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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A comparative study of giardia and cryptosporidium infections in feedlot cattle in Western Australia and Alberta, Canada

brenda.ralston@gov.ab.ca, Brenda Jane Ralston January 2009 (has links)
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.
2

Epidemiology of toe tip necrosis syndrome in western Canadian feedlot cattle

2014 September 1900 (has links)
Lameness continues to cause significant problems in profitability, productivity, and animal welfare in the feedlot industry. Toe tip necrosis syndrome (TTNS) is a new name for a previously reported condition. By definition, TTNS is separation of the apical white line with tissue necrosis and clinical lameness. This definition includes complications such as pedal (P3) osteitis, middle (P2) and proximal (P1) phalangeal osteomyelitis, tendonitis, tenosynovitis, cellulitis, and embolic pneumonia. Anecdotal experiences from practitioners report this lameness in feedlot cattle will develop within weeks after feedlot entry. Often the hindlimbs, specifically the lateral claw, are affected where a separation of the dorsal wall and sole will be noticed. Secondary infections will progress deeper into the foot and become systemic. Unfortunately, despite treatment, these animals can become very lame and will need to be euthanized. The overall objective of this project was to describe the epidemiology of TTNS in western Canadian feedlot cattle. The specific objectives were 1) to use clinical examinations, imaging modalities, and necropsy findings to aid in description, classification, and characterization of TTNS lesions, 2) to describe the epidemiology of TTNS in feedlot cattle, and 3) to evaluate risk factors for TTNS. Upon further investigation into this arrival related condition it became apparent that there were many different descriptors: P3 necrosis, toe abscess, apicus necrotica, apical pedal bone necrosis or toe necrosis. These names and descriptors of toe tip lesions were based on anecdotal experiences and previous case reports. As a result, traditional epidemiological approaches that included field investigations, clinical and necropsy examinations were implemented to identify, characterize and describe this condition. Based on clinical findings, imaging modalities, and necropsy specimens examined during September to December 2012, inclusive, a more specific name and descriptive case definition were introduced. TTNS descriptive epidemiology was described by use of a retrospective database analysis from Feedlot Health Management Services (FHMS) with 702 veterinarian confirmed TTNS cases by necropsy examination. From this database, there were 30% (210/702) of necropsy cases treated for TTNS and 70% of cases (492/702) that were not treated. Of those animals treated, the mean and standard deviation (median) interval from feedlot arrival to first treatment was 18.9 ±1.7 d (12 d). The mean (standard deviation) days on feed until death from TTNS was the earliest in grass-fed calves (32.4 ± 22.1 d), followed by auction-derived (40.6 ± 40.6 d), ranch direct (44.1 ± 53.1 d), and back-grounded calves (69.0 ± 75.6 d) (P < 0.001). Yearlings were on feed for a mean (standard deviation) days of 37.1 ± 32.0 d when compared to calves at 49.5 ± 57.0 d before death (P < 0.001). The greatest proportion of deaths occurred from September to November. There were 96.2% (1,832/1,904) of lots without one case of TTNS and 3.8% (72/1,904) of lots had one or more TTNS cases. A prospective case-control study to identify TTNS risk factors consisted of 148 total necropsy submissions (82 cases, 66 controls) from three feedlot veterinary practices and 16 feedlots during October 2012 to January 2013, inclusive. Confirmation of feet samples by the principal investigator at the Western College of Veterinary Medicine reduced the total to 135 animals: 67 cases and 68 controls. The measure of agreement (kappa) on classification of TTNS cases and controls between the veterinary practice and WCVM was 0.778 (P < 0.001). Bacterial culture results revealed that 75% of pure isolates in TTNS cases were attributed to Escherichia coli, Streptococcus spp., Trueperella pyogenes, Fusobacterium necrophorum. TTNS cases were 3.8 times more likely than control animals to have BVDV isolated (95% CI 1.7-8.5; P < 0.001). TTNS animals were 2.2 times more likely than control animals to have histopathological evidence of vasculitis (95% CI 1.0-4.6; P = 0.04). BVDV samples were 11.2 times more likely to show histopathological evidence of vasculitis than non-BVDV samples (95% CI 4.7-27.0; P < 0.001). A decreased difference was found in sole thickness at the toe tip (P < 0.001). There was no evidence of pedal bone rotation between case and control animals (P = 0.15). In summary, TTNS is a specific term for apical white line separation with tissue necrosis and clinical lameness. A practitioner's field diagnosis of TTNS based on apical white line separation and tissue necrosis is accurate on clinical signs alone. TTNS is a transport or arrival related condition in feedlot cattle that has a propensity for cases to cluster together. Pure bacterial isolates provide an understanding of the pathogens responsible for TTNS and that environmental pathogens contribute to an ascending infection. BVDV, vasculitis and apical sole thickness were risk factors associated with TTNS; however, their exact role requires further investigation.
3

Effect of graded levels of wheat-based dried distiller's grains in a barley ration on the growth performance, carcass quality and rumen characteristics of feedlot steers

Beliveau, Renee Maxine 10 September 2008
Two trials were conducted to evaluate the effects of titrated levels of wheat-based dried distillers grains on feedlot performance, carcass characteristics and rumen fermentation parameters of cattle fed wheat-based dried distillers grains with solubles (DDGS). In trial 1, a barley grain-based diet (0% DDGS) was used as a control. It was formulated to 12% CP and 1.52 and 0.93 Mcal kg-1 net energy of maintenance (NEm ) and net energy of gain( NEg) respectively, during the backgrounding period and to 13% crude protein (CP) and 1.90 and 1.26 Mcal kg-1 NEm and NEg respectively, during finishing. Wheat-based DDGS replaced on a dry matter basis (DM) barley grain at levels of 8, 16, 24 and 32% during backgrounding and 6, 12, 18 and 23% during finishing. During backgrounding dry matter intake (P = 0.02), ADG (P = 0.04), and ultrasounded (US) longissimus. dorsi gain (P = 0.02) exhibited a cubic response to DDGS inclusion level with theoretical minima at 6.9, 8.1 and 6.9% DDGS respectively, and theoretical maxima responses at 27.2, 30.8 and 23.9% DDGS, respectively. Feed efficiency exhibited a quadratic response (P = 0.02) to DDGS inclusion level with a theoretical poorest response at 13.1% DDGS. Similar responses were noted during the first 56 d of the finishing period, however over the course of the finishing period no effect of DDGS inclusion level was noted on average daily gain (ADG), DMI, feed efficiency (FE), ultrasound measurements or on any carcass traits. <p>Trial 2 examined the effects of graded levels of wheat-based DDGS (0, 7, 14, 21% DM basis) on rumen fermentation characteristics using rumen cannulated heifers. Rumen pH measurements indicated that the pH mean at or below 5.8 and 5.5 decreased as DDGS inclusion level increased to 14% DM. The highest values (P<0.05) for pH area between the benchmarks of 5.5 and 5.2, pH area below 5.2 and time below pH 5.2 were found at the 14% DDGS inclusion level, pointing to rumen fermentation characteristics associated with severe rumen acidosis. Ammonia nitrogen levels, percent acetate, percent butyrate and the acetate: propionate ratio increased linearly (P < 0.0001) with DDGS. Propionate concentration decreased linearly (P = 0.006) as the level of DDGS increased. In situ rumen degradation kinetics showed that the DM and CP soluble fraction of DDGS to be significantly higher than that of rolled barley, however effective degradability of dry matter (EDDM) and effective degradability of crude protein (EDCP) were greater for barley. The results of this trial indicate that wheat-based DDGS has an energy value at least equal to that of barley grain with no adverse effects on cattle performance or carcass quality. Furthermore, since all treatments showed equal susceptibility to sub-acute ruminal acidosis (SARA) and therefore, wheat-based DDGS as a dietary ingredient is unable to mitigate rumen fermentation conditions associated with SARA.
4

Effect of graded levels of wheat-based dried distiller's grains in a barley ration on the growth performance, carcass quality and rumen characteristics of feedlot steers

Beliveau, Renee Maxine 10 September 2008 (has links)
Two trials were conducted to evaluate the effects of titrated levels of wheat-based dried distillers grains on feedlot performance, carcass characteristics and rumen fermentation parameters of cattle fed wheat-based dried distillers grains with solubles (DDGS). In trial 1, a barley grain-based diet (0% DDGS) was used as a control. It was formulated to 12% CP and 1.52 and 0.93 Mcal kg-1 net energy of maintenance (NEm ) and net energy of gain( NEg) respectively, during the backgrounding period and to 13% crude protein (CP) and 1.90 and 1.26 Mcal kg-1 NEm and NEg respectively, during finishing. Wheat-based DDGS replaced on a dry matter basis (DM) barley grain at levels of 8, 16, 24 and 32% during backgrounding and 6, 12, 18 and 23% during finishing. During backgrounding dry matter intake (P = 0.02), ADG (P = 0.04), and ultrasounded (US) longissimus. dorsi gain (P = 0.02) exhibited a cubic response to DDGS inclusion level with theoretical minima at 6.9, 8.1 and 6.9% DDGS respectively, and theoretical maxima responses at 27.2, 30.8 and 23.9% DDGS, respectively. Feed efficiency exhibited a quadratic response (P = 0.02) to DDGS inclusion level with a theoretical poorest response at 13.1% DDGS. Similar responses were noted during the first 56 d of the finishing period, however over the course of the finishing period no effect of DDGS inclusion level was noted on average daily gain (ADG), DMI, feed efficiency (FE), ultrasound measurements or on any carcass traits. <p>Trial 2 examined the effects of graded levels of wheat-based DDGS (0, 7, 14, 21% DM basis) on rumen fermentation characteristics using rumen cannulated heifers. Rumen pH measurements indicated that the pH mean at or below 5.8 and 5.5 decreased as DDGS inclusion level increased to 14% DM. The highest values (P<0.05) for pH area between the benchmarks of 5.5 and 5.2, pH area below 5.2 and time below pH 5.2 were found at the 14% DDGS inclusion level, pointing to rumen fermentation characteristics associated with severe rumen acidosis. Ammonia nitrogen levels, percent acetate, percent butyrate and the acetate: propionate ratio increased linearly (P < 0.0001) with DDGS. Propionate concentration decreased linearly (P = 0.006) as the level of DDGS increased. In situ rumen degradation kinetics showed that the DM and CP soluble fraction of DDGS to be significantly higher than that of rolled barley, however effective degradability of dry matter (EDDM) and effective degradability of crude protein (EDCP) were greater for barley. The results of this trial indicate that wheat-based DDGS has an energy value at least equal to that of barley grain with no adverse effects on cattle performance or carcass quality. Furthermore, since all treatments showed equal susceptibility to sub-acute ruminal acidosis (SARA) and therefore, wheat-based DDGS as a dietary ingredient is unable to mitigate rumen fermentation conditions associated with SARA.
5

Classical and molecular epidemiology of campylobacter, in particular <i>Campylobacter jejuni</i>, in the Alberta beef industry

Hannon, Sherry J 25 February 2009
This research used classical and molecular epidemiology tools to assess the potential importance of feedlot cattle as Campylobacter reservoirs. The project was conducted from November 2004 to September 2005 in southern Alberta.<p> Fresh pen-floor fecal samples were collected from commercial feedlot cattle near slaughter weight in seven feedlots. Overall, 87% of 2,776 fecal samples were culture positive for Campylobacter species (86% of 1,400 in winter, 88% of 1,376 in summer), and 69% of 1,486 Campylobacter positive isolates were identified as <i>Campylobacter jejuni</i>. After accounting for clustering within pen and feedlot, the number of days-on-feed and feedlot size were associated (p ¡Ü 0.05) with Campylobacter species isolation rates.<p> Retail ground beef was collected from 60 grocery stores (four chains, three cities). None of the 1,200 packages were culture positive for Campylobacter species. Polymerase chain reaction (PCR) results from a subset of samples (n=142) indicated that 48% of packages were positive for Campylobacter DNA. By species, 14.8% (21/142), 26.8% (38/142) and 1.4% (2/142) of packages were PCR positive for <i>C. jejuni</i>, <i>C. coli</i> and <i>C. hyointestinalis</i> DNA, respectively. The collection period (1, 2, 3 or 4) was associated (p ¡Ü 0.05) with the odds of detecting Campylobacter species DNA using PCR.<p> Oligonucleotide DNA microarrays were used as a platform for comparative genomic hybridization (CGH) analysis of 87 C. jejuni isolates (46 bovine, 41 human) obtained within the same geographical regions and time frame. Of the 13 CGH clusters identified based on overall comparative genomic profile similarity, nine contained human and cattle isolates, three contained only human isolates, and one contained only cattle isolates. In addition, human clinical and feedlot cattle C. jejuni isolates were compared on a gene-by-gene basis and only a small number of the 1,399 genes tested were unequally distributed between the two groups (p ¡Ü 0.05).<p> The high isolation rates of Campylobacter species and <i>C. jejuni</i> reported here may have implications for food safety, public health and environmental contamination. Our findings suggest that feedlot cattle and human <i>C. jejuni</i>strains are very similar and may be endemic within southern Alberta.
6

Classical and molecular epidemiology of campylobacter, in particular <i>Campylobacter jejuni</i>, in the Alberta beef industry

Hannon, Sherry J 25 February 2009 (has links)
This research used classical and molecular epidemiology tools to assess the potential importance of feedlot cattle as Campylobacter reservoirs. The project was conducted from November 2004 to September 2005 in southern Alberta.<p> Fresh pen-floor fecal samples were collected from commercial feedlot cattle near slaughter weight in seven feedlots. Overall, 87% of 2,776 fecal samples were culture positive for Campylobacter species (86% of 1,400 in winter, 88% of 1,376 in summer), and 69% of 1,486 Campylobacter positive isolates were identified as <i>Campylobacter jejuni</i>. After accounting for clustering within pen and feedlot, the number of days-on-feed and feedlot size were associated (p ¡Ü 0.05) with Campylobacter species isolation rates.<p> Retail ground beef was collected from 60 grocery stores (four chains, three cities). None of the 1,200 packages were culture positive for Campylobacter species. Polymerase chain reaction (PCR) results from a subset of samples (n=142) indicated that 48% of packages were positive for Campylobacter DNA. By species, 14.8% (21/142), 26.8% (38/142) and 1.4% (2/142) of packages were PCR positive for <i>C. jejuni</i>, <i>C. coli</i> and <i>C. hyointestinalis</i> DNA, respectively. The collection period (1, 2, 3 or 4) was associated (p ¡Ü 0.05) with the odds of detecting Campylobacter species DNA using PCR.<p> Oligonucleotide DNA microarrays were used as a platform for comparative genomic hybridization (CGH) analysis of 87 C. jejuni isolates (46 bovine, 41 human) obtained within the same geographical regions and time frame. Of the 13 CGH clusters identified based on overall comparative genomic profile similarity, nine contained human and cattle isolates, three contained only human isolates, and one contained only cattle isolates. In addition, human clinical and feedlot cattle C. jejuni isolates were compared on a gene-by-gene basis and only a small number of the 1,399 genes tested were unequally distributed between the two groups (p ¡Ü 0.05).<p> The high isolation rates of Campylobacter species and <i>C. jejuni</i> reported here may have implications for food safety, public health and environmental contamination. Our findings suggest that feedlot cattle and human <i>C. jejuni</i>strains are very similar and may be endemic within southern Alberta.
7

Quality Assessment of Feeder Cattle and Processes Based on Available Background Information

Franke, Jake 02 October 2013 (has links)
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.
8

Evaluation of canola meal derived from Brassica juncea and Brassica napus as an energy source for cattle

2013 December 1900 (has links)
Two trials were carried out to evaluate the effect of inclusion level of canola meal derived from Brassica (B.) napus and B. juncea on cattle performance and nutrient utilization. Trial 1 consisted of backgrounding (54 d) and finishing (153 d) phases. The control diet for the backgounding (BK) phase consisted of 39% barley silage, 30.4% barley grain, 22.8% brome grass hay and 7.8% supplement (DM). Treatments consisted of B. napus or B. juncea at 15 or 30% (DM) inclusion, replacing barley grain. The finishing control diet consisted of 88.3% barley grain, 4.4% barley silage and 7.3% supplement (DM). Treatments consisted of B. napus or B. juncea at 10 or 20% (DM) inclusion, replacing barley grain. During BK, dry matter intake (DMI), average daily gain (ADG), gain: feed (G:F) increased linearly (P < 0.01) as the level of inclusion of B. juncea meal increased. Cattle fed B. napus meal showed a quadratic response (P = 0.05) in DMI and linear increase (P = 0.02) in ADG with increasing inclusion. During finishing, DMI increased linearly (P = 0.05) for cattle fed B. juncea meal while a quadratic response (P = 0.02) was seen with B. napus meal. Feed efficiency and NEg content of the diet (P ≤ 0.02) decreased linearly with increasing inclusion of both meals. Trial 2 evaluated dietary rumen fermentation and total tract digestibility characteristics in a 5 x 5 Latin Square Design. Diets were similar to finishing phase of Trial 1. There was no effect of treatment on rumen pH, however a linear increase in acetate (P ≤ 0.01), ammonia (P < 0.01) and decrease (P < 0.01) in propionate was seen with both meal types. Crude protein and acid detergent fiber digestibility increased (P = 0.03) linearly with increasing inclusion of B. juncea meal. The results indicate that canola meal derived from B. napus and B. juncea is not suitable as a supplemental energy source replacing for barley grain in finishing diets but canola meal from B. juncea can be fed at levels up to 30% of the DM in backgrounding diets if priced appropriately.
9

Evaluation of genetic and physiological parameters associated with meat tenderness in South African feedlot cattle

Marais, Gertruida Louisa 26 June 2008 (has links)
The objective of this study was to compare prediction of meat tenderness by means of gene technologies (markers) with established physical estimates of meat tenderness. Weaned, young bulls (n = 60) were selected on phenotype from various commercial producers to represent a Brahman (Bos indicus; n = 20), Simmental (continental Bos Taurus; n = 20) and Nguni (Sanga; n = 20) crossbred group. After being raised under intensive feedlot conditions the animals were slaughtered according to normal South African slaughter procedures at an A-age (10 - 12 months) with a fatness class of two or three (lean-medium fatness). At slaughter the carcasses were not electrical stimulated because electrical stimulation influences the processes of meat tenderness, and the emphasis was on the expression of the inherent tenderness characteristics without external post mortem influences. Carcasses were halved, chilled at 4 ˚C within 2 hours post mortem. The M. longissimus thoracis et lumboram (LT and LL) of the right and left sides were removed from the third last rib to the last lumbar vertebra and sub sampled for shear force evaluations, SDS-PAGE, Western-blotting, myofibril fragmentation (MFL), sarcomere length (SL), calpain, calpastatin, total collagen, % collagen solubility and marker analysis. The position of sampling for each test was consistent and the different samples were either frozen immediately at -20 ˚C or -80 ˚C or vacuum packed and aged (2 ± 2 ˚C) for 7 or 14 days post mortem. Two single nucleotide polymorphism (SNP) markers were employed in this study for the bovine CAPN1 gene, which is found or situated on bovine chromosome 29, namely a SNP marker which is situated on exon nine (CAPN1-316) and the other on intron 17 (CAPN1-4751). The inhibitor, calpastatin (CAST) found on chromosome seven was also analysed in this study. Both the CAST markers (CAST and CAST-Brahman) lie in the three prime untranslated regions (3' UTR) of the CAST gene. Genotype data of two- markers were used to determine the two-marker haplotypes. The results of the study showed that differences exist in meat quality of the different crossbreds. Brahman- and Nguni-crosses had lower shear force values (more tender) than that of the Simmentaler-crosses under these specific experimental conditions. The pH decline did not differ significantly (p > 0.001) between the crossbreds. The carcass temperature and temperature decline rate although similar between the Brahman- and the Simmentaler-crosses for three hours and up to eight hours post mortem differed significantly from that of the Nguni-crosses (p < 0.006). The sarcomere lengths were mostly under 1.7 µm, which indicate that shortening (caused by rapid chilling) can not be eliminated. No significant differences were found between the different crossbreds for the calpastatin levels but significant differences were found for the µ-calpain activity and µ-calpain / calpastatin activity ratios. The Brahman-crosses had longer myofibril fragment lengths on average, indicating lower proteolysis / myofibrillar fragmentation compared to the other crossbreds. Myofibrillar protein degradation (titin, nebulin, desmin) and myofibrillar protein formation (30 kDa) during post mortem ageing was examined as a confirmation for the myofibril fragment length results. Significant differences between the crossbreds were found for titin degradation. Nguni-cross animals had significantly (p < 0.033) more titin present than the other crossbreds. Nebulin degradation showed a significant (p < 0.038) breed effect at 7 days post mortem and a significant degradation rate difference for breed types between 1 day and 7 days post mortem (p < 0.03) and 1 day and 14 days post mortem (p < 0.034). Desmin degradation evaluated with SDS-PAGE and Western-blotting indicated that the Simmentaler-cross animals had significantly (p < 0.018; p < 0.024, respectively) lower desmin levels compared to the other crossbreds. For the 30 kDa proteins there were no significant (p > 0.001) differences in data evaluated at 1 day, 7 and 14 days post mortem as well as for the formation rate. The results indicates that Brahman-crosses had the highest frequency for haplotypes that are associated with increased shear force, and thus tougher meat compared to the Simmentaler-crosses that had the highest frequency for haplotyes that are associated with lower shear force, and thus more tender meat, while Nguni-crosses were intermediate. A multiplex marker system incorporating both markers (316 and 4751) and indexes for the markers at CASTand CAPN1 genes were evaluated in this study. Considering the average index for the interactions between the CAST and CAPN1 genes, it can be concluded that the Nguni-cross was overall the breed with the highest potential for inherently tender meat. In general, the animals in this study had the tendency for tougher meat. The genetic markers (CAST and CAPN1) showed no association with Warner-Bratzler shear force (WBSF) (p > 0.05), which suggest that various mechanisms and environmental factors may be involved and give another outcome compared to the genetic make up. Simple correlation coefficients were generated between the different characteristics measured. If the group of animals in this study is indeed a typical representation of South African feedlot finished crossbred animals, the relatively high WBSF values emphasise the challenge to manipulate their intrinsic tenderness potential by making use of various pre- and post-slaughter techniques and procedures. / Dissertation (MSc(Agric) (Animal Science))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted
10

Crude glycerin in feedlot cattle diets and as a solvent in Maillard reaction processes intended for manufacturing value-added protein meals

Schneider, Cody James January 1900 (has links)
Master of Science / Department of Animal Sciences and Industry / James S. Drouillard / Two trials were conducted to evaluate effects of crude glycerin, a byproduct of the biodiesel industry, on feedlot performance, carcass characteristics, and diet digestibility in cattle. A third study was conducted to investigate the use of glycerin as a solvent in Maillard reaction processes used to manufacture value added protein meal. In trial 1, crossbred yearling heifers were fed low levels of glycerin (0, 0.5, or 2% of diet DM) in corn finishing diets, or diets that combined corn with soybean hulls and wet distiller’s grains (0 or 2% glycerin). Results indicated that feeding glycerin decreased DMI (P = 0.04), and feeding byproducts increased DMI (P < 0.01) when compared to control without byproducts or glycerin. Feeding byproducts or glycerin decreased the percentage of carcasses that graded USDA Choice or higher (P < 0.05). Other live performance traits and carcass characteristics were similar across treatments. Trial 2 evaluated effects of crude glycerin on growth performance and diet digestibility in heifers fed high forage growing diets. Treatments consisted of 0, 4, or 8% crude glycerin added to growing diets containing corn silage (60% of DM) and wet corn gluten feed. Apparent total tract digestibilities were calculated from total fecal collections. Adding glycerin linearly increased (P = 0.01) feed efficiency over the entire feeding period, and linearly decreased (P = 0.02) DMI for a portion of the feeding period. No other effects of glycerin on animal growth performance were observed. Digestibility measurements indicated that glycerin decreased DM, OM, and NDF intakes linearly (P < 0.01), but did not affect fecal outputs of DM, OM, or NDF. Apparent total tract digestibilities of DM, OM, and NDF therefore decreased linearly (P < 0.01) with increasing levels of glycerin. The third trial involved several experiments, which were conducted to determine if glycerol could be used as a solvent in processes designed to facilitate non-enzymatic browning of protein meals. Results indicated that glycerol may serve as a more suitable solvent for browning processes than water because its chemical and physical properties may enhance browning processes, increase process efficiency, and yield products with superior resistance to microbial degradation.

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