Environmental sources within 5 feedlots were sampled for E. coli O157:H7 and O157:NM to determine the prevalence of this pathogen with a view to minimize or control its spread in the feedlot environment. Monthly samples were taken from the feedlots in the Panhandle and South Plains of Texas over a nine-month period. Samples were examined by an immunomagnetic bead separation, followed by plating onto CT-SMAC and CHROMagar O157 media. Sorbitol-negative colonies were tested using ImmunoCard Stat! E. coli O157:H7 Plus and confirmed as E. coli O157:H7, using biochemical (Vitek system) and serological tests (latex agglutination). Additionally, one hundred sponge samples were collected from the hides of stunned cattle at the slaughter plant. All isolates were subjected to rep-PCR DNA fingerprinting and antimicrobial profiling. E. coli O157 was isolated from hide (56%) and environmental samples (4%). E. coli O157 was isolated from all environmental sources, with peak prevalence during November (9%) and March (10%). At least one sample from each feedlot was positive 42% of the time. The most contaminated sites were the chute area (6%) and sludge from waste water ponds (6%). Positive samples were most frequently found from feedlot 5 (7%) and the greatest variation in positive samples between feedlots (0-34%) occurred during March. A decrease in the presence of E. coli O157 in feedlots was observed during January (0%), when ambient, water, and pond sludge temperatures were consistently low. No correlation with other environmental factors was observed. Hide was a primary source of E. coli O157 on carcasses with an overall prevalence of 56%. Of two sampling days, the number of positive hide samples varied from 14% for the first day to 98% for the second day. The total positive samples collected (environmental (47); hide (56)) were 64% H7, and 36% NM. The environmental isolates showed similar antibiotic resistance patterns, regardless of the source. Most E. coli O157 isolates from the feedlots and hides showed a high level of resistance to cephalothin (45%) and sulfisoxazole (56%). E. coli O157 isolates from feedlots were resistant to more than 10 antibiotics (9/317). All of the isolates appeared highly similar, with an average similarity of 53% by rep-PCR DNA fingerprinting.

The study evaluates the potential of pine litter for use as a substrate in the propagation of vegetable transplants in trays. Sub-optimum pH and electrical conductivity of pine litter were addressed by incorporating 10 % feedlot manure by volume. The water holding capacities of pine litter and the pine litter-feedlot manure mixture were higher than the minimum required, but their air filled porosities were below optimum. The pine litter-feedlot manure mixture reduced the germination percentages of cabbage seedlings by 17 % and lettuce seedlings by 13 % relative to composted pine bark, but the germination percentage of tomato seedlings was similar in both substrates. There were no significant differences in the growth of vegetable transplants between the two substrates. In both substrates increasing nutrient availability by adding controlled-release fertilizer had similar positive effects on the growth transplants. Substrate-nutrient availability interactions were only observed in dry shoot mass of lettuce seedlings and dry root mass of tomato seedlings. Composting the pine-litter animal manure mixture could possibly improve the observed low germination percentage of vegetable transplants in pine litter.

No description available.

A comparative study of the parasites Cryptosporidium andersoni and Giardia duodenalis in feedlot cattle in Western Australia (n=502) and Alberta, Canada (n=852) was conducted. The objectives were to determine the prevalence, infection patterns and impact on cattle performance of these protozoan parasites. Utilizing molecular tools G. duodenalis was genotyped and C. andersoni samples were confirmed positive. C. parvum was absent from all cattle sampled in Alberta, Canada and Western Australia, likely due to the advanced age of the cattle being sampled (6-36 months of age). No C. bovis or C. ryanae were observed in the study cattle. C. andersoni was present in 25% of the groups of feedlot cattle sampled in Western Australia with a prevalence range of 0-26% and in all 3 of the Alberta, Canada study groups with a prevalence range of 2.9-12%. All three Alberta, Canada studies collected performance data, however, there was no significant difference between infected and non-infected steers’ ADG in the feedlot. G. duodenalis was present in 83% of the groups sampled in Western Australia with prevalence ranging from 0–22% and all three study groups sampled in Alberta, Canada were positive with a prevalence ranging from 39–82%. The prevalence of G. duodenalis is significantly higher in the Alberta, Canada studies as compared to the Western Australia studies, probably due to climatic factors. Molecular characterization of a small number of the Alberta, Canada G. duodenalis positive samples (10) revealed 30% (3) genotype A, and 70% (7) genotype E. The same characterization of the Western Australia samples (10) showed 20%(2) genotype A, 40% (4) genotype E, 10% (1) genotype B, 10% (1) genotype C, 10% (1) genotype D and 10% (1) genotype B and E. Due to the unusual finding of genotypes C and D in cattle on such a small number of samples this result should be further studied to either confirm or refute the existence of genotypes C and D in cattle. Based on these results 30% of the animals from Alberta, Canada have the potential to be zoonoti (genotypes A and B) and 40% from the Western Australia studies. The results of this study demonstrate that C. andersoni and G. duodenalis are prevalent in the study feedlot cattle in Western Australia and Alberta, Canada however the impact of these parasites was not negative on animal performance in the Alberta, Canada studies where it was measured.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The 2011 National Feeder Cattle Audit evaluated 42,704 cattle in 260 lots from 12 Texas and five Nebraska feedyards to determine BQA adherence, the effects prior management and transportation practices had on feedyard performance and health, and established industry benchmark data so that future advancements and improvements in beef quality related areas can be monitored. This study suggested most feedyard managers and some cow-calf producers and stocker operators have implemented Beef Quality Assurance plans into their respective operations. Survey data documents that the many stakeholders in the beef cattle industry have followed BQA guidelines in an effort to improve the quality and safety of beef being produced. The lots of cattle traveled an average distance of 468 miles from their origin to the feedyard and spent an average of 185.7 days on feed. The majority of the lots were from a single-source origin. Of the cattle where feedlot performance data was available, they gained an average of 3.2 lb/day and converted at 6.2:1. Across all lots, the average animal cost per day was $3.30. Cattle in the feedyard appeared healthy with a 1.7% average death loss and 19.6% average morbidity rate. Processing costs averaged $14.47 per animal, and medicine costs were $5.22 per animal in the lot. The majority of lots had lot tags present in their ear (98.8%), were branded with at least one hide brand (64.3%) and were polled (79.8%). The cattle had primarily a solid hide color (70.7%) and were black (49.6%). Lots appeared uniform with 82.9% being termed slightly to extremely uniform and only 17.1% of the evaluated lots being assessed as slightly to extremely variable. Cattle that traveled further distances to the feedyard had higher processing costs, but in turn did not have differences in medicine costs through the finishing period. It appears the industry will need more communication across the different segments to ensure a sustainable future. Continuing to track cattle origin and what management practices have been done will be important so that cattle can be received with the appropriate processing protocol. Across-segment collaboration and communication provides economic opportunities for beef cattle producers.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Daniel U. Thomson / In current literature, there is a limited amount of large scale data available demonstrating lameness morbidity in beef cattle feedlots, the subsequent outcomes of individuals exhibiting lameness, the morbidity and mortality of various lameness diagnoses, or the effect of locomotion score at the time of first morbidity and its effect on outcome. In addition, current perceptions of lameness by feedlot industry participants are not known and a reliable locomotion scoring system fit for use in a feedlot setting has not been developed. Consequently, the objectives of this research were three-fold. First, to obtain a baseline of the perception of lameness within the feedlot industry. Second, to develop a functional locomotion scoring system for use in feedlots and to test a training program implementing this locomotion scoring system for inter-rater reliability. Third, determine the association of lameness diagnosis and locomotion score at time of initial lameness diagnosis with case outcome in feedlot cattle and provide beef cattle feedlot lameness morbidity, mortality, and realizer incidence rates due to different lameness etiologies in a large scale, multisite study. One hundred forty-seven consulting nutritionists, veterinarians, and feedlot managers participated in the feedlot cattle lameness survey. The median response of estimated lameness incidence in the feedyard was 2%, with a mode of 1% and a mean of 3.8%. Participants indicated that footrot, injury, and toe abscesses were the most common causes of lameness. A locomotion scoring system was developed to clinically assess locomotion of beef cattle. The scoring system consisted of 4 categories: normal movement (0), slightly affected gait (1), obviously shortened stride or bobbing of head (2), and reluctance to move or apply weight to the limb while walking or standing (3). A total of 50 commercial feedlot employees and agricultural students were trained to use the scoring system in either English or Spanish. The scoring system was tested for inter-rater agreement and rater agreement against a cooperative standard based on consensus score by a team of individuals involved in the development of the scoring system, which included beef cattle veterinarians and welfare experts. Intra-class correlation coefficient (ICC) and Fleiss’s kappa were used to evaluate inter-rater agreement and rater agreement against the cooperative standard. Inter-rater agreement using ICC was 0.85 (95% CI; 0.75 to 0.93) while the mean kappa value was 0.52 (moderate agreement). Rater agreement with the cooperative standard resulted in mean kappa value of 0.64 (substantial agreement). A dynamic population longitudinal study with an initial study population of 245,494 head of feedlot cattle, with 524,780 animal arrivals and 527,220 animal departures recorded over the 12-month study was conducted over a year by trained personnel in six participating feedlots located in Kansas and Nebraska. Lameness morbidity incidence was 1.04 cases per 100 animal-years; lameness mortality was 0.397 cases per 100 animal-years. Cattle locomotion score (LMS; scale of 0 to 3 at time of initial diagnosis) were LMS1(22% of lameness cases), LMS2 (31%), and LMS3(22%). 24% of the lameness cases were not assigned a locomotion score (NS). Mortality risks were greatest for LMS3 (33.0%) and NS (31.3%), and were least for LMS1 (10.0%) with LMS2 (19.1%) being intermediate (P < 0.05).

The objective of this study was to characterize genetic relationships between growth and carcass traits measured in commercial feedlot and purebred cattle that would aid in determining the effectiveness of combined crossbred and purebred selection (CCPS) strategies for sire selection. Data included 2,183 steers and 418 heifers enrolled in the Tri-County Steer Carcass Futurity (TC). Feedlot traits evaluated were initial body weight at time of delivery (IBW) and final BW at time of harvest (FBW) and carcass backfat thickness at the 12th rib (CFAT), marbling score at the 12th rib (CMAR) and ribeye area at the12th rib (CREA). Purebred data from the American Angus Association (AAA) included records of 139,602 bulls, 130,944 heifers and 6,656 steers for weaning weight (WW); 85,702 bulls, 76,603 heifers and 1,908 steers for yearling weight (YW); and 62,752 bulls and 45,958 heifers for ultrasound measures of backfat thickness at the 12th rib (UFAT), intramuscular fat percentage at the 12th rib (UMAR) and ribeye area at the 12th rib (UREA). The genetic correlations between IBW and WW, FBW and YW, CFAT and UFAT, CMAR and UMAR, and CREA and UREA were 0.01 ° 0.21, 0.43 ° 0.22, 0.66 ° 0.19, 0.65 ° 0.17, and 0.92 ° 0.12, respectively. Regressions of TC traits on corresponding sire EPD resulted in coefficients of 0.23 ° 0.19, 0.57 ° 0.16, 0.67 ° 0.19, 93.3 ° 12.3, and 1.08 ° 0.17 for IBW, FBW, CFAT, CMAR, and CREA, respectively. Three selection indices were evaluated on the basis of relative efficiency of genetic progress toward TC goal traits. The index including AAA records on an individual sire with TC records on his progeny was most effective, thus indicating the benefit of CCPS. / Master of Science

Doctor of Philosophy / Diagnostic Medicine/Pathobiology / David G. Renter / Shiga toxin-producing Escherichia coli serogroups (O26, O45, O103, O111, O121, O145, and O157; STEC-7) are recognized as major food-borne pathogens with outbreaks, human infections, and occasional deaths associated with the consumption of contaminated foods. Cattle are recognized as the primary reservoir for STEC-7 and shed these bacteria in their feces, which are considered a principal source of contamination of cattle hides and carcasses at harvest. Pre-harvest interventions that effectively reduce fecal shedding of STEC-7 have the potential to reduce the public health concerns and economic impact of these bacteria and enhance food safety. In the research presented in this dissertation, distinct study designs were used to evaluate the impact of commercially available pre-harvest interventions and develop a better understanding of the epidemiology of STEC-7 in commercial feedlot cattle. A randomized pen-level trial indicated that a commercially available vaccine significantly reduced the fecal prevalence of STEC O157 and prevalence of high shedders compared to unvaccinated pens. However, there was no evidence of a direct-fed microbial (DFM) effect on either measure of STEC O157 shedding. In a continuum of the efficacy study, the performance and carcass characteristics associated with these pre-harvest interventions were quantified. Results indicated that feeding the DFM to cattle improved performance, whereas the vaccine negatively impacted performance during the intervention period, though most of these attributes were not reflected at the time the animals were harvested. Later, a cross-sectional observational study was used to determine the regional-, feedlot- and pen-level fecal prevalence of enterohemorrhagic Escherichia coli (EHEC), a subset of STEC, in commercial feedlot cattle. Results indicated that EHEC serogroup O157 was detected more frequently than non-O157 serogroups of EHEC; however, all feedlots had at least one sample positive for both O157 and non-O157 EHEC. Further, risk factors associated with non-O157 serogroups of EHEC were identified; further evaluation of these factors as potential control points may enable the ability to positively impact public health concerns and food safety by reducing the pathogen load prior to harvest. Overall, the research described in this dissertation provides an assessment of pre-harvest interventions and multi-level prevalence estimates of STEC-7 in commercial feedlot operations.

Two studies were performed to investigate the ability of a portable near-infrared spectrophotometer (NIRS) for on-site analysis of nutrient components in feces from cattle. In trial 1 of study 1, growing dairy steers were fed diets containing either 86 or 90% concentrate. Regression values from a calibration set of 56 samples were promising for CP, DM, and NDF, but not for ADF or starch. In trial 2 of study 1, finishing dairy steers were fed diets containing either thick (512 g/L) or thin (460 g/L) steam-flaked corn. Regression values from a calibration set of 126 samples were poor for all nutrients. Both studies showed statistically valid NIRS calibrations, but further validation was required to make regression values acceptable (R² > 0.80) for all fecal nutrient components. In study 2, NIRS analysis was employed on novel research. Young dairy bull calves were fed diets containing either whole or steam-flaked corn from pre-weaning until 8 weeks post-weaning when the first animal was heavy enough for inclusion into a commercial feedlot. Again, although statistically valid, regression values from a calibration set of 220 samples were promising for CP and ADF, but not predictive for DM, NDF, ash, and starch. Growth performance parameters were similar between diets, with starch digestibilities diverging after weaning and changing to a Holstein starter diet. These 2 studies show that commercial and research application of a portable NIRS for on-site analysis of the nutrient composition of feces from young, growing, and finishing dairy steers statistically possible but requires further validation research. Also, results from the second study imply that there is no advantage in feeding steam-flaked corn to dairy calves from pre-weaning to 8 weeks post-weaning or until reaching feedlot weight. However, starch digestibility begins to improve for steam-flaked corn to whole corn once the animal has been weaned.