Investigation Of Transforming Growth Factor-Alpha And Its Potential Role In Promoting Ovarian Follicular Dominance

Intraovarian growth factors play a vital role in influencing the fate of ovarian follicles. They affect proliferation versus apoptosis of granulosa cells (GCs), and can influence whether small antral follicles continue their growth or undergo atresia. Transforming Growth Factor-alpha (TGFα), an oocyte-derived growth factor, is thought to regulate granulosa cell function, yet has been largely overshadowed by current interest in TGF-beta superfamily members, such as bone morphogenetic proteins (BMPs) and anti-Mullerian hormone (AMH). In the current study, effects of TGFα on bovine GC proliferation, intracellular signaling and cytokine-induced apoptosis were evaluated. Briefly, all small antral follicles (3-5mm) from bovine ovaries were aspirated and the cells were initially plated in T25 flasks containing DMEM/F12 medium, 10% FBS, and antibiotic-antimycotic, and incubated at 37 degrees Celsius in 5% CO2 for 3-4 days. Once confluent, the cells were sub-cultured to 96-, 12- or 6-well plates in serum-free conditions (insulin 100 ng/mL; transferrin 55 ng/mL; sodium selenite 6.7 pg/mL). 24-hour treatment of bovine GCs with TGFα (10 and 100ng/mL) stimulated cell proliferation compared to control (p\u3c0.05; n = 7 ovary pairs). Cell proliferation was accompanied by a concomitant increase in mitogen-activated protein kinase (MAPK) signaling within 2 hours of treatment, as measured by phosphorylated ERK1/2 expression (p\u3c0.05, n = 3 ovary pairs). These effects were entirely negated, however, by the MAPK inhibitor, U0126 (10uM, p\u3c0.05). Additionally, pre-exposure of the bovine GCs to TGFα (100ng/mL) failed to prevent Fas Ligand (100ng/mL)-induced apoptosis, as determined by caspase 3/7 activity (P\u3c0.05, n = 7 ovary pairs). Collectively, the results indicate TGFα stimulates proliferation of bovine GCs from small antral follicles via a MAPK/ERK-mediated mechanism, but this action alone fails to prevent apoptosis, suggesting TGFα may be incapable of promoting the persistence of follicles during the process of follicular selection and deviation

Comparison of GMO and Conventional Corn Stover: Chemical Composition, Digestibility, and Intake Preferences by Beef Cows—Year 1 Progress Report

Data from this analysis suggest that differences in chemical composition likely exist when comparing conventional and GMO corn stover. However, the myriad of brands, hybrids, and trait combinations that exist highlight that more controlled plot-based studies need to be conducted, focusing on trait variation within a single corn isoline as to determine individual trait effects on these potential differences in feeding value

Comparison of GMO and Conventional Corn Stover: Chemical Composition, Digestibility, and Intake Preferences by Beef Cows—Year 1 Progress Report

Data from this analysis suggest that differences in chemical composition likely exist when comparing conventional and GMO corn stover. However, the myriad of brands, hybrids, and trait combinations that exist highlight that more controlled plot-based studies need to be conducted, focusing on trait variation within a single corn isoline as to determine individual trait effects on these potential differences in feeding value.</p

Effect of Circulating Blood or Plasma Urea Nitrogen Concentrations on Reproductive Efficiency in Beef Heifers and Cows

The objective was to examine the relationship between circulating blood or plasma urea nitrogen concentrations (BPUNC) and reproductive efficiency in beef heifers and suckled beef cows. Data from nulliparous heifers (n = 284) as well as primiparous (n = 241) and multiparous (n = 806) beef cows were compiled across 15 experiments. A single blood sample collected from each female during estrous or ovulation synchronization was analyzed for BPUNC. Only females that were maintained on the same nutritional management scheme (pasture or coproduct-based drylot ration) for at least 1 week prior to synchronization though the first 21 days of the breeding season were included in the analysis. Based on the data, when cattle are allowed to adapt to a nutritional management scheme prior to breeding and maintained on that diet through the first 21 days of the breeding season, BPUNC is not negatively associated with first-service pregnancy rates. Instead, a positive relationship was observed</p