A New Instrument for Artificial Insemination of Cattle Remarks on Physiologic Breeding Failure Alfred Kissileff, V.M.D. THE DEVELOPMENT of any new method or technic which is designed to displace an old, established one-especially in the field of animal husbandryis a slow and uncertain process. The instrument described in this paper was developed through many models before a satisfactory result was obtained. Work on it was begun in 1938; 4 by 1944 a plastic model which was made by hand was completed. It took 2 more years, however, to make a successful working model, and 5 more years until a sufficient number were tested and used long enough to determine whether or not it would be of practical value. During these years, since 1938, artificial insemination of dairy cattle had its inception in the United States and has expanded to include over four million cows at the present time. It may be conservatively estimated that artificial insemination is now a twenty-million-dollar business. While no one can predict just how widespread this practice will become, on the strength of its economic value alone it must continue to grow. Its advantages and conveniences have been widely discussed and enthusiastically supported by organized breeders throughout the world and whether they realize it or not, these breeders will come. to depend more and more upon artificial insemination to meet the constant demand for higher production at lower costs. Eventually they will find themselves in much the same position as the poultrymen, who, today, have no choice but to replenish their flocks with chicks from commercial hatcheries. And, as 149
150 KISSILEFF [Fertility & Sterility the poultry husbandman was faced with the new biologic problems presented by intensified domestication, so will the dairy husbandman be faced with similar problems. The lowered breeding efficiency which results when animals are taken from their natural environment and subjected to the artificial environment of domestication has always been a cause for concem 1 and though it is not yet a problem of alarming proportions to cattle breeders, unless proper steps are taken to overcome some of the causes it will become more serious in the future. As the cow population decreases, the value of the individual cow will increase, and breeding efficiency will, to a great extent, control the economy of every commercial herd. Since close confinement of herd bulls and artificial insemination represent just about the highest degree of domestication yet reached, some decline in the reproduction rate is inevitable. To prevent this decline, improvements in breeding management and technic and the introduction of new and better methods of artificial insemination are necessary. The device presented at this meeting was developed on the principle that it would help to offset, directly and indirectly, some of the causes of physiologic breeding failure and focus attention on the importance of timing the insemination, as well as on the preparation of the cow for breeding. The idea of reproduction of livestock by artificial methods is not new. It has attracted the attention of agriculturists as far back as the beginnings of recorded history. The Mediterranean breeds of fowl have been raised for hundreds of generations by artificial incubation and brooding, but not without a weakening of their normal reproductive powers. The egg -setting instinct in these breeds has become suppressed and the maternal instinct unreliable. During the last 50 years the artificial incubation of eggs has become a huge, almost completely mechanized industry, and the rooster and broody hen are no longer seen in the modem henhouse. This extreme degree of domestication was successfully accomplished only after careful and painstaking studies of natural incubation; it should be remembered that all the improvements in artificial incubation were inspired by observation of the setting hen. The early, primitive types of incubators depended upon artificial heat alone to hatch the eggs. After a low percentage of hatches indicated that other factors might be involved, more serious attention was paid to temperature controls, humidity, ventilation, cooling, turning, and the position of the egg itself. Each step in the improvement of these conditions brought
Vol. 4, No. 2, 1953] ARTIFICIAL INSEMINATION OF CATTLE 151 increased hatchability. This experience of the poultry industry is an outstanding example of the weakening of certain animal instincts which result from the effects of artificial conditions imposed by domestication, and the tendency toward a lowered reproductive vitality when unfavorable conditions are present. Under domestication certain instincts become suppressed while others become intensified. Since the condition of domestication cannot be avoided, it is necessary to overcome the unfavorable effects of artificial conditions by improvements or new artificial methods. 5 For example, it is well-known that certain types of hothouse plants require hand pollination because there are no insects to do it. The adverse effects of confinement must be offset by providing housing improvements, such as artificial heating, lighting and ventilation. Each artificial condition of environment created through domestication leads to adaptational changes in the domesticated subject, and these changes must be dealt with by the intelligent application of new and better methods of husbandry. The problem of physiologic breeding failure now faces the breeder of dairy cattle. It arises from the same basic causes discussed, and it must be solved by investigation of these causes. Present methods of artificial insemination achieve a conception rate which is said to compare favorably with that of natural breeding 7 as it is practiced on the average dairy farm with confined bulls, but it does not equal the efficiency of pasture breeding. There is some feeling that artificial insemination has been responsible for an increase in breeding failure, but so far this has not been demonstrated. It is argued that rather than an increase in the number of cases, there is simply an increase in the finding of cases because with artificial insemination more accurate records are kept and the physical operation of inseminating is more carefully supervised. Whichever thought is favored, the fact still remains that breeding failure is a major problem which demands our attention. At the American Veterinary Medical Association Convention in August a report 2 was made on studies of 104 non breeding cows in an artificial breeding association. Included among the factors found to be responsible for repeat breeding were a small number of abnormalities which interfered with conception; 40 per cent conceived but developed various conditions which destroyed the embryo, and 31 per cent just failed to conceive. The 31 per
152 KISS I LEFF [Fertility & Sterility cent which "just failed to conceive" is the group with which we should be immediately concerned. When so large a proportion of normal, healthy cows does not breed, the situation cannot be dismissed lightly. There is no logical reason why any healthy cow mated to an equally healthy bull should not conceive at the first breeding operation, but unfortunately the conception rate in dairy cows is nowhere near 100 per cent. An average of 60 per cent on the first service is considered good, whether with natural or artificial breeding. Before there is any prospect of improving this poor performance the breeder must recognize the fact that wasted services are costly and should be fully investigated. This applies to every wasted service and not just those wasted on the exceptionally difficult cows or those known to be diseased or sterile. A review of everyday methods and management of so-called natural breeding as it is practiced on the average dairy farm may be a good takingoff point for the revelation of some of the underlying causes of so many breeding failures. Mating habits of cattle are not often discussed in great detail in the lay press, and illustrations which could be highly instructive are rarely permitted the privilege of uncensored publication. Brief and carefullyworded descriptions must be used; any frank and open discussion of the subject invariably invites criticism. This reluctance to speak freely on a subject which is equal in scientific interest to feeding, milking, or the treatment of disease has hindered the proper education of livestock handlers so that they look upon the chore of servicing a cow as a job to get done with as quickly and surreptitiously as possible. The common practice is to imprison the herd bull in close quarters away from the female herd and treat him as a potentially dangerous criminal. Such treatment does not improve his disposition, and he eventually becomes too dangerous to handle. When a cow in pasture is discovered to be in heat she is immediately punished by removal from the herd and is locked in her stall. When the service is to be performed she is again restrained in a breeding stall or "rack" and the bull is permitted brief access to her. The mating is usually a crude and sudden form of assault which, although called natural breeding, bears only slight resemblance to the natural procedure as it would occur on the range or as it occurs in other species. Our knowledge of the mating habits of other animals does not recall any living creature in which copulation is not normally preceded by some form of courtship or at least
Vol. 4, No. 2, 1953] ARTIFICIAL INSEMINATION OF CATTLE 153 an interview. The purpose of these activities preliminary to the copulatory act is definite and necessary to prepare the female for fertilization; this should not be ignored. The accepted rule that reproduction in cattle requires only a transfer of semen to the oviduct must be liberalized so that more of the natural phenomena associated with and necessary to conception are not ignored. The physiologic purpose of bovine copulation is not limited to transfer of semen as its sole objective. Many other stimuli, common to all mature animals, play their respective parts in the complex mechanism of reproduction. The season of the year, the normal breeding cycle, preparation for fertilization, behavior preceding the copulatory phase and copulation, and probably many other influences all contribute to an intricate process, methodically planned and controlled by a fundamental biologic law solely directed to the purpose of reproduction. There is abundant evidence to support this contention. Many of the smaller animals, such as cats and rabbits, on which complete studies have been made, cannot ovulate without the stimulus of excitation and coition. Range-bred mares, where the stallion is free to mount them at will and at the optimum moment for fertilization to occur, conceive at a rate of better than 90 per cent, while hand-bred mares rarely do better than 50 per cent. 3 Pasture-bred cows, if healthy, conceive with surprising regularity, but cows bred to confined bulls frequently require two or more breedings over a period of several estrous cycles. The recent report of Marion and others 7 is a most important contribution to our knowledge of fertilization in the bovine. These investigators discovered that there is a significant relationship between service by a vasectomized (sterile) bull and the time required for ovulation to take place. The sterile service was found to shorten ovulation time, thus lending further proof to the contention that the function of copulation includes more than just semen transfer. There is no question that in many cases of breeding failure pathologic conditions are responsible, but there are probably just as many cases of breeding failure in which no pathologic conditions are found and in which none exist. In the absence of any pathologic condition or other interference, every service should accomplish successful fertilization; but we must admit that it doesn't. Among many domesticated animals the incidence of physiologic breeding failure increases with the degree of domestication, and it is not unreasonable
154 KISS IL E F F [Fertility & Sterility to attribute the success of natural breeding in wild animals to the freedom from interference and the presence of natural environmental conditions which permit all of the normal activities of mating to proceed in order. In unrestrained range cattle, a herd bull will unerringly select and pursue the cow that is ready for breeding. He will prepare her for fertilization by driving her for hours until she has reached the proper stage of excitement, and he will also attend to the cleansing of the external breeding organs. When all of these preparations are completed, the cow will be mounted repeatedly to stimulate ovulation and assure that fertilization will be accomplished. In contrast with this form of natural mating, we have service by a confined bull whose activities are restricted to a minimum. His function consists of mounting the cow without ceremony and lunging at her, often with questionable accuracy. The attendant, in order to further hasten the proceeding, usually pulls the cow's tail out of the way or helps to guide the excursion of the bull' s penis with his free hand. Before the cow has had sufficient time to recover from the surprise of the encounter, the bull is hustled back to his pen and the job is considered finished. The fact that a fair number of these services does result in conception is probably due to coincidence more than to sound breeding practice on a scientific level. Perhaps one of the reasons why the advent of artificial insemination has not, by itself, lowered conception rates is the difference in the preparation of the cow for the deposit of semen. The trained technician carefully washes and cleans the external genitalia of the cow beforehand, and the cow responds favorably to this stimulus, much the same as she responds to the washing of the udder prior to milking. If for no other reason than that the cow is favorably stimulated, there is great value afforded by it, since the cow is encouraged to be receptive to the insemination. Any breeding operation, whether natural or artificial, should respect the attitude of the cow to the extent that the experience should be acceptable to the cow. If it is not, the cow will make every effort within her power to resist and frustrate the purpose of the insemination. Future improvements in artificial insemination technic should be directed toward encouraging the cow to cooperate. The most logical approach in this direction is the development of a technic which more closely simulates natural impregnation. A technic which combines proper transfer and emplacement of the semen with the elicitation of a favorable response in the
Vol. 4, No. 2, 1953] ARTIFICIAL INSEMINATION OF CATTLE 155 cow should increase the chances of conception taking place, and is worthy of trial on a larger scale. The device presented here was constructed with this purpose in mind. The instrument consists of only three parts: a rubber barrel, an inseminating tube, and a semen bulb (Fig. 1). To operate, the semen is drawn up into the bulb, which fits snugly on the inseminating tube, and the tube is then fitted into the bore of the rubber barrel, completing the assembly 2 Fig. 1. Inseminator with tube and bulb removed. assembled for use. Fig. 2. Bovine inseminator ( Fig. 2). After carefully washing and cleaning the external parts of the cow to be inseminated, the instrument is inserted into the vaginal canal as far forward as it will go until strong resistance is met. At this point the tip of the inseminator is in close contact with the cervix and slight pressure on the bulb will deposit the semen at the entrance to the cervical canal. A cow in full heat is the best subject for the use of this instrument, for at this stage of heat the instrument may be easily inserted and the muscular action of the walls of the vagina will aid in directing it to the proper location. The device offers specific advantages which are not possible with technics now in common use. It is comparatively easy to operate and requires no extensive technical training; this makes it possible to perform insemination at the farm without outside help, in turn permitting timing of the insemination to be achieved with great accuracy. It eliminates certain undesirable features of current inseminating tech-
l 156 KISSILEFF [Fertility & Sterility nics, such as the intrusion of the rectum by the arm of the deep method operator 9 and the ballooning of the vagina which often occurs with the speculum method. 8 The hazard of broken glass in the vagina or cervix is completely eliminated. The instrument is of extremely simple construction and can be readily cleaned and sterilized. By more closely imitating natural service, its use is favored by the cow, who will stand quietly for the insemination. This is a decided improvement when compared with the struggle which attends the forcible entry of the rectum for the purpose of directing and inserting a slender catheter into the cervix, especially in heifers and in the beef breeds. The only disadvantage so far encountered is some mild opposition to its use because it threatens to some extent to displace methods which have been in use for more than a decade. This is a minor consideration, however, for there are many breeders whose farms are located too far from cooperative breeding centers to be convenient for the technicians. Making it possible for these remote farms to take advantage of artificial insemination benefits, which they are now denied, will increase the usefulness of many good bulls and afford opportunity for more widespread breed improvement. And this in the last analysis is the essential purpose of the artificial insemination program. SUMMARY Throughout the history of domestication of animals there are numerous examples of lowered reproductive powers paralleling the degree of domestication. With dairy cattle, breeding to confined bulls and artificial insemination are considered to be the highest degree of domestication yet reached. Servicing of cows by confined bulls, as practiced on the average dairy farm, is an abrupt departure from natural breeding since it does not permit free functioning of all the mating activities necessary to insure fertilization. The author believes that there is a strong relationship between physiologic breeding failure and the degree of domestication to which cattle are subjected. In order to prevent further decline in the reproductive rate from such causes, more attention should be paid to the proper preparation of the cow for fertilization, and insemination should be timed with the optimum receptive stage of the heat period. This can be accomplished by closer
Vol. 4, No. 2, 1953] ARTIFICIAL INSEMINATION OF CATTLE 157 observation of the normal mating habits of cattle and by improving artificial methods and conditions to simulate these habits more closely. A bovine inseminating device is presented which provides a closer imitation of natural service than present artificial methods and which offers a more simplified technic. Bethlehem Pike, Flourtown, Pennsylvania REFERENCES 1. DARWIN, C. Origin of Species. H. M. Caldwell Co., 1860. 2. DREHER, W. H. Proc. A.V.M.A. Convention, August 23, 1951. 3. DUKES, H. H. The Physiology of Domestic Animals. Comstock Publishing Co. Inc., 1947. 4. KISSILEFF, A. Aitificial insemination of dairy cattle in private practise. ].A.V.M.A. 96:309, 1940. 5. LIPPINCOTT, W. A. Poultry production. Lea & Febiger, 1916. 6. MARION, G. B. et al. The effect of sterile copulation on time of ovulation in dairy heifers. ]. Dairy Sc. 88:885, 1950. 7. PERRY, E. J. Artificial insemination of farm animals. Rutgers University Press, 1951. 8. RAPS, G. Relative effectiveness of two methods used in insemination of dairy cattle. North American Vet. 29:221, 1948. 9. SALISBURY, G. W., and VANDEMARK, N. L. The effect of cervical, uterine, and cornual insemination on fertility of the dairy cow. ]. Dairy Sc. 84:69, 1951.