Submitted by FELIPE PELICIA LUIZ null (felipepelicia@yahoo.com.br) on 2016-09-13T10:17:01Z No. of bitstreams: 1 Dissertação de Mestrado Final 2.pdf: 781555 bytes, checksum: 2c33b3a220163de59e8b43b89c7d389e (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-09-14T19:01:20Z (GMT) No. of bitstreams: 1 luiz_fp_me_bot.pdf: 781555 bytes, checksum: 2c33b3a220163de59e8b43b89c7d389e (MD5) / Made available in DSpace on 2016-09-14T19:01:20Z (GMT). No. of bitstreams: 1 luiz_fp_me_bot.pdf: 781555 bytes, checksum: 2c33b3a220163de59e8b43b89c7d389e (MD5) Previous issue date: 2016-08-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste estudo foi estudar o efeito do uso combinado de monensina sódica (MON) e virginiamicina (VM) sobre as características da carne fresca (pH, teor de proteína bruta, extrato etéreo, umidade, matéria mineral, perda por cocção e cor), além da avaliação da carne cozida através de painel sensorial e força de cisalhamento. Foram utilizados 72 animais machos não castrados da raça Nelore, com peso vivo médio inicial de 388±31,07 kg, provindos de sistema de recria em pasto. Os animais foram divididos em 4 tratamentos de acordo com associação ou não dos aditivos nas fases de adaptação e terminação: MON (30 mg/kg) na adaptação + terminação; MON (30 mg/kg) + VM (25 mg/kg) na adaptação e VM (25 mg/kg) na terminação; MON (30 mg/kg) + VM (25 mg/kg) na adaptação e VM (25 mg/kg) + MON (30 mg/kg) na terminação e VM (25 mg/kg) na adaptação e MON (30 mg/kg) + VM (25 mg/kg) na terminação, caracterizando assim delineamento em blocos casualizados, com 6 repetições cada tratamento (3 animais por baia, sendo as baias as unidades experimentais). A duração do experimento foi de 90 dias, sendo 19 dias de adaptação, divididos em três períodos (7, 5 e 7 dias) com dietas de 69, e 79% de ingredientes concentrados, respectivamente; e 71 dias de terminação, com dieta contendo 84% de concentrado. Para avaliação da qualidade de carne foram utilizados 24 animais. A associação de MON e VM não apresentou influência pH, composição centesimal, perda por cocção e força de cisalhamento da carne fresca. O aroma e o sabor da carne cozida também não apresentaram diferença em relação aos tratamentos. Portanto mediante os dados apresentados e discutidos, é possível utilizar desta estratégia nutricional sem maiores preocupações com impactos negativos sobre a qualidade da carne. / The experiment was designed to evaluate the effect of combined use of monensin (MON) and virginiamycin (VM) on the characteristics of fresh meat (pH, protein, fat content, moisture, ash, cooking water loss and hue), and the evaluation of cooked meat through sensory panel and shear force.Were used 72 bulls Nelore cattle, with average live weight 388 ± 31.07 kg, coming from pasture system. The animals were divided on four treatments according to affix or not of additives on adaptation phases and finishing: MON (30 mg / kg) on adaptation and finishing ; MON (30 mg / kg) + VM (25mg / kg) on the adaptation and VM (25mg / kg) at finishing; MON (30 mg / kg) + VM (25mg / kg) in the adaptation and MV (25 mg / kg) + MON (30 mg / kg) on the finishing and VM (25 mg / kg) in the adaptation and MON (30 mg / kg) + VM (25 mg / kg) on the finishing, characterizing a randomized block design, where each treatment had 6 replicates (3 animals per pen, and they were considered as experimental units bays). The experiment lasted 90 days, 19 days of adaptation, divided into three periods (7, 5 and 7 days) diets of 69, 74 and 79% of concentrated ingredients, respectively; and 71 days finishing, with ration containing 84% concentrate. To evaluate the quality of meat were used 24 animals. The MON and VM association not caused effect on the pH, protein, fat content, moisture, ash, cooking water loss and meat color. The smell and taste of cooked meat also showed no difference in relation to treatment. So by the data presented and discussed, it's possible the use this nutritional strategy without major concerns about negative impacts on the quality of meat.

Master of Science / Department of Animal Sciences and Industry / James S. Drouillard / Ruminal characteristics and feedlot performance were measured for steers adapted to a high-grain diet using a traditional 22-d step-up program (Control) and for steers adapted over 10 d with the aid of M. elsdenii NCIMB 41125 fresh culture administered as an oral gavage (Fresh), an oral gavage of rehydrated lyophilized culture (Rehyd), or Rehyd combined with lyophilized culture powder administered daily as a ration top-dress (Rehyd+Daily). Yearling steers (n = 435; initial BW = 408 ± 5 kg) were blocked by weight and randomly allocated to 64 concrete surfaced pens with 7 steers/pen and 16 pens/treatment. Step-up diets contained 40, 30, and 20% corn silage, and were followed by a finishing diet containing 10% corn silage and 90% concentrate. Ruminal fluid was obtained from a subset of steers by rumenocentesis 26 h after their first feeding, and inoculated into culture tubes containing lactate medium to determine differences in capacity for lactate metabolism over 24 h. A radiofrequency pH bolus was placed in the reticulorumen of 32 steers, that measured ruminal pH every 10 min for 124 d. Steers were fed once daily ad libitum for 156 d, then weighed, and transported 450 km to a commercial abattoir for harvest. HCW and incidence of liver abscesses were determined at harvest and carcass traits were evaluated after 36 h of refrigeration. No differences were detected for feedlot performance (P > 0.20), liver abscesses (P = 0.45), or carcass traits (P > 0.20). Capacity for lactate utilization was increased with all forms of M. elsdenii, as evidenced by increases in optical density (absorbance) of M. elsdenii cultures, disappearance of lactate, and increase in butyrate production (P < 0.01). Steers on Rehyd and Rehyd+Daily treatments spent less time between pH thresholds of 5.6 > pH > 5.2 (P < 0.01); 5.2 > pH > 5.0 (P < 0.01); and pH < 5.0 (P < 0.01) than Controls throughout the finishing period. In conclusion, steers dosed with M. elsdenii can be stepped up to finishing diets in 10 d with no adverse effects on performance. Ruminal fluid containing fresh cultures or freeze-dried and rehydrated cultures of M. elsdenii NCIMB 41125 were equally effective in metabolizing lactic acid. Lyophilized M. elsdenii resulted in less time below important pH thresholds, but no further benefit of daily administration was realized in this experiment.

Master of Science in Biomedical Sciences / Department of Clinical Sciences / Robert L. Larson / Bradley J. White / Feedlot cattle frequently endure high environmental temperature-humidity index conditions in the summer months within cattle feeding regions of North America. Heat stress develops when the total heat gain (combined effects of environmental and metabolic factors) exceeds an animal’s heat loss capabilities. The objective of my research was evaluating heat mitigation strategies and developing a practical method to identify animals that are of greatest risk of heat stress; thus improving animal welfare and performance. A number of heat abatement strategies have been utilized in US feedlots including shade, sprinklers, nutritional modifications, and misters. A literature review was performed using published journal articles demonstrated significant benefits of providing shade to feedlot cattle. Sprinkling the pen surface may be just as beneficial as sprinkling or misting cattle. Sprinkling the ground not only cooled the ground which increased the thermal gradient between lying cattle and the ground, but also provided increased thermal conductivity and better heat flow down that gradient. A study was performed to develop a noninvasive, remotely applied, practical method to identify animals at risk for heat stress. Infrared thermography images were obtained during the morning hours and pant scores obtained in the afternoon hours. Data mining techniques were employed to evaluate accuracy of potential classification methods to identify heat stress events in the afternoon based on the known morning data. Using infrared technology as a diagnostic test was not accurate for predicting heat stress events in the study presented. Finally a retrospective study of Kansas feedlot performance, medical and weather data was performed. Findings indicate that diagnostic counts of bovine respiratory disease are associated with elevated ambient temperature two days prior. In conclusion, heat stress in beef feedlot animals is an important area of research. Heat mitigation methods such as shade have been proven to be effective at reducing heat stress in beef feeder cattle. Further research is needed to evaluate the use of infrared technology to predict heat stress events in the feedlot setting.

Master of Science / Department of Biological & Agricultural Engineering / James K. Koelliker / In 2003, the EPA changed Confined Animal Feedlot Operation (CAFO) regulations to allow an alternative treatment system for feedlot runoff if a 25-year simulation can show better performance for the alternative treatment system when compared to a traditional lagoon system. A continuous computer simulation model written in C was developed to compare the release of water, nitrogen (N), phosphorous (P) and chemical oxygen demand (COD) from a Vegetated Treatment Area (VTA) system and a conventional lagoon system in Kansas. The model simulates the transport of water and constituents in a feedlot, settling basin, lagoon, and VTA. The feedlot runoff is based on NRCS unit hydrograph method for the water balance and AnnAgNPS for the constituent runoff concentrations. The settling basin is a simple water balance with sediment, organic-N, P, and COD removed with settling of the solids. The VTA is designed to calculate infiltration with Green-Ampt Equation and overland flow with Manning's Law. The VTA removes organic-N and P with the Kentucky Filtration Model. The lagoon is derived from Koelliker et al. model water balance and pumping schedule with constituent balance from Miner et al. model. VTA portion of the model was analyzed for sensitivity and calibrated with three storms. The sensitivity analysis showed that the size of the VTA and conductivity of the soil in the VTA causes the greatest variability in the release of N, P, and COD. The calibration of the release of organic-N and P for mean particle diameter showed that a diameter of 1.5 µm produced the best agreement. The model was used for a lagoon and VTA system at two sites in Kansas with 35 years of weather data. The sites were located in Ottawa and Greenwood Counties, KS. The simulated results showed that the lagoon system performed better for both sites when comparing the mean values of total-N, total-P, and COD released over the 35 years. The VTA system performance was better when median values of total-P and COD were compared at Greenwood County. This model was designed for use in Kansas, but with modifications may be useful in other areas.

Rumen acidosis is a common problem under feedlot conditions where cattle change from a roughage-based to a high concentrate-based diet. It is associated with an imbalance between lactic acid producing and lactic acid utilizing bacteria. Megasphaera eldenii is an important lactic acid utilizing bacteria which can now be produced for commercial use and supplemented for the prevention of lactic acid build up in the rumen and subsequent acidosis. The adaptation period is required in order for numbers of lactate utilizers such as M. elsdenii to increase to levels effective against subsequent build up of lactic acid. The purpose of this trial is to identify the effects of a strain, NCIMB 41125 (MeCH4), of Megasphaera elsdenii on the adaptation period of feedlot cattle on diets formulated for high starch levels. MeCH4 was isolated from the rumen of cattle adapted to high starch diets. By converting lactic acid in the rumen to volatile fatty acids (VFA’s) such as butyrate, M. elsdenii should be able to at least reduce the adaptation phase, if not totally eliminate the need for it without effects on intake patterns, feed conversion rates, health and carcass yield. . If results are positive, this strain of M. eldenii will have great economic implications to all feedlot farmers. There may be one major conclusion to be drawn from this trail and this was the fact that a decrease in adaptation days to reach the high concentrate grower diet had no statistically significant influence on key performance parameters relevant to the feedlot industry However, possibly the most attractive implication of these results is the lower need for roughage and therefore the implications tied in with the buying in and storage thereof. / Dissertation (MSc)--University of Pretoria, 2010. / Animal and Wildlife Sciences / unrestricted

Bovine respiratory disease complex (BRD) consists of a largely single clinical entity of bronchopneumonia that is usually associated with the assembly of large numbers of especially weaner cattle into a feedlot environment. It has a multifactorial aetiology and develops as a result of complex interactions between environmental factors, host or animal factors and pathogens. It is often difficult to determine the exact role played by the various pathogens involved in an individual outbreak of disease. None of the many organisms isolated will on their own, reliably reproduce the natural disease in experimental animals. Observations from research studies and clinical experience have indicated that the presence of mycoplasmas increases the severity of respiratory disease. However, the role of Mycoplasma spp. in BRD complex as a primary or secondary pathogen remains controversial. The various stresses associated with the feedlot causes a breakdown of the defense mechanisms that normally hold the nasal infections in check, resulting in a rapid proliferation of virulent Mannheimia haemolytica serotype A1 in particular and the spread to the lower respiratory tract. The various viruses and mycoplasmas have however been shown to have the same effect as stress on the Pasteurella populations of the nasal mucosa. More than 10 species of Mycoplasma have been isolated from the bovine respiratory tract, but not all are pathogenic. They are able to act as a stress-causing agent, leading to a decreased host defense mechanism by altering the immune responsiveness or by causing tissue damage and thereby allowing bacteria to invade and colonise the lung and so causing a severe pneumonia. M. bovis and M. dispar are the more important lung isolates, with M. bovis being the most invasive and destructive and has been shown to increase the severity of calf pneumonias. M. bovis has been isolated from bovine pneumonias, arthritis, mastitis, tendosynovitis, genitalia, keratoconjunctivitis and is considered to be the primary pathogen in endemic pneumonia in younger calves. According to the literature, mycoplasmas are isolated from 25% to 80% of pneumonic lungs in feedlot cattle and the aim of the study was to identify the isolation rates in South African feedlots over a period of 2000 to 2004. To achieve this, 446 transtracheal aspirates (TTA’s) were collected from more than 25 feedlots around South Africa, except for the western Cape. Collection criteria included: pulled for respiratory disease; febrile (≥40ºC); depressed; anorexia and/or lack of rumen fill; nasal discharge or failure to clean muzzle; cough; increased respiratory rate >40 and most importantly, no prior treatment. Samples were also collected from 31 ‘healthy’ animals as controls. Samples collected were used for Mycoplasma isolations, as well as the aerobic bacteria to establish an antibiogram profile of bacteria commonly isolated in cattle feedlots. Mycoplasma spp. were isolated from 52.8% of samples taken from sick animals, with 67 out of 201 isolates (33.3%) being identified as M. bovis. According to the literature, M. bovis, M. haemolytica or P. multocida are isolated from bronchial lavage fluids from healthy calves in only a few cases, with estimates being put at 5 – 10% levels for Mycoplasma. Isolation rates of Mycoplasma spp. from healthy animals in this study was 22.7%, which was considerably higher than anticipated and could possibly be due to problems with the definition of a healthy animal. Although the number of samples from healthy animals was relatively small in this study, it was possible to show that there was a statistically significant association between Mycoplasma isolation and respiratory disease, p = 0,001 and with an odds ratio (OR) of 3,75 in cattle from those feedlots included in the study and thereby proving the hypothesis put forward. / Dissertation (MMedVet (Bovine Medicine))--University of Pretoria, 2007. / Production Animal Studies / MMedVet / Unrestricted

The Namibian meat industry relies on the export of weaners to the South African feedlot industry while the largest part of the cattle population in the communal areas of Namibia remain underutilised. Producing a marketable cattle carcass for slaughter, which contributes the most to the Namibian economy, remains a challenge that needs a high level of understanding of all management variables under control by the rangeland manager. The nutritional requirements of cattle are one the important areas for maximising the return from the land and ensuring long term sustainability of the farming enterprise. A commercial farming enterprise, with the same climate and sandy soils that were predominantly found in the communal farming areas of Namibia, was chosen as experimental site. Three groupings of cattle were exposed to different experimental techniques and treatments over a 15 month trial period. The first grouping of cattle was 6 oesophageal fistulated cattle used, to collect veld samples selected by the cattle, every 3 weeks to estimate the contribution of the tree and shrub savannah towards the diet of the cattle. The second grouping was 110 cattle allocated to different nutrient supplementation treatments for slaughter at 28months of age. Five different nutrient supplementation treatments were chosen for 5 groups of 22 cattle, consisting of steers and heifers, for the duration of the period on an ad libitum basis. The 5 treatments were applied to illustrate the economic concept of diminishing marginal returns as the increasing feeding cost progressively deteriorated the amount of profit that would be expected. The optimal supplementation strategy would thus be identified according to the financial resources available to a farmer. Some of the treatments were also planned to progressively result in negative associative effects on forage intake, as energy containing raw materials in such treatments would replace the intake of natural available forage. The need for replacing forage was a common practice in droughts when the availability of forage was limiting or when the finishing of cattle during a short period before slaughter was planned. The cattle needed to be foraging less to conserve energy and thus increase protein accretion and fat deposition. The control of the experiment was the rock salt treatment group (RST) which only received a rock salt lick throughout the dry and wet seasons of the year. This was generally used for the supplementation of wildlife and cattle on rangeland in Namibia and it placed nearly no strain on the finances of a farmer. The remaining four treatments received commercially manufactured lick products with a diverse set of applications that were not strictly used according to the manufacturer's guidelines. During the wet season it was a well-established practice to only supplement with phosphorus and trace mineral containing licks due to the forage having maximum nutritional value during this time in which no additional benefit would be derived from the supplementation of protein and energy containing licks. All treatments, except for the rock salt treatment group (RST), were thus placed on a phosphorus and trace mineral lick during the wet season as part of the nutrient supplementation treatment programs. Different licks were made available to the cattle in the treatment groups, during the dry season, from which the treatment groups derived their names. One group was placed on a phosphorus and trace mineral lick for the duration of the trial, during the wet and dry season, and defined as the 6% phosphorus treatment group (6%PT). A maintenance treatment group (MTT) received protein in addition to phosphorus in the lick during the dry season. The production treatment group (PDT) received energy containing raw materials in addition to the minerals and protein as established in the MTT. The finisher treatment group (FST) received a larger amount of energy containing materials which diluted the mineral and protein concentration of the dry season lick even further than in the PDT. The third experimental procedure was to establish a group of 5 ruminally cannulated cattle that would individually be rotated every 3 weeks between the supplement fed treatment groups. The cattle would then be sampled for ruminal fluid, blood and faeces to observe the short term impact of the supplements during the different seasons on these variables and the diagnostic value of these parameters to indicate the nutritional status of cattle. The results clearly illustrated that the cattle had exhibited “nutritional wisdom”. The selection of higher quality plant material than what was on offer in the veld was highlighted in a review of previous oesophageal fistulated cattle research. The strong influence of rainfall on the forage quality (increased phosphorus and protein) was highlighted. During spring the phosphorus and protein reached their maximum concentrations. It was only during the wet season that animal performances were optimised when the quantity of high quality forage increased. The average daily ad libitum nutrient supplement consumption per animal on the different treatments was strongly influenced by these seasonal changes in forage quality and quantity. The lick intake increased as the dry season progressed and the quality of the forage the animals were able to select decreased. During spring the lick intake sharply decreased as the forage quality improved. The cattle adapted their intake level with the aim of maximising their energy intake, which resulted in the highest possible performance possible, from the forage and lick that was on offer to them. Monitoring the average monthly lick intake per animal would give valuable information to the farmer on the quality of the forage selected. The trends observed in average lick intake during the year could be used as an inexpensive indicator of veld qualit. An upper threshold could be set on lick intakes that would signal that a specific area was optimally grazed and that a camp rotation would aid in conserving the rangeland and optimise animal performance. The year round supplementation of rock salt lick group (RST), or alternatively no nutrient supplement, under these conditions had clearly shown a minimal contribution to the nutritional status of cattle and that this strategy would lead to certain financial underperformance or ruin of the cattle farmer. From the results presented, the year round supplementation with a phosphorus and trace mineral lick (6%PT) was indicated as the absolute minimum nutrient supplementation strategy that would need to be followed in all communal and commercial cattle farming areas of Namibia and probably similar farming locations around the world. Free access to phosphorus licks throughout the year to growing cattle must be ensured by the farmer to allow the cattle to select the correct amount that it would require to optimise performance. This strategy required the least amount of capital to implement and had the largest return on investment for a newly established farmer. If limited amounts of energy containing materials (molasses, maize, bran) were included in the nutrient supplement on offer it allowed the animal the opportunity to only consume the minimum amount of phosphorus that it required throughout the year to balance the shortages that occurred in the forage that it was selecting from. The finisher lick given during the dry season on the FST clearly illustrated that salt and phosphorus were poor regulators of supplemental intake if the cattle were able to increase their total energy retention by over consuming and probably excreting of minerals. The optimum nutrient supplementation strategy was the MTT that alleviated the primary phosphorus and secondary protein shortages during the dry season. This strategy had a much higher capital requirement and would be most suitable for the established cattle farmer that was able to afford this strategy or had access to credit. The PDT and FST were associated with higher supplementation costs that resulted in the highest turnover for the cattle farmer, although at lower profit than the MTT. The PDT and FST supplementation strategies would be more appropriate if the improved nutritional status of the cattle was utilised in a cow herd for improved reproduction or in stud farming when genetic expression of growth potential would offset the cost of supplementation. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

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

O objetivo desse experimento foi avaliar a inclusão (7 e 15% com base em MS), de 2 co-produtos, derivados da indústria de ácido cítrico: Micélio (77% de FDN e 0,5% de lignina com base em MS) e Raffinate (25,5% de açúcares solúveis e 32% de fibra solúvel com base em MS) em dietas com alto teores de milho do tipo Flint para 200 tourinhos Nelore em terminação (peso inicial = 396,4 ± 37,7kg). Os animais foram blocados com base no peso inicial e foram distribuídos aleatoriamente em 25 baias. A dieta controle conteve 11,73% de bagaço de cana de açúcar, 67,2% de milho moído, 18% de farelo proteinoso de milho, 2,07% de suplemento mineral e 1% de ureia. Os outros 4 tratamentos foram: Micélio 7, Micélio 15, Raffinate 7 e Raffinate 15. Os co-produtos substituíram parcialmente o milho nas dietas. Os parâmetros avaliados foram ingestão de matéria seca (IMS), ganho médio diário (GMD), eficiência alimentar (GMD/IMS) e características de carcaça. Os dados foram analisados pelo PROC MIXED do SAS e as médias foram comparadas por contrastes, considerando blocos como efeito aleatório e tratamento como efeito fixo. A inclusão de 7 e 15% de Micélio na dieta (base seca) em substituição parcial ao milho \"flint\" moído aumentou (P=0,1) de forma quadrática o CMS. Já os animais alimentados com dietas contendo Raffinate apresentaram aumento linear no CMS (P<0,1) em relação ao tratamento controle e também maior CMS quando comparados com os animais que receberam o tratamento Micélio (P<0,1). Não houve diferença na eficiência alimentar (GPD/CMS) entre os tratamentos (P > 0,1). A inclusão de ambos co-produtos (Micélio ou Rafinatte) resultou em aumento no GDP dos animais (P< 0,1). O efeito positivo foi quadrático (P<0,1) para a inclusão de Micélio e linear (P<0,1) para a inclusão de Raffinate. A densidade energética das dietas não foi alterada pela inclusão de co-produtos. Não houve efeito de tratamento (P> 0.01) para as características de carcaça. Os valores médios para rendimento de carcaça (%), espessura de gordura subcutânea (mm) e áreas de olho de lombo (cm2) foram 53,79, 2,84 e 64,08 respectivamente. A inclusão de 7% de Micélio ou de 15% de Raffinate melhora o GPD dos animais em virtude do maior CMS. Micélio, Rafinate e milho \"flint\" moído têm o mesmo valor energético para bovinos em Terminação. / The objective of this experiment was to evaluate the inclusion (7 and 15%, DM basis) of two corn by-products derived from the citric acid industry: Micelio (77% NDF, 0.5% lignin, DM basis) and Raffinate (25.5% soluble sugars, 32% soluble fiber, DM basis) in diets with high levels of flint corn fed to 200 finishing Nellore bulls (initial BW = 396.4 ± 37.7 kg). Animals were blocked according to initial BW and randomly allocated to 25 pens. The control diet contained 11.73% sugarcane bagasse, 67.2% corn, 18% corn gluten feed, 2.07% mineral supplement and 1% urea. The other four treatments were Micelio 7, Micelio 15, Raffinate 7 and Raffinate15. The by-products partially replaced corn in the diets. The parameters evaluated were dry matter intake (DMI), average daily gain (ADG), feed efficiency (ADG/DMI) and carcass traits. The data were analyzed using PROC MIXED of SAS and means were compared by contrasts, considering the block as random effect and treatment as fixed effect. The inclusion of 7 and 15% of Micelio in the diet (dry basis) in partial replacement of ground corn increased (P = 0.1) DMI quadratically. The animals fed diets containing Raffinate showed linear increase in DMI (P <0.1) compared to the control treatment and DMI was, also higher when compared with animals that received the Micelio treatment (P <0.1). There were no differences in feed efficiency (ADG / DMI) among treatments (P> 0.1). The inclusion of both by-products (Micelio or Rafinatte) resulted in an increase in ADG animals (P <0.1). The positive effect is quadratic (P <0.1) for adding Micelio and linear (P <0.1) for adding Raffinate. The energy density of the diet was not altered by the inclusion of by-products. There was no treatment effect (P> 0.01) for carcass traits Average values for dressing (%), back fat thickness (mm) and rib eye area (cm2) were 53.79, 2.84, and 64.08, respectively. The inclusion of 7 or 15% of Micelio or Raffinate in partial replacement of ground flint corn in finishing diets does not affect cattle performance. The inclusion of 7% of Micelio or a 15% Raffinate improved ADG of animals because of the increased DMI. Micelio, Raffinate and ground corn have the same energy value for cattle finishing.

Orientador: Mário De Beni Arrigoni / Resumo: O objetivo do presente estudo foi avaliar a eficiência da suplementação de 25-hidroxicolecalciferol no desempenho produtivo, características de carcaça, qualidade da carne e na expressão de genes relacionados ao anabolismo e ao catabolismo do músculo esquelético de bovinos de categoria Nelore confinados. Cento e vinte machos, com peso inicial médio de 370± 20 kg provindos de pastagem contínua, foram divididos em três tratamentos de acordo com a quantidade suplementada ou não a dieta durante o período experimental: T1 - tratamento controle sem inclusão de 25-hidroxicolecalciferol; T2 - dieta + 1mg/cab/dia de 25-hidroxicolecalciferol; T3 - dieta + 3mg/cab/dia de 25-hidroxicolecalciferol, delineados em blocos casualizados (40 animais por tratamento, 5 animais por baia e 8 baias por tratamento, sendo as baias as unidades experimentais). A duração do experimento foi de 96 dias, sendo 15 dias de adaptação, divididos em dois períodos (7 e 8 dias) de dietas com níveis crescentes de concentrado (76% e 81%), respectivamente; 28 dias de crescimento e a partir desse período foram fornecidas as dietas de terminação durante 53 dias com 91% de concentrado. Os dados obtidos foram submetidos à análise de variância utilizando-se o procedimento PROC MIXED do software SAS (2003) e o teste de Tukey para comparação entre as médias, considerando significativos valores de p≤0,05. No período total do confinamento, a suplementação com 1 mg aumentou o rendimento de carcaça dos animais e os resultados d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of the present study was to evaluate the efficiency of 25-hydroxycholecalciferol supplementation in productive performance, carcass characteristics, meat quality and expression of genes related to anabolism and catabolism of skeletal muscle in Nellore cattle. One hundred and twenty male from continuous pasture, with an average initial weight of 370 kg± 20 kg, divided into three treatments: T1: control treatment without the inclusion of 25-hydroxycholecalciferol, T2: diet + inclusion of 1 mg / cab / day of 25-hydroxycholecalciferol and T3: diet + inclusion of 3 mg / cab / day of 25-hydroxycholecalciferol, outlined in randomized blocks (40 animals per treatment, 5 animals per pen and 8 pens per treatment, the pens being the experimental units). The duration of the experiment was 96 days, with 15 days of adaptation, divided into two periods (7 and 8 days) of diets with increasing levels of concentrate (76% and 81%), respectively; 28 days of growth and after that period the finish diets were provided for 53 days with 91% concentrate. The selected data will be used in the analysis of variance using the PROC MIXED procedure of SAS software (2003) and Tukey test for comparison between media, considering P values ≤ 0.05. In the total feedlot period, supplementation with 1 mg increase carcass yield and meat pH results showed a linear increase between treatments. In addition, for the variables of blood 25 (OH) D3, iCa and muscle Ca the results were higher for the treatmen... (Complete abstract click electronic access below) / Mestre