1,559 research outputs found
Genetics of feed intake and efficiency in grazing dairy cows : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science
Feed efficiency in dairy cows is widely acknowledged as a highly desirable
characteristic to improve because of its well-documented impact on production costs.
Traditional measures of feed efficiency have used ratio traits, specifically energy
conversion efficiency, but these have undesirable statistical properties. Alternative
measures of feed efficiency are those based on the residuals from regression-type
statistical models, the most common of which is residual energy intake (REI). Residual
energy intake is defined as the difference between actual and predicted intake and is
usually derived from least squares regression models. The general objective of this
thesis was to quantify phenotypic and genetic (co)variances between the feed intake
complex, performance, and fertility traits in lactating Holstein-Friesian dairy cows. A
total of 8,199 feed intake records from 2,693 lactations on 1,412 grazing lactating
Holstein-Friesian dairy cows from experimental farms were used. Several alternative
efficiency definitions were developed, each with their own respective strengths and
weaknesses. Exploitable genetic variation was demonstrated to exist for the range of
alternative efficiency traits, and the magnitude of this variation was sufficiently large to
justify consideration of the feed efficiency complex in future dairy breeding goals. The
heritability estimates for the different efficiency traits estimated using repeatability
models varied from 0.06 to 0.21. Variance components, however, differed across
lactation when estimated using random regression models; for example, the heritability
of REI varied from 0.04 (34 DIM) to 0.11 (280 DIM) across lactation. Phenotypic
correlations among many traits including REI and energy balance (EB) differed not only
by stage of lactation but also by cow parity. Moderate to strong genetic correlations
existed between REI and EB across lactation (ranging from 0.45 to 0.90). Albeit
associated with large standard errors, estimated genetic correlations between feed
efficiency and reproductive performance were either neutral or favourable suggesting
greater genetic merit for feed efficiency does not appear to be antagonistically
genetically correlated with reproductive performance. Selection index calculations using
the current economic weights in the Irish Economic Breeding Index, and genetic
(co)variances estimated in this thesis, indicate that the inclusion of REI in the index
with an economic weight of €0.078/UFL will generate animals with improved REI
On the Torus Degeneration of the Genus Two Partition Function
We consider the partition function of a general vertex operator algebra
on a genus two Riemann surface formed by sewing together two tori. We consider
the non-trivial degeneration limit where one torus is pinched down to a Riemann
sphere and show that the genus one partition function on the degenerate torus
is recovered up to an explicit universal -independent multiplicative factor
raised to the power of the central charge.Comment: 18 page
A direct N-body model of core-collapse and core oscillations
We report on the results of a direct N-body simulation of a star cluster that
started with N = 200 000, comprising 195 000 single stars and 5 000 primordial
binaries. The code used for the simulation includes stellar evolution, binary
evolution, an external tidal field and the effects of two-body relaxation. The
model cluster is evolved to 12 Gyr, losing more than 80% of its stars in the
process. It reaches the end of the main core-collapse phase at 10.5 Gyr and
experiences core oscillations from that point onwards -- direct numerical
confirmation of this phenomenon. However, we find that after a further 1 Gyr
the core oscillations are halted by the ejection of a massive binary comprised
of two black holes from the core, producing a core that shows no signature of
the prior core-collapse. We also show that the results of previous studies with
N ranging from 500 to 100 000 scale well to this new model with larger N. In
particular, the timescale to core-collapse (in units of the relaxation
timescale), mass segregation, velocity dispersion, and the energies of the
binary population all show similar behaviour at different N.Comment: 9 pages, 8 figures, accepted for publication in MNRA
The effect of grass genotype and spring management on the nutritive value of mid-summer ryegrass swards
End of project reportThe objective of this project was to investigate the environmental, morphological and management factors that control reproductive initiation and development in Lolium perenne L. (perennial ryegrass) and their influence on mid-season sward quality. These factors were assessed on eight perennial ryegrass cultivars through spaced plant and plot studies. The first part of this project determined the effects of meteorological conditions and latitude on reproductive initiation and ear emergence of cultivars over two consecutive years. It was concluded that the critical day length requirement for reproductive initiation varies between perennial ryegrass cultivars and is independent of latitude and the normal range of conditions. Using this information a strong correlation (r2 = 0.94) was found between the critical day length for ear initiation and the ten year standardised ear emergence dates of the cultivars. This correlation was sufficiently robust to predict the critical initiation date for any perennial ryegrass cultivar on a UK recommended list or on the EU common catalogue by using their heading dates from the UK Plant Breeders Rights trials at Crossnacreevy. Large variation was observed for secondary initiation and re-heading between cultivars of similar and varying maturity, which is a major factor reducing mid-season sward quality. The propensity for initiation of re-heading was strongly influenced by the severity of defoliation (intense to very lax), but there was also evidence to suggest that critical day length post-solstice, may determine the latest date when further reproductive initiation could occur. Differences in plant growth modes were clearly evident as the sward structure, plant morphology and nutritive compositions differed significantly between cultivars during the mid-season. Defoliation management also significantly affected mid-season sward structure, morphology and nutritive composition. While the effect of defoliation height on the sward physical and chemical compositions was inconclusive, an intensive (30 mm) defoliation resulted in plants returning to a vegetative growth mode earlier compared to a lax (60 mm) defoliation treatment. It was observed that defoliation at a critical growth stage can significantly affect subsequent sward structures. Delaying initial spring defoliation resulted in a greater leaf proportion and swards of greater herbage quality in the plot study. This study, therefore, established the need for more detailed evaluation of cultivars by national testing authorities to allow farmers to select cultivars for grazing use that will optimise animal intake and performance
Book Review: “IT”
Book Review of: Stephen King, “IT” (Viking, 1986
The solar flare and cosmic gamma-ray burst experiment aboard the Ulysses spacecraft
The HUS-Ulysses team has prepared an instrument for the Ulysses spacecraft consisting of 2 Csi detectors and 2 Si surface barrier detectors for measuring x rays in the range 5 to 200 keV with up to 8 ms time resolution. The prime objectives of the experiment are the study of solar flares and cosmic gamma-ray bursts. The Ulysses mission will leave the ecliptic during the forthcoming solar maximum. The total time above ecliptic latitudes + or - 70 degrees is expected to be 230 days. The solar data can be used in conjunction with other experiments to measure the directivity of the emission and for correlative studies
The 9/11 Commission: Working Together to Keep America Safe
Streaming video requires RealPlayer to view.The University Archives has determined that this item is of continuing value to OSU's history.Michael Hurley, a career CIA officer, has twenty-one years in that
organization. He served on the 9/11 Commission's staff as a
senior counsel and director of the counterterrorism policy
investigation. In the course of the investigation into the
September 11 attacks on the United States, the team he headed
interviewed more than 150 officials and reviewed hundreds of
thousands of pages of sensitive documents. His team took the
lead in organizing the March 2003 public hearings of highest-level
officials of the Clinton and Bush administrations, and the early
April public hearing of Dr. Condoleezza Rice, President Bush's
national security advisor. His team drafted substantial portions of
the policy chapters of the Commission's final report.Ohio State University. Mershon Center for International Security StudiesEvent webpage, streaming vide
Public Participation in Canadian Local Government: A Study of the Meadowlily Secondary Plan Process in London, Ontario
This paper examines whether the facilitation of public participation in local government is a worthwhile objective, using public engagement in the Meadowlily Secondary Plan in London, Ontario as a case study. An online survey was administered to citizens who participated in the City’s land use planning process. The findings reveal that by participating in decision-making, citizens learned about the processes and responsibilities of municipal government, in addition to other forms of learning, which demonstrates that the facilitation of public participation in municipal government is indeed a worthwhile objective
Gastrointestinal stromal tumour as a rare association with neurofibromatosis type 1
Gastrointestinal stromal tumours (GIST) are rare tumours of mesenchymal origin. These can be associated with neurofibromatosis type 1 (NF1), which is an autosomal dominant disorder. The prevalence of GIST in NF1 is estimated at 3.9-25%. This paper describes the presentation of a GIST arising from the jejenum in a 75-year-old lady with NF1, who presented with gastrointestinal bleeding. This was diagnosed by CT angiography. She was managed with laparotomy, with resection of small bowel, and an ischaemic segment of large bowel with two primary anastomoses. Pathology showed GIST of spindle cell type (Figs 3 and 4), 90 mm in size, with complete local excision. The patient was discharged on the eighth post-operative day and is currently undergoing regular clinic follow-up after multidisciplinary team meeting discussion
Dynamical Interactions Make Hot Jupiters in Open Star Clusters
Explaining the origin and evolution of exoplanetary "hot Jupiters" remains a
significant challenge. One possible mechanism for their production is
planet-planet interactions, which produces hot Jupiters from planets born far
from their host stars but near their dynamical stability limits. In the much
more likely case of planets born far from their dynamical stability limits, can
hot Jupiters can be formed in star clusters? Our N-body simulations of
planetary systems inside star clusters answer this question in the affirmative,
and show that hot Jupiter formation is not a rare event. We detail three case
studies of the dynamics-induced births of hot Jupiters on highly eccentric
orbits that can only occur inside star clusters. The hot Jupiters' orbits bear
remarkable similarities to those of some of the most extreme exoplanets known:
HAT-P-32 b, HAT-P-2 b, HD 80606 b and GJ 876 d. If stellar perturbations formed
these hot Jupiters then our simulations predict that these very hot, inner
planets are often accompanied by much more distant gas giants in highly
eccentric orbits.Comment: 18 pages, 4 figure
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