Browsing by Subject "intake"
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Item Evaluation of Performance in Yearling Crossbred Steers following Bovine Viral Diarrhea Virus Challenge(2013-10-31) Runyan, Chase AnthonyThis study investigated the effects of vaccine type, sire, day, threshold rectal temperature status, and their potential interactions on growth, daily feed intake and daily feed bunk frequency in response to a standardized Bovine Viral Diarrhea Virus (BVDV) challenge. Yearling, F2 and F3 Nellore-Angus steers (n = 380) from the Texas A&M McGregor Genomics herd were utilized over 4 years, and were stratified by sire over three vaccine groups of modified-live (MLV), killed (KV), and non-vaccinated (NON). Vaccines were used in accordance to label directions, and MLV steers were separated from KV and NON steers for 7 to 10 days to prevent transmission of viral particles. All steers were intranasally challenged with BVDV type 1b strain CA0401186A on day 0 of each year. Clinical signs of illness and feeding behavior data were collected daily, while rectal temperature and weight records were collected at days 0, 3, 7, 10, 14, 28, and 42 post-vaccination. The influence of sire was a significant source of variation as both a main effect or as an interaction term for all response variables analyzed. Vaccine type was a significant source of variation as components of interaction terms; lower (P < 0.05) mean rectal temperature was seen in MLV as compared to KV and NON steers. Variation from sire and vaccine type interaction suggests the potential of matching genetic profiles and vaccine protocols to achieve optimum levels of production measures. Daily feed intake and daily bunk visit frequency tended to decrease through day 7, but these traits should be interpreted separately due to the effects of sire and sire by vaccine type interactions. Higher number of bunk visits did not explain levels of intake within some sire groups and vaccine groups. Lung tissue disruption based on color scores of 3 or 4, on 5-point scale was present in more than 65% of cattle that did not have elevated rectal temperature above 40oC, the threshold basis for provision of antibiotic treatment. Interactions involving sire, vaccine type or rectal temperature status with other factors in this trial illustrates complexity regarding interpretation of cattle health impacts on production traits.Item External detection and measurement of inhaled radionuclides using thermoluminescent dosimeters(Texas A&M University, 2007-04-25) Prause, Christopher AlvinMany radiation detection programs use bio-assays, whole-body counters, or air sampling to estimate internal doses. This study examines the possibility of using a common external thermoluminescent dosimeter (TLD) badge as a device for detecting inhaled radionuclides through radiation those radionuclides emit which escape the body. The three common radionuclides chosen for modeling due to their varying decay modes and use or production in the nuclear industry were Cs-137, U-238, and Sr-90. These three radionuclides were modeled for biological and radiological removal in the dynamic systems modeling program of STELLA II and modeled for TLD dose per organ in the geometry and radiation simulation program of MCNP. The results show that none of the nuclides in the study can be detected at air concentrations below regulatory limits for acute inhalation exposures. To achieve a detectable dose from an 8-hour work exposure, with a 90-day wait until the TLD is read, the airborne concentrations for the inhalation classes that produced the most dose per Bq would be 37.9 kBq/m3, 146 MBq/m3, and 1.67 MBq/m3 for Cs-137, U-238, and Sr-90, respectively.Item Fecal near-infrared reflectance spectroscopy calibrations for predicting diet quality and intake of donkeys(Texas A&M University, 2006-08-16) Kidane, Negusse FessehayeThe objective of these studies was to develop near-infrared reflectance spectroscopy calibration equations from diet-fecal pair datasets to predict the diet quality and intake of donkeys. One hundred-forty diet-fecal pair samples were generated from two independent in vivo feeding trials conducted in the United States (N = 100) and Africa (N = 40). At each site, ten female donkeys were fed mixed diets blended from 25 forage and crop residues. The modified partial least square model (MPLS) was used to develop calibration equations for crude protein (CP), digestible organic matter (DOM), dry matter digestibility (DDM) and organic matter digestibility (OMD), for the US, Africa and US/Africa combined datasets, and dry matter (DM) and organic matter (OM) intake calibrations from the US datasets. Crude protein (CP) equations were developed with standard error of calibration (SEC) < 1.0 and coefficient of determination (R2) > 0.90, (SEL = 0.5). The US, US/Africa and Africa CP equations had SEC value of 0.77, 0.97 and 0.88 with corresponding R2 of 0.97, 0.95 and 0.88, respectively. Validation of the US CP equation resulted in a standard error of prediction (SEP) of 1.79 with corresponding coefficient of correlation (r2) of 0.82 and slope of 0.84 indicating high accuracy of prediction. In vivo derived DOM equations were also developed for the US, Africa and US/Africa datasets with SEC values of 2.58, 4.91 and 3.52, and R2 of 0.60, 0.81 and 0.84, respectively. In addition, the SEC and R2 values were 3.25 and 0.72 for US OMD, 3.28 and 0.79 for US DDM, and 4.2 and 0.85 for US/Africa OMD, and 4.3 and 0.87 for US/Africa DDM equation, respectively. Calibration equations for predicting DMI and OMI have resulted in SEC values of 3.45 and 3.21 (g/kgw0.75) and R2 values of 0.89 and 0.84, respectively. The present study explored the relationship between DMI and diet quality attributes. Crude protein and digestible organic matter to crude protein ration (DOM/CP) with r2 values of 0.60 and 0.39, respectively, have shown good correlations with intake. The present studies have confirmed the potential for the fecal NIRS profiling for predicting CP, DOM, DDM, OMD, DMI and OMI of donkeys. Both calibration and validation results have indicated that the present donkey equations were comparable to previously developed equations for ruminants; they have the capability for accurate prediction of diet quality and intake, and can be a useful tool for monitoring the nutritional well-being of donkeys with acceptable accuracy. Research works to further expand the present calibration equations with additional diet-fecal samples particularly from Africa that did not meet the required accuracy level is recommended.