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United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
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Mechanisms Controlling The Formation And Persistence Of The Corpus Luteum, L. L. Anderson, R. M. Melampy
Mechanisms Controlling The Formation And Persistence Of The Corpus Luteum, L. L. Anderson, R. M. Melampy
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Mechanisms which control formation of corpora lutea during the estrous cycle, and particularly factors affecting their persistence and regression in various reproductive stages, have been of considerable interest to physiologists concerned with developing methods for control of the estrous cycle in domestic animals. Some recent reviews on control of ovarian function are those by Chester Jones and Ball (30), Anderson et al. (9) and Short (121).
Comments And Conclusions Concerning Studies On Estrous Control In Domestic Animals, H. H. Cole
Comments And Conclusions Concerning Studies On Estrous Control In Domestic Animals, H. H. Cole
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Let me allay at once any apprehension you may have that I am about to recapitulate all that has been said during the past two days. Redundancy at this time would merely accentuate your current soporific state. Thus I shall take advantage of the prerogative of seniority to modify the title of my talk to "Comments and conclusions concerning studies on estrous control in domestic animals."
The Lifespan Of Corpora Lutea Induced During The Luteal Phase Of The Estrous Cycle In Swine., B. N. Day
The Lifespan Of Corpora Lutea Induced During The Luteal Phase Of The Estrous Cycle In Swine., B. N. Day
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
A more complete understanding of the mechanisms involved in the function and maintenance of the corpus luteum would be very useful in developing more effective methods of controlling the estrous cycle in farm animals. Various types and classes of experimental animals have been utilized in an effort to define the factors causing the persistence of the corpus luteum. In swine, several different experimental approaches have been made in an attempt to extend, experimentally, the functional lifespan of the corpus luteum in non-pregnant animals. Less frequently, attempts have been made to induce premature regression. In general, the procedures used to induce …
Roles Of Hypothalamus And Hypophysis In The Control Of The Estrous Cycle, A. V. Nalbandov
Roles Of Hypothalamus And Hypophysis In The Control Of The Estrous Cycle, A. V. Nalbandov
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
The interrelation between the hypothalamus and the anterior pituitary gland has been firmly established. It is not the intention of this report to review the literature on this extensive subject. Such reviews are available in "Advances in Neuroendocrinology" (Nalbandov, 2), and since the time of this publication many papers on this subject have appeared in current journals. For the purposes of the present discussion a few fundamental facts will be restated, but the major part of my presentation will deal with my own views of the research areas which should be of special interest to animal scientists concerned with phenomena …
Hormonal Control Of Reproductive Activity In The Ewe, J. F. Wagner
Hormonal Control Of Reproductive Activity In The Ewe, J. F. Wagner
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
There are many advantages which result from synchronizing the estrous period in a ewe flock. In situations where the ewes are not hand bred to the ram, the synchronization of estrus makes the application of artificial insemination (AI) techniques more efficient. Detection of estrus usually is more reliable in a synchronized flock. Only 3 to 4 days are needed to detect estrus in 90 percent of a synchronized flock, whereas 16 to 18 days are normally required. This allows the AI technician to plan the number of breedings and have semen available. When hormones are given in the feed, an …
Some Side-Effects And After-Effects Of Experimental Endocrine Treatments Used To Modify The Natural Estrual Rhythm, L. E. Casida
Some Side-Effects And After-Effects Of Experimental Endocrine Treatments Used To Modify The Natural Estrual Rhythm, L. E. Casida
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
The side-effects and after-effects to be considered in this discussion are those which grow out of experimental attempts to modify the natural estrual rhythm, and which have a bearing on the subsequent fertility ofthe animal. They are the effects that at one-and-the-same- time are the despair and the hope of workers on technological control of reproduction. They are the despair in that they detract from our immediate ability to control reproduction; they are the hope in that we may be able to learn more about the reproductive process in our attempts to analyze and understand them.
Response Of Sheep And Swine To Treatments For Control Of Ovulation, P. J. Dziuk
Response Of Sheep And Swine To Treatments For Control Of Ovulation, P. J. Dziuk
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Control of the estrous cycle is essential to precise research in gamete and zygote physiology and could be useful in animal husbandry. The conception rate in sheep during the breeding season following treatments to control ovulation has varied from about normal (Dauzier, 4; Robinson, 20; Evans et al., 9; Lamond and Bindon, 17; Brunner et al., 3; Hinds et al., 15), to distressingly low levels in other cases (Braden et al., 2; Davies, 5; Lamond, 16). Treatments during the anestrous season have given a variable response but usually only 30 to 50 percent of ewes lamb (Gordon, 13; 14).
The Role Of Light In The Regulation Of Cyclical Estrous Activity In Sheep, M. T. Clegg, H. H. Cole, W. F. Ganong
The Role Of Light In The Regulation Of Cyclical Estrous Activity In Sheep, M. T. Clegg, H. H. Cole, W. F. Ganong
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
The widespread existence of biological clocks among animals is documented by a considerable body of evidence. Recently Farner (13) has reviewed this subject covering information on a large variety of animals. In this paper an attempt will be made to restrict most of the discussion to sheep. Experimental data from other species, however, will be cited when it can be usefully related to an understanding of the mechanisms controlling seasonal breeding activity in this species. As far as present knowledge is concerned, the factors regulating or at least monitoring annual physiologic cycles appear to depend greatly upon the influence of …
Factors Influencing The Regression Of Corpora Lutea In The Ewe, Rabbit And Rat, H. G. Spies
Factors Influencing The Regression Of Corpora Lutea In The Ewe, Rabbit And Rat, H. G. Spies
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Stages in the life of corpora lutea may be divided logically into formation, function and regression. Mechanisms controlling each stage may be independent or overlapping depending on the species. Anderson et al.,(4) have pointed to lack of current evidence to allow a clear distinction between luteinizing hormone (LH) and luteotropic hormone (LTH) in farm animals. Initial LTH release is probably sufficient to form and maintain the corpora lutea for the normal estrous cycle (Aldred et al., 1). Maintenance of corpora lutea for the normal duration of an estrous cycle in hypophysectomized ewes (Denamur and Mauleon, 6) and sows (du Mesnil …
Contents For Proceedings: Conference On Estrous Cycle Control In Domestic Animals, July 9-10, 1964
Contents For Proceedings: Conference On Estrous Cycle Control In Domestic Animals, July 9-10, 1964
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
This publication is a record of the papers presented at a conference on estrous cycle control in domestic animals, held July 10-14, 1964 at the University of Nebraska. Objectives of the conference were to review the status quo of research on this problem, to provide a forum for exchange of ideas and experiences, and to point up the direction of future research.
Evaluation Of Methods For Controlling The Estrous Cycle, William Hansel
Evaluation Of Methods For Controlling The Estrous Cycle, William Hansel
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Truly effective estrous cycle synchronization techniques are of great potential value to commercial producers of beef and dairy cattle, sheep, and swine. Many commercial beef cattlemen recognize the merits of using outstanding sires through artificial insemination (AI) to produce greater numbers of faster gaining cattle having the most desirable carcass characteristics. The relatively high heritability of feedlot gains makes this idea particularly attractive. Nevertheless, progress in attaining this goal has been rather slow, mainly because of the practical problems involved in breeding range cattle artificially and the low conception rates frequently obtained. Methods for cycle regulation compatible with the most …
Evaluation Of Some Methods For Controlling The Bovine Estrous Cycle, R. G. Zimbelman
Evaluation Of Some Methods For Controlling The Bovine Estrous Cycle, R. G. Zimbelman
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
This paper will deal primarily with the evaluation of various methods to control the estrous cycle in cattle. Consideration will be given to four methods of altering the normal estrual cycle. (A) The inhibition of ovulation as a means of altering the estrual cycle appears to be receiving most attention in recent years. The bulk of this paper will deal with ovulation inhibition by progestogens; thus, it would seem appropriate to give a brief evaluation of the other three methods.