blood ring, denoting a ruptured blood vessel. It is unneccssory for me to go into details of the years of research work till in 1008 I was able to prove to the incubating world that an excess of pure air in the early stages of incubation is harmful. Briefly, the oxygen in t the pure air unduly increases the circulation with a result —ruptured blood vessel. I further claimed that where there is an excess of fresh air through the machine during the embryonic stage that the chicks from the hatch will not have the frame and bone those chicks will have where the circulation of air has been retarded. Again, to give you a year’s work in a few wurds:—o.o2, by which is meant carbon dioxide of the air, plays a very important part in both natural and artificial incubation. I -will just give my readers a little experiment which can be performed for yourselves, and you start to know something about carbon dioxide. Take a bottle and put a caudle in it. Melt a little of the wax in the bottom of the-bottle, set the candle in the wax and then light the candle. Take a rubber tube, put one end down to the bottom of the bottle and breathe into the bottle the air which comes from your lungs. One good long breath or two wall extinguish the caudle. Now, remember you do not blow' out the candle with a draught of air, but the candle being extinguished shows that the air wdiich is exhaled is in a different condition from when it was inhaled. Now, thepporerw r er of the exhaled air to extinguish the candle is due to an ingredient known as carbon dioxide, which is breathed out by all living creatures. The same substance is found in largo quantities in the atmosphere under the hen sitting on an ordinary nest of fertile eggs. The carbon dioxide, in conjunction wdth moisture, has the effect of decomposing (or rotting, as it might be more familiarly termed) ithe shell of the egg thus rendering it an easy matter for .a fully developed chick to breyc it. Carbon dioxide converts the carbonate of lime wdiich forms the shell of the egg, wdiich is insoluble in ordinary water, into bicarbonate of lime, which is soluble in ordinary moisture, or water, and it now acknowledged by research workers that a considerable portion of th 6 shell of the egg is absorbed by the growing embryo and builds up the frame of the chick. This is the chief reason wdiy in many cases chicks hatched under hens are supposed to have bettor constitutions than those hatched in incubators. Most markers of incubators have since my first article appeared in 1908 considerably reduced the ventilation, and it is now generally advised that ventilators shall be closed till after the fifth or sixth day, und this .advice is correct. There is far loss risk wdth the ordinary machine with ventilators closed in. the early stages of the hatch, and I must again impress on those using incubators that the chicks do not breathe through their lungs till shortly prior to breaking out of the shell. I might state that at the time I was experimenting I placed fertile eggs in boxes, etc., packed in bran and other loose material. In some cases I even nailed the lid ou the boxes. The boxes were placed in the incubator, and the boxes turned over occa*

sionally, but even when the lid was not removed I found that the embryo went oh developing till the eighth or tenth day. After that period ifywas not getting sufficient air. Remember that was extreme tests, but it does go to show that air is not necessary in the early stages —in fact an excess is harmful. To go for a moment from artificial to natural incubation, we find further proof of this. The wild turkeys of Queensland, together with some other birds, do not set on or incubate their own eggs, but they gather together a nuiSs of vegetable matter often live or six feet high. The eggs are deposited in the middle of the heap, and are hatched by the heat generated by flic fermentation of the decay of vegetable matter, which must necessarily give offl a considerable quantity of carbonic gas. Now I ask my readers where is the circulation over or around the eggs, or the current of pure air so often advocated?

When I was experimenting enthusiasm was aroused in several friends, including one who is now a noted medico —in fact ho represented a certain country at the late medical conference. He on several occasions developed embryo up to about the tenth, day by simply immersing the eggs in a heap of horse manure which had been thrown in a heap, and after remaining for a few days the heat was broken down and remade so that the first fierce heat had been lost,, and' the second making was a more even »heat. This is a practice often carried out by gardeners in making a hot bed. AVe found that if the eggs were not left in the manure for a longer period that six or seven days, and then placed in an incubator, they invariably hatched strong chicks. Still another enthusiast placed fertile eggs in ordinary sand in a kerosene tin with a. lamp at the bottom of the tin. There were nine inches of sand at the bottom of the tin, then a layer of eggs, then sand, followed again by eggs, till the tin was practically full. Twice a day the tin was emptied of eggs and sand, and the eggs on the top layer were placed at the bottom layer. The embryo continued to develop in some cases till the fourteenth or fifteenth day, admitted the eggs would get a certain amount of airing whilst being changed, but that would bo very slight in comparison with what one believed was necessary. Summed up, practically no extra ventilation is required up to the sixth day, then ventilators can be very slowly opened, till, at the finish, when the chicks arc breathing through their lungs, you cannot give too much providing the door is not open. Sl