• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 13
  • 5
  • 4
  • Tagged with
  • 24
  • 24
  • 7
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
11

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
12

The effect of essential oils and calcified marine algae as natural alternatives to ionophore antibiotics on performance of feedlot cattle

Haasbroek, Emile Francois January 2013 (has links)
viii SUMMARY The effect of essential oils and calcified marine algae as natural alternatives to ionophore antibiotics on performance of feedlot cattle by Emile Francois Haasbroek Supervisor: Prof. L.J. Erasmus Department: Animal and Wildlife Sciences Faculty: Natural and Agricultural Sciences Degree: MSc (Agric) Animal Science: Animal Nutrition Ionophore antibiotic supplementation is standard practice in almost all feedlots in the USA, South Africa and many other countries due to its effectiveness to increase feed efficiency and modulate feed intake. Public concern over the emergence of antibiotic resistant bacteria and the consumers’ demand for safe, high quality nutritious food has stimulated the search for natural alternatives to ionophores in ruminant diets. The objectives of this study were: (i) to compare the effect of a specific blend of essential oils (XTract X60 – 7065 (XTract)) and a rumen buffer (Acid Buf) to monensin and its effects on the performance of feedlot cattle under both experimental and commercial conditions (ii) to determine the effect of these feed additives on the health status of feedlot cattle and (iii) to determine whether Acid Buf can replace monensin as feed additive in high energy feedlot diets based on hominy chop. For the experimental growth trial 180 Bonsmara type animals were blocked into two groups and then allocated to 6 pens with 10 animals each per treatment using a randomised complete block design. The basal diets (starter, intermediate finisher and final finisher) were the same for the Control XTract and Acid Buf; the only difference being the Control treatment was supplemented with monensin (21 – 33 mg /kg DM), the XTract treatment supplemented with XTract (1000 – 1200 mg /h /d) and the Acid Buf treatment supplemented with Acid Buf at 0,6% dietary DM. For the commercial trial, animals were blocked according to the same criteria but for each treatment there were 3 pens, standing 130 head of cattle per pen, therefore 390 animals per treatment. The experimental pen trial was designed for evaluation of growth and the commercial pen trial for evaluation of health status and growth under practical feedlot conditions. In the small pen trial there were no differences (P > 0.05) in DMI, FCR or ADG between treatments. In the commercial trial the XTract supplemented cattle had a higher EW (429.3 vs. 417.5 kg) and ADG (1.77 kg /d vs. 1.70 kg /d) (P < 0.05) compared to monensin supplemented cattle and the Acid Buf supplemented cattle tended (P > 0.10) towards a higher EW (425.3 vs. 417.5 kg) and ADG (1.74 vs. 1.70 kg /d) compared to monensin supplemented cattle. The feed conversion ratios were 5.67 and 5.26 for XTract and monensin supplemented cattle and did not differ (P = 0.26). The feed conversion ratios were 5.22 and 5.26 respectively for Acid Buf and monensin supplemented cattle and did not differ (P = 0.86). Treatments affected health parameters in the commercial pens with 78% healthy animals (not pulled) in the monensin supplemented animals compared to 82% for XTract and 66% for the Acid Buf supplemented animals (P < 0.01). Rumen damage occurred in 73% of monensin supplemented animals compared to 51% for the Acid Buf supplemented animals and only 24% of the XTract supplemented animals (P < 0.01). Differences in health parameters did not seem to affect the overall growth performance of the cattle, suggesting a relatively minor effect on performance. Results from this large scale study should provide South African feedlot operators with sufficient information to make informed decisions on natural alternatives when the day comes that ionophores are placed on the banned list of ruminant feed additives. Further research, however, is needed on determining the optimal dose, dietary dependant responses, adaptation of rumen microbial populations and potential additive or synergistic effects when supplemented together with other rumen modifiers. Furthermore, the cost: benefit ratio should be determined under the prevailing conditions in different countries. / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted
13

Estudo sobre confinamentos de gado de corte no Estado de São Paulo, com ênfase na legislação ambiental e automação / Study of beef cattle feedlots in São Paulo with emphasis on legislation and automation environmental

Ferreira, Flávia Nunes Gomes 11 May 2015 (has links)
Estudos indicam que a população humana deverá apresentar um crescimento significativo nos próximos anos e a produção de alimentos deverá apresentar um aumento de 70% (setenta por cento) a fim de se assegurar segurança alimentar em todo o mundo. São aguardadas mudanças no padrão de consumo, elevando-se o consumo de carne vermelha. Os sistemas produtivos de gado de corte enfrentam o desafio de manter e elevar sua produção, lidando com escassez de recursos naturais e pressões para diminuição de impactos ambientais. Nas últimas décadas o Brasil vem se destacando no cenário mundial como grande produtor de alimentos e, consequentemente, como potência agrícola mundial, com exportação crescente dos excedentes de sua produção. No Brasil, em especial no Estado de São Paulo, o aumento do preço das terras e a competição com outras culturas agrícolas de maior lucratividade, têm contribuído para a adoção de sistemas mais intensivos na pecuária de corte. A partir do final dos anos 90, o número de animais confinados no Brasil cresceu rapidamente, devido, principalmente, ao aumento nas exportações de carne, aumento da produção agrícola e da boa oferta e preço dos animais aptos a abastecerem os confinamentos. O Estado de São Paulo figura entre os Estados que mais confinam no país. Assim, questões ligadas a possíveis impactos ambientais decorrentes da atividade e sua regulação pela legislação ambiental, bem como a automação do setor surgem. A presente pesquisa teve como objetivos gerais avaliar as legislações ambientais passíveis de incidência e as tendências de automação relacionadas à atividade de criação de gado de corte em confinamento no Estado de São Paulo. A metodologia se valeu de levantamento bibliográfico, levantamento da legislação ambiental pertinente, visita a um confinamento de gado de corte situado no Estado de São Paulo e entrevistas a pessoas pertencentes a quatro grupos definidos para a pesquisa, quais sejam, confinadores de gado de corte do Estado de São Paulo, professores universitários/pesquisadores ligados ao tema, órgãos ambientais e proprietários de empresas fabricantes de máquinas para pecuária. Os resultados da pesquisa indicam que é crescente a incorporação de tecnologias nos confinamentos de bovinos de corte do Estado de São Paulo. Em relação à legislação ambiental, constatou-se a existência de legislação ambiental passível de incidência nos confinamentos de bovinos de corte paulistas, contudo, uma carência de legislação que regule especificamente a atividade no Estado. Também verificou-se ser reduzida a fiscalização da atividade, que ocorre majoritariamente diante de acidentes ambientais ou denúncias, o que pode gerar um enfraquecimento da previsão legislativa. / Studies indicate that the human population is expected to present a significant growth in the coming years and food production will present an increase of 70% (seventy percent) in order to ensure food security worldwide. Are expected changes in the consumption pattern, rising consumption of red meat. The production of beef cattle systems face the challenge of maintaining and increase production, dealing with scarcity of natural resources and pressures to decrease environmental impacts. In recent decades, Brazil has stood out on the world stage as a major producer of food and, consequently, as a global agricultural powerhouse, with growing export of surplus production. In Brazil, especially in São Paulo state, the increase in land prices and competition with other crops of higher profitability, have contributed to the adoption of more intensive systems in livestock. From the late 90s, the number of animals confined in Brazil grew rapidly, mainly due to the increase in exports of meat, increased agricultural production and good supply and price of animals capable of supplying feedlots. The State of São Paulo is among the states that more confined in the country. Thus, issues related to potential environmental impacts of the activity and its regulation by environmental legislation, as well as industry automation arises. This research was general objectives assess environmental legislation likely to impact and automation trends related to beef cattle breeding activity in confinement in São Paulo. The methodology is worth a literature review, survey of the relevant environmental legislation, visit to a beef cattle feedlot located in São Paulo state and interviews with people belonging to four groups defined for the study, namely, beef cattle feedlots of State of São Paulo, academics professors / researchers involved in the area, environmental agencies and owners of livestock for machine manufacturers. The survey results indicate that increasing the incorporation of technologies in the confines of São Paulo state beef cattle. Regarding environmental legislation, there was the existence of environmental legislation likely to impact on the confinements of São Paulo state beef cattle, however, a lack of legislation specifically governing the activity in the state. Also found to be reduced to monitoring the activity that takes place mostly on accidents or complaints environmental, which can lead to a weakening of the legislative prediction.
14

Effects of dietary inclusion levels of a low lignin hull, high-oil groat oat on the performance, carcass characteristics and rumen fermentation characteristics of feedlot cattle

Arya, Sushama 17 March 2010
Two experiments were conducted to evaluate the effects of dietary inclusion level of a low lignin hull, high-oil groat (CDC SO-I) oat on the performance, carcass characteristics and rumen degradation characteristics of feedlot cattle. In the first trial, 200 crossbred steers (average weight of 427.3 ± 22.4 kg) were allocated to 20 pens. Five treatments, formulated by replacing barley with increasing levels of CDC SO-I oat (Barley grain:CDC SO-I oat ratios of 100:0; 75:25; 50:50; 25:75 and 0:100 ; DM basis) were used. Four pens were randomly allocated to each treatment diet. Over the entire study there was a linear decrease (P< 0.01) in DMI and ADG with increasing inclusion level of CDC SO-I oat, whereas feed efficiency (gain:feed) decreased (P= 0.03) quadratically. Days on feed also increased (P= 0.03) quadratically for the steers fed the higher levels of CDC SO-I oat. Increasing the inclusion level of CDC SO-I oat in the diet also decreased (P< 0.01) carcass weight, dressing percentage and grade fat linearly. However, there was no effect of treatment on rib eye area and lean yield percentage. There was no significant effect of treatment on marbling score. While the results of this trial point to a negative effect of CDC SO-I oat on finishing performance, there were minimal differences between cattle fed 100% barley as the concentrate versus those fed 75% barley: 25% oat blend.<p> Trial 2 involved a metabolism trial to determine the effect of CDC SO-I oat inclusion level on rumen fermentation parameters of 5 fistulated heifers fed the same diets used in Trial 1. A 5 × 5 Latin square experiment design was used. Rumen degradation parameters (rumen pH, VFA, osmolality and ammonia nitrogen levels) and feeding behavior (time spent eating, ruminating, chewing and drinking) were measured. Mean rumen pH for the barley-based diet was 5.88 which was not different (P> 0.05) than the mean pH of 5.5 for the oat-fed cattle. Treatment did not affect (P> 0.05) time spent below pH cutoff values of 5.8, 5.5 and 5.2. No effect of oat inclusion level (P> 0.05) was observed on total VFA levels, molar proportion of individual fatty acids and osmolality while isobutyrate (P= 0.05) and ruminal ammonia nitrogen concentrations decreased linearly (P= 0.02) with the higher inclusion of CDC SO-I oat. Time spent eating was linearly (P< 0.01) increased with higher inclusion level of CDC SO-I oat.<p> Over all, the results of this study indicate that the replacement of barley by CDC SO-I oat in finishing diets decreases dry matter intake and as a result leads to reduced ADG, increased days on feed and lower slaughter and carcass weights. The reduced performance might be the result of higher fat content, high hull and/or faster degradation rate of oat starch leading to subacute ruminal acidosis in cattle fed higher levels of oat. However, replacing barley with CDC SO-I oat does not significantly change the rumen environment. The results of this study indicate that CDC SO-I oat can be successfully included up to a maximum level of 25% without any adverse effect on performance and carcass characteristics in the diets of finishing cattle.
15

Effects of dietary inclusion levels of a low lignin hull, high-oil groat oat on the performance, carcass characteristics and rumen fermentation characteristics of feedlot cattle

Arya, Sushama 17 March 2010 (has links)
Two experiments were conducted to evaluate the effects of dietary inclusion level of a low lignin hull, high-oil groat (CDC SO-I) oat on the performance, carcass characteristics and rumen degradation characteristics of feedlot cattle. In the first trial, 200 crossbred steers (average weight of 427.3 ± 22.4 kg) were allocated to 20 pens. Five treatments, formulated by replacing barley with increasing levels of CDC SO-I oat (Barley grain:CDC SO-I oat ratios of 100:0; 75:25; 50:50; 25:75 and 0:100 ; DM basis) were used. Four pens were randomly allocated to each treatment diet. Over the entire study there was a linear decrease (P< 0.01) in DMI and ADG with increasing inclusion level of CDC SO-I oat, whereas feed efficiency (gain:feed) decreased (P= 0.03) quadratically. Days on feed also increased (P= 0.03) quadratically for the steers fed the higher levels of CDC SO-I oat. Increasing the inclusion level of CDC SO-I oat in the diet also decreased (P< 0.01) carcass weight, dressing percentage and grade fat linearly. However, there was no effect of treatment on rib eye area and lean yield percentage. There was no significant effect of treatment on marbling score. While the results of this trial point to a negative effect of CDC SO-I oat on finishing performance, there were minimal differences between cattle fed 100% barley as the concentrate versus those fed 75% barley: 25% oat blend.<p> Trial 2 involved a metabolism trial to determine the effect of CDC SO-I oat inclusion level on rumen fermentation parameters of 5 fistulated heifers fed the same diets used in Trial 1. A 5 × 5 Latin square experiment design was used. Rumen degradation parameters (rumen pH, VFA, osmolality and ammonia nitrogen levels) and feeding behavior (time spent eating, ruminating, chewing and drinking) were measured. Mean rumen pH for the barley-based diet was 5.88 which was not different (P> 0.05) than the mean pH of 5.5 for the oat-fed cattle. Treatment did not affect (P> 0.05) time spent below pH cutoff values of 5.8, 5.5 and 5.2. No effect of oat inclusion level (P> 0.05) was observed on total VFA levels, molar proportion of individual fatty acids and osmolality while isobutyrate (P= 0.05) and ruminal ammonia nitrogen concentrations decreased linearly (P= 0.02) with the higher inclusion of CDC SO-I oat. Time spent eating was linearly (P< 0.01) increased with higher inclusion level of CDC SO-I oat.<p> Over all, the results of this study indicate that the replacement of barley by CDC SO-I oat in finishing diets decreases dry matter intake and as a result leads to reduced ADG, increased days on feed and lower slaughter and carcass weights. The reduced performance might be the result of higher fat content, high hull and/or faster degradation rate of oat starch leading to subacute ruminal acidosis in cattle fed higher levels of oat. However, replacing barley with CDC SO-I oat does not significantly change the rumen environment. The results of this study indicate that CDC SO-I oat can be successfully included up to a maximum level of 25% without any adverse effect on performance and carcass characteristics in the diets of finishing cattle.
16

Using comparative genomics to identify virulence traits and vaccine candidates in Mannheimia haemolytica

2015 June 1900 (has links)
Bovine respiratory disease (BRD) is the principal cause of morbidity and mortality among feedlot cattle. Mannheimia haemolytica is consistently implicated in this condition, but treatment options are diminishing with the rise of antimicrobial resistance and intensifying consumer pressure to reduce reliance on conventional therapies. Thus, sustainable alternatives like vaccination are required. In this study, the phenotypic and genotypic diversity of BRD pathogens were examined with the objective to identify vaccine targets using reverse vaccinology, an innovative approach to identify antigens via genomic sequence. Preliminary surveillance confirmed M. haemolytica serotype 2 isolates were predominant in healthy animals (75.5%) while serotypes 1 (70.7%) and 6 (19.5%) were common in diseased animals. Pathogens of BRD, including M. haemolytica, Pasteurella multocida and Histophilus somni were also isolated from North American BRD mortalities, and compared using pulsed-field gel electrophoresis and antimicrobial susceptibility. Concurrently, polymerase chain reaction detection of bacterial and viral agents confirmed that M. haemolytica with bovine viral diarrhea virus were the most prevalent. Whereas isolates from live cattle were found to have a relatively low level of resistance, several pathogens from the mortalities were found to contain integrative conjugative elements (ICE) conferring resistance to seven antimicrobial classes. These ICEs were transferred via conjugation to other bacterial species, emphasizing the need for alternative antimicrobial therapies. Collectively, data from these investigations informed the selection of 11 diverse M. haemolytica strains for whole genome sequencing and comparative analyses. Several bacteriophage associated genes and CRISPR-Cas regulated gene expression systems were identified and are likely contributing to virulence in M. haemolytica. Coding sequences across all genomes were screened using pan-genome analysis, identifying 291 candidates with cell-surface associated signatures. Using a cell-free translation system and enzyme-linked immunosorbent assay the candidates were screened against serum from cattle challenged with serovar 1, 2 or 6 of M. haemolytica, and ranked according to immunogenicity. The top five vaccine candidates included Ssa1, ComE, a solute binding protein, an outer membrane protein, and the periplasmic component of an ABC transporter. With further characterization, these unique antigenic candidates could be developed into a vaccine to effectively reduce the dependence on antimicrobial therapies.
17

Fornecimento estratégico de leveduras vivas e monensina sódica no desempenho e saúde ruminal em bovinos Nelore terminados em confinamento / Strategic management of live yeasts and monensin sodium in the performance and ruminal health in Nelore bulls finished in feedlot

Miranda, Lucas Domingos Ferreira 04 December 2017 (has links)
Submitted by Lucas Domingos Ferreira Miranda null (lucas_f.miranda@hotmail.com) on 2017-12-06T17:08:53Z No. of bitstreams: 1 Dissertação final.pdf: 1348044 bytes, checksum: eeb10efea599f5584d89b047b4a2485c (MD5) / Approved for entry into archive by ROSANGELA APARECIDA LOBO null (rosangelalobo@btu.unesp.br) on 2017-12-11T12:05:13Z (GMT) No. of bitstreams: 1 miranda_ldf_me_bot.pdf: 1348044 bytes, checksum: eeb10efea599f5584d89b047b4a2485c (MD5) / Made available in DSpace on 2017-12-11T12:05:13Z (GMT). No. of bitstreams: 1 miranda_ldf_me_bot.pdf: 1348044 bytes, checksum: eeb10efea599f5584d89b047b4a2485c (MD5) Previous issue date: 2017-12-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se com esse trabalho avaliar o efeito de leveduras vivas e monensina sódica, em associação ou não, no desempenho produtivo, características de carcaça, perfil sanguíneo, comportamento ingestivo, seletividade da partícula e saúde ruminal em bovinos Nelore terminados em confinamento. Foram utilizados 77 animais machos não castrados, com peso vivo médio inicial de 353,23 ± 34,89 kg e provenientes de recria em sistema de pastejo contínuo. O delineamento experimental foi em blocos casualizados em arranjo fatorial 2x2, sendo os fatores a inclusão de monensina ou leveduras vivas, e todos os tratamentos receberam a mesma dieta diferenciando apenas na inclusão dos aditivos. Cada tratamento foi composto por 6 baias (3 a 4 animais/baia), sendo estas consideradas as unidades experimentais para este estudo. O período experimental foi de 90 dias com adaptação em step up, aumentando o nível de concentrado da dieta de 67 até 87% na dieta de terminação. Os resultados foram avaliados por meio do procedimento MIXED do SAS, sendo considerado significativo P<0,05. Houve efeito significativo na ingestão de massa seca para os animais do tratamento monensina (P<0,01), assim como na conversão e eficiência alimentar (P=0,03 e P=0,02, respectivamente) quando comparados aos tratamentos sem monensina. A levedura por sua vez não proporcionou diferença nos parâmetros de desempenho produtivo e não houve interação entre os aditivos. Os animais que receberam monensina apresentaram menor flutuação de consumo (P<0,01) e maior energia líquida de ganho (P<0,01). O perfil sanguíneo dos animais tratados com monensina diferiu significativamente dos tratamentos sem monensina nos parâmetros pressão de O2 (P=0,01), total de CO2 (P=0,03) e bicarbonato (P=0,04), enquanto a levedura proporcionou menor lactato sanguíneo (P<0,01). Não houve interação entre aditivos ou entre aditivos e fases, no entanto houve diferença significativa entre as fases de adaptação e terminação para praticamente todos os parâmetros avaliados (P<0,01), exceto para pH, pressão de O2 e saturação de O2. Houve interação entre monensina e fase no comportamento ingestivo, para os parâmetros tempo de alimentação e tempo de ócio. Houve interação entre fornecimento de leveduras e fase nos parâmetros de seletividade de partículas, nas peneiras 1 e 2. Para os parâmetros de saúde ruminal, os animais dos tratamentos com monensina apresentaram maior índice de rumenites (P<0,01) e melhores resultados para área média das papilas (P=0,01), área de superfície absortiva (P<0,01), representatividade da participação das papilas na área de superfície absortiva (P<0,01) comparado com os tratamentos sem monensina. Não houve interações ou efeito do uso de levedura nos parâmetros de morfologia ruminal. Na avaliação da histologia ruminal, a monensina proporcionou maior largura das papilas (P=0,03), menor espessura de queratina (P<0,01) e maior índice mitótico (P=0,03) em comparação aos animais controle. Os tratamentos com levedura obtiveram maior largura de papilas (P=0,03) e menor índice mitótico (P<0,01). Houve interação para área média das papilas (P=0,01). Os resultados deste estudo demonstram que as leveduras vivas podem ser uma alternativa em confinamentos de bovinos Nelore quando mercados mais exigentes não permitirem a utilização de ionóforos. / The objective of this study was to evaluate the effect of live yeasts and monensina sodium, in association or not, on the productive performance, carcass characteristics, blood profile, ingestivo behavior, particle selectivity and ruminal health in Nellore cattle terminated in feedlot. A total of 77 uncastrated male animals were used, with initial average live weight of 353.23±34.89 kg and from rearing in a continuous grazing system. The experimental design was a randomized complete block design in a 2x2 factorial arrangemen, with the inclusion of monensin or living yeasts, all treatments received te same diet differing only in the inclusion of the additives. Each treatment consisted of 6 pen (3 to 4 animals/pen), these being considered the experimental units for this study. The experimental period was 90 days with step up adaptation, increasing the level of diet concentrate from 67 to 87% in the finishing diet. The results were evaluated through the SAS MIXED procedure, being considered significant P<0.05. There was a significant effect on dry matter intake for monensin (P<0.03 and P=0.02, respectively) when compared to treatments without monensin. The yeast did not provide any difference in the parameters of productive performance and there was no interaction between the additives. The animals receiving monensin showed lower consumption flutuation (P<0.01) and higher net gain energy (P<0.01). The blood profile of animals treated with monensin differed significantly from the treatments without monensin in the parameters O2 (P=0.01), total CO2 (P=0.03) and bicarbonate (P=0.04), while yeast lower blood lactate (P<0.01). There was no interaction between there was a significant difference between the adaptation and finishing phases for practically all the evaluated parameters (P<0.01), except for pH, O2 pressure and O2 saturation. There was interaction between monensin and phase in the ingestive behavior, for the parameters feeding time and leisure time. There was interaction between yeast supply and phase in the particle selectivity parameters in sieves 1 and 2. For the ruminal health parameters, the animals of the monensin treatments presented higher rumenites (P<0.01) and better results for the mean área of the papillae (P+0.01), the absorptive surfarce área (P<0.01), representativeness of the participation of the papillae in the absorptive surface área (P<0.01) compared to the treatments without monensin. There was no interaction or effect of yeast use on ruminal morphology. In the evaluation of ruminal histology, monensin provided greater papila width (P=0.03, lower keratin thickness (P<0.01) and higher mitotic index (P=0.03) compared to control animals. Yeast treatments obtained greater papila width (P=0.03) and lower mitotic index (P<0.01). There was interaction for the mean área of the papillae (P=0.01). The results of this study demonstrate that live yeasts may be na alternative in feedlots of Nellore cattle when more demanding markets don’t allow the use of ionophores. / FAPESP: 2016/02435-2
18

Using the eddy covariance technique to measure gas exchanges in a beef cattle feedlot

Prajapati, Prajaya January 1900 (has links)
Doctor of Philosophy / Department of Agronomy / Eduardo Alvarez Santos / Measurements of methane (CH₄) emissions from livestock production could provide invaluable data to reduce uncertainties in the global CH₄ budget and to evaluate mitigation strategies to lower greenhouse gas (GHG) emissions. The eddy covariance (EC) technique has recently been applied as an alternative to measure CH₄ emissions from livestock systems, but heterogeneities in the source area and fetch limitations impose challenges to EC measurements. The main objectives of this study were to: 1) assess the performance of a closed-path EC system for measuring CH₄, CO₂, and H₂0 fluxes; 2) investigate the spatial variability of the EC fluxes in a cattle feedlot using flux footprint analysis; 3) estimate CH₄ emission rates per animal (Fanimal) from a beef cattle feedlot using the EC technique combined with two footprint models: an analytical footprint model (KM01) and a parametrization of a Lagrangian dispersion model (FFP); and 4) compare CH₄ emissions obtained using the EC technique and a footprint analysis with CH₄ emission estimates provided by a well-stablished backward-Lagrangian stochastic (bLS) model. A closed-path EC system was used to measure CH₄, CO₂, and H₂0 fluxes. To evaluate the performance of this closed-path system, a well-stablished open-path EC system was also deployed on the flux tower to measure CO₂ and H₂0 exchange. Methane concentration measurements and wind data provided by that system were used to estimate CH₄ emissions using the bLS model. The performance assessment that included comparison of gas cospectra and measured fluxes from the two EC systems showed that the closed-path system was suitable for the EC measurements. Flux values were quite variable during the field experiment. A one-dimensional flux footprint model was useful to interpret some of the flux temporal and spatial dynamics. Then, a more comprehensive data analysis was carried out using two-dimensional footprint models (FFP and KM01) to interpret fluxes and scale fluxes measured at landscape to animal level. The monthly average Fanimal, calculated using the footprint weighed stocking density ranged from 83 to 125 g animal⁻¹ d⁻¹ (KM01) and 75–114 g animal⁻¹ d⁻¹ (FFP). These emission values are consistent with the results from previous studies in feedlots however our results also suggested that in some occasions the movement of animals on the pens could have affected CH₄ emission estimates. The results from the comparisons between EC and bLS CH₄ emission estimates show good agreement (0.84; concordance coefficient) between the two methods. In addition, the precision of the EC as compared to the bLS estimates was improved by using a more rigorous fetch screening criterion. Overall, these results indicate that the eddy covariance technique can be successfully used to accurately measure CH₄ emissions from feedlot cattle. However, further work is still needed to quantify the uncertainties in Fanimal caused by errors in flux footprint model estimates and animal movement.
19

Estudo sobre confinamentos de gado de corte no Estado de São Paulo, com ênfase na legislação ambiental e automação / Study of beef cattle feedlots in São Paulo with emphasis on legislation and automation environmental

Flávia Nunes Gomes Ferreira 11 May 2015 (has links)
Estudos indicam que a população humana deverá apresentar um crescimento significativo nos próximos anos e a produção de alimentos deverá apresentar um aumento de 70% (setenta por cento) a fim de se assegurar segurança alimentar em todo o mundo. São aguardadas mudanças no padrão de consumo, elevando-se o consumo de carne vermelha. Os sistemas produtivos de gado de corte enfrentam o desafio de manter e elevar sua produção, lidando com escassez de recursos naturais e pressões para diminuição de impactos ambientais. Nas últimas décadas o Brasil vem se destacando no cenário mundial como grande produtor de alimentos e, consequentemente, como potência agrícola mundial, com exportação crescente dos excedentes de sua produção. No Brasil, em especial no Estado de São Paulo, o aumento do preço das terras e a competição com outras culturas agrícolas de maior lucratividade, têm contribuído para a adoção de sistemas mais intensivos na pecuária de corte. A partir do final dos anos 90, o número de animais confinados no Brasil cresceu rapidamente, devido, principalmente, ao aumento nas exportações de carne, aumento da produção agrícola e da boa oferta e preço dos animais aptos a abastecerem os confinamentos. O Estado de São Paulo figura entre os Estados que mais confinam no país. Assim, questões ligadas a possíveis impactos ambientais decorrentes da atividade e sua regulação pela legislação ambiental, bem como a automação do setor surgem. A presente pesquisa teve como objetivos gerais avaliar as legislações ambientais passíveis de incidência e as tendências de automação relacionadas à atividade de criação de gado de corte em confinamento no Estado de São Paulo. A metodologia se valeu de levantamento bibliográfico, levantamento da legislação ambiental pertinente, visita a um confinamento de gado de corte situado no Estado de São Paulo e entrevistas a pessoas pertencentes a quatro grupos definidos para a pesquisa, quais sejam, confinadores de gado de corte do Estado de São Paulo, professores universitários/pesquisadores ligados ao tema, órgãos ambientais e proprietários de empresas fabricantes de máquinas para pecuária. Os resultados da pesquisa indicam que é crescente a incorporação de tecnologias nos confinamentos de bovinos de corte do Estado de São Paulo. Em relação à legislação ambiental, constatou-se a existência de legislação ambiental passível de incidência nos confinamentos de bovinos de corte paulistas, contudo, uma carência de legislação que regule especificamente a atividade no Estado. Também verificou-se ser reduzida a fiscalização da atividade, que ocorre majoritariamente diante de acidentes ambientais ou denúncias, o que pode gerar um enfraquecimento da previsão legislativa. / Studies indicate that the human population is expected to present a significant growth in the coming years and food production will present an increase of 70% (seventy percent) in order to ensure food security worldwide. Are expected changes in the consumption pattern, rising consumption of red meat. The production of beef cattle systems face the challenge of maintaining and increase production, dealing with scarcity of natural resources and pressures to decrease environmental impacts. In recent decades, Brazil has stood out on the world stage as a major producer of food and, consequently, as a global agricultural powerhouse, with growing export of surplus production. In Brazil, especially in São Paulo state, the increase in land prices and competition with other crops of higher profitability, have contributed to the adoption of more intensive systems in livestock. From the late 90s, the number of animals confined in Brazil grew rapidly, mainly due to the increase in exports of meat, increased agricultural production and good supply and price of animals capable of supplying feedlots. The State of São Paulo is among the states that more confined in the country. Thus, issues related to potential environmental impacts of the activity and its regulation by environmental legislation, as well as industry automation arises. This research was general objectives assess environmental legislation likely to impact and automation trends related to beef cattle breeding activity in confinement in São Paulo. The methodology is worth a literature review, survey of the relevant environmental legislation, visit to a beef cattle feedlot located in São Paulo state and interviews with people belonging to four groups defined for the study, namely, beef cattle feedlots of State of São Paulo, academics professors / researchers involved in the area, environmental agencies and owners of livestock for machine manufacturers. The survey results indicate that increasing the incorporation of technologies in the confines of São Paulo state beef cattle. Regarding environmental legislation, there was the existence of environmental legislation likely to impact on the confinements of São Paulo state beef cattle, however, a lack of legislation specifically governing the activity in the state. Also found to be reduced to monitoring the activity that takes place mostly on accidents or complaints environmental, which can lead to a weakening of the legislative prediction.
20

The effects of feeding dry distiller’s grains with solubles on ruminal metabolism, growth performance, and carcass traits of feedlot cattle

Uwituze, Solange January 1900 (has links)
Master of Science / Department of Animal Sciences and Industry / James S. Drouillard / Three trials were conducted using dried distiller's grains with solubles (DDGS) to evaluate effects on feedlot performance, carcass characteristics, ruminal fermentation, and diet digestibility in cattle fed steam-flaked corn-based diets. In trial 1, crossbred yearling heifers were used in a finishing trial to evaluate interactions between corn-DDGS feeding levels and roughage source (alfalfa hay vs corn silage) in terms of impact on feedlot performance and carcass characteristics. Experimental diets were based on steam-flaked corn and contained 0% DDGS with 6% alfalfa hay (AH), 0% DDGS with 10% corn silage (CS), 25% DDGS with 6% AH, or 25% DDGS with 10% CS (DM basis). Results indicated no interaction between levels of DDGS and roughage source. Heifers fed DDGS as a partial replacement for steam-flaked corn had similar growth performance and carcass merit compared to heifers fed diets without DDGS. Corn silage and alfalfa hay were comparable roughages when a portion of steam-flaked corn was replaced with DDGS. The second trial was a companion metabolism study in which ruminal fermentation characteristics and diet digestibility were examined in 12 cannulated Holstein steers fed steam-flaked corn finishing diets with or without DDGS, using alfalfa hay or corn silage as roughage sources. Diets were similar to those fed in the performance study and consisted of steam-flaked corn with 0 or 25% DDGS (DM basis) and 6% AH or 10% CS (DM basis). Feeding DDGS decreased ruminal pH and ruminal ammonia concentrations, and digestion of DM and OM were less compared to diets without DDGS. The decrease in digestibility was largely attributable to poorer digestion of CP and, to a lesser extent, a reduction in starch digestion. The third study was designed to investigate effects of pH (5.0, 5.5, and 6.0) on in vitro fermentative activity by ruminal microorganisms from cattle adapted to a finishing diet containing 25% DDGS (DM basis). Higher pH led to greater dry matter disappearance in vitro (P < 0.01). DDGS can be an effective substitute for steam-flaked corn. Efforts to address low ruminal pH and low ruminal ammonia may prove beneficial for improving value of DDGS as cattle feed.

Page generated in 0.4459 seconds