Master of Science, The Ohio State University, 2021, Animal Sciences

Mastitis is a key challenge for the dairy industry. Defined as inflammation of the mammary gland, mastitis is most commonly caused by a bacterial intramammary infection (IMI). A large proportion of dairy heifers have an IMI prior to calving and beginning their first lactation. An infection during this time is expected to be deleterious to the growth and development of the mammary gland (quarter), diminishing future milk production and producer profitability. The objectives of these works were to describe the effects an IMI has on primigravid heifer mammary secretions, determine if prepartum administration of an internal teat sealant (ITS) in heifers reduced the odds of IMI at calving, and determine if administration of ITS earlier (75 vs 35 days prepartum) differentially affected the odds of IMI at calving. A total of 270 heifers were utilized. Aseptic secretion samples were obtained from one quarter of every heifer at 75 days prepartum and another quarter of every heifer at 35 days prepartum. Immediately following sampling, the designated quarter was administered ITS. The other 2 quarters of every heifer were not interfered with prior to calving. After calving, each quarter of every heifer was sampled. Both prepartum secretion as well as colostrum samples were bacterially cultured to determine quarter infection status and the somatic cell count (SCC) was enumerated. Prepartum secretion samples were scored based on viscosity as thick or thin. At 75 days prepartum, 26% of quarters had an IMI, and 28% were infected at 35 days prepartum. Uninfected secretion samples were 133.2 (95% confidence interval (CI): 16.8 - > 999.9) times more likely to be thick compared to samples infected with a major pathogen, and 14.3 (95% CI: 8.5 - 24.1) times more likely to be thick compared to samples infected with non-aureus staphylococci (NAS). Secretion SCC was elevated when an IMI was present within the quarter; quarters with an IMI caused b (open full item for complete abstract)

Committee: Benjamin Enger (Advisor); Jessica Pempek (Committee Member); Craig Zimmerly (Committee Member) Subjects: Animal Sciences

Master of Science, The Ohio State University, 2022, Animal Sciences

The dairy cow requires a fully grown and developed udder to produce copious amounts of milk during lactation. Most mammary growth and development occurs during the animal's first gestation, however coupled at this time is the increased prevalence of intramammary infections (IMI). Such IMI are expected to impair mammary growth and shortchange development, negatively impacting future milk production. Dairy heifers represent a significant financial investment for producers and therefore should enter first lactation healthy so that they yield maximal return on investment. However, how these IMI affect mammary gland growth and development in rapidly growing and developing mammary glands has not been investigated. The objectives of these works were to histologically compare uninfected and Staphylococcus aureus-infected mammary glands by quantifying tissue areas occupied by different tissue types and determine whether infection status affects the degree of cellular proliferation and apoptosis in rapidly growing mammary glands. Non-lactating dairy heifers (n = 16) were administered estradiol and progesterone for 14 d to stimulate mammary growth and development and 2 quarters of each heifer were either infused with Staphylococcus aureus (CHALL) or served as an uninfected control (UNINF) on d 8. Heifers were randomly euthanized on either the last day of hormonal injections (GRO), or 13 d post-injections (DEV) and mammary iii tissues were collected from the center and edge parenchymal regions of each mammary gland. In GRO tissues, CHALL quarters had less epithelial tissue area and greater tissue area occupied by intralobular stroma, coinciding with the greater percentage of apoptotic mammary epithelial cells (MEC) and lower percentage of apoptotic stromal cells compared to UNINF quarters. Additionally, edge parenchyma contained a greater percentage of apoptotic stromal cells compared to center parenchyma. Coinciding with this observ (open full item for complete abstract)

Committee: Benjamin Enger (Advisor); R. Michael Akers (Committee Member); Sheila Jacobi (Committee Member) Subjects: Animal Sciences

Master of Science (MS), Wright State University, 2011, Biological Sciences

My study was conducted to understand tree community structure and how soil moisture and fire frequency influence them. Eighteen plots were placed in the Edge of Appalachia Nature Preserve of unglaciated southern Ohio: nine within a prescribed burn site and nine control sites outside the burn. Sites were stratified in triplicate across GIS-derived integrated soil moisture index (IMI) classes. Burning was done in 1996. Overstory species dbh and sapling species were sampled 1997, 2001, and 2008. Overstory stems were located in 2009 using range finders. Stem locations were loaded into GIS using novel techniques to quantify individual stem IMI values. Nonmetric multi-dimensional scaling identified greater heterogeneity among intermediate and mesic sites than xeric sites. Multi-response permutation procedures did not detect community differences between burned and unburned sites, but did detect strong (A=0.3 to 0.2, T=-3.6 to -4.1) distinct community differences that were statistically significant (P < 0.05) among xeric, intermediate, and mesic IMI classes. Analysis of variance identified significant initial effects of burning on Carya saplings and overstory Sassafras albidum stems, as well as lasting effects significant on Carpinus caroliniana. ANOVA detected significant differences across all sampling years in sapling relative number for Acer rubrum, Sassafras albidum, and Carpinus caroliniana saplings, as well as Quercus prinus, and Liriodendron tulipifera overstory stems between IMI classes. Bonferroni adjusted Kolmogorov-Smirnov tests were used to identify and quantify IMI habitat restrictions of species. Quercus prinus dominated xeric sites (IMI quartiles 18-24), Carya occupied intermediate sites (IMI quartiles 22-44), Acer saccharum occupied intermediate to mesic sites (IMI quartiles 33-44), Sassafras albidum (IMI quartiles 20-40, IMI median 43) and Liriodendron tulipifera (IMI quartiles 39-45) were restricted to mesic sites. My r (open full item for complete abstract)

Committee: James Runkle PhD (Advisor); James Amon PhD (Committee Member); Thomas Rooney PhD (Committee Member) Subjects: Ecology

Doctor of Philosophy, The Ohio State University, 2004, Evolution, Ecology, and Organismal Biology

The study was conducted at four sites in the unglaciated Allegheny Plateau region of southeastern Ohio, each was comprised of an unburned treatment unit, a periodic burn unit (prescribed fires in 1996 & 1999) and an annual burn unit (prescribed fires 1996-1999). The study sites were stratified by an integrated soil moisture index (IMI). Prior to fire treatments (1995), variation in understory species composition was most strongly correlated with topographic variations in predicted soil moisture (IMI), N mineralization rate, nitrification rate, and soil pH. Species richness was positively correlated with N mineralization rate and nitrification rate. Understory vegetation responded similarly on both the periodic and annual burn treatments, among the four study sites, and across the three IMI classes (xeric, intermediate, mesic). Post-burn compositional shifts resulted primarily from shade-intolerant species and summergreen herbs that increased in frequency from seed bank germination and also from tree seedlings that decreased in frequency. Species richness and evenness became significantly greater on burned plots as forb and graminoid richness increased. Prescribed fires also had moderate effects on tree seedling populations. Frequencies of several shade-tolerant species were significantly lower on burned sites. The frequencies of oaks (Quercus) and hickories (Carya) were not affected significantly. In 2002, there was no significant difference in the abundance of shade-tolerant seedlings among the fire treatments. Oak+hickory seedling abundance was highly variable with a small subset burned xeric plots supporting high densities (>1500/ha) of large seedlings. The rare woodland grass Calamagrostis porteri subsp. insperata was also monitored on burned and unburned sites. On annual burn patches, tiller density increased significantly relative to unburned and periodically burned patches, and annual burn patches also exhibited a sharp increase in flowering. Overall, this st (open full item for complete abstract)

Committee: Ralph Boerner (Advisor) Subjects: