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Full-Text Articles in Life Sciences

Effects Of Adrenergic Or A Combination Of Adrenergic And Opioid Drugs On Assessments Of Insulin Sensitivity In Mares, Lauren Kerrigan Aug 2019

Effects Of Adrenergic Or A Combination Of Adrenergic And Opioid Drugs On Assessments Of Insulin Sensitivity In Mares, Lauren Kerrigan

LSU Master's Theses

Excitement is a problem when conducting endocrine tests on fractious horses. Epinephrine (EPI), for example, was shown to obliterate the insulin-induced decrease in blood glucose concentrations. Sedation may be a solution; however, perturbation of results may preclude useful information. The objectives of the four experiments presented herein were 1) to determine the effects of EPI on insulin response to glucose infusion (IR2G), 2) to assess the effects of the α-adrenergic sedative, detomidine (DET), alone or in combination with the opioid agonist, butorphanol (BUT), on IR2G and glucose response to insulin (GR2I), and 3) to assess the effects of BUT alone ...


The Impact Of Equine-Assisted Activities And Therapy (Eaat) On Depression, Annalisa Brandt Jan 2019

The Impact Of Equine-Assisted Activities And Therapy (Eaat) On Depression, Annalisa Brandt

Creative Components

Equine-Assisted Activities and Therapy (EAAT) encompasses a variety of therapeutic techniques involving horses, and it is used by health professionals to treat physical, mental, or emotional disorders. Recently, EAAT has been utilized in cases of depression, a serious health concern that can lead to significant decreases in health and overall quality of life. It is predicted that EAAT would alleviate symptoms of depression, and the purpose of this review is to analyze research to determine if EAAT is an appropriate treatment option for depression. Four studies were found that directly measured levels of depression in association with EAAT treatment. The ...


The Old Versus The New Equestrian Circus: Demonstrating And Promoting Equine Welfare, Veronica Painter Jul 2018

The Old Versus The New Equestrian Circus: Demonstrating And Promoting Equine Welfare, Veronica Painter

Theses and Dissertations

Circus is an art form that was originally considered as a humanitarian art, promoting equine welfare by shedding a new light on the horse and human relationship. During a time where horses were used for war, work, and transportation; fancy riding and liberty stood as the framework for a new togetherness between man and beast. The animal activist revolution centered on exotic animals in circus, yet the effects of these demanding pressures caused a major blow to the equestrian circus. This comparative study examines possible improvements to the industry in order to keep this art alive. Keeping up with eclectic ...


Characterization And Evaluation Of Androgen-Binding Protein, Sex Hormone-Binding Globulin, And Thyroxine-Binding Globulin In The Horse, Blaire O'Neil Fleming Jan 2018

Characterization And Evaluation Of Androgen-Binding Protein, Sex Hormone-Binding Globulin, And Thyroxine-Binding Globulin In The Horse, Blaire O'Neil Fleming

Theses and Dissertations--Veterinary Science

The objectives of this study are to characterize two carrier proteins in the horse that significantly decrease in humans following anabolic androgenic steroid administration: sex hormone-binding globulin (SHBG) and thyroxine-binding globulin (TBG). For SHBG characterization, qPCR, RNA sequencing, and immunohistochemistry were performed on testes and equine livers. Free and total testosterone immunoassays were utilized to confirm the presence of a carrier protein in equine circulation. SHBG was detected in the testes using qPCR, RNA sequencing, and IHC, indicating the presence of the isoform androgen-binding protein (ABP). SHBG was not detected in any liver samples. Evidence of a carrier protein was ...


Effects Of Endophyte-Infected Tall Fescue Seed And Bromocriptine On Endocrine And Immune Function In Horses, Jessica Marie Hanneman Jan 2018

Effects Of Endophyte-Infected Tall Fescue Seed And Bromocriptine On Endocrine And Immune Function In Horses, Jessica Marie Hanneman

Theses and Dissertations--Veterinary Science

Consumption of endophyte-infected (E+) grasses has long been associated with health problems in animals. In cattle E+ tall fescue consumption leads to fescue toxicosis, and in horses it leads reproductive problems. The health-related issues associated with endophyte consumption have been attributed to the effects caused by the ergot alkaloids produced by the fungus. These ergot alkaloids are considered D2-like receptor agonists, and 5-HT2 serotonin and α-adrenergic receptor partial agonists. Many studies in humans, swine, cattle, and horses have identified that ergopeptines cause a decrease in prolactin production due to their dopaminergic activities. Additionally, these molecules have been found to cause ...


Whole-Body Protein Metabolism In Mature And Growing Horses Receiving Predominantly Forage Diets, Sophie A. Stratton Jan 2018

Whole-Body Protein Metabolism In Mature And Growing Horses Receiving Predominantly Forage Diets, Sophie A. Stratton

Theses and Dissertations--Animal and Food Sciences

There has been limited investigation as to whether a predominantly forage-based diet can provide adequate amounts of limiting amino acids (AA) to horses. The first objective was to determine if AA supplementation of AA believed to be limiting to protein synthesis in forage-based diets would affect measures of whole-body protein metabolism in sedentary mature horses. The effect of forage type (timothy or alfalfa) and AA supplementation (lysine, threonine or histidine) on plasma urea nitrogen (PUN) and AA concentrations and measures of whole-body phenylalanine kinetics were evaluated. There was no effect of either forage type or AA supplement on rates of ...


The Impact Of Insulin Dysregulation On Protein Metabolism In Horses, Caroline Margot Marcelle Loos Jan 2018

The Impact Of Insulin Dysregulation On Protein Metabolism In Horses, Caroline Margot Marcelle Loos

Theses and Dissertations--Animal and Food Sciences

Insulin plays a vital role in whole-body metabolism and provides a major anabolic stimulus for cellular signaling pathways, including those involved in the metabolism of glucose and protein. Consequently, insulin dysregulation (ID) is known to alter molecular signal transduction in insulin-sensitive tissues such as skeletal muscle, thereby disrupting glucose metabolism and compromising protein synthetic capacity. Our first objective was to induce ID in healthy horses by administering dexamethasone (DEX), a potent glucocorticoid, for 21 days. We evaluated the effects on insulin-stimulated muscle protein signaling components involved in the mammalian target of rapamycin (mTOR) pathway. DEX-induced ID reduced insulin-stimulated activation of ...


Applications In Utilization Of Forage Chemical Composition And Predicting Equine Digestibility, Veronica Taylor Bill Jan 2018

Applications In Utilization Of Forage Chemical Composition And Predicting Equine Digestibility, Veronica Taylor Bill

Theses and Dissertations--Animal and Food Sciences

Most forage quality models were developed for ruminant nutrition, and may not apply to the horse. This two-part study evaluated the relationship between forage chemical composition and dry matter digestibility (DMD) using an in vitro method with equine feces as the inoculums. The first experiment determined that compared to 48 h of incubation, 72 h of incubation resulted in higher DMD for some forages. As a result of experiment 1, incubations in experiment 2 were conducted using 48 and 72 h incubation periods at 38 degrees C. The second experiment evaluated the effect of chemical composition on DMD. Thirty-one hay ...


Lymphocyte-Mediated Inflamm-Aging In The Horse, Melissa Hope Siard Jan 2017

Lymphocyte-Mediated Inflamm-Aging In The Horse, Melissa Hope Siard

Theses and Dissertations--Veterinary Science

Senior horses (≥20 years) exhibit inflamm-aging, or chronic, low-grade inflammation that occurs systemically with aging, similarly to humans. Inflamm-aging has previously been characterized in the horse in circulation as well as specifically being mediated by lymphocytes and monocytes. In humans, inflamm-aging has been associated with increased morbidity and mortality. However, in the horse, relatively little about inflamm-aging is known regarding clinical effects or factors influencing severity. The contribution of lymphocytes to inflamm-aging of senior horses was examined, specifically through determining the relationships of inflamm-aging with various other health parameters, effects of seasonality, and the extent to which inflamm-aging can be ...


Effects Of Equine Assisted Activities And Therapies On Equine Stress And Welfare, Sarah Jean Reega Jan 2017

Effects Of Equine Assisted Activities And Therapies On Equine Stress And Welfare, Sarah Jean Reega

Honors Theses and Capstones

Equine assisted activities and therapies (EAATs) are becoming an increasingly popular approach for therapy, therapeutic recreation, and learning for a broad range of human clients and participants. In the EAAT field, most research has been human-centric, focusing primarily on benefits of EAATs for participants and clients. Relatively little research has been conducted on the effects of EAATs on equine stress and welfare for equines engaged in EAAT sessions.

The effects of equine assisted activities and therapies on equine stress and welfare were studied by way of exploring current EAAT professionals’ experiences and views related to equine stress and welfare in ...


Towards Determination Of The Threonine Requirement Of Yearling Horses Fed Varying Dietary Compositions Using The Indicator Amino Acid Oxidation Method, Kelsey M. Smith Jan 2016

Towards Determination Of The Threonine Requirement Of Yearling Horses Fed Varying Dietary Compositions Using The Indicator Amino Acid Oxidation Method, Kelsey M. Smith

Theses and Dissertations--Animal and Food Sciences

The amino acid requirements of growing horses are currently unknown, and studies suggest that threonine is a limiting amino acid in common horse diets. Thus, the objective of this study was to determine the threonine requirement of growing horses fed two different forage to concentrate ratios using the indicator amino acid oxidation method. The study consisted of a high concentrate phase (HC; 60% concentrate and 40% forage) and a high forage phase (HF; 25% concentrate and 75% forage). Within each phase, 6 female yearling Thoroughbred horses were randomly assigned each of 6 dietary treatments in a 6 x 6 Latin ...


Digestibility Of Two Complete Pelleted Diets By The Horse (Equus Caballus) As A Model Animal For Nondomestic Hindgut Fermenters, Emily M. Schwartz Dec 2015

Digestibility Of Two Complete Pelleted Diets By The Horse (Equus Caballus) As A Model Animal For Nondomestic Hindgut Fermenters, Emily M. Schwartz

Master's Theses and Project Reports

Estimating nutrient and energy requirements of exotic animals is a necessary component of nutrition management in zoos and other wildlife facilities. In the absence of species-specific data, domestic animal models are often referenced. Herbivorous hindgut fermenters, such as horses, zebra, and rhinoceros, rely on microbial fermentation in the cecum and colon to utilize dietary structural carbohydrates. The study objective was to measure the digestible energy of two (LOW, HIGH) complete pelleted diets by the horse as a model for nondomestic hindgut fermenters. Seven, individually housed, adult Quarter Horse (Equus caballus) geldings were assigned to one of two diets as 100 ...


Use Of Genomic Tools To Discover The Cause Of Champagne Dilution Coat Color In Horses And To Map The Genetic Cause Of Extreme Lordosis In American Saddlebred Horses, Deborah G. Cook Jan 2014

Use Of Genomic Tools To Discover The Cause Of Champagne Dilution Coat Color In Horses And To Map The Genetic Cause Of Extreme Lordosis In American Saddlebred Horses, Deborah G. Cook

Theses and Dissertations--Veterinary Science

Champagne dilution of coat color in horses is caused by dominant gene action. Three sire families were identified as segregating for this trait. Genome wide linkage analysis using 104 microsatellite DNA markers was used to map the gene to ECA14 (LOD > 11.0). Four genes, namely SPARC, SLC36A1, SLC36A2 and SLC36A3, were selected from the region implicated by linkage and their exons sequenced. DNA sequences were compared for two homozygotes for Champagne dilution, two heterozygotes and two horses without dilution. A single base change in exon 2 of SLC36A1 was found unique to horses exhibiting Champagne dilution. This change in ...


Design, Construction And Cost Analysis Of Manufacturing Horse Bits, Erica L. Timmermans Jun 2013

Design, Construction And Cost Analysis Of Manufacturing Horse Bits, Erica L. Timmermans

BioResource and Agricultural Engineering

This report discusses the design, fabrication and cost analysis of two unique horse bits. On the market today, there are many different kinds of bits to serve a multitude of purposes. However, this project explored the option of having two different shanks types made of stainless steel in addition to three mouthpieces that are able to fit in both types of shanks.


The Effect Of Rider Level On Equine Mean Heart Rate At The Trot, Jacqueline Marinoff Apr 2013

The Effect Of Rider Level On Equine Mean Heart Rate At The Trot, Jacqueline Marinoff

Honors Theses and Capstones

The effect of riders at two different levels of riding ability on the mean heart rates (HR) of school horses at the trot was studied. Five horses were each paired with a beginner (n=4) and an intermediate (n=5) rider, and the mean HR generated by the two riders at the trot were compared for each horse. There was a significant (p


Detection Of Antibodies Against Parascaris Equorum Excretory-Secretory Antigens, Steffanie V. Burk Jan 2013

Detection Of Antibodies Against Parascaris Equorum Excretory-Secretory Antigens, Steffanie V. Burk

Theses and Dissertations--Animal and Food Sciences

Parascaris equorum is a nematode parasite that infects young horses, sometimes causing unthriftiness, respiratory signs, or intestinal impaction in severe cases. Infection can be diagnosed by detection of eggs in feces, but this is only possible after the worms are fully mature. The goal of this study was to develop an antibody-based test for prepatent diagnosis of P. equorum infection. To produce western blot (WB) antigen, P. equorum larvae were cultured for collection of excretory-secretory antigens (ESA). Sera from 18 pregnant broodmares, their subsequent foals, and a group of 12 older mares and geldings were analyzed. In order to check ...


The Effect Of Pituitary Pars Intermedia Dysfunction On Protein Metabolism And Insulin Sensitivity In Aged Horses, Laurel M. Mastro Jan 2013

The Effect Of Pituitary Pars Intermedia Dysfunction On Protein Metabolism And Insulin Sensitivity In Aged Horses, Laurel M. Mastro

Theses and Dissertations--Animal and Food Sciences

Equine pituitary pars intermedia dysfunction (PPID) typically occurs in horses older than 15 years of age and is characterized by hair coat abnormalities, muscle atrophy and decreased insulin sensitivity. The first objective of this research was to compare the rate of whole body protein metabolism and relative abundance of key factors in the signaling pathways associated with muscle protein synthesis and protein breakdown in response to feeding in Control and PPID horses. No differences (P > 0.05) were seen between the PPID and Control groups in whole-body protein metabolism or post-prandial activation of the muscle signaling pathways regulating skeletal muscle ...


Factors Affecting Basal And Post-Exercise Prolactin Secretion In Horses, Lisa C. Digiovanni Jan 2013

Factors Affecting Basal And Post-Exercise Prolactin Secretion In Horses, Lisa C. Digiovanni

LSU Master's Theses

There has been thorough documentation to support the role of dopamine in the control of prolactin production and secretion in various mammalian species, including the horse. However, there is evidence that other factors are involved in prolactin secretion. Seven experiments were conducted to assess factors that potentially might affect prolactin secretion in the horse. The first two experiments were conducted (separately) to test whether arginine vasopressin (AVP) or vasoactive intestinal polypeptide (VIP) affected prolactin secretion. In each experiment, AVP or VIP was administered intravenously and blood samples were collected to determine the effect on prolactin secretion. Neither peptide produced any ...


Insulin Dose Response Curves And Factors Affecting Insulin Sensitivity In Horses, Jeanne D. Lestelle Jan 2012

Insulin Dose Response Curves And Factors Affecting Insulin Sensitivity In Horses, Jeanne D. Lestelle

LSU Master's Theses

Three experiments were conducted to further study the use of intravenous insulin injection to measure insulin sensitivity in horses. In the first experiment, glucose responses to multiple doses of recombinant human insulin were compared in insulin sensitive and insensitive mares. Regression lines describing the responses in insensitive mares had less (P = 0.003) steep slopes and greater (P = 0.006) effective doses at 50% response (ED50) compared to sensitive mares. Curvilinear regression models provided a good fit (R2 = 0.95) for the prediction of ED50 from the individual responses to 50 mU/kg BW insulin. The second experiment estimated the ...


Repeatability Of Prolactin Responses To Sulpiride In Mares And Geldings And The Effect Of Pergolide And Cabergoline, Rebekah C. Hebert Jan 2012

Repeatability Of Prolactin Responses To Sulpiride In Mares And Geldings And The Effect Of Pergolide And Cabergoline, Rebekah C. Hebert

LSU Master's Theses

Four experiments were conducted in an effort to develop a method, based on prolactin secretion, for assessing the efficacy and duration of activity of dopaminergic agonists for the treatment of pituitary pars intermedia dysfunction (PPID) in horses. In the first experiment, prolactin response to a low dose of the dopamine antagonist, sulpiride, was generally repeatable in estrogen-primed geldings in winter over 8 every-other-day challenges. It was concluded that estrogen-primed, sulpiride-challenged geldings in winter could serve as a model for the study of potential dopaminergic drugs for the treatment of PPID in horses. The second experiment was performed in the summer ...


Effects Of Dietary Supplementation Of Conjugated Linoleic Acid In Horses, Shannon Headley Dec 2011

Effects Of Dietary Supplementation Of Conjugated Linoleic Acid In Horses, Shannon Headley

All Theses

Conjugated linoleic acid (CLA) reduces inflammation via the inhibition of cyclooxygenase II , thus reducing prostaglandin E2 (PGE2) production. Conjugated linoleic acid has a suggested osteoclast-suppressive role in bone remodeling and osteoarthritis, which are dependent on bone resorptive stimulator PGE2. Bone resorption marker, deoxypyridinoline (DPD), and bone formation marker, bone alkaline phosphatase (BAP), have been modulated by CLA supplementation in other species. Recent research in equine exercise physiology investigated dietary supplementation of polyunsaturated fatty acids as a possible prevention and treatment for osteoarthritis, but CLA supplementation has putative effects on skeletal function or inflammation in horses has not been reported. Our ...


Factors Affecting Skeletal Muscle Protein Synthesis In The Horse, Ashley Leigh Wagner Jan 2011

Factors Affecting Skeletal Muscle Protein Synthesis In The Horse, Ashley Leigh Wagner

Theses and Dissertations--Animal and Food Sciences

Skeletal muscle protein synthesis is regulated by the mammalian target of rapamycin (mTOR) signaling pathway. The first objective was to optimize the methodological procedures for assessing mTOR signaling in horses. The response of mTOR signaling (P-Akt Ser473, P-S6K1 Thr389, P-rpS6 Ser235/26 & 240/244, and P-4EBP1 Thr37/46 by Western blotting techniques) to meal consumption was determined at three gluteal muscle biopsy depths (6, 8, and 10 cm), and the repeatability of the contralateral side at 8 cm during 5 days of repeated biopsies. There was no effect (P > 0.05) of sampling side or biopsy ...


Development And Permeability Of Equine Blastocysts, Brittany Reshel Scott Jan 2011

Development And Permeability Of Equine Blastocysts, Brittany Reshel Scott

LSU Master's Theses

Equine embryo cryopreservation is unsuccessful in larger, more easily collected, day-7 embryos. It is imperative that methods to successfully cryopreserve large equine embryos or develop reliable methods to determine embryo size before collection. Therefore the objectives for this study were to quantify the amount of tritiated glycerol that would permeate various sizes of equine embryos and to determine if circulating progesterone concentration was correlated with in utero embryo size. Mean embryo diameter (± SEM) across treatments (1.4M and 3.4M tritiated glycerol) was 696.5µm ± 108.6µm and 925.9 µm ± 214.1µm, respectively and were not different (P=0 ...


Diagnosis And Management Of Horses With Equine Metabolic Syndrome (Ems), Kelly Ann Chameroy Dec 2010

Diagnosis And Management Of Horses With Equine Metabolic Syndrome (Ems), Kelly Ann Chameroy

Doctoral Dissertations

In horses, a painful and often debilitating disease known as laminitis can result in impaired function and, in severe cases, euthanasia. Equine Metabolic Syndrome (EMS) is a syndrome in horses that results in development of laminitis and is characterized by the presence of general and/or regional adiposity (“cresty neck”), aberrations in blood lipid concentrations, insulin resistance (IR) and/ or hyperinsulinemia. Therapies have focused on improving the state of obesity and insulin resistance with the goal of diminishing the likelihood of laminitis development. A definitive cause for laminitis has not been established, but hyperinsulinemia and IR are likely candidates as ...


The Internal Hoof Morphology Of The Pl, P2, And P3 Bones In Equine, Heather Caldwell Apr 2009

The Internal Hoof Morphology Of The Pl, P2, And P3 Bones In Equine, Heather Caldwell

Life and Environmental Sciences Undergraduate Theses

The purpose of this study was to investigate the P3 pedal angle of the feet of healthy equine exhibiting no P3 bone rotation in comparison to equine with corrective shoeing or apparent P3 bone rotation or laminitis. The internal pedal bones of 51 equine were radiographed, digitally photographed, and scanned into the EponaTech program. The overall internal pedal anatomy of the Pl, P2, P3, and navicular bone was compared between all 51 equine. Seven landmarks were used in assessment: angle of the palmer surface of P3, hoof wall to coffin bone length, dorsal hoof wall depth, length of the bottom ...


Equine Obesity-Related Hyperleptinemia, Nan Killen Huff Jan 2007

Equine Obesity-Related Hyperleptinemia, Nan Killen Huff

LSU Doctoral Dissertations

Plasma leptin concentrations in obese adult horses have been shown to vary widely, and horses tend to fit into two groups: low leptin (<10 ng/mL) and hyperleptinemic (10 to 50 ng/mL). Observations over time revealed that the hyperleptinemic condition was consistent, possibly indicating a relatively permanent underlying cause. Based on these observations, three experimental approaches were used to further study equine obesity-related hyperleptinemia. The first experiment determined the prevalence of hyperleptinemia among postpartum, lactating mares, evaluated its consequence on their re-breeding success, and investigated correlations between leptin levels in lactating and non-lactating mares. Postpartum mares (n = 198) and non-foaling mares (n = 31) were categorized based on their leptin status: normoleptinemic or hyperleptinemic. Leptin in the lactating mares averaged 4.8 ng/mL, and 11 of the 198 (13%) displayed hyperleptinemia. Leptin in the non-lactating mares averaged 7.5 ng/mL, with 9 mares (29%) displaying hyperleptinemia. Of the 198 lactating mares bred, 81% became pregnant; there was no effect of leptin status on re-breeding success. To study one possible cause for hyperleptinemia in well-fed horses, a second experiment explored polymorphism(s) within exon 2 of the equine leptin gene. The DNA from five hyperleptinemic and five normal mares of high body condition was used to analyze exon 2 of the leptin gene for polymorphisms. Based on the 10 mares tested, there was no polymorphism in exon 2 of the equine leptin gene; therefore, polymorphism is not a likely explanation for the high vs. low leptin difference. The third experiment explored the possible effects of hyperleptinemia on the endocrine and immune systems. Endotoxin was given to mares and geldings to investigate the role and/or regulation of leptin in the pro-inflammatory cytokine response. Of the endpoints measured, only platelet count differed between normal and hyperleptinemic horses. Endotoxin infusion caused the expected pro-inflammatory cytokine and endocrine responses, but leptin status was not a significant factor for any endpoint. It is concluded that hyperleptinemia in mares is not associated with polymorphism in exon 2 of the leptin gene, does not affect re-breeding rates of foaling mares, and does not alter the endotoxin-induced responses of the endocrine and immune systems.


Evaluation Of A Plasmid Delivery System For Production Of Gnrh And Ghrh In The Horse And Goat, William Andrew Storer Jan 2006

Evaluation Of A Plasmid Delivery System For Production Of Gnrh And Ghrh In The Horse And Goat, William Andrew Storer

LSU Doctoral Dissertations

The efficacy of a novel plasmid delivery system was assessed for long-term expression of gonadotropin releasing hormone (GnRH) and growth hormone releasing hormone (GHRH) in horses and goats. The efficacy of the technology was demonstrated using 3 novel plasmids: pSEAP [expressing secreted embryonic alkaline phosphatase (SEAP)], pGHRH (expressing GHRH), and pGnRH (expressing GnRH). Geldings were electroporated with a reporter plasmid expressing SEAP in 3 muscle sites. Expression of SEAP, measured from jugular plasma samples, indicated muscle specificity for uptake and expression of the plasmid. Concentrations of SEAP were greatest (P < 0.05) after pectoralis injection, which was chosen as the site for electroporation in subsequent studies. In a second experiment, stallions were electroporated with pGHRH or pSEAP to evaluate the effect of long-term GHRH treatment on the growth hormone (GH) axis and testicular function. Stallions treated with pGHRH had increased (P < 0.05) plasma concentrations of IGF-I, increased (P < 0.05) volume of accessory sex gland fluid, and increased (P < 0.05) number of normal spermatozoa in the ejaculate relative to controls. In the third experiment, stallions were electroporated with pGnRH or pSEAP to test the effects of GnRH on the reproductive axis. Treatment with pGnRH increased (P < 0.05) plasma testosterone concentrations to d 56 and increased (P < 0.01) the LH response to GnRH on d 21, but did not alter (P > 0.1) seminal characteristics evaluated after 36 d of treatment ...


Somatic Cell Interspecies Nuclear Transfer, Marina Julia Sansinena Jan 2004

Somatic Cell Interspecies Nuclear Transfer, Marina Julia Sansinena

LSU Doctoral Dissertations

The low efficiency of the nuclear transfer (NT) procedure requires large number of oocytes to produce embryos and live offspring. A series of experiments were conducted to evaluate the ability of the bovine cytoplast to reprogram nuclei from horses and llamas. In a preliminary study, equine oocytes from small (<20mm diameter) follicles were either pretreated with roscovitine or placed in maturation (IVM only) prior to NT. Roscovitine pretreatment did not improve nuclear maturation rates (roscovitine pretreatment 57% vs. IVM only 66%) and no fusion was obtained from roscovitine-pretreated oocytes after NT. Another preliminary study was conducted with the objective to produce llama NT embryos and to compare their development in two in vitro culture conditions (G1.2® vs. CR1aa). No difference was found in the number of embryos cleaved after 2 d of culture. This resulted in the first scientific report of somatic cell NT, in vitro culture and transfer of NT embryos in the llama. In the next experiment, adult horse and llama fibroblasts were injected into enucleated cow oocytes. The results showed the cow cytoplasm is capable of partially reprogramming nuclei from other species and support mitotic divisions. However, this study also showed a consistent embryonic developmental arrest at the 8- to 16- cell stage when horse or llama donor cells were used as donor nuclei. When a more closely related species of donor cell (banteng) and recipient oocyte (domestic cattle) were used for NT, no embryonic developmental arrest was found. Embryos progressed to achieve high blastocyst rates (banteng male cell line 28% vs. banteng female cell line 15%). Two banteng interspecies NT pregnancies were established and subsequently lost from the banteng male cell line. In the final study, the effect of a mixed mitochondrial population (heteroplasmy) on early embryonic development was investigated. Ooplasmic transfer performed in combination with NT procedure indicated presence of foreign mitochondria clustered in a small portion of the cytoplasm in early stages of embryo development. When goat ooplasm was transferred into interspecies (cow oocyte-goat donor cell) NT embryos, fusion and cleave rates were reduced suggesting an increased level of heteroplasmy or nuclear-ooplasmic incompatibilities.


Leptin In Horses: Influences Of Body Condition, Gender, Insulin Insensitivity, Feeding, And Dexamethasone, Joshua Allen Cartmill Jan 2004

Leptin In Horses: Influences Of Body Condition, Gender, Insulin Insensitivity, Feeding, And Dexamethasone, Joshua Allen Cartmill

LSU Doctoral Dissertations

The experiments described herein were designed to answer questions that arose from initially attempting to determine whether treatment with dexamethasone increased concentrations of leptin in geldings. Dexamethasone treatment did in fact increase leptin concentrations in mares, geldings, and stallions. Additional experiments were designed to determine leptin's interaction, not only with the adrenal axis, but with the thyroid axis, the growth hormone/insulin-like growth factor-1 axis, as well as glucose and insulin metabolism in geldings, mares, and stallions. During the course of these experiments, differences in leptin concentrations in the horse were attributed to degree of body condition, gender, and ...