Supposing a hatch to be started at the beginning of the above period, by the end of the first week, with the excessive evaporation, due to a low vapor pressure, the eggs would all be several per cent. below the normal water content; the fact that the next week was warm and rainy, and the vapor pressure rose until the loss was entirely counterbalanced, would not repair the injury, even though the eggs showed at the end of incubation exactly the correct amount of shrinkage. A man might thirst in the desert for a week, then, coming to a hole of water fall in and drown, but we would hardly accept the report of a normal water content found at the post-mortem examination as evidence that his death was not connected with the moisture problem.
The change of evaporation, due to weather conditions, is, under hens, less marked than in incubators. This is because there are no drafts under the hen, and because the hen's moist body and the moist earth, if she sets on the ground, are separate sources of moisture which the changing humidity of the atmosphere does not affect. Among about forty hens set at different times at the Utah Station and the loss of moisture of which was determined at three equal periods of six days each, the greatest irregularity I found was as follows: 1st period, 5.81 per cent; 2d period, 3.86 per cent; 3d period, 6.15 per cent. Compare this with a similar incubator record at the same station in which the loss for the three periods was 5.63, 9.18 and 2.15.
I think the reader is now in position to appreciate the almost unsurmountable difficulties in the proper control of evaporation with the common small incubator in our climate. It is little wonder that one of our best incubator manufacturers, after studying the proposition for some time, threw over the whole moisture proposition, and put out a machine in which drafts of air were slowed down by felt diaphragms and the use of moisture was strictly forbidden.
The moisture problem to the small incubator operator presents itself as follows: If left to the mercies of chance and the weather, the too great or too little evaporation from his eggs will yield hatches that will prove unprofitable. In order to regulate this evaporation, he must know and be able to control both vapor pressure and the currents of air that strike the eggs. Now he does not know the amount of vapor pressure and has no way of finding it out. The so-called humidity gauges on the market are practically worthless, and even were the readings on relative humidity accurately determined, they would be wholly confusing, for their effect of the same relative humidity on the evaporation will vary widely with variations of the out-of-door temperature.
If the operator knows or guesses that the humidity is too low, he can increase it by adding water to the room, or the egg chamber, but he cannot tell when he has too much, nor can he reduce the vapor pressure of the air on rainy days when nature gives him too much water. As to air currents he is little better off—he has no way to tell accurately as to the behavior of air in the egg chamber and changes in temperature of the heater or if the outside air will throw these currents all off, since they depend upon the draft principle.
Taking it all in all, the man with the small incubator had better follow the manufacturer's directions and trust to luck.
The writer has long been of the conviction that a plan which would keep the rate of evaporation within as narrow bounds as we now keep the temperature, would not only solve the problem of artificial incubation, but improve on nature and increase not only the numbers but the vitality or livability of the chicks. With a view of studying further the relations between the conditions of atmospheric vapor pressure, and the success of artificial incubation, I have investigated climatic reports and hatching records in the various sections of the world.
The following are averages of the monthly vapor pressures at four points in which we are interested:
A study of the extent of daily variations is also of interest. As a general thing they are less extreme in localities when the seasonal variations are also less. In Cairo, however, which has a seasonal variation greater than San Francisco, the daily variations during the hatching season are much less than in California. This is due to a constant wind from sea to land, and an absolute absence of rainfall, conditions for which Egypt is noted.
Nearness to a coast does not mean uniform vapor pressure, for with wind alternating from sea to land, it means just the opposite.
As will be readily seen the months in spring which give the best hatches, occupy a medium place in the humidity scale. The fact that both hens and machines succeed best in this period, is to me very suggestive of the possibility that with an incubator absolutely controlling evaporation, much of the seasonal variation in the hatchability would disappear.
The uniform humidity of the California coast is shown in the above table. This is not inconsistent with the excellent results obtained at Petaluma.
The Egyptian hatcher in his long experience has learned just about how much airholes and smudge fire are necessary to get results. With these kept constant and the atmosphere constant, we have more nearly perfect conditions of incubation than are to be found anywhere else in the world, and I do not except the natural methods. The climatic conditions of Egypt cannot be equaled in any other climate, but as will be shown in the last section of this chapter, their effect can be duplicated readily enough by modern science and engineering.
Mr. Edward Brown, who was sent over here by the English Government to investigate our poultry industry, was greatly surprised at our poor results in artificial incubation. Compared with our acknowledged records of less than 50 per cent. hatches, he quotes the results obtained in hatching 18,000 eggs at an English experiment station as 62 per cent. I have not obtained any data of English humidity, but it is undoubtedly more uniform than the eastern United States.
Ventilation—Carbon Dioxide.
The last of the four life requisites we have to consider is that of oxygen. The chick in the shell, like a fish, breathes oxygen which is dissolved in a liquid. A special breathing organ is developed for the chick during its embryonic stages and floats in the white and absorbs the oxygen and gives off carbon dioxide. The amount of this breathing that occurs in the chick is at first insignificant, but increases with development. At no time, however, is it anywhere equal to that of the hatched chicks, for the physiological function to be maintained by the unhatched chicks requires little energy and little oxidation.
Upon the subject of ventilation in general, a great misunderstanding exists. Be it far from me to say anything that will cause either my readers or his chickens to sleep less in the fresh air, yet for the love of truth and for the simplification of the problem of incubation, the real facts about ventilation must be given.
In breathing, oxygen is absorbed and carbon dioxide and water vapor are given off. It is popularly held that abundance of fresh air is necessary to supply the oxygen for breathing and that carbon dioxide is a poison. Both are mistakes. The amount of oxygen normally in the air is about 20 per cent. Of carbon dioxide there is normally three hundredths of one per cent. During breathing these gasses are exchanged in about equal volume. A doubling or tripling of carbon dioxide was formerly thought to be "very dangerous." Now, if the carbon dioxide were increased 100 times, we would have only three per cent., and have seventeen per cent. of oxygen remaining. This oxygen would still be of sufficient pressure to readily pass into the blood. We might breathe a little faster to make up for the lessened oxygen pressure. In fact such a condition of the air would not be unlike the effects of higher altitudes.
Some investigations recently conducted at the U.S. Experiment Station for human nutrition, have shown the utter misconception of the old idea of ventilation. The respiratory calorimeter is an air-tight compartment in which men are confined for a week or more at a time while studies are being made concerning heat and energy yielded by food products. It being inconvenient to analyze such an immense volume of air as would be necessary to keep the room freshened according to conventional ventilation standards, experiments were made to see how vitiated the air could be made without causing ill effects to the subject.
This led to a remarkable series of experiments in which it was repeatedly demonstrated that a man could live and work for a week at a time without experiencing any ill effects whatever in an atmosphere of his own breath containing as high as 1.86 per cent. of carbon dioxide, or, in other words, the air had its impurity increased 62 times. This agrees with what every chemist and physiologist has long known, and that is that carbon dioxide is not poisonous, but is a harmless dilutant just as nitrogen. This does not mean that a man or animal may not die of suffocation, but that these are smothered, as they are drowned, by a real absence of oxygen, not poisoned by a fraction of 1 per cent. of carbon dioxide.
In the same series of experiments, search was made for the mysterious poisons of the breath which many who had learned of the actual harmlessness of carbon dioxide alleged to be the cause of the ill effects attributed to foul air. Without discussion, I will say that the investigators failed to find such poisons, but concluded that the sense of suffocation in an unventilated room is due not to carbon dioxide or other "poisonous" respiratory products, but is wholly due to warmth, water vapor, and the unpleasant odors given off by the body.
The subject of ventilation has always been a bone of contention in incubator discussions. With its little understood real importance, as shown in the previous section, and the greatly exaggerated popular notions of the importance of oxygen and imagined poisonous qualities of carbon dioxide, the confusion in the subject should cause little wonder.
A few years ago some one with an investigating mind decided to see if incubators were properly ventilated, and proceeded to make carbon dioxide determinations of the air under a hen and in an incubator. The air under the hen was found to contain the most of the obnoxious gas. Now, this information was disconcerting, for the hen had always been considered the source of all incubator wisdom. Clearly the perfection of the hen or the conception of pure air must be sacrificed. Chemistry here came to the rescue, and said that carbon dioxide mixed with water, formed an acid and acid would dissolve the lime of an egg shell. Evidently the hen was sacrificing her own health by breathing impure air in order to soften up the shells a little so the chicks could get out. Since it could have been demonstrated in a few hours in any laboratory, that carbon dioxide in the quantities involved, has no perceptible effect upon egg shells, it is with some apology that I mention that quite a deal of good brains has been spent upon the subject by two experiment stations. The data accumulated, of course, fails to prove the theory, but it is interesting as further evidence of the needlessness in the old fear of insufficient ventilation.
At the Ontario Station, the average amounts of carbon dioxide under a large number of hens was .32 of one per cent., or about ten times that of fresh air, or one-sixth of that which the man breathed so happily in the respiratory calorimeter. With incubators, every conceivable scheme was tried to change the amount of carbon dioxide. In some, sour milk was placed which, in fermenting, gives off the gas in question. Others were supplied with buttermilk, presumably to familiarize the chickens with this article so they would recognize it in the fattening rations. In other machines, lamp fumes were run in, and to still others, pure carbon dioxide was supplied. The percentage of the gas present varied in the machines from .06 to .58 of one per cent. The results, of course, vary as any run of hatches would. The detailed discussion of the hatches and their relation to the amount of carbon dioxide as given in Bulletin 160 of the Ontario Station, would be unfortunately confusing to the novice, but would make amusing reading for the old poultryman. Speaking of a comparison of two hatches, the writer, on page 53 of the bulletin says, "The increase in vitality of chicks from the combination of the carbon dioxide and moisture over moisture only, amounting, as it does, to 4.5 per cent. of the eggs set, seems directly due to the higher carbon dioxide content." I cannot refrain from suggesting that if my reader has two incubators, he might set up a Chinese prayer machine in front of one and see if he cannot in like manner demonstrate the efficacy of Heavenly supplications in the hatching of chickens.
The practical bearing of the subject of ventilation in the small incubator is almost wholly one of evaporation. The majority of such machines are probably too much ventilated. In a large and properly constructed hatchery, such as is discussed in the last section of this chapter, the entire composition of the air, as well as its movement, is entirely under control. Nothing has yet been brought to light that indicates any particular attention need be given to the composition of such air save in regard to its moisture content, but as the control of this factor renders it necessary that the air be in a closed circuit, and not open to all out-doors, it will be very easy to subject the air to further changes such as the increasing oxygen, if such can be demonstrated to be desirable.
Turning Eggs.
The subject of turning eggs is another source of rather meaningless controversy. Of course, the hen moves her eggs around and in doing so turns them. Doubtless the reader, were he setting on a pile of door knobs as big as his head, would do the same thing. As proof that eggs need turning, we are referred to the fact that yolks stick to the shell if the eggs are not turned. I have candled thousands of eggs and have yet to see a yolk stuck to the shell unless the egg contained foreign organism or was several months old. However, I have seen hundreds of blood rings stuck to the shell. Whether the chick died because the blood rings stuck or whether the blood rings stuck because the chicken died I know not, but I have a strong presumption that the latter explanation is correct, for I see no reason if the live blood ring was in the habit of sticking to the shell, why this would not occur in a few hours as well as in a few days.
In the year 1901 I saw plenty of chicks hatched out in Kansas in egg cases, kitchen cupboards and other places where regular turning was entirely overlooked.
Mr. J.P. Collins, head of the Produce Department of Swift & Co., says that he was one time cruelly deserted in a Pullman smoker for telling the same story. The statement is true, however, in spite of Mr. Collins' unpleasant experience. Texas egg dealers frequently find hatched chickens in cases of eggs.
Upon the subject of turning eggs the writer will admit that he is doing what poultry writers as a class do on a great many occasions, i.e.: expressing an opinion rather than giving the proven facts. In incubation practice it is highly desirable to change the position of eggs so that unevenness in temperature and evaporation will be balanced. When doing this it is easier to turn the eggs than not to turn them, and for this reason the writer has never gone to the trouble of thoroughly investigating the matter. But it has been abundantly proven that any particular pains in egg turning is a waste of time.
Cooling Eggs.
The belief in the necessity of cooling eggs undoubtedly arose from the effort to follow closely and blindly in the footsteps of the hen. With this idea in mind the fact that the hen cooled her eggs occasionally led us to discover a theory which proved such cooling to be necessary. A more reasonable theory is that the hen cools the eggs from necessity, not from choice. In some species of birds the male relieves the female while the latter goes foraging.
But there is no need to argue the question. Eggs will hatch if cooled according to custom, but that they will hatch as well or better without the cooling is abundantly proven by the results in Egyptian incubators where no cooling whatever is practiced.
Searching for the "Open Sesame" of Incubation.
The experiment station workers have, the last few years, gone a hunting for the weak spot in artificial incubation. Some reference to this work has already been made in the sections on moisture and ventilation. Before leaving the subject I want to refer to two more efforts to find this key to the mystery of incubation and in the one case at least correct an erroneous impression that has been given out.
At the Ontario Station a patent disinfectant wash called "Zenoleum" was incidentally used to deodorize incubators. Now, for some reason, perhaps due to the belief that white diarrhoea was caused by a germ in the egg, this idea of washing with Zenoleum was conceived to be a possible solution of the incubator problem. In the numerous experiments at that station in 1907 Zenoleum applied to the machine in various ways was combined with various other incipient panaceas and at the end of the season the results of the various combinations were duly tabulated. The machine with buttermilk and Zenoleum headed the list for livable chicks.
For reasons explained in the chapter on "Experiment Station Work," the idea of contrasting the results of one hatch with one sort with the average results of many hatches of another sort is very poor science. Feeling that the Station men would hardly be guilty of expressing as they did in favor of such a method without better reason, I very carefully went over the results and compared all machines using Zenoleum with all machines without it. The results in favor of Zenoleum were less marked but still perceptible. I was somewhat puzzled, as I could see no rational explanation of the relation between disinfecting incubator walls and the hatchability of the chick in its germ-proof cage. Finally I hit upon the scheme of arranging the hatches by dates and the explanation became at once apparent. The hatching experiments had extended from March to July, but the Zenoleum hatches were grouped in April and early in May, when, as one would expect from weather conditions, all hatches were running good. After allowing for this error Zenoleum appeared as harmless and meaningless as would the Attar of Roses.
The second link after the missing link of incubation to which I wish to call your attention also occurred at the Ontario Station. The latter case, however, is happier in that no unwarranted conclusions were drawn and that an interesting bit of scientific knowledge was added to the world's store. The conception to be tested was an offshoot from the carbon dioxide theory. You will remember at the Utah Station the idea was that carbon dioxide was to dissolve the shell so the chick could break out easier.
At the Guelph Station the conception was that the carbon dioxide might dissolve the lime of the shell for the chick to use in "makin' hisself." As an egg could not be analyzed fresh and then hatched, a number were analyzed from the same hens and others from those hens were then incubated with the various amounts of carbon dioxide, buttermilk, Zenoleum, and other factors. The lime content of the contents of the fresh egg averaged about .04 grams. At hatching time the lime in the chick's body averaged about .20 grams and was always several times as great as the maximum of the eggs.
Clearly calcium phosphate of the chick's bones is made by the digestion of the calcium carbonate from the shell and its combination with the phosphorus of the yolk. Certainly a remarkable and hitherto unexplained fact. The amount of lime required is not great enough, however, to materially weaken the shell, but, of course, the process is vital to the chick as bones are quite essential to his welfare, but it is an "inside affair" of which the three-tenths of one per cent of carbon dioxide incidentally present under the hen is entirely irrelevant.
A further observation made by the investigator is that the chicks which obtained the lowest amount of lime were abnormally weak. As long as we are powerless to aid the chick in digesting lime this fact, like the other, belongs in the field of pure, rather than applied science. I think that we are safe in saying that the weakness caused the shortage of lime rather than vice versa; if the writer remembers runts in other animals are usually a little short of bone material.
The chemist of the station is to be given special credit for not jumping at conclusions. In the summary of this work he states: "There is apparently no connection between the amount of lime absorbed by the chick and the amount of carbon dioxide present during incubation."
The Box Type of Incubator In Actual Use.
Although the fact is not so advertised and frequently not recognized even by the makers, the success of existing incubators is directly proportional to the extent with which they control evaporation. In order to show this I have only to call attention briefly to two or three of the most successful types of incubators on the market.
Let me first repeat that evaporation increases with increased air currents and with decreased vapor pressure. Now, the vapor pressure undergoes all manner of changes with the passing of storm centers and the changes of prevailing winds. But there is a general tendency for vapor pressure to increase with increase in outside temperature. Now, the movement of air in all common incubators depends upon the draft principle and the greater the difference in machine temperature and outside temperature the greater will be this draft. Thus, we have two factors combining to cause variation in the rate of evaporation. The tendency for the rate of airflow to vary is diminished when a cellar is used for an incubator room, but the cellar does not materially remedy the climatic variation in vapor pressure.
The general tendency of incubators as ordinarily constructed, is to dry out the eggs too rapidly. With a view of counteracting this, water is placed in pans in the egg room. A surface of water exposed to quiet air does not evaporate as fast as one might think, as is easily shown by the fact that air above rivers, lakes and even seas is frequently far from the saturation point. The result of the moisture pan with a given current of air is that the vapor pressure is increased a definite amount, but by no means is it regulated or made uniform. Inasmuch as too much shrinking is the most prevalent fault in box incubators, the use of moisture is on the whole beneficial, but in hot, murky weather, with less circulation and higher outside vapor pressure, the moisture is overdone and the operator condemns the system.
The subject not being clearly understood and no means being available for vapor pressure determinations, the system results in confusion and disputes. When the felt diaphragm machine was brought into the market it was advertised as a no-moisture machine. The result of the diaphragm is that of choking off air movement and consequently reducing evaporation. This gives exactly the same results as the use of moisture, but the machine is easier to operate and seemed to do away with the vexatious moisture problem which, together perhaps, with some fancied resemblance of felt diaphragms to hen feathers, has resulted in the widespread use of this type of machine.
The latest effort along the lines of reducing evaporation is the sand tray machine that followed in the wake of the Ontario investigation. This device simply gives a greater evaporating surface to the water and hence a greater addition to the vapor pressure. The results in practice I had given me by a man who last year hatched sixty-five thousand chicks and as many more ducklings.
He said: "The sand tray early in the season gave the best hatches and most vigorous chicks we had, but later on things got too wet and the chickens drowned." No nicer demonstration of science in practice could be desired.
In the present-day incubator of either type we are wholly at the mercy of sudden climatic changes of vapor pressure. For the slower changes from season to season some control by greater and less amounts of supplied moisture, or by ventilator slides is available, but little understood and seldom practiced.
It will certainly be of interest to my readers to know the actual hatches obtained with the prevailing type of box incubator. By actual hatches we mean the per cent. of live chicks taken out of the machine to the per cent. of eggs put in. The ordinary published hatches, based on one per cent. of fertile hatches, are a delusion and a snare. When eggs are tested out many dead germs come out with them and the separation of microscopic dead germs from the infertile egg is, of course, impossible. Such padded and show hatching records do not interest us.
Where incubators are run on top of the ground I have found the results to be poor and to improve, the bigger and deeper and damper and warmer and less ventilated the cellar is made. The reason for this is plain. In such a cellar the vapor pressure of the air is not only greater but is less influenced by the shifting vapor pressure of the outside air. In a good cellar the operator, though his knowledge of the factors with which he deals is grievously deficient, learns, through long and costly experience, about what addition of moisture or about what rate of ventilation will give him the best results. In the room more subject to outside influences, the conditions are so constantly changing that uniformity of practice never gives uniform results, and hence the operator is without guidance, either intelligent or blind, and the results are wholly a product of chance.
As proof of my contention I may give results of a series of full season hatches for 1908, each involving several thousand eggs.
First, a state experiment station, the name of which I do not care to publish. Incubators kept in a cement basement which has flues in which fires were built to secure "ample ventilation." This caused a strong draft of cold, dry air, making the worst possible condition for incubation. The hatch for the season averaged 25 per cent. and was explained by lack of vitality in the stock.
Second, Ontario Agricultural College. A room above ground, moisture used in most machines and various other efforts being made to improve the hatches by a staff of half a dozen scientists. Results: Hatch 48 per cent.—incubator manufacturers call the experimenters names and say they are ignorant and prejudiced.
Third, Cornell University: dry ventilated basement representing typical conditions of common incubator practice of the country. Results: Hatch 52 per cent., results when given out commonly based on fertile eggs and every one generally pleased.
Fourth: One of the most successful poultrymen in New York State, who has, without knowing why, hit upon the plan of using a no-moisture type of incubator in a basement which is heated with steam pipes, which maintains temperature at 70 degrees and has a cement floor which is kept covered with water. Results: Hatch 59 per cent.
Fifth: As a fifth in such a series I might mention again the Egyptian machine with the uniform vapor pressure of the climate and the three chicks exchanged for four eggs.
While an official in the United States Department of Agriculture, I gathered data from original records of private plants covering the incubation of several hundred thousand eggs. Such information was furnished me in confidence as a public official and as a private citizen I have no right to publish that which would mean financial profit or loss to those concerned.
Of records where there were ten thousand or more eggs involved, the lowest I found was 44 per cent. and the highest, that mentioned as the fourth case above, or 59 per cent. The great majority of these records hung very closely around the 50 per cent. mark.
The following is a fair sample of such data. It is the record of hatching hen eggs for the first six months of 1908, at one of the largest poultry plants in America:
The Future Method of Incubation.
The idea of the mammoth incubator which would hatch eggs by the hundred thousand and a minimum of expense is the dream of the American incubator inventor. We have long had available such methods of insulation and regulating the supply of heat as would point to the practicability of such a dream.
The past efforts in this direction have fallen down for the following simple reason: All eggs were placed in a single big room with a view of the man's entering the room to take care of them. Contact with cold walls, the opening of doors, the hatching of chicks or introduction of fresh eggs set up air currents, the hot air rising and the cold air settling until great differences in temperature would be found in the room. No systematic regulation of evaporation was contemplated, as the principles at stake or the means of such regulation were unknown.
The attempt just referred to was made several years ago by one of the most successful of incubator manufacturers and because of his failure other inventors were inclined to steer clear of the proposition. Meanwhile the need of such an incubator has grown enormously. At the time that above effort was made no duck ranch existed whose annual production ran over thirty or forty thousand ducklings, whereas we now have several in the one hundred thousand class.
Much more remarkable has been the growth of the day-old chick business. The discovery that newly hatched chicks could be successfully shipped hundreds of miles with less loss than shipping eggs for hatching, has resulted in a few years' time in the growth of hatcheries of considerable size where chicks are hatched by means of common incubators. Still another opportunity for the use of large hatcheries has been by the growth of poultry communities. There are other communities besides those mentioned in this book which would amply support public hatcheries. If half the poultry growers of Lancaster County, Pa., were to be prevailed upon to patronize a public hatchery, the county would support between fifteen and twenty 100,000 egg incubators. Any of the numerous trolley centers in Indiana, Ohio and Southern Michigan would likewise be profitable locations for the establishment of public hatcheries.
The demand for the incubator of large capacity has, within the last year or so, brought two or three "mammoth" incubators into the market. The devices I now refer to consist of a row of box incubators which, instead of being heated by single lamps, are heated by continuous hot water pipes. This scheme effects a considerable saving in fuel cost and labor, but the bulkiness of construction and the woeful lack of evaporation control are still to be dealt with.
The writer now wishes briefly to describe the plan of construction and operation of a new type of hatchery, the success of which has recently been made feasible by inventions and technical knowledge hitherto unavailable. The plan of the hatchery is on that of a cold storage plant as far as insulation and general construction go. The eggs are kept in bulk in special cases which are turned as a whole and may rest on either of four sides. At hatching time the eggs are spread out in trays in a special hatching room, which is only large enough to accommodate chicks to the amount of one-sixth of the incubator capacity, for twice a week deliverings, or one-third if weekly deliveries are desired.
There are no pipes or other sources of heat in the egg chambers. All temperature regulation is by means of air heated (or cooled as the case may be) outside of the egg rooms and forced into the egg rooms by a motor driven cone fan, maintaining a steady current of air, the rate of movement of which may be varied at will. The air movement maintained will always be sufficiently brisk, however, to prevent an unevenness of temperature in different parts of the room.
So simple is this that the reader will doubtless wonder why it was not developed earlier. The reason is that air subject to the climatic influences will, with any forced draft sufficient to equalize temperature, result in a fatal rate of evaporation. Sprinkling the air has not generally been thought practical because of the notion that air must not be used in the egg chamber but once, which involved quite a waste of heat necessary in warming a large bulk of air and evaporating sufficient water. Moreover, no means has, in the past, been available for making a sufficiently accurate measurement of the evaporating power of the air.
The hair hygrometers commonly sold to incubator operators are known by scientists to be absolutely unreliable. The range between the wet and dry bulb thermometers was found in the Ontario experiments to give readings with and without fanning that varied 15 to 20 per cent. in relative humidity which, at the temperature of an egg chamber, would amount to a variation of three to four hundred of vapor pressure units, which, with the forced draught plan, would ruin a hatch of eggs in a few hours. The sling psychrometer as used by the U.S. Weather Bureau should, in the hands of an expert, give results making possible measurements accurate to two or three per cent. of relative humidity or forty to sixty units of vapor pressure. In contrast with these blundering instruments we now have available an instrument with which the writer has frequently determined vapor pressure accurately to within a range of two or three vapor pressure units and the instrument is capable of being constructed for even finer work.
As it is only by means of air with the moisture content absolutely controlled that the use of a large room becomes possible, we can now see why this type of hatching remained so long undeveloped. By means of such vapor pressure control the large egg chamber is not only feasible but the rate of evaporation at once becomes subject to the control of the operator and we achieve a perfection in artificial incubation hitherto unattained.
The means by which the air moisture is regulated is similar to that used in up-to-date cold storage plants where the air is made moist by sprinkling and dried with deliquescent salts. The regulation of vapor pressure, like that of temperature, may be by electrically moved dampers which switch a greater or less proportion of the incoming current to the sprinkler or dryer as the case may be. The ordinary incubator thermostat gives the necessary impulse for the control of the temperature dampers, while the instrument above referred to is used for the vapor pressure control.
As the entire air circuit is closed, the chemical composition of the air may also be regulated at will. This results in a reduction of the quantity of heat required to a minimum; in fact, with the incubator in full swing, the air will, at times, need cooling rather than warming.
The question of the cost of incubation by this method, or of profit of such a hatchery operated for the public is almost wholly one of the size of operations. Where sufficient eggs may be obtained and sufficient demand exists for the chicks to make it profitable to operate, the additional cost of hatching extra chicks will be insignificant compared with the present system.
The Egyptian poultryman gives four eggs for three chicks, but the American poultryman would be willing to give four eggs for one chick, as is shown by the fact that he sells eggs for from 1 to 3 cents apiece and buys day-old chicks for ten to fifteen cents. A plant with a seasonable capacity of 100,000 eggs has a basis to work upon something as follows:
With a fifty per cent. hatch and chicks at 10 cents each there would be a gross income of $5,000 annually. From this we must subtract for eggs at 2 cents each, $2,000. Salary for operator $1,000, wages for helper $300. Fuel, supplies and repairs $500. Cost of delivery and sales of chicks $200. This leaves a residue of $1,000, which would pay a 20 per cent. interest on the necessary investment of $5,000. Personally, I think this is about the minimum unit of hatching that would prove worth while as independent institutions.
Any increase in the percentage of the hatch would, of course, reduce the unit of size necessary for profitable operation. Upon a single poultry plant as a duck farm the cost of operation would be materially reduced, as the operator himself would take the place of the intelligent manager and the cost of gathering eggs and the delivery of the product would be eliminated.
The most profitable method of hatchery operation undoubtedly will be upon a plan analogous to what, in creamery operation, is called centralization. The success of this scheme depends upon the fact that transportation and agencies at country stores are relatively less important items of expense than plant construction and high salaries for skilled labor. A hatchery with a million capacity can be built and run at not more than twice the cost of one hundred-thousand plant and better men can be kept in charge of it. A portion of the saving will of course be expended in maintaining a system of buying eggs and selling chicks.
The material advantage of operating a hatchery in connection with a high-class egg handling and poultry packing establishment, or as one feature of a poultry community, is at once apparent, for the system of collecting the market produce will be utilized for gathering eggs and distributing chicks, each business helping the other.
The public hatchery also gives an excellent opportunity for the introduction of good stock among farmers who would be too shiftless to acquire it by ordinary methods.
The old adage that a little knowledge is a dangerous thing is nowhere better illustrated than in the scientific phases of poultry feeding. The attempted application of the common theoretical feeding standards to poultry has caused not only a great waste of time but has also resulted in expenditures for high-priced feeds when cheaper feeds would have given as good or better results.
The so-called science of food chemistry is really a rough approximation of things about which the actual facts are unknown. Such knowledge bears the same relation to accurate science as the maps of America drawn by the early explorers do to a modern atlas. Like these early efforts of geography the present science of food chemistry is all right if we realize its incompleteness. In practice, the poultryman, after a general glance at the "map," will find a more reliable guide in simpler things.
I am writing this book for the poultryman, not the professor, and because I state that the particular kind of science wherein the professor has taken the most pains to teach the poultryman is comparatively useless, I fear it may arouse a mistrust of the value of science as a whole. I know of no way to prevent this except to point out the distinction between scientific facts and guesses couched in scientific language.
When a scientist states that a hen cannot lay egg shells containing calcium without having calcium in her food, that is a fact, and it works out in practice, for calcium is an element, and the hen cannot create elementary substances. When the same scientist, finding that an egg contains protein, says that wheat is a better egg food than corn because it has the largest amount of protein, that is a guess and does not work in practice because protein is not a definite substance, but the name of a group of substances of which the scientist does not know the composition, and which may or may not be of equal use to the hen in the formation of eggs.
All substances of which the world is made are composed of elements which cannot be changed. When these elements are combined they form definite substances with definite proportions entirely independent of the original elements. The pure diamond is carbon. Gasoline is carbon and hydrogen. Several hundred other things are also carbon and hydrogen. Sugar is carbon combined with hydrogen and oxygen. These three elements make several thousand different substances, including fats, alcohol and formaldehyde. Hydrocyanic acid is carbon combined with hydrogen and nitrogen, and is the most deadly poison known.
The failure of food science is partly because we do not know the composition of many of the substances of food and partly because these substances are changed in the animal body in a manner which we do not understand and cannot control.
Conventional Food Chemistry
The conventional analysis of feeding stuff divides the food substances in water, carbohydrates, fat, protein and ash. The amount of water in the body is all-important, but, with the exception of eggs during incubation, I confess I prefer to rely upon the chicken's judgment as to the amount required.
The carbohydrate group contains starch, sugar, cellulose and a number of other things. Carbohydrates constitute two-thirds to three-fourths of all common rations and nine-tenths of that amount is starch. The proposition of how much carbohydrates the hen eats is chiefly determined by the quantity of grain she consumes.
Of fats there are many kinds of which the composition is definitely known. The amount of fats the hen eats is unimportant because she makes starch into fat. The protein or nitrogen containing substances of the diet is the group of food substances over which most of the theories are expounded. The hen can make egg fat from corn starch or cabbage leaves because they contain the same elements. She cannot make egg white from starch or fat because the element of nitrogen which is in the egg white is lacking in the starch and fats.
The substances that have nitrogen in them are called protein. They are very complex and difficult to analyze. In digestion these proteins are all torn to pieces and built up into other kinds of protein. Just as in tearing down an old house, only a portion of the material can be used in a new house, so it is with protein and laboratory analysis cannot tell us how much of the old house can be utilized in building the new one.
In practice the whole subject simmers down to the proposition of finding out by direct experiment whether the hen will do the work best on this or that food, irregardless of its nitrogen content as determined in the laboratory.
The results of many experiments and much experience has shown that lean meat protein will make egg protein and chicken flesh protein and that vegetable protein pound for pound is not its equal. I know of no results that have proven that the high priced vegetable foods such as linseed meal, gluten feed, etc., have proven a more valuable chicken food than the cheapest grains.
With cows and pigeons this is not the case, but the hen is not a vegetarian by nature and high priced vegetable protein doesn't seem to be in her line. Of the three standard grains there is some indication of the value of the proteids for chickens and of the following ranks, 1st oats, 2d corn, 3d wheat.
The false conceptions of the value of wheat proteids has been specially the cause of much waste of money. Digestive trials and direct experiments both show that, as chicken foods, wheat is worth less, pound for pound, than corn and yet, though much higher in price, it is still used not only as a variety grain, but by many poultrymen as the chief article of diet. Wheat contains only 3 per cent. more proteid than corn. The man who substitutes wheat at one and one-half cents a pound for corn worth one cent a pound pays 17 cents a pound for his added protein. In beef scrap he could get the protein for 5 cents a pound and have a very superior article besides.
Milk as a source of protein ranks between the vegetable proteids and those of meat. It is preferably fed clabbered. The dried casein recently put on the market is a valuable food but is not worth as much as meat food and will not be extensively utilized until the demand for meat scrap forces up the price to a point where the casein can be sold more cheaply. Meat scrap, to be relished by the chickens, must not be a fine meal, but should consist of particles the size of wheat kernels or larger. The fine scrap gives the manufacturer a chance to utilize dried blood and tankage which is cheaper in quality and price than particles of real meat.
The last and least understood of the groups of food substances is mineral substance or ash. Now, the chemist determines mineral substance by burning the food and analyzing the residue. In the intense heat numerous chemical changes take place and the substances that come out of the furnace are entirely different from those contained in the fresh food.
The lay reader will probably ask why the chemist does not analyze the substances of the fresh material. The answer is that he doesn't know how. Progress is made every year but the whole subject is yet too much clouded in obscurity to be of any practical application. At present the feeding of mineral substance, like the feeding of protein, can best be learned by experimenting directly with the foods rather than by attempting to go by their chemical composition.
In practice it is found that green feed supplies something which grain lacks, presumably mineral salts. Moreover we know that such food fed fresh is superior to the same substance dried. This may be because of chemical changes that occur in curing or simply because of greater palatability.
The other chief source of mineral matter is meat preparations with or without ground bone. Recent experiments at Rhode Island have attempted to show the relative value of the mineral constituents of meat by adding bone ash to vegetable proteids, as linseed and gluten meal. The results clearly indicate that mineral matter of animal origin greatly improves the value of the vegetable diet, but that the latter is still sadly deficient. Of course the burning process used in preparing the bone ash may have destroyed some of the valuable qualities of the mineral salts. Practically, we do not care whether the value of animal meal be due to protein, mineral salts or both.
In time the world will become so thickly populated that we cannot afford to rear cattle and condemn a portion of the carcass to go through another life cycle before human consumption. By that time the necessary food salts will doubtless be known and we will be able to medicate our corn and alfalfa and do away with the beef scrap. The poultrymen will do well, however, not to count on the chemistry of the future, for the chemist that makes the "tissue salts" for the hen may manufacture human food with Niagara power and fresh eggs will come in tin cans.
How the Hen Unbalances Balanced Rations.
Let the poultryman who figures the nutritious ratio of chicken feed try this simple experiment. Place before a half dozen newly hatched chicks a feed of one of the commercial chick feeds. When they have had their fill, sacrifice these innocents on the altar of science and open their crops. He will find that one chick has eaten almost exclusively of millet seed, another has preferred cracked corn, another has filled up heavily on bits of beef scrap and mica crystal grit, while a fourth fancied oats and granulated bone. In short the chick has, in three minutes, unbalanced the balanced ration that it took a week to figure out. This experiment can be varied by placing hens in individual coops and setting before each weighed portions of every food in the poultryman supply man's catalogue.
There is only one kind of feeding that will balance rations and that is to feed exclusively on wet mash. This is successfully done in the duck business, but the duck is a Chinese animal and his ways are not the ways of the more fastidious hen.
In dairy work the individual preferences of the cows are given attention and their whimsy catered to by the herdsman. I know of nothing that makes a man more feel his kinship to the beast than to hear a good dairyman talk of the personalities and preferences of his feminine co-operators.
With commercial chicken work, humanly guided individual feedings is out of the question, though, if used, it might hasten the coming of the two-egg-per-day hen. Individual feeding with the hen as sole judge as to what she shall eat, which means each food in separate hoppers and free range, is the best system of chicken feeding yet evolved.
The duty of the poultryman is to supply the food, giving enough variety to permit of the hens having a fair selection. In practice this means that every hen must have access to water, grit (preferably oyster shell), one kind of grain, one kind of meat, and one kind of green food. In practice it will pay to add granulated bone for growing stock. One or two extra grains for variety and as many green foods as conveniences will permit to increase palatability—hence increase the amount of food consumed, for a heavy food consumption is necessary for egg production.
As corn is the cheapest food known, let it be the bread at the boarding house and other grains the rotating series of hash, beans and bacon. The grain hopper may have two divisions. The corn never changes but the other should have a change of grain occasionally. The extent of the use made of the various grains will be determined by their price per pound.
The proportions of food of the various classes that will be consumed is about as follows:
Of 100 lbs. of dry matter: 8 to 12 lbs. meat; 66 to 75 lbs. grain; 15 to 25 lbs. green food.
The profits of the business will be increased by supplying the green food in such tempting forms as to increase the amount consumed and cut down the use of grains.
The methods we have been describing in which various dry unground grains, beef scrap and oyster shell, each in a separate compartment, are exposed before the hen at all times, together with the abundant use of green food, either as pasture or a soiling crop, is the method of feeding assumed throughout this book.
The hopper feeding of so-called dry mash or ground grain mixture has been quite a fad in the last few years. The tendency of the hens to waste such food has occasioned considerable trouble. They are picking it over for their favorite foods and trying to avoid disagreeable foods. This difficulty is relieved when the food be separated into its various components and the hen offered each separately. As a matter of fact, there is no occasion for feeding ground feed except in fattening rations and here the wet mash is desirable.
The use of the products of wheat milling has been the chief excuse for such practices, but unless these get considerably lower in price per pound than corn they may be left off the bill-of-fare to advantage. The great use made of these products in poultry feeding was chiefly a result of the attempted application of the balanced ration idea, but as has already been shown the efforts to raise the protein ratio with grain foods is generally false economy.
The old-fashioned wet mash which the writer does not recommend because of the labor involved, is, nevertheless, a fairly profitable method of poultry feeding. It is used in the Little Compton district of Rhode Island and was also used in the famous Australian egg laying contests elsewhere described. Personally I would prefer feeding ground grain wet, especially wheat bran and middlings, to feeding it dry.
The scattering of grain in litter so generally recommended in poultry literature is all right and proper, but is rather out of place in commercial poultry farming. It is used on the large poultry plants with the yards and long houses, but is not used on colony farms or in any of the poultry growing communities. I should recommend littered houses for Section 6 and the northern half of Section 3 (see Chapter IV), but with warmer soils and climate where the snow does not lie on the ground it would add a labor expense that would very seriously handicap the business.
The systems of poultry feeding that are commonly advertised are based either on some patent nostrum or a recommendation of green food in novel form, such as sprouted oats. The joke about poultry feed at 10 cents a bushel, absurd though it may seem, has caught lots of dollars. To take a bushel of oats worth 50 cents, add water, let them sprout and have five bushels costing 10 cents, is certainly a wonderful achievement in wealth getting. The only reason a man couldn't run a soup kitchen on the same principle is that he can't do a soup business by mail. Sprouted oats are a good green food, however, though somewhat laborious to prepare. I should certainly recommend them if for any reason the regular green food supply should run out.
The points already mentioned are about all the practical suggestions that the science of animal nutrition has to offer the poultryman. The discussion of feeding from its technical viewpoint is sufficiently covered in the chapter on "Farm Poultry" and the discussion of the management and economics of various types of poultry production.