8,096 research outputs found
Increasing the Frequency of Twinning in Beef Cows
The beef cow must be maintained throughout the year to produce only one useful product, a weaner calf. If she fails to wean a calf, the costs of maintaining her must be borne by the productive members of the herd. In the United States, the estimated percent calf crop ranges from 65 to 90% with 85% suggested as average for the more productive areas of the country. This means maintaining 100 cows for every 85 calves weaned. However, the rancher normally must add replacement heifers at the rate of 15% of the cow herd each year. This means marketing 70 weaning calves per 100 cows. One potential method of improving production efficiency is to increase the number of calves per 100 cows. Twinning could be a method of reaching this goal
A Comparison of Visual Observation and KaMar Heat Detectors as a Means of Detecting Heat in Heifers
The key to any successful artificial insemination program is doing an adequate job of detecting cows in heat. Not only is heat detection difficult for the inexperienced person, it requires considerable time and labor. There are devices available on the market which are designed to reduce labor requirements associated with heat detection. One of these devices is the heatmotmt detector called KaMar® (KaMar Inc., Steamboat Springs, Colorado). The purpose of this study was to compare the KaMar patch to a person experienced in detecting yearling heifers in heat
Influence of Temporary Chemical Immobilization of Boar Spermatozoa Upon In Vitro Survival
The use of artificial insemination (AI) in swine has been restricted because of the inability to store semen. It is usually recommended that for AI use boar semen not be stored more than 48 hours. Obviously, the goal is to develop a technique whereby boar semen could be stored indefinitely such as is the case with bull semen. However, until such a technique is developed, a method of storing boar semen for a few days would be of value for promoting AI in swine
An Integral Field Study of Abundance Gradients in Nearby LIRGs
We present for the first time metallicity maps generated using data from the
Wide Field Spectrograph (WiFeS) on the ANU 2.3m of 9 Luminous Infrared Galaxies
(LIRGs) and discuss the abundance gradients and distribution of metals in these
systems. We have carried out optical integral field spectroscopy (IFS) of
several several LIRGs in various merger phases to investigate the merger
process. In a major merger of two spiral galaxies with preexisting disk
abundance gradients, the changing distribution of metals can be used as a
tracer of gas flows in the merging system as low metallicity gas is transported
from the outskirts of each galaxy to their nuclei. We employ this fact to probe
merger properties by using the emission lines in our IFS data to calculate the
gas-phase metallicity in each system. We create abundance maps and subsequently
derive a metallicity gradient from each map. We compare our measured gradients
to merger stage as well as several possible tracers of merger progress and
observed nuclear abundances. We discuss our work in the context of previous
abundance gradient observations and compare our results to new galaxy merger
models which trace metallicity gradient. Our results agree with the observed
flattening of metallicity gradients as a merger progresses. We compare our
results with new theoretical predictions that include chemical enrichment. Our
data show remarkable agreement with these simulations.Comment: Accepted for publication in ApJ. 26 pages, 18 figure
The Terzan 5 puzzle: discovery of a third, metal-poor component
We report on the discovery of 3 metal-poor giant stars in Terzan 5, a complex
stellar system in the the Galactic bulge, known to have two populations at
[Fe/H]=-0.25 and +0.3. For these 3 stars we present new echelle spectra
obtained with NIRSPEC at Keck II, which confirm their radial velocity
membership and provide average [Fe/H]=-0.79 dex iron abundance and
[alpha/Fe]=+0.36 dex enhancement. This new population extends the metallicity
range of Terzan~5 0.5 dex more metal poor, and it has properties consistent
with having formed from a gas polluted by core collapse supernovae.Comment: Accepted for publication on ApJ Lette
Physical, Chemical and Biological Assessment of Yoncalla Log Ponds
The Yoncalla Log Ponds are a series of four ponds located in within the city limits of the town in Yoncalla in northern Douglas County, Oregon. The ponds were created in stages between the late 1930s and the 1950s and used for log storage through the 1970s (North Douglas Betterment 2014). North Douglas Betterment purchased the land surrounding the ponds and contracted with the Center for Lakes and Reservoirs at Portland State University to assess the current morphometry, vegetation and water quality status of the ponds and provide recommendations for management of the aquatic vegetation. The scope of this document covers the current status assessment of the ponds using data collected from June 2013 through May 2014
Deep near-IR observations of the Globular Cluster M4: Hunting for Brown Dwarfs
We present an analysis of deep HST/WFC3 near-IR (NIR) imaging data of the
globular cluster M4. The best-photometry NIR colour-magnitude diagram (CMD)
clearly shows the main sequence extending towards the expected end of the
Hydrogen-burning limit and going beyond this point towards fainter sources. The
white dwarf sequence can be identified. As such, this is the deepest NIR CMD of
a globular cluster to date. Archival HST optical data were used for
proper-motion cleaning of the CMD and for distinguishing the white dwarfs (WDs)
from brown dwarf (BD) candidates. Detection limits in the NIR are around F110W
approx 26.5 mag and F160W approx27 mag, and in the optical around F775W approx
28 mag. Comparing our observed CMDs with theoretical models, we conclude that
we have reached beyond the H-burning limit in our NIR CMD and are probably just
above or around this limit in our optical-NIR CMDs. Thus, any faint NIR sources
that have no optical counterpart are potential BD candidates, since the optical
data are not deep enough to detect them. We visually inspected the positions of
NIR sources which are fainter than the H-burning limit in F110W and for which
the optical photometry did not return a counterpart. We found in total five
sources for which we did not get an optical measurement. For four of these five
sources, a faint optical counterpart could be visually identified, and an upper
optical magnitude was estimated. Based on these upper optical magnitude limits,
we conclude that one source is likely a WD, one source could either be a WD or
BD candidate, and the remaining two sources agree with being BD candidates. For
only one source no optical counterpart could be detected, which makes this
source a good BD candidate. We conclude that we found in total four good BD
candidates.Comment: ApJ accepted, 28 pages including 16 figure
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