Studies in horse breeding

Introduction

In a former edition it was my purpose to so prepare the text that it would enlist the interest of the farmerbreeder and stallion owner. I had in mind only these two classes of men at that time, while in this edition it has been my purpose to interest the student as well.

As before, I have left nothing undone to make brevity a striking feature of the text, yet at the same time I have endeavored to tell the story of the horse from a simple elemental cell, until we find him in a mature form. As before, I have aimed to give "The most possible, in the smallest possible space," without sacrificing any of the vital facts bearing upon the .subject. The nature of this? work has made necessary the use of many technical terms, but in all cases the word more commonly employed to express the same thing has been given, making the text easy of understanding by either student or breeder. Every paragraph discussing a subject of general interest has been given a number for the purpose of reference, and these numbers are frequently referred to throughout the text. This will add some to the value of the work as one of reference.

No apologies are ottered for the frequent reference to the draft horse. No one has a higher appreciation of the warm bred horse than the writer, yet the fact remains that the draft horse is the horse of, and for, the American farm. He can be produced as easily and cheaply as a steer, and will sell for three or four times as much. Then again, while I have made a few experiments with light horses in breeding, nearly all my work has been carried on with draft horses. It is largely my own experience and the statistics gathered and compiled by myself that I am recording — I have spent much time and a large sum of money in such work, more I believe than has ever been spent in such work by all others in this country put together. One has only to consider some of the data collected to have this made clear.

The chief object of this work has been to help in improving the horses of this country, and to be the means, in a measure at least, of employing better means in their production. That our methods have been wasteful throughout all the years of the past, is a fact well known to all breeders. There are now bred annually in this country 2,500.000 mares with no foals resulting. At $80 for each foal this means a loss of $200,000,000 annually to the horse breeders of the United States. The barren mare problem is no longer a national problem ; it is now an international one — Belgium, Canada, France, Great Britain, and other countries are having their troubles as well as ourselves. The world's loss annually as a result of barren mares is enough to bankrupt a strong government. The figures are startling. They far exceed $1,000,000,000 annually. Can an intelligent and progressive people afford to permit such a loss?

In spite of this wasteful method no industry connected with the soil, or carried on in connection with the farms of this country, has yielded so liberal returns for the labor and money employed as the breeding of good horses.

No live stock bred upon the famis of the United States has increased in value so rapidly as horses and mules. In 1869 the value of all horses and mules owned in the United States was $469,000,000. In 1899 the same live stock was valued at $607,000,000. In 1910 the value of this same live stock has reached the enormous sum of $2,500,000,000.

Although the breeding- of horses and mules is now one of our most profitable industries, yet little has ever been done in a public way to encourage it, by either the Federal or State Governments, or to aid the farmer and breeder in adopting more intelligent means of producing them. Bulletins without number upon other subjects of much less importance have been annually forthcoming, yet nothing upon that of producing better horses, or of employing more economical and intelligent means in their production.

The same is true of individual help in the way of breeding horses. No embryologist has ever made a special study of the horse. There are reasons for this. The great Teutonic race has given to the world its most eminent embryologists. In the Teuton's native land, even more than elsewhere, horses have always represented too much value to be sacrificed for such purposes. Mares dying and which could be had for investigation of this kind were usually barren because of old age. So far as the horse is concerned, how the ovaries perform their various functions; how, when and where fertilization takes place ; or of the early development of the fetus and fetal membranes, nothing is really known.

Our colleges and our professional men when regarded as a whole are many years behind the times in work of this kind. Even the farmer breeder iu many instances has passed them in progressive work and investigations of interest to the breeder. Our colleges from the beginning of time have been teaching that widely differing species or genera could not be crossed, and yet Luther Burbank has crossed the blackberry and apple; deciduous and citric fruits; hard woods with soft woods, and scores of other equally radical crosses. The same will yet prove possible with the crossing of our domestic animals. It will probably require a thousand failures to make one success, but it will be done. Within ten years all our text books upon such subjects will have to be changed.

AVhile the horse breeding business as a whole has been very profitable for many years, yet one branch of it, that of handling stallions for service, has been conducted at a loss. Several forces have been at work which are responsible for this condition. A want of a proper knowledge of the business, and a tainted live stock press are the two best known of these forces. It has been the policy of many of our farm and live stock journals to so boom the business of their advertisers that it has filled the country with small, cheap and unsound stallions to the great injury of the industry. This same press has taken advantage of every influence they could bring to bear in defeating all legislation compelling the use of sound stallions only.

The world's most urgent need today, is for more men with special training to carry on its great work. In its last and best analysis the business of breeding horses does not differ from that of any other — only those best fitted, best equipped for the business shall survive. No rapid progress in producing better horses need be expected until more intelligent means be employed in producing them.

Then again, 1 believe one is justified in appealing to the civic pride of the country, which is more or less developed in all mankind, upon the question of producing better horses. I have observed that throughout all the rural world, the best and highest type of citizenship is always to be found in the districts of the best bred stock. To improve the live stock of a country is a potent means of raising the standard of its citizenship. The production of high-class animals calls into activity intelligence of the highest order.

No country is better fitted by reason of its climate ; its nutritious grasses ; its abundance of grain ; its pure water; and the high intelliience of its breeders in the production of high-class horses, than a large part of the United States. No better evidence of this is needed than the fact that in nearly all the breeds we have produced many individuals imsurpassed in any country, and what can be done by a few breeders can be done by others.

The most encouraging feature of the coming improvement in the horse breeding industry, is the kindly and courteous interest shown by the breeders of this and other coimtries in my investigations. I am under many obligations to veterinarians throughout all parts of the country for their many words and acts of encouragement. They are awakening to the fact that before a horse can be treated, he must be produced. In this connection I wish to acknowledge my appreciation of the help extended to the horse breeding industry, by the Kansas City Veterinary College. Never before in the history of such eclueation in this country has a professional body of men done so much to help a great industry. The same appreciation is due the editor of the Stallion and Jack News, of Kansas City, Mo. It requires a large fund of both moral courage and enterprise to embark in a neAv and untried field of endeavor. This journal is devoted exclusively to the production of the best in horses and mules, and has taken a high position in advocating better methods, and the practice of higher business ethics in their production.

The country is awakening as never before to the importance of the horse breeding industry to the best life of the country, and is appreciating as never before the need of educational aid in that direction.

G. L. CARLSON.

Norfolk, Nebr., Sept. 1, 1910.

Chapter I. The Sexual Product Of The Stallion

1. The Beginning of a New Life. In all animals the beginning of a new life can take place only when the reproductive elements of the two sexes are properly nnited. Under natural conditions this is done by the procreative act, or sexual union of the two sexes. These reproductive elements are known as spermatozoa and egg-cells, or ova, the former being the product of the stallion, while the latter are the product of the mare.

2. The Sexual Organs of the Stallion. The origin of the reproductive elements of the stallion will require some study of the genital organs, shown in figure 1. Only the essential organs of reproduction will be described in this work, which consists of the testicles, the vasa efferentia, the epididymis, the vasa deferentia (vas deferens), and the vesiculae seminales (seminal vesicles).

3. The Testicles. The origin of the reproductive element is in the testicles. These organs are suspended in a pouch between the thighs, which is known as the scrotum. This is a single sac enclosing both testicles. Immediately under the scrotum one finds the dartos, a thin laver of elastic tissue. The dartos is a dependency

THE SEXUAL PRODUCT OF THE STALLION from the abdominal structure, and forming two cavities, with H doubh' partition between them, througli

Figure 1. The genital organs of the stallion, shown from the right side. 1, right testicle; 2, 3, vas deferens; 4, seminal vesicle; 5, prostate gland; 6, urethra; 7, Cowper's glands; 9, fold of peritoneum; 10, vessels and nerves of left testicle cut off; 11, Abdominal ring; 12, bladder.

which the penis passes. The cremaster is a muscle forming a partial covering for the testicle, and the

STTDIKS IN HORSE I5REF.DIXG tunica vaginalis is the serous covering of this organ.

Strictly speaking the testicle proper is enclosed with a fibrous capsule, the tunica albuginea. This fibrous tissue is extended into the substance of the testicle, dividing the organ into separate lobules. In each lobule are found many seminal tubules, commencing in a highly convoluted portion, but ending in a straight tube, and piercing the tunica albuginea at the anterior extremity of the testicle. These seminal tubules con-

Figure 2. The testicle of the stallion with other organs, dissected of their serous covering. 1, testicle; 2, glands in which are found the spermatoblast cells; 3, vasa efferentia; 4, epididymis; 5, vas aberrans; 6, vas deferens; 7, spermatic artery.

sist of several layers of cells, known as the spermatoblast cells, which form spermatozoa. See figure 2.

4. The Vasa Efferentia and Epididymis. The vasa efferentia are but the continuation of the seminal tubules which have now pierced the tunica albuginea and they in turn terminate in the globus major of the epididymis. No part of the genital organs of the stallion show such a variation in individuals as the epididymis.

THE SEXUAL PKODUC'T OF THE S TALLIOX 13

Never have I found two stallions the same in this particular. In some stallions we find the head, or globus major, some three inches in diameter, and suddenly terminatino: into a small tube, or globus minor. In others we find a large convoluted canal of even size throughout its length, and I am inclined to the belief

Figure 3. The bladder and seminal vesicles dissected of their serous covering. 1, bladder; 2, 2, vas deferens; 3, 3, seminal vesicles; 4, prostate gland; 5, ureter; 6, urethra.

that the latter form is found in the case of the most virile stallions.

5. The Vasa Deferentia. These are the excretory ducts of the testicles, each tube having the thickness of a small pencil. The semen is thus carried from the epididymis to the upper face of the bladder, terminating in a short constricted portion, under the prostate, into the ejaculatory duct.

6. The Vesiculae Seminales. The seminal vesicles are the two oval bodies placed between the bladder below and the rectum above. They are the chief depositories for the storage of semen. Here under normal conditions of all the bodily functions, semen may be stored for months. Shown in figure 3.

Figure 4. Spermatozoa shown in two positions, and showing flattened form of head. 1, head; 2, middle piece; 3, tail.

7. The Ejaculatory Ducts. These are two short tubes formed beneath the prostate gland by the junction of the vas deferens and the neck of the seminal vesicle, whore the duct soon opens into the urethra.

8. Spermatic Cord. The testicle is suspended by means of the spermatic cord, and blood is supplied by the spermatic artery.

9. The Penis. AVith this organ, which is the stallion's organ of copulation, may be concluded the chief

THE SEXUAL PBODUCT OF THE STALLION 15

organs of reproduction. The penis consists of erectile tissue and is divided into two portions, the one permanent as to place, the other free. The free portion is suspended in a sling known as prepuce, which is a sheath covered by a skin possessing an extremely fine texture and smooth surface. The anterior extremity of the penis consists of an enlargement, the glans penis. The blood is supplied by the external and inter-

Figure 5. Spermatozoa of the stallion. (Sketched.)

nal pudic and obturator arteries. The nerve supply is by the internal pudic and sympathetic nerves, the most sensitive in the nervous system of the horse. It is because of the very sensitive nature of this portion of the penis, that injury so often results from the use of breeding bags. The same injury to this organ may result from sudden and forced blows, such as kicks, or striking the end of the penis with any foreign object.

STUDIES IN HORSE liREEUIXQ

Injury of a serious nature has been known to follow forced copulation.

10. The Urethra. This is properly a part of the penis, and is a long membranous tube or canal extending from the neck of the bladder to the glans penis. It is common to both generative and urinary systems.

Figure 6. Spermatozoa of the stallion, showing the wider and thicker form as a result of using stains. This figure also shows the large corpuscles frequently found in the seminal fluid of some stallions.

The commencement of the urethra is very constricted, but the membranous portion is more dilated.

11. Spermatozoa. It has already been shown (3) that the i-ei)foductive elements, or spermatozoa, nave their origin in the testicles, yet a mature spermatozoon, or one capable of showing any other than a rotary

THE SEXUAL PRODUCT OF THE STALLIOX motion, has never been found in the testicles of a stallion. It requires the same process of maturation to develop spermatozoa, as we find in the case of the egg of the mare. Motion is observed as soon as the spermatozoa reach the vasa efferentia, but it is still rotary.

Figure 7. Seminal eoi-puscles found in the semen of all stallions. This figure also represents the semen of a sterile stallion in which no spermatozoa are present.

Greater activity will be observed as they reach the epididymis, and more active yet when found in the vas deferens. Evidence of full maturity is wanting, however, until they reach the seminal vesicles.

The best test one can make of the full maturity of spermatozoa, is in experiments with external fertilization. The egg of the mare has no attraction for any spermatozoa found before reaching the seminal vesicles. Here one finds them as capable of fertilizing the egg, as are those secured by copulation.

12. The Discovery of Spermatozoa. The discovery of spermatozoa in the seminal fluid of the males, and later that a spermatozoon is but a cell containing the

Figure 8. nifled.

A spermatozoon of the stallion greatly mag fundament or primary structure of a future being, has been of far reaching importance to the study of embryology. During the eighteenth century, and even up to the middle of the nineteenth, there was a wide diversity of opinion among the most eminent scientists upon this subject. In fact very little was really known. Spermatozoa were first discovered by a German student in the year 1677.

THE SEXUAL PRODUCT OF THE STALLION

13. Ovists and Animalculists. One school of physiologists held to the opinion that it was the egg that supplied the germ or cell from which the future being had its origin. They were called ovists. After the discovery of spermatozoa another school of theorists came into existence, who were of the opinion that the spermatozoa were provided with all the organs of the developed animals. They were called animalculists. Then there were those who held to the evolution theory of development, and others who believed in the performation theory. Each of these schools and theories had the support of some of the master minds of that time. It remained for C. F. Wolff, in 1759, to give to the world the relative importance of the sexes in the process of fertizilation, and that the germ becomes organized only in consequence of fertilization.

14. Spermatozoa Organized. The early anatomists and physiologists were almost a unit in the belief that spermatozoa were organized. Later investigators were as well agreed in the theory of unorganized germinal matter. Better optical instruments have during the past twenty-five years established the organized cell theory of the present time. This theory is not that the sperm cell of the stallion is organized in the sense of a fully developed horse, but only in the sense that the primary or elemental organs are present. No one has been able to state the fact with more force than Hertwig, when he said, "If the organ is not present, that which mak-^s it is."

15. Description of Spermatozoa. The spermatozoa of mammals are the smallest elementary parts of the body. They are developed in great numbers in the

THE SEXUAL PROIHTCT OF THE STALLION 21

seminal fluid of the stallion, Init can be seen in it only by bringing to our aid the use of high magnification. A good penetrating eye can observe them with a magnification of 100 diameters. The best success I have ever had in photo-micro-graphic work is by using from 240 to 280 diameters. A magnification of 500 diameters will show the width of the head at about one-sixteenth of an inch and the entire length at one and one-half inches. A spermatozoon consists of three parts, head, tail and a middle portion. By far the greatest width is found in the head, which in shape is oval, slightly excavated on both surfaces, and much thinner at the anterior end. Viewed from the side it has much the appearance of a wedge, as shown in figure 4. Chemical reactions show the head to consist of nuclear substance.

The tail, which is composed of protoplasm, is a long, contractile appendage, and capable of executing serpentine motions, by means of which the spermatozoa can move forward in the seminal fluid with great velocity, relatively greater than the fully developed horse. The head and tail are united by a short middle piece, which is about one-fifth of the entire length of the spermatozoon. On the whole there is not the diversity of form found in the spermatozoa of the many species of mammals, that characterizes the egg-cell of the same species.

16. Relative Size of Spermatozoa, In twenty-seven years of investigation, I have never found two spermatozoa of the same size, even in the same discharge, when measured with the photo-micograph. The size of the stallion has little to do with the size of the spermatozoa. They are always relatively larger in small stallions than in large ones. The spermatozoa discharged by an imported Shetland stallion weighing 350 pounds, were about one-half the size of those from a Shire stallion weighing 2,250 pounds, the Shire being nearly seven times as large as the pony. The spermatozoa of Shire stallions are slightly larger than those of any other breed. ,

17. Photographing Spermatozoa. A gelatinous substance incloses spermatozoa in all their parts, and which is distinct from the surrounding fluid. If treated with chemical reagents of a mild alkaline nature, this inclosing substance takes up stains with avidity, giving the spermatozoa a wider and thicker appearance than when not so treated. Even by this process a part of the tail is lost, also giving the spermatozoa a shorter appearance than should be given them. This can be better understood by comparing figure 5 with figure 6. The former shows spermatozoa as they appear to the eye without the aid of reagents, while the latter shows them as photographed with the aid of reagents. In the use of stains, whenever it is chemically possible, red is to be preferred to blue, as the former will take black, while the latter always takes white.

18. The Seminal Fluid. The semen of the stallion consists in addition to the spermatozoa of a homogenous fluid — the liquor seminus — in which we observe minute rounded corpuscles, or seminal granules. These are found in the semen of all stallions both virile and sterile. These vary greatly as to size and numbers in the semen of different stallions, and in some stallions we find two kinds of these corpuscles, differing widely in size. In some instances a magnification of 200 diam-

THE SEXUAL PRODUCT OF THE STALLION 23

eters will disclose small clusters of corpuscles of varying shapes, and from tAVO to a dozen corpuscles in a cluster, and appearing sufficiently large with that magnification to be accurately counted. These take up stains quite readily. Figure 6 shows clusters of these larger corpuscles. If this same semen is placed under a higher magnification the smaller corpuscles common to all semen will be disclosed as shown in figure 7. These smaller corpuscles are about 1-2000 of an inch in diameter, and do not readily yield to chemical reagents.

19. The Development of Spermatozoa. The development of spermatozoa clearly demonstrates that they are really metamorphosed cells, and that each spermatozoon is developed out of a single seminal cell. The development of a spermatozoon offers the investigator many interesting surprises. We have already observed (11) that a considerable time is required in maturing or developing a spermatozoon and we have likewise observed (11) that a mature spermatozoon possesses a head, a tail and a middle portion. Of these three portions the flat and wedge-like head is developed from the nucleus, and the caudal appendage out of the protoplasm.

In the earliest stage of development at which the sperm cell can be recognized, only a bell shaped cell f.an be observed. This grows out into an elongated cone, the base of which becomes the point of attach-- ment for the middle piece. This cone now develops into a still more elongated cone and narrowed into a rod shaped structure. At this stage of development a retrogression is seen to take place, so far as form or shape js concerned, until finally it assumes the form of a mature spermatozoon. The progression and retrogression of these changes are well illustrated in figure 9.

The fundament of the middle portion first makes its appearance at the time the nucleus begins to elongate. It is first observed at the base of the nucleus in the form of a small oval and in a short time from it the tail appears.

From the above we learn that a spermatozoon passes through a process of development, not unlike that of the development of the fetus. At first there is but a single seminal cell out of which is developed the head. From the head is formed the middle piece, and finally the tail from the protoplasm.

20. Number of Spermatozoa in One Discharge. The number of spermatozoa in one discharge of a stallion is from 10,000 to 75,000, depending upon the sexual vigor of the stallion and the frequency of service. A virile stallion making but one service a day will discharge from 50,000 to 75,000 of them at each service. The amount of fluid discharged at each service of a stallion is from four to twelve ounces. The less frequent the service, the larger the amount of fluid, and the higher the number of spermatozoa. If stallions are made to do service too often, the semen will not contain mature spermatozoa.

21. Jacks. In the service of jacks one does not find as much fluid as in the service of stallions, nor does this fluid contain as many spermatozoa. Some virile jacks do not discharge more than an ounce of fluid, and very few of them more than three ounces. This makes

THE SEXITAI, PRODUCT OF THE STALLIOX 25

breeding by the capsule method more difficult than when using stallions to make the necessary service. The spermatozoa of jacks are not as tenacious of life as those of stallions. Scientifically speaking, no jack is as certain of impregnating mares, as a virile stallion. This is particularly true when mated with mares, since the production of hybrids is never as certain in the case of all animal life, as when the mating is of one kind. There is a widely distributed belief to the contrary, but it is an erroneous one. Because of their temperamental difference, jacks make a more complete service than stallions ; that is to say they deposit the semen in the uterus more often than stallions. This better service would result in a larger number of foals, even with a lower vitality of the spermatozoa.

22. Vitality and Power of Resistance of Spermatozoa. The life force of spiM'matozoa depends much upon the sexual vigor of the stallion from whence they came. In the case of the horse they have been known to retain their vitality for thirty days after having been introduced into the sexual passages of the mare. In dissecting a mare that had been killed at a railroad crossing twenty-seven days after she had been bred, I found thousands of live spermatozoa attached to the membranes of the vagina, uterus and also in the intestinal cavity. In this case the mare had been pregnant for about three weeks. I have kept the spermatozoa of the horse under artificial conditio7is for fifteen days. At the end of this time I found every spermatozoon active. However, I made many failures before I succeeded in doing this. To succeed in keeping spermatozoa alive for any considerable time one must keep them from

(MHiiitiii' ill <'t>iit;ict with both air and lii^lit, and a iionnal tempei-aturc is an absolntc ncct'ssity. They may be fro/.on and k('|)t I'or niontlis, wlicn tliey will show activity npoii bcini; thawed ont, yet lil'e soon eeases uiuler sneh eondilions. The bottle or tnbe in which they are to be kept iiinst be sterilized in boiling water before beino- used. If kept in jar, bottle oi- culture tube, these nuist l)e black so as to exclude all lii^ht. IMy success in this came as a result of fillini^' and sealing a small black bottle from the vagina of a mare that had just been served by a stalli(ui. b]\periments which 1 made in testing the longevity of spermatozoon life with regard to color I'l'sulted in i-ed being next below black, then yellow, green, blu(> and white.

23. Power of Resistance as Compared with the Egg. Both the dui-ation of life and the power of resistance are much greater in the spei-matozoa of the stallion thau in the egg of the mare. This is made necessary because of the egg being non-motive. In no other way could fertilization be accomjilished. A great division of labor has arisen between the two, since each has adapted itself to a ditferent mission. The non-mobile egg nuist be united with the mobile spermatozoon,which requires not only the migratory character of the latter, but a far greater duration of life as well. The egg-cell is very sensitive to all external infiuences, and is easily destroyed by influences having no etfcct upon the life of the spermatozoon. A normal salt solution, that is such a solution of about seven-tiMiths of one per cent, greatly stimulates the activity of spermatozoa, as do many weak solutions of an alkaline character, while

Chapter II. The Sexual Product Of The Mare

24. Receptacle for Life Germ. Some place in which to be is as indispensable a condition of material existence as magnitnde or form. Nothing can be, without being somewhere. The life germ, the product of the stallion, must have some place in which to develop all its delicate organs. It requires both protection and warmth, as well as nourishment. This receptacle must be something which can receive and hold that seminal fluid in which it is floated from stallion to mare. Nature has very wisely provided the uterus of the mare for this important work. But this is not all, for in addition the mare's nature in a measure must be incorporated in with its organic structure. This leads one up to the study of the mare; to the part she plays in the reproduction of her kind ; to her sexual product.