Effects of fescue toxicosis on growth and thermoregulation of rats [abstract]

Abstract only availableFaculty Mentor: Don Spiers, Animal SciencesTall fescue (Festuca arundinacia), a cool season forage grass, has been utilized by many farmers for over fifty year to feed livestock. Unfortunately, about half of fescue pastures are infected with an endophytic fungus (Acremonium coenophialum). The fungus produces toxins which cause health and reproduction problems in animals resulting in economic losses. Previous studies have found that intake of infected fescue during hot weather produces hyperthermia, rough hair coats, increased respiration rates, lowered milk production, dystosia, lameness, decreased feed intake and average daily gain, and reduced prolactin, progesterone, and cholesterol levels. This study was done to investigate the effects of heat stress combined with infected tall fescue seed and associated decreased feed intake on male reproduction. Twelve male rats were implanted with telemetric thermometers (Mini-Mitter, Inc.) to record core body temperature and activity every ten minutes. Rats were randomly assigned to either heat stress (HS; 31o C) or thermoneutral conditions (TN; 21o C) and fed one of three diets: endophyte-infected seed (E+), endophyte-free seed (E-), or E- diet fed in the same amount as consumed by the E+ rats the preceding day. Feed intake and body weight were recorded daily. Semen was examined for sperm motility, concentration and morphology. Tissue samples were removed from testis, epidymis, seminal vesicles, and liver and examined histologically. Other organs were collected and weighed. Toxin, heat stress, or feed restriction caused a similar reduction in growth rate, but all showed some recovery by the end of the study (

Fescue toxicosis affects the reproduction and thermoregulatory systems of male rats exposed to heat stress

Abstract only availableTall fescue (Festuca arundinacia), a cool season forage grass, has been utilized by many farmers for over fifty year to feed livestock. Unfortunately, about half of fescue pastures are infected with an endophytic fungus (Acremonium coenophialum). The fungus produces toxins which cause health and reproduction problems in animals resulting in economic losses. Previous studies have found that intake of infected fescue during hot weather produces hyperthermia, rough hair coats, increased respiration rates, lowered milk production, dystosia, lameness, decreased feed intake and average daily gain, and reduced prolactin, progesterone, and cholesterol levels. This study was done to investigate the effects of heat stress combined with infected tall fescue seed and associated decreased feed intake on male reproduction. Twelve male rats were implanted with telemetric thermometers (Mini-Mitter, Inc.) to record core body temperature and activity every ten minutes. Rats were randomly assigned to either heat stress (HS; 31 C) or thermoneutral conditions (TN; 21 C) and fed one of three diets: endophyte-infected seed (E+), endophyte-free seed (E-), or E- diet fed in the same amount as consumed by the E+ rats the preceding day. Feed intake and body weight were recorded daily. Semen was examined for sperm motility, concentration and morphology. Tissue samples were removed from testis, epidymis, seminal vesicles, and liver and examined histologically. Other organs were collected and weighed. Toxin, heat stress, or feed restriction caused a similar reduction in growth rate, but all showed some recovery by the end of the study (P< .0013). Liver (P< .0096) and heart (P< .01) weights decreased in treatment animals. Core body temperature showed differences between treatments; E+ rats showed hyperthermia and adaptation towards the end of the study. Activity was extremely variable and no conclusions could be drawn, given that each group was assigned only 1-2 animals. There was no significant effect on kidney, adrenal, spleen, testes, and seminal vesicle weight. The rough hair coat characteristic of fescue toxicosis was also observed in E+ rats. Analysis of sperm function and morphology are being conducted. Understanding the interaction between fescue toxins, heat stress, nutrition, and reproduction function will help in finding a treatment for fescue toxicosis and developing management strategies.Life Sciences Undergraduate Research Opportunity Progra

A feed-restriction model to identify factors responsible for fescue toxicosis-induced reduction in food intake [abstract]

Abstract only availableFescue toxicosis results from intake of ergopeptine alkaloids derived from a fungus (Neotyphodium coenophialum ) in tall fescue, and produces reduced productivity. Contributors to this reduction are decreased feed intake and growth. There have been few attempts to characterize these changes. A study was conducted to develop a model for this component using rats in a feed restriction experiment described previously by others. Each animal was trained over a minimum 11 d period to eat their entire daily ration from 1300-1500. This allows one to evaluate the effect of potential treatments more precisely by using a 2 hours rather than 24. Group I animals were first fed in this order an endophyte-free seed (E-) diet (ad libitum ), a restricted E- diet, a restricted endophyte-infected seed (E+) diet, and lastly an E- diet (ad libitum ). There was no decrease in feed intake (α= 0.05) from restricted E- to restricted E+ diets, but reduced growth while on E+ diet. Return to E- diet restored growth. A different routine was used with Group II. Rats were first fed ground commercial diet (ad libitum ), followed by restricted ground diet, restricted E- diet, and lastly restricted E+ diet. Initial exposure to restricted diet decreased feed intake and growth (α = 0.05), followed by partial recovery or adaptation over following 4 days. Shift to restricted E- produced no change in feed intake and a greater return of growth. Restricted E+ diet intake reduced feed intake and growth within 24 hours (α = 0.05). This reduction was stable over the entire 2 week period. These responses agree with previous studies using long-term ad libitum E+ treatment. This new model can now be used to identify mechanisms for fescue toxicosis-induced reduction in feed intake and growth, and develop potential treatments

Thermal status for different breeds of dairy cattle exposed to summer heat stress in a grazing environment [abstract]

Abstract only availableA study was conducted to investigate thermal balance of lactating dairy cattle managed in an intensive managed rotational grazing system. The farm was located at the University of Missouri Southwest Research Center in Vernon County, MO. Thirty six lactating dairy cows were blocked by parity, days in milk, milk production and breed. Cows were grouped by breed with 100% Holstein (H, n=8), 75%H:25% Jersey (J) (75H, n=5), 50%H:50%J (50H, n=8), 25%H:75%J (75J, n=7), and 100% J (J, n=8), and maintained on the same pastures from June 15 through August 1, 2006. Cows were rotated to paddocks to maintain ad libitum access to pasture. Ambient variables, including air temperature (Ta) and relative humidity, were measured continuously. Ranges of Ta and calculated THI were 12 to 38C and 55 to 87, respectively. Thermal balance was evaluated prior to morning (0500) and afternoon (1600) milkings by measuring rectal temperature (Tre) and respiration rate (RR) on 16 days throughout the study during periods of maximum and minimum heat stress. Breed groups had different body weights (p < 0.0001) ranging from 530 kg (H) to 378 (J). However, body weight was similar for 75J and 75H (460 kg versus 501 kg, respectively). Although body weights were different across breed, combined change in rectal temperature with Ta (r = 0.89) and THI (r = 0.92) was predictable (p < 0.0001). Change in Tre with increasing Ta and THI was slowest for J and 75J, and highest for H and 75H. Change in Tre was influenced more by breed more than body weight. Respiration rate was correlated with Ta (r = 0.88) and THI (r = 0.89) (p < 0.0001), with 75J being more responsive than 75H. These results suggest that breed selection can be used to improve thermal balance of cows in intensively managed rotational grazing systems.CAFNR On Campus Research Internshi

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

A measurement of the production cross-section for top quark pairs(\ttbar) in $pp$ collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron $e$ or muon $\mu$) with large missing transverse energy and at least four jets, and dilepton ($ee$, $\mu\mu$ or $e\mu$) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be $12.2 \pm 3.9$ events and $2.5 \pm 0.6$ events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

Measurement of the flavour composition of dijet events in pp collisions at root s=7 TeV with the ATLAS detector

This paper describes a measurement of the flavour composition of dijet events produced in pp collisions at &#8730;s=7 TeV using the ATLAS detector. The measurement uses the full 2010 data sample, corresponding to an integrated luminosity of 39 pb−1. Six possible combinations of light, charm and bottom jets are identified in the dijet events, where the jet flavour is defined by the presence of bottom, charm or solely light flavour hadrons in the jet. Kinematic variables, based on the properties of displaced decay vertices and optimised for jet flavour identification, are used in a multidimensional template fit to measure the fractions of these dijet flavour states as functions of the leading jet transverse momentum in the range 40 GeV to 500 GeV and jet rapidity |y|&#60;2.1. The fit results agree with the predictions of leading- and next-to-leading-order calculations, with the exception of the dijet fraction composed of bottom and light flavour jets, which is underestimated by all models at large transverse jet momenta. The ability to identify jets containing two b-hadrons, originating from e.g. gluon splitting, is demonstrated. The difference between bottom jet production rates in leading and subleading jets is consistent with the next-to-leading-order predictions

Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of √s=7 TeV proton-proton collisions

Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV