Submitted by JOSÉ RICARDO BARBOZA SILVA null (jose.ricardo_medvet@hotmail.com) on 2018-03-10T14:57:32Z No. of bitstreams: 1 Silva, J.R.B., 2018. Dissertação vs final arquivo.pdf: 2884438 bytes, checksum: 1aeb3fe55c567c7423c443a4d83a7ae2 (MD5) / Approved for entry into archive by Maria Lucia Martins Frederico null (mlucia@fca.unesp.br) on 2018-03-12T13:06:22Z (GMT) No. of bitstreams: 1 silva_ jrb_me_botfca.pdf: 2796813 bytes, checksum: 80083164ac1f3e931aed7c335545c884 (MD5) / Made available in DSpace on 2018-03-12T13:06:22Z (GMT). No. of bitstreams: 1 silva_ jrb_me_botfca.pdf: 2796813 bytes, checksum: 80083164ac1f3e931aed7c335545c884 (MD5) Previous issue date: 2018-03-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Na abordagem dos bovinos com enfermidades digestivas, durante o exame físico, exames complementares são necessários, de forma a retificar a suspeita clínica, contribuir para o estabelecimento do prognóstico e decisão clínica. Tais exames compreendem a avaliação do perfil hematológico, bioquímico, líquido peritoneal, ruminal, exame ultrassonográfico abdominal e laparotomia exploratória. Este último por se tratar de uma abordagem cirúrgica convencional, está associado as complicações e custos inerentes a técnica. Neste cenário a videolaparoscopia se apresenta com uma possibilidade para reduzir as complicações trans e pós-operatórias. O objetivo deste trabalho foi revisar e comparar a utilização da videolaparoscopia, ultrassonografia e demais métodos diagnósticos das enfermidades digestivas dos bovinos. Foram utilizados 7 bovinos mestiços, atendidos na Clínica de Bovinos de Garanhuns, unidade hospitalar da UFRPE. Realizou-se exame físico, ultrassonografia abdominal, videolaparoscopia exploratória, coleta de amostras de sangue, para a realização de hemograma, determinação plasmática da proteína total e fibrinogênio, e do soro foram realizadas análises dos indicadores bioquímicos: Proteína total, albumina, globulinas, relação albumina/globulina, glicose, L-lactato, uréia, creatinina, as atividades enzimáticas da aspartato aminotransferase (AST), gama glutamiltransferase (GGT), creatino quinase (CK) e lactato desidrogenase (LDH). Foi coletado líquido peritoneal e realizada análise físico-química e bioquímica. Diante dos resultados, observamos que a videolaparoscopia e ultrassonografia abdominal auxiliam na determinação do diagnóstico e prognóstico precisos das enfermidades digestivas. / 2016/2006-4

Made available in DSpace on 2014-06-11T19:29:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-27Bitstream added on 2014-06-13T20:19:15Z : No. of bitstreams: 1 rocha_nas_me_jabo.pdf: 503011 bytes, checksum: f1714a5fae847fcec5ec5165da511227 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O estudo foi conduzido com o objetivo de avaliar os efeitos da suplementação com antioxidantes intracelulares e extracelulares em diferentes etapas da PIV (MIV e/ou CIV), e da tensão de oxigênio durante o CIV sobre o desenvolvimento e criotolerância de embriões bovinos. No Exp.1 foi realizada a suplementação com antioxidantes {0,6 mM cisteína (CIST), 0,6 mM cisteína associado á 100 μM de cisteamina (C+C) e 100 UI catalase (CAT)} durante todo o período de CIV, em diferentes atmosferas gasosas {5% CO2 em ar (20% O2) ou atmosfera controlada (7% O2, 5% CO2 e 88% N2)}. Já, no Exp. 2 foi realizada a suplementação com antioxidantes {0,6 mM cisteína (CIST), 100 UI catalase (CAT) e 100 μM de β-mercaptoetanol (β-ME)} durante 72 horas de CIV, nas diferentes atmosferas gasosas. Posteriormente, após definir a tensão de oxigênio, bem como, o período de suplementação adequado para o CIV, foi realizada a adição de antioxidantes durante a maturação in vitro (MIV) e/ou 72 horas de CIV (Exp.3). No Exp.1, a taxa de desenvolvimento embrionário foi adversamente afetada (P<0,05) pelos tratamentos CIST (11,2%) e C+C (1,4%), em relação ao Controle (26,6%), e pela tensão de oxigênio (17,2% e 11,1%; 20 e 7% O2, respectivamente). Em relação à taxa de re-expansão, após reaquecimento e cultivo in vitro por 24 horas, não houve diferença significativa (P>0,05) entre os tratamentos avaliados (66,7% a 100%). No Exp.2, as taxas de blastocistos não foram afetadas (P>0,05) pelos tratamentos CIST, β-ME e CAT (43,7% a 48,5%), porém a baixa tensão de oxigênio afetou adversamente (P<0,05) o desenvolvimento embrionário (52,1% e 38,4%; 20 e 7% O2 respectivamente). A mensuração dos níveis intracelulares de ROS não foi afetada (P>0,05) pelas variáveis tratamentos (0,95 a 0,78) e tensão de oxigênio... / This study was conducted to evaluate the effects of intracellular and extracellular antioxidants supplementation, in different stages of IVP (IVM and/or IVC), and oxygen tension during IVC on development, quality and cryotolerance of bovine embryos. Exp.1 was performed with the supplementation with antioxidants {0.6 mM cysteine (CIST); 0.6 mM cysteine associated to 100 μM cysteamine (C+C); 100 UI catalase (CAT)} during entire period of IVC in different gaseous atmospheres {5% CO2 in air (20% O2) or controlled atmosphere (7% O2, 5% CO2 and 88% N2)}. Already, in Exp.2 was performed the antioxidant supplementation {0.6 mM cysteine (CIST); 100 μM β-mercaptoethanol (β-ME); 100 UI catalase (CAT)} for 72 hours of IVC in different gaseous atmospheres. Later, after setting the oxygen tension as well as the supplementation period suitable for IVC, was carried out the addition of antioxidants during in vitro maturation (IVM) and/or 72 hours of IVC (Exp.3). In Exp.1, the rate of embryo development was adversely affected (P<0.05) by the treatments CIST (11.2%) and C+C (1.4%), compared to Control (26.6%), and oxygen tension (17.2% and 11.1%, 20 and 7%O2, respectively). Regarding the re-expansion rate after warming and in vitro culture for 24 hours, no difference (P>0.05) between the treatments were found (66.7% to 100%). In Exp.2, blastocysts rates were not affected (P>0.05) by treatments CIST, β-ME and CAT (43.7% to 48.5%), but the low oxygen tension adversely affected (P<0.05) embryo development (52.1% to 38.4%, 20 and 7%O2, respectively). The quantification of intracellular levels of ROS was not affected (P>0.05) by the variables treatments (0.95 to 0.78) and oxygen tension... (Complete abstract click electronic access below)

Orientador: Gisele Zoccal Mingoti / Banca: Joaquim Mansano Garcia / Banca: Juliana Corrêa Borges Silva / Resumo: O estudo foi conduzido com o objetivo de avaliar os efeitos da suplementação com antioxidantes intracelulares e extracelulares em diferentes etapas da PIV (MIV e/ou CIV), e da tensão de oxigênio durante o CIV sobre o desenvolvimento e criotolerância de embriões bovinos. No Exp.1 foi realizada a suplementação com antioxidantes {0,6 mM cisteína (CIST), 0,6 mM cisteína associado á 100 μM de cisteamina (C+C) e 100 UI catalase (CAT)} durante todo o período de CIV, em diferentes atmosferas gasosas {5% CO2 em ar (20% O2) ou atmosfera controlada (7% O2, 5% CO2 e 88% N2)}. Já, no Exp. 2 foi realizada a suplementação com antioxidantes {0,6 mM cisteína (CIST), 100 UI catalase (CAT) e 100 μM de β-mercaptoetanol (β-ME)} durante 72 horas de CIV, nas diferentes atmosferas gasosas. Posteriormente, após definir a tensão de oxigênio, bem como, o período de suplementação adequado para o CIV, foi realizada a adição de antioxidantes durante a maturação in vitro (MIV) e/ou 72 horas de CIV (Exp.3). No Exp.1, a taxa de desenvolvimento embrionário foi adversamente afetada (P<0,05) pelos tratamentos CIST (11,2%) e C+C (1,4%), em relação ao Controle (26,6%), e pela tensão de oxigênio (17,2% e 11,1%; 20 e 7% O2, respectivamente). Em relação à taxa de re-expansão, após reaquecimento e cultivo in vitro por 24 horas, não houve diferença significativa (P>0,05) entre os tratamentos avaliados (66,7% a 100%). No Exp.2, as taxas de blastocistos não foram afetadas (P>0,05) pelos tratamentos CIST, β-ME e CAT (43,7% a 48,5%), porém a baixa tensão de oxigênio afetou adversamente (P<0,05) o desenvolvimento embrionário (52,1% e 38,4%; 20 e 7% O2 respectivamente). A mensuração dos níveis intracelulares de ROS não foi afetada (P>0,05) pelas variáveis tratamentos (0,95 a 0,78) e tensão de oxigênio... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study was conducted to evaluate the effects of intracellular and extracellular antioxidants supplementation, in different stages of IVP (IVM and/or IVC), and oxygen tension during IVC on development, quality and cryotolerance of bovine embryos. Exp.1 was performed with the supplementation with antioxidants {0.6 mM cysteine (CIST); 0.6 mM cysteine associated to 100 μM cysteamine (C+C); 100 UI catalase (CAT)} during entire period of IVC in different gaseous atmospheres {5% CO2 in air (20% O2) or controlled atmosphere (7% O2, 5% CO2 and 88% N2)}. Already, in Exp.2 was performed the antioxidant supplementation {0.6 mM cysteine (CIST); 100 μM β-mercaptoethanol (β-ME); 100 UI catalase (CAT)} for 72 hours of IVC in different gaseous atmospheres. Later, after setting the oxygen tension as well as the supplementation period suitable for IVC, was carried out the addition of antioxidants during in vitro maturation (IVM) and/or 72 hours of IVC (Exp.3). In Exp.1, the rate of embryo development was adversely affected (P<0.05) by the treatments CIST (11.2%) and C+C (1.4%), compared to Control (26.6%), and oxygen tension (17.2% and 11.1%, 20 and 7%O2, respectively). Regarding the re-expansion rate after warming and in vitro culture for 24 hours, no difference (P>0.05) between the treatments were found (66.7% to 100%). In Exp.2, blastocysts rates were not affected (P>0.05) by treatments CIST, β-ME and CAT (43.7% to 48.5%), but the low oxygen tension adversely affected (P<0.05) embryo development (52.1% to 38.4%, 20 and 7%O2, respectively). The quantification of intracellular levels of ROS was not affected (P>0.05) by the variables treatments (0.95 to 0.78) and oxygen tension... (Complete abstract click electronic access below) / Mestre

Fertility is the most important factor controlling mammalian reproduction. Bull fertility, ability of the sperm to fertilize and activate the egg, and support embryonic development is crucial for early development. Similarly, the hormonal environment of the embryo also plays a critical role in successful embryonic development. We know that molecular health of the sperm as well as progesterone enhancing the development of the embryo is important for early development and implantation. The gaps in the knowledge base are 1) how early mammalian embryo development is paternally affected is not fully clear and 2) how progesterone improves the survival of the transferred embryo in the uterus still remains elusive. The central hypothesis was that low expression of MHC1 and Magel2 would cause a dysfunction in early embryo development and that progesterone will increase the survivability of the embryo via its associations with TNF-alpha and PGF2alpha. The objectives of this study were to 1) determine the expression of mhc1 and magel2 in single in vivo and in vitro blastocysts derived from low fertility and high fertility sires as well as to determine main pathways by which protein products of these genes regulate early development, and 2) identify the role of progesterone in regulating TNF-alpha and PGF2alpha. To accomplish these goals, we performed real time reverse transcriptase reaction and bioinformatics approaches, and ELISA and commercially available radioimmunoassay kits, respectively. The results of the experiments showed that 1) expression of mhcI transcripts were greater in high fertility in vivo embryos compared to their low fertility in vivo counterparts. Magel2 results showed an increase (P ≤ 0.05) in expression levels of high fertility in vivo embryos compared to their high fertility in vitro counterparts. Low fertility in vivo embryos had higher expression than high fertility in vitro embryos as well.

Management of female infertility is a primary determinant of economic efficiency in the cattle industry. Management factors involved in impacting fertility include identification of females with suboptimal fertility and reducing the period of anestrus, prior to pubescence and after parturition. The use of anti-Müllerian hormone in the identification of females with suboptimal follicular populations allows for selection of females with optimal follicular populations and could reduce infertility resulting from a decrease in the quantity of follicles. A reduction in the period of anestrus also impacts fertility and management strategies that induce an ovulatory response in anestrous females improves fertility. Biostimulation has advanced pubescence in heifers and reduced the length of postpartum anestrus in cows. Advancing the understanding of anti-Müllerian hormone and the biostimulatory effect allows for further assessment of these management factors and their impact on infertility. Improved management of female infertility increases profitability of cattle production.

Bovine parvovirus (BPV) is a helper-independent parvovirus. It has a small icosahedral capsid with a single stranded DNA genome. It is a highly stable virus with a narrow host range. It causes acute gastroenteritis in calves. It is considered to be a cytolytic virus because it kills the host cells. However, the mechanism by which the virus causes cell death is not known. The work described in this thesis assessed different parameters of cell death in BPV infected embryonic bovine tracheal (EBTr) cells. There are several ways for viruses to induce cell death. Viruses can induce apoptosis in the infected cell. They can also kill the host cell by necrosis. Several approaches were used in this work to look for evidence of apoptosis and necrosis. Cells undergoing apoptosis exhibit cardinal signs that distinguish them from other dying cells. Among these signs are the exposure of phosphatidylserine to the outer surface of the plasma membrane, DNA fragmentation into non-random DNA sections that are multimers of 180bp, nuclear morphology changes and caspase activation. These signs were studied in this research and data collected from these experiments did not show any positive sign of apoptosis in infected cells due to virus infection. Cells undergoing a necrotic cell death have a different pattern. The cells swell then burst releasing their cytoplasmic contents. The DNA is fragmented in a random fashion. Cellular morphology was studied in this research and the data suggested that BPV infected cells swell, then shrink and detach from the surface of the culture vessel. Moreover, formation of apoptotic bodies was not detected in dying infected cells. Release of cytoplasmic contents was also assessed by looking at concentrations of LDH enzyme, viral haemagglutinin, and the number of infectious viral particles in the media of infected cells. Data from the different approaches employed in this study do not support the hypothesis that BPV kills the infected EBTr cell by apoptosis, rather, infected cells in culture become necrotic, swell, release their cytoplasmic contents, and detach.

Bovine mastitis is a significant disease affecting the dairy industry worldwide. The most frequently causative agent of contagious bovine mastitis is Staphylococcus aureus that produces numerous virulence factors contributing to its pathogenesis. However, it is not clearly defined which virulence factors play a critical role in bovine mastitis due to the heterogeneous virulence factor profiles in S. aureus isolated from different hosts and disease types. Among many virulence factors, it has long been postulated that staphylococcal cytotoxins and superantigens (SAgs) play an important role in the pathogenesis of S. aureus in bovine mastitis due to their potent toxicity toward host immune response. However, it has been a great challenge to determine the definite role of staphylococcal cytotoxins and SAgs in S. aureus pathogenesis due to the presence of multiple redundant cytotoxins and SAgs in a single S. aureus strain. Our longterm goal is to develop an effective vaccine to protect dairy cattle from S. aureus infection. The objective of this study is to; 1) determine the role of staphylococcal cytotoxins and superantigens in bovine mastitis; 2) develop a inducible and secretory expression vector and host system for a high production yield of recombinant protein; and 3) evaluate the protective effect of recombinant protein vaccine composed of staphylococcal cytotoxins and SAgs. The rationale of the proposed research is that development of an effective vaccine against S. aureus will prevent significant economic loss in the dairy industry and reduce the use of antibiotics in the dairy industry to prevent emergence of antibiotic resistance pathogens

This study examines the growing phenomenon to protect the bovine in the United States and will question to what extent religion plays a role in the formation of bovine sanctuaries. My research has unearthed that there are approximately 454 animal sanctuaries in the United States, of which 146 are dedicated to farm animals. However, of this 166 only 4 are dedicated to pigs, while 17 are specifically dedicated to the bovine. Furthermore, another 50, though not specifically dedicated to cows, do use the cow as the main symbol for their logo. Therefore the bovine is seemingly more represented and protected than any other farm animal in sanctuaries across the United States. The question is why the bovine, and how much has religion played a role in elevating this particular animal above all others. Furthermore, what constitutes a sanctuary? Does not the notion of a sanctuary denote a religious affiliation to salvation and sanctity, and as such are bovines so sacred that they need sanctuaries? Or is it simply that they are so exploited by the livestock industry that they, above all other animals, need salvation? In such a way, this study asks the question, who is the benefactor: the bovine or the human? I highlight that depending upon the motivation the roles can be reversed, so that at a Hindu based cow sanctuary the cow is the benefactor, venerated in gratitude for the numerous gifts it bestows upon us. However, at the Vegan inspired cow sanctuaries it is the human who takes on the role of the “bovine benefactor,” for they are specifically looking to protect and offer bovines sanctuary so that they can lead an autonomous life free from exploitation. I have therefore coined the term “bovine benefactories” to refer not only to the sanctuaries where are they are venerated and protected, but also as an apt juxtaposition to the ‘fear factories’ where the bovines are made to suffer – fear factories being a more figurative name for what the industry labels as CAFOs (concentrated animal feeding operations). At the heart of this study is therefore an emphasis upon the stark juxtapositions and contradictions that Americans have with the bovine. What is deemed holy by one bovine sanctuary is deemed profane by another. At the same time, all bovine sanctuaries stand united in complete contrast to the present-day treatment of bovines within the livestock industry. Furthermore, there is an intriguing juxtaposition between America’s reliance and infatuation with beef and dairy products and their treatment of the bovine. For what is deemed more holy to Americans than the hamburger? As such, I also question whether such a dependence and passion for bovine products is a form of religious expression in itself? This study therefore analyzes to what extent food is deemed sacred to a diverse American public. For example, is the bovine sacred to a secular America because it is their ultimate benefactor? As such, this study looks to deconstruct and question what constitutes bovine veneration, highlighting that the bovine is not only venerated for its virility, aggression, and abundance, but that it has also taken on new significance as a symbol for exploitation, consumerism, and speciesism. In such a way, I highlight that there are many different religious motivations for protecting and offering bovines sanctuary. While some seek to venerate and use the bovine as a symbol, others seek to award the bovine its own autonomy – whereby it is not merely a symbol, but also an animal, with its own identity, will, and purpose beyond that of the human. This work therefore stands squarely on the shoulders of many postmodern and critical theorists that have come before me, from Judith Butler and Rebecca Alpert to Clifford Geertz and David Chidester. Their work has demonstrated that all constructs are limited by presuppositions of what is considered to be the normative – and as such, what is religion and what is deemed sacred is relative to both the individual and the community that one seeks to identify with. In such a way, I shall conclude that the largescale rearing of bovine, the mass producing and consuming of beef and dairy products, and indeed the offering of sanctuary to the bovine can all be analyzed and interpreted as unique, and at the same time intertwined, forms of religious expression and practice. / Religion

Scientists have developed techniques like ovum pick up (OPU) and follicular ablation as a large source of oocytes for creating IVP bovine embryos. These techniques have allowed for more efficient dissemination of valuable female genetics compared to traditional artificial insemination or embryo flushing. IVP embryos have lower embryo development rates and quality, leading to lower pregnancy rates. Nerve growth factor-beta (NGF), however, has been previously shown to improve 48-hour cleavage rates and the number of hatching/ hatched blastocysts out of total presumptive zygotes. We hypothesize that NGF will improve IVP embryo development by positively influencing cleavage and blastocyst rates. The first two experiments' objectives were to determine the effect of recombinant bovine (60 or 90% purity) and human NGF (97% purity) supplementation during in vitro fertilization on 24- and 48-hour cleavage and day 8 blastocyst development rates. The objective of the third experiment was to assess the effect of the supplementation of bovine NGF (90% purity) on heat shocked and non-heat shocked in vitro-matured cumulus-oocyte complexes, assessing cleavage rates at 48 and 72 hours post insemination and blastocyst development rates. The results of experiment 1 show there were no differences between any of the three treatment groups (bNGF60, hNGF95, and control) for 24 hour (P = 0.66) or 48 hour (P = 0.33) embryonic cleavage rates. Additionally, there were no differences between treatments in the total percentage of blastocysts per oocyte (P = 0.91) or the percentage of blastocysts per cleaved embryo (P = 0.32). The results of experiment 2 also showed no differences between any of the three treatment groups (bNGF90, hNGF95, and control) for 24 hour (P = 0.16) or 48 hour (P = 0.18) embryonic cleavage rates. Additionally, there were no differences between treatments in the total percentage of blastocysts per oocyte (P = 0.42) or the percentage of blastocysts per cleaved embryo (P = 0.57). In the 3rd experiment, there was not a significant effect of treatment (P ≤ 0.05) at all stages of embryonic development assessed. On the contrary, in the third experiment, non-heat stressed NGF treatment had an interestingly detrimental effect on early cleavage rates of embryos compared to the non-treated control embryos. These results showed that NGF could not improve in vitro embryonic development rates in standard conditions; however, this negative impact of NGF on early cleavage was not observed in heat-shocked embryos. Suggesting that there could be a protectant factor in NGF that warrants further investigation. / Master of Science / Nerve growth factor (NGF) was initially thought to only play a role in nerve cell development, but research has since shown an influence on female reproduction in cattle. NGF and its receptors have been identified in the follicular fluid and reproductive cell types of females, contributing to egg maturation. Previous data on NGF supplementation with IVP embryos, which took place during the summer, showed that NGF positively affected in vitro-produced embryo development when added to fertilization media, specifically on cleavage rates (division without growth, must be two cells or greater) and blastocyst development. The actual role of NGF on embryo development is still unclear. Therefore, replication of this study is essential. First, we added either recombinant human nerve growth factor (90% pure) or bovine nerve growth factor (60% or 90% pure) to the IVF medium. The goal was to determine if NGF would have the same effects on cleavage rates as bovine purified NGF when supplemented during the fertilization stage, as well as to decide if protein purity and species affected how NGF influenced embryo development rates. For the second part of the study, we heat-shocked oocytes during maturation in a "hot incubator" and supplemented them with bovine 90% NGF. This was done to mimic the summer month heat stress that may have occurred in the abstract data. Our objective was to determine if NGF could mitigate the detrimental heat shock during development and potentially improve embryo developmenNerve growth factor (NGF) was initially thought to only play a role in nerve cell development, but research has since shown an influence on female reproduction in cattle. NGF and its receptors have been identified in the follicular fluid and reproductive cell types of females, contributing to egg maturation. Previous data on NGF supplementation with IVP embryos, which took place during the summer, showed that NGF positively affected in vitro-produced embryo development when added to fertilization media, specifically on cleavage rates (division without growth, must be two cells or greater) and blastocyst development. The actual role of NGF on embryo development is still unclear. Therefore, replication of this study is essential. First, we added either recombinant human nerve growth factor (90% pure) or bovine nerve growth factor (60% or 90% pure) to the IVF medium. The goal was to determine if NGF would have the same effects on cleavage rates as bovine purified NGF when supplemented during the fertilization stage, as well as to decide if protein purity and species affected how NGF influenced embryo development rates. For the second part of the study, we heat-shocked oocytes during maturation in a "hot incubator" and supplemented them with bovine 90% NGF. This was done to mimic the summer month heat stress that may have occurred in the abstract data. Our objective was to determine if NGF could mitigate the detrimental heat shock during development and potentially improve embryo development rates under these stressful conditions. The results of all experiments indicated that NGF could not influence development rates. positively. On the contrary, in the third experiment, non-heat stressed NGF treatment had an interestingly detrimental effect on early cleavage rates of embryos when compared to non-treated control embryos. This negative impact of NGF on early cleavage was not observed in heat-shocked embryos pointing to a possible protectant factor in NGF that needs further investigation.t rates under these stressful conditions. The results of all experiments indicated that NGF could not influence development rates. positively. On the contrary, in the third experiment, non-heat stressed NGF treatment had an interestingly detrimental effect on early cleavage rates of embryos when compared to non-treated control embryos. This negative impact of NGF on early cleavage was not observed in heat-shocked embryos pointing to a possible protectant factor in NGF that needs further investigation.

Many factors influence male fertility, and conventional fertility evaluations are not able to reliably identify sub-fertile animals. The overall goal of this work was to explore the expression of phosphatidylserine (PS) on bovine sperm and investigate what factors may impact it, as previous research demonstrated that phosphatidylserine (PS) plays a role in murine fertilization. Despite conventionally being an apoptotic marker, it is present on viable and fertilization-competent murine sperm, however, less is known of the possible role of PS in bovine fertilization. In experiment 1, viable bovine sperm cells expressing PS were identified and PS levels in fresh and frozen semen were compared. Phosphatidylserine levels in frozen samples were significantly less than in fresh samples. We conclude that the cryopreservation process has an impact on PS expression in sperm by altering the proportion of sperm cells which are capable of fertilization. Experiment 2 examined PS levels in bulls with varying fertility levels based on sire conception rate (SCR). There was no difference in PS levels between high and low fertility bulls. There was a significant difference in PS levels of uncapacitated samples and those capacitated for one hour. These results warrant further investigation into the role of phosphatidylserine in bovine fertilization. / Master of Science / Improving the fertility of cattle is incredibly important to meet ever-growing consumer demands for animal protein. Researchers and producers can utilize a variety of reproductive technologies to improve their herds' reproductive efficiency. Phosphatidylserine (PS) is a glycerophospholipid which makes up a part of all cellular plasma membranes. Typically, it is used as a marker for cell death or apoptosis, however, some cells expose it on their surface temporarily while still viable, including sperm. Phosphatidylserine was found to be exposed on sperm from mice that were still viable and able to fertilize oocytes. Following that, the expression of PS in bovine sperm was investigated. Using bulls as a model, fresh semen was collected and analyzed for the level of PS expression then frozen and reanalyzed. We saw that there was a significant decrease in the level of PS expression in sperm that had been previously frozen, possibly due to damage to their membranes during the freezing process. Frozen semen from beef bulls with either high or low fertility was also analyzed. No difference was observed between bulls with varying levels of fertility. Addressing fertility issues in bulls is a complicated and multi-faceted issue which requires the use of many technologies and fertility markers. Further developing the knowledge of PS exposure in bulls and its relation to fertility and fertilization is worthwhile to attempt to improve the reproductive efficiency of cattle herds.