J. B. LYON COMPANY, PRINTERS
1922
A STUDY OF SOME FACTORS INFLUENCING FERTILITY AND STERILITY IN THE BULL
HERBERT L. GILMAN
Veterinary Experiment Station, Cornell University
Normal reproduction is the fundamental foundation upon which the entire cattle industry rests. For this reason, any factor capable of interfering with it is a detriment to the industry, and a matter of prime importance to the breeder and the veterinarian. With the relative increase in number and value of cattle, and the fact that the profession is depending more and more on this industry for a livelihood, these problems are assuming greater importance. The part played by the bull has been emphasized entirely too little, with the result that, as in human medicine, many fail to appreciate the effects of sterility or lowered fertility in the male. The part played by the sire in the spread of genital infections, though discussed frequently, has received little systematic investigation.
The bull mast be regarded as at least half the herd, not only from the standpoint of the characters he imprints upon his progeny, but because of his relation to the reproductive efficiency in the herd. It seems quite probable that he does disseminate during copulation, infection associated with the genital organs, with the result that the bull is a very important factor in a study of the subject. Too frequently, his ability to copulate in an apparently normal manner, is taken as a standard of fertility. Gross changes in his genitalia, or the absence of spermatozoa from the semen are given due consideration, while other more obscure abnormalities are not looked for nor regarded in their proper light. Neither fertility nor sterility are always absolute, but the terms should be used relatively inasmuch as we may have all degrees of infertility or impotency. All too frequently we forget the many delicate and intricate mechanisms involved in the reproductive process, with the result that many phases of the problem are neglected or disregarded. The genital organs work as a unit, each part of which must function in perfect accord with the others to the end that full fertility may result. The physiological factors involved in the formation of the semen are too little understood, or at best, our knowledge regarding them is more or less hazy.
The purposes of the present work have been: (1) to summarize the work so far done on the subject, (2) to review briefly the known facts throwing light on the anatomy and physiology of the male genital organs, (3) to carry our systematic studies upon the pathology and bacteriology of the genital tract of the bull, and (4) to ascertain if possible whether the bull is a disseminator of those infections which interfere with reproduction in the female.
The work has been carried on for the most part from the point of view of a laboratory man cooperating with clinicians. No attempt is made in this paper to give detailed clinical data, methods for physical examinations, etc. There are included many statements and some data, given in a preliminary article on the subject. While the subject is broad in its scope, in fact too broad for great detail, it is hoped that a start has been made toward future and more detailed investigations.