Life Sciences Commons^™

G85-755 How To Set Goals For Your Breeding Program, Jeffrey F. Keown

University of Nebraska-Lincoln Extension: Historical Materials

This NebGuide describes how to determine which trait(s) to select for, and how multiple trait selection affects genetic progress.

Dairy producers are often concerned with placing emphasis on different production traits in their breeding program. Selecting on only economically important traits should be the objective of every producer. The use of artificial insemination (A.I.) sires is the most economical and productive way to increase the genetic potential of the herd.

A cow's record is a measure of her genetic potential, which is modified by the environment in which she is kept. Environmental factors that directly influence a cow's record include …

G85-759 Prominent Congenital Defects In Nebraska Beef Cattle, J. L. Johnson, H. W. Leipold, Donald B. Hudson

University of Nebraska-Lincoln Extension: Historical Materials

This NebGuide describes congenital defects that affect the economic value of beef cattle, and provides recommendations on how to minimize them in breeding programs.

Congenital defects are abnormalities of structure or function present at birth. They may be caused by genetic or environmental factors, or a combination of both. The causes of many defects remain unknown.

Developmental defects may be lethal, semi-lethal, or compatible with life, causing very little effect or only aesthetic effect.

With the increasing use of artificial insemination (AI) in cattle, defects are no longer rare occurrences and are important collectively to the cattle industry. Congenital defects …

The Effects Of Photoperiod And Melatonin Injections On The Reproductive System Of The Male Mongolian Gerbil (Meriones Unguiculatus), Luis Jose Cova Marchan

Master's Theses

This work was undertaken to study the effects of photoperiod and melatonin on fertility in male Mongolian gerbils (Meriones unguiculatus). Four groups of fifteen animals each, were placed in different photoperiods (ambient, ranging from 14L:10D to 11.3L:12.3D; 24L:10D; 14L:10D; and 1L:23D). After 35 days, three gerbils from each photoperiod condition were sacrificed and the testes, epididymides, seminal vesicles, prostate, kidneys, adrenals, thymus and hypophysis were weighed. The testes and epididymides were placed in Bouin's fixative and used for histological studies. Also, two males from each photoperiod condition were paired individually with a female. The remaining animals of each photoperiod condition …

Testicular Growth In Boars Of Different Genetic Lines And Its Relationship To Reproductive Performance , Allan Schinckel, R. K. Johnson, R. A. Pumfrey, Dwane R. Zimmerman

Department of Animal Science: Faculty Publications

Testicular growth of 377 boars was compared by obtaining in situ measurements of testes width and length and excised tissue weights. Two experiments involved a line selected nine generations for ovulation rate (OR) and a control line (CL), and two experiments contained boars of the OR line and two other lines; WL, a Large White-Landrace cross, and a line founded by crossing lines OR and CL and selected six generations for increased average daily gain and decreased backfat (LG line). In situ testes measurements were similar for the OR and CL lines and were curvilinearly related to age. The LG …

Environmental Psychology And Great Ape Reproduction, Terry L. Maple

Zoos and Aquariums Collection

At the 1980 Great Ape Infertility Workshop, we concluded that "physical and social environments must be improved if not optimized if great apes are to reproduce satisfactorily ... " In 1982, the trend toward improvement continues and there are some promising signs that reproduction has been enhanced as predicted. The problem of designing and evaluating captive environments which will facilitate interaction, reproduction, appropriate parenting, and socialization is well within the scope of Environmental Psychology. I intend to illustrate the promise of this applied research field in the remarks that follow.

Courtship And Reproduction In The Bali Mynah, Leucopsar Rothschildi (Aves : Sturnidae), Ann Patterson Marshall

University of the Pacific Theses and Dissertations

Reproductive behavior of captive Bali Mynahs (Leucopsar rothschildi) was studied at the Smithsonian Institution's Conservation and Research Center, Front Royal, Virginia. Courtship and copulation are followed by egg-laying, then incubation, hatching, brooding and feeding, fledging, and feeding. Parents become aggressive toward their young at the start of a new reproductive period, marked by a renewal of courtship.

The female does the majority of the incubation, brooding, and feeding of the young, although the male participates as well. The male performs both the bobbing· display and the crest display more than the female does. During these displays, the crest is prominently …

G81-574 Reproductive Diseases In Cattle, Duane Rice

University of Nebraska-Lincoln Extension: Historical Materials

The reproductive diseases mentioned in this NebGuide comprise some of the more common problems confronting the cattle industry today.

Although many advances have been made in controlling reproductive diseases in cattle, serious losses are still common. These losses can be reduced by recognizing the diseases and following the proper management recommendations that are available today. Nearly 50 percent of reproductive failure in cattle is due to infectious diseases, and there are vaccines available that can prevent some of these. Management recommendations may include: 1) vaccines, 2) general sanitation, 3) artificial insemination (AI) or, if a problem is already present, 4) …

The Effects Of Photoperiod And Melatonin Injections On The Reproductive System Of Male Mice, Mus Musculus, Icr Strain, Margaret Ann Shugart

Master's Theses

The reproductive effects of long (24L:OD), natural (14L:lOD), and short (1L:23D) photoperiods were studied in the male mouse, Mus musculus, ICR strain. One third of the mice in each photoperiodic regimen were sacrificed after 45 days. Half of the remaining mice in each regimen received daily melatonin (5-methoxy-N-acetyl tryptamine) injections for 45 additional days. Body weights, testicular and accessory sex organ weights were measured and microscopic examinations of the testes were made. Plasma testosterone levels were determined using radioimmunoassay. Other organ (pituitary, kidney, adrenal, thymus, thyroid) weights were also obtained.

The Relationships Between Plasma Progesterone And Lh And The Numbers Of Corpora Lutea And Embryos In Purebred And Crossbred Gilts, R. P. Wettemann, R. K. Johnson, I. T. Omtvedt

Department of Animal Science: Faculty Publications

Relationships between plasma progesterone and luteinizing hormone (LH) and the numbers of corpora lutea and embryos were determined in 133 8-month-old purebred Duroc, Hampshire and Yorkshire gilts and two-breed crosses among the three breeds. The numbers of corpora lutea and normal embryos were determined at slaughteronday 30.8 ± .2 of pregnancy, and progesterone and LH were quantified in plasma obtained the previous day. Progesterone concentrations in plasma were influenced by sire (P<.10), breed of dam (P<.05) and breed of sire x breed of dam (P<.05). Hampshire gilts had higher concentrations of progesterone in plasma than did Durocs (P<.05) and Yorkshires (P<.01). None of the effects in the model was significant for LH. Plasma progesterone and LH had heritability estimates of .48 ± .41 and .29 ± .40, respectively. Most genetic and phenotypic correlations of plasma progesterone and LH with other traits were small. These data indicate that progesterone concentrations in plasma at 30 days of pregnancy are not a satisfactory predictor of the numbers of corpora lutea and embryos. The differences in plasma progesterone between breeds illustrate the need to consider the breed of gilts when selecting animals for the study of luteal function or physiological factors that may influence progesterone concentrations in plasma.

G80-537 Reproductive Trace Anatomy And Physiology Of The Cow, Gene H. Deutscher

University of Nebraska-Lincoln Extension: Historical Materials

Knowledge of basic reproduction will help a producer to obtain higher conception rates when using estrous synchronization and/or artificial insemination. The reproductive performance of a cow herd has a great influence on the income and profit realized. A good understanding of the anatomy and physiology of the cow's reproductive system is, therefore, beneficial for successful management. Knowledge of basic reproduction will help a producer to obtain higher conception rates when using estrous synchronization and/or artificial insemination. It will also allow for a better understanding of pregnancy examinations, reproductive diseases and calving difficulty problems.

G80-536 Reproductive Trace Anatomy And Physiology Of The Bull, Gene H. Deutscher

University of Nebraska-Lincoln Extension: Historical Materials

Understanding the anatomy and physiology of the bull's reproductive tract is beneficial for proper management. Good reproductive performance of a bull is necessary to obtain a high percent calf crop. A bull must be fertile and capable of servicing a large number of cows during a short breeding season for optimum production. Understanding the anatomy and physiology of the bull's reproductive tract is beneficial for proper management. A basic knowledge of the reproductive system will also help the producer to understand fertility examinations, reproductive problems and breeding impairments.

Increased Lamb Production With Rams Exposed To Short Daylengths During The Nonbreeding Season, B. D. Schanbacher

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Exposure of rams during the nonbreeding season (anestrous period) to short daylengths will initiate a new sexual cycle characterized by testicular growth, increased mating activity and improved semen quality. Lambing results accumulated from 300 potential matings indicate that rams exposed to artificial photoperiods of 8 hr light and 16 hr darkness for 10 weeks (referred to as rams on short-days) are more fertile than control rams maintained under the relatively long days of spring. When five control rams were penned individually with 30 ewes synchronized with progestogen and PMSG, 67% of the ewes were mated. Eighty-nine percent of the ewes …

Observations On The Reproductive Morphology Of Some California Spionid Polychaetes, F. Scott Mceuen

University of the Pacific Theses and Dissertations

This study considers the morphology of the sperm, nephridia, seminal receptacles, and gonads among a number of California spionid species. The data collected provide support for the general observation of other workers.

Feeding Habits And Reproduction Of Three Sympatric Lizard Species From West-Central Utah, John B. Andre

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The feeding habits and reproduction of Uta stansburiana, Crotaphytus collaris and Cnemidophorus tigris during spring and summer 1976 are described. Feeding habits are expressed in percent total number and volume of prey items and frequency of occurrence of each prey category. Importance Values are also calculated. These values better illustrate the feeding habits of the lizard species than either percent total number and volume and frequency of prey category occurrence.

Lizards consume a variety of food items throughout the growing season. Hymenoptera, Coleoptera, Orthoptera and Arachnida are the major prey categories of U. stansburiana. The major prey categories …

Contributions To The Reproductive Biology And Natural History Of The Pirateperch, Aphredoderus Sayanus, Edward O. Murdy

Biological Sciences Theses & Dissertations

The purpose of this study was to describe the micro and macro-anatomy of the reproductive system and the testicular and ovarian development in Aphredoderus sayanus.

Specimens were collected at least once a month from September, 1976, through May, 1977, in Cypress Pond, a part of the Dismal Swamp drainage, outside of Suffolk, Virginia. Forty-three specimens had their gonads examined histologically, of these 13 were males, 29 were females and in one specimen the sex was not determinable.

Aphredoderus sayanus is a spring spawner, spent gonads were found on and after April 13, 1977. Gonads began to ripen in the …

An Analysis Of The Dependency Structure Between A Gilt's Prebreeding And Reproductive Traits. I. Phenotypic And Genetic Correlations, L. D. Young, R. K. Johnson, I. T. Omtvedt

Department of Animal Science: Faculty Publications

This study involved the records of 339 purebred Duroc, Hampshire and Yorkshire gilts and 192 two-breed cross gilts resulting from matings among the three breeds. The primary purpose of this paper was to investigate the relationship of prebreeding traits, including the growth of the gilt and her littermates, with subsequent measures of reproduction. Heritabilities were estimated for several traits and in general the estimates were somewhat higher than most estimates in the literature. Genetically, all measures of growth were favorably and moderately to highly correlated to ovulation rate, with the relationship being stronger for traits measured late in growth as …

An Analysis Of The Dependency Structure Between A Gilt's Prebreeding And Reproductive Traits. Ii. Principal Component Analysis, L. D. Young, R. K. Johnson, I. T. Omtvedt

Department of Animal Science: Faculty Publications

Seventeen variables measured before breeding and three measures of reproduction were taken on 339 purebred Duroc, Hampshire and Yorkshire gilts and 192 two-breed cross gilts resulting from matings among these breeds. Eight principal components accounted for 90% of the dependency structure existing among the 17 traits measured before breeding. Two principal components accounted for 97% of the dependency structure existing among the three reproductive traits.

The first principal component (PCll) from the prebreeding traits was a general measure of growth ability and accounted for 28% of the variation in the 17 measurements. The second principal component (PC12) contrasted slow growing …

Acute And Chronic Effects Of Gonadotropin Releasing Hormone On Reproductive Characteristics Of Rams During The Nonbreeding Season, B. D. Schanbacher, D. D. Lunstra

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Acute and chronic effects of gonadotropin releasing hormone (GnRH) administration on reproductive characteristics of 32 rams have been assessed during the nonbreeding season. Rams injected intramuscularly with 50 µg of GnRH had elevated (P<.01)concentrations of serum testosterone and noticeably higher (60%) mating activities when compared to control animals injected with saline. Daily injections of GnRH resulted not only in higher testosterone concentrations and mating activity, but also in increased testes size (P<.05). The apparent change in testicular function may account for the improvement in semen quality which was observed in these animals. Although benefits were only slight for percentages of live sperm, normal sperm and sperm with normal acrosomes, sperm motility was markedly increased (P<.05).

These data suggest that reproductive performance in rams is related to testicular androgen secretion and that a spring decline in those characteristics normally associated with high fertility in the male can be lessened by chronic treatment with GnRH.

Localization Of Neurosecretory Cells Within The Cerebral Ganglia Of Amphiphorus Imparispinosus Griffin, 1898 (Hoplonemertea) And Their Possible Regulatory Role In The Annual Reproductive Cycle, Gail H. Jacobson

Dissertations and Theses

Nemerteans are common invertebrates along coastlines in both temperate and arctic climates throughout the world. Amphiphorus imparispinosus is a carnivorous member of this phylum that is found abundantly in the intertidal areas of the Oregon coast. As in many other invertebrate phyla, endocrine integration within the nemerteans is thought to be accomplished by neurosecretory mechanisms. In Amphiphorus the presence of these neurosecretory systems has not been previously shown. This project was undertaken to determine if neurosecretory cells are present within the central nervous system of this species and. further, to examine seasonal changes in the number and appearance of these …

Reproductive Performance Of Swine Bred To Produce Purebred And Two-Breed Cross Litters, L. D. Young, R. K. Johnson, I. T. Omtvedt

Department of Animal Science: Faculty Publications

These data included the records of 818 purebred gilts and sows of Duroc, Hampshire and Yorkshire breeding mated to produce all purebreds and all possible two-way crosses. A total of 212 gilts were slaughtered 30-day postbreeding (72 purebred matings and 140 crossbred matings) to evaluate ovulation rate, number of live embryos, average embryo length and embryo survival rate. A total of 450 litters (161 purebred and 289 crossbred) were farrowed to evaluate litter size, litter weight and average pig weight at O, 21 and 42 days postfarrowing. Litters were farrowed in the spring and fall of 1971 and 1973 and …

The Effect Of Photoperiod On The Regressive Phase Of The Ovarian Cycle Of The Lizard, Anolis Carolinensis., John Dickens Pinch

Master's Theses

The effects of constant photoperiod (14 hours of light) and decreasing photoperiod (13-8 hours of light) on the regressive phase of the ovarian cycle of the lizard Anolis carolinensis were investigated. Changes in body, liver, ovary and oviduct weights were measured and microscopic examinations of several ovarian parameters were made. In both light regimens body and liver weights decreased over the first four weeks of the experiment but both increased at the sixth week. In addition, ovary weight was highly variable but exhibited a decreasing trend and oviduct weight decreased. There were decreases in the number of previtellogonic follicles and …

Reproduction By Adfluvial Salmonids In Spawn Creek, Cache County, Utah, David R. Bernard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The migration and production of indigenous populations of brown, brook, and cutthroat trouts in Spawn Creek, Cache County, Utah, were studied in 1973 and 1974 to elucidate the role of this stream vis-a-vis the rest of the watershed. Spawn Creek and its watershed were described climatically, hydrologically, geologically, vegetatively, recreationally, and chemically. The prevalent, aquatic taxa of fauna and flora were also listed. The equipment and techniques used in the study to collect data, including a two-way fish trap and electro-fishing gear, were delineated. The collected data consisted of periodic estimates of mean weight and density stratified by year classes. …

Reproductive Parameters For Nine Avian Species At Moore Creek, Merritt Island National Wildlife Refuge, G. Tanner Girard

Retrospective Theses and Dissertations

No abstract provided.

Reproduction And Hematology Of The Cache Elk Herd, Thomas B. Follis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The initial three years of a 10-year reproductive study of elk involved three major phases. A fourth was added because of convenience. Objective 1 was to ascertain pregnancy rates in yearling and mature elk by rectal palpation, associate these rates with subsequent fall cow/calf ratios, and to test concurrently an ultrasonic fetal heart detector. Rectally observed anatomical changes in gravid uteri of cattle were directly applicable to elk. Ultrasonic detections of pregnancies in elk and deer were unsuccessful.

Pregnancy rates in the 1969-70 winter of 100 and 0 percent, respectively, for 19 adult and five yearling elk were associated with …

Influence Of Size Of Cone Crop On Diameter Growth Of Engelmann Spruce (Picea Engelmannii Parry), Herbert Hager

T.W. "Doc" Daniel Experimental Forest

The influence of the average annual cone crop of 170 Engelmann spruce trees on the average basal area increments over a period of 23 years was tested in climatically compensated and uncompensated multiple regression models. In addition, three outstanding cone producing trees were analyzed with the climate compensating model. The cone production of the individual trees were analyzed for the effect on each basal area increment without climatic compensation. A multiple regression model with bimonthly climatic parameters for the growing season, yielded the best prediction (R2 = 98%) of annual basal area increment from the independent parameters among which was …

Asexual Reproduction In Planaria Characteristics Of The Inhibitor(S), Linda Gail Sheffield

Theses and Dissertations

A study was made of the postulated fission-inhibiting substance located in the cephalic region of Dugesia dorotocephala. Rearing decapitated planaria in four different concentrations (25, 50, 75 or 100 ug/ml) of head or whole body extract resulted in a positive correlation between the inhibition of fission rate and the concentration of extract. The difference in inhibitory activity between the two types of extracts was three percent at maximum. The inhibitory substance was partially inactivated at 60° C. There was a direct correlation between the length of time that the extract was heated and the inactivation of inhibitor. The active substance …

Asexual Reproduction In Planaria Studies On Inhibition, Hal R. Fitzgerald

Theses and Dissertations

The invertebrates display several methods of asexual reproduction, such as fission and gemnule formation and budding (Hay, 1966). Planaria reproduce asexually only by fission.

Reproductive Biology Of Thais Emarginata (Deshayes, 1839) And Thais Canaliculata (Dulcos, 1832), Roy Seamands Houston

University of the Pacific Theses and Dissertations

Thais emarginata (Deshayes, 1839) and Thais canaliculata (Dulcos, 1832), are two common Pacific coast gastropods (Family: Muricidae). T. emarginata is found in semi-protected rocky areas from Alaska to Baja California, while T. canaliaulata occurs in quiet bays from Alaska to Monterey Bay, California (Ricketts and Calvin, 1966). Both species occur on rocks and jetties where they can be seen feeding upon barnacles and young mussels. Despite the abundance of these species their reproductive biology has not been examined.

In the present study, the following aspects of the reproductive biology of T. emarginata and T. canalieulata are presented: Relationship of gonadal …

The Effect Of Cattle, Sheep, And Other Factors On Aspen (Populus Tremuloides) Reproduction After Clear-Cut Logging In Southern Utah, Paul A. Lucas

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Aspen is the most widespread deciduous tree of the western United States and the aspen type is important for water, forage, and wood products. Aspen reproduction on cutover areas was thought to be hindered by browsing and other factors, therefore a study was conducted to determine the effects of livestock, pocket gophers, disease, and snowpack damage on aspen reproduction during the first three years after clear-cutting. An enclosure was constructed and divided into nine paddocks. Controlled grazing by cattle and sheep was applied to six different paddocks during three summer periods. Three paddocks were protected from grazing. Results show that …

Reproduction In The Wolverine, Gulo Gulo, Philip L. Wright, Robert L. Rausch

Harold W. Manter Laboratory of Parasitology: Faculty and Staff Publications

The reproductive habits of the wolverine, largest of the terrestrial mustelids, have remained largely unknown. Recently Rausch (1953) has concluded that the American and European wolverines belong to the same species (Gulo gulo). In this paper, the reproduction of this species is investigated.