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Fenugreek (Trigonella foenum-graecum L.) is a single-cut, annual legume typically grown for seed. Fenugreek has potential as a forage because it maintains high quality throughout the growing season, and offers the benefits of a legume in a crop rotation. This work aimed to evaluate the growth of two fenugreek genotypes, AAFC F70 and CDC Quatro, in the central AB area over two growing seasons, and to evaluate fenugreek haylage degradation and digestion in dairy cows. In general, the two genotypes were similar in their growth patterns and fenugreek biomass yield was comparable to alfalfa in the same area. Plant quality was sufficient to be used for lactating dairy cows. The digestion studies revealed that while Quatro haylage was comparable to alfalfa haylage, F70 haylage was of lower quality and was not utilized to the same extent by dairy cows as the other two forage types. / Plant Science

Master of Science / Department of Animal Sciences and Industry / J.S. Drouillard / A series of experiments were conducted in which wheat gluten film forming solutions were modified by various means to produce films that would improve resistance to ruminal degradation. There was an interaction between pH and temperature, whereby low pH (pH 3) and high temperature (75°C) of film forming solution resulted in films that had highest resistance to microbial degradation. Strategies that proved unsuccessful in improving resistance to ruminal degradation included use of the cross-linking enzyme, transglutaminase; induction of a Maillard reaction; and increasing the time of heating film forming solutions. Utilizing HCl versus acetic acid as the means to lower the pH of the film forming solution resulted in poor film formation, which can be attributed to glutenin‟s solubility in acetic acid. When acetic acid was replaced with 25% HCl, however, no compromise in film formation was observed and ruminal degradability was not affected. In order to develop an economical and effective means of encapsulating lysine for rumen bypass, wheat gluten and corn zein were evaluated as encapsulation materials. Coating soybean meal with either wheat gluten or zein resulted in superior protection against ruminal degradation when compared to unprotected soybean meal. Compared to wheat gluten, zein was observed to have greater resistance to ruminal degradation in vitro. Lysine was encapsulated by the spray dry method with wheat gluten or zein. Results from an in vitro ammonia release experiment were inconclusive with respect to effectiveness of the encapsulation process. Wheat gluten films were approximately 59% degraded in pepsin solution. Our results suggest that 72% of the wheat gluten film will bypass the rumen and 59% of the bypass fraction of the film will be degraded in the abomasum. Wheat gluten and zein are suitable candidates for development of encapsulated nutrients for ruminal protection.

The occurrence of plastic impaction in ruminants is a growing concern. As indiscriminate feeders, cattle may consume plastic foreign materials incorporated into their diets and it is currently estimated that 20% of cattle contain plastic foreign materials in their rumen. These materials are indigestible and accumulate for the lifetime of the animal. As these materials accumulate, they may reduce feed efficiency and production by erosion and ulceration of rumen epithelium, stunting of papillae, blockage of the reticulo-omasal orifice, and leaching of toxic heavy metals. It is necessary to reduce the incidences of plastic impaction in domestic ruminants. Using polyhydroxyalkanoate (PHA) and poly(butylene succinate-co-adipate) (PBSA) biodegradable materials for feed storage products such as bale netting could reduce the incidences and effects of polyethylene-based plastic impaction in ruminants. The objectives of these studies were to evaluate the degradability of PHA and PBSA materials in the reticulorumen via in vitro, in situ, and in vivo methods. Our hypothesis was that these materials would degrade in the rumen and that a melt-blend of PHA and PBSA may degrade faster than its individual components. An in vitro study incubated a proprietary PHA-based polymer, PBSA, and PBSA:PHA melt blend nurdles, and forage controls in rumen fluid for up to 240h in DaisyII Incubators. Mass loss was measured, and digestion kinetic parameters were estimated. Thermogravimetric and differential scanning calorimetry analyses were conducted on incubated samples. Results indicated that the first stage of degradation occurs within 24h and PHA degrades slowly. Degradation kinetics demonstrated that polymer treatments were still in the exponential degradation phase at 240h with a maximum disappearance rate of 0.0031%/h, and mass loss was less than 2% for all polymers. Melting temperature increased and onset thermal degradation temperature decreased with incubation time, indicating structural changes to the polymers starting at 24h. Further in situ degradation, however, indicated these biodegradable materials degrade at more accelerated rates in the rumen. Polyhydroxyalkanote, PBSA, PBSA:PHA blend, and low-density polyethylene (LDPE) films were incubated in the rumens of three cannulated, non-lactating Holsteins for 0, 1, 14, 30, 60, 90, 120, and 150d. In situ disappearance (ISD) and residue length were assessed after every incubation time. Polyhydroxyalkanoate achieved 100% degradation by 30d, with initiation occurring at 14d indicated by ISD and a reduction in residue length. The fractional rate of disappearance of PHA was 7.84%/d. Poly(butylene succinate-co¬-adipate) and Blend did not achieve any significant ISD, yet fragmentation of PBSA occurred at 60d and the blend at just 1d likely due to abiotic hydrolysis. Low-density polyethylene achieved no ISD and residue length did not change over incubation time. From these results, we proposed a PBSA:PHA blend is a valid alternative to polyethylene single-use agricultural plastic products based on its fragmentation within 1d of incubation. Administration of PBSA:PHA film boluses compared to LDPE films and a control further supported this dissemination. Holstein bull calves (n = 12, 62 ± 9d, 74.9 ± 8.0kg) were randomly allocated to one of three daily bolus treatments: 13.6g of PBSA:PHA in 4 gelatin capsules (Blend), 13.6g of LDPE in 4 gelatin capsules (LDPE), or 4 empty gelatin capsules (Control) for 30d. Hemograms were conducted on blood samples collected on d0 and d30. On d31, animals were sacrificed to evaluate gross rumen measurements and pathology, determine papillae length, and characterize polymer residues present in rumen contents. Feed intake, body weight, body temperature, and general health were determined throughout the study. No animals presented any symptoms related to plastic impaction and animal health was not particularly affected by treatment. Daily grain and hay intake, body weight, rectal temperature, hematological parameters, gross rumen measurements and pathology, and rumen pH and temperature were not affected by treatment. There was evidence that degradation of PBSA:PHA may release byproducts that support rumen functionality. Methylene blue reduction time of Blend calves tended to be decreased by 30% compared to LDPE calves, and caudal ventral papillae length of Blend calves were 50% longer than those of Control animals. Though studies are needed to specifically elucidate the production of byproducts due to degradation of PBSA:PHA and their correlations. Polymer accumulation and residue length differed among treatments. Calves dosed with LDPE retained 6.7% of the dosed polymer, undegraded, while Blend calves retained 0.4% of the dosed polymer. The polymer residues in Blend calves were 10% of their original size. Single-use agricultural plastics developed from PBSA:PHA may be a suitable alternative to LDPE-based products in the case of ingestion in ruminants due to no acute health inflictions, fragmentation of polymers with 1d, and improved clearance from the reticulorumen. As such, utilization of these materials may reduce the incidences of plastic impaction in ruminants in commercial operations. Further long-term feeding studies are needed to evaluate specific byproduct production of PBSA:PHA and their potential influences on rumen function and animal health and production in normal commercial conditions. / Master of Science in Life Sciences / Plastic feed-storage materials may unintentionally be incorporated into animal feeds. Net wraps and bale twines may be stuck or left on forages when they are ground and incorporated into mixed rations. As cattle are largely non-selective, they may inadvertently consume these plastic materials. Approximately 20% of cattle contain plastic foreign materials in their rumen. These materials are indigestible and accumulate for the animal's lifetime. As plastics build up in the rumen, they may reduce feed efficiency, body weight, and milk production by damaging the rumen lining, blocking the digestive tract, and leaching toxic heavy metals. Therefore, it is necessary to reduce the incidences of plastic impaction in domestic ruminants to improve their health and productivity. Using biodegradable materials that degrade by bacteria, such as polyhydroxyalkanoate (PHA) and poly(butylene succinate-co-adipate) (PBSA), for feed storage products could reduce the occurrence and effects of plastic impaction in ruminants due to the materials' potential degradation in and passage from the rumen. The objectives of these studies were to evaluate the breakdown of PHA and PBSA materials in the rumen. Our hypothesis was that these biodegradable materials would degrade in the rumen and that a blend of PHA and PBSA may degrade faster than its individual components. In our first study, PHA, PBSA, a PBSA:PHA blend, and forage controls were incubated in rumen fluid for up to 240h. Mass loss, degradation rate, and the structure of polymers were determined over incubation time. Results indicated that biodegradable polymers may begin to break down within 24h. Polymer treatments were still in the early stages of degradation at 240h with a maximum degradation rate of 0.0031%/h, and mass loss of polymers was less than 2%. However, within 24h, the structures of polymers may have altered to promote future degradation at longer incubation times. Accelerated degradation was observed when PHA, PBSA, PBSA:PHA (Blend), and polyethylene (LDPE) films were incubated in the rumens of three Holstein cows up to 150d. Mass loss and the length of the remaining polymers were assessed monthly. Polyhydroxyalkanoate began to degrade by 14d and completely degraded by 30d with a disappearance rate of 7.84%/d. The remaining polymer did not achieve any mass loss. However, PBSA and Blend residue size began to decrease by 60d and 1d, respectively. Based on Blend's structural degradation within 1d of incubation that may promote its clearance from the rumen if ingested, we proposed that the material may be an alternative to polyethylene single-use agricultural plastic products. When Blend films were fed to calves, breakdown of the material further supported our dissemination that PBSA:PHA may be a suitable alternative to LDPE in the case of animal ingestion. Holstein bull calves (n = 12, 62 ± 9d, 74.9 ± 8.0kg) were randomly allotted to one of three daily bolus treatments: 13.6g of PBSA:PHA (Blend), 13.6g of polyethylene (LDPE), or no polymer (Control) distributed over 4 gelatin capsules for 30d. Feed intake, body weight, body temperature, and general health were determined throughout the study. Blood analyses were conducted on blood samples collected before and after the experimental period. On d31, animals were sacrificed to evaluate rumen growth and health, measure rumen papillae length, and describe polymers that may reside in the rumen. No animals presented any signs related to plastic impaction and animal health was not particularly affected by treatment. Daily grain and hay intake, body weight, rectal temperature, blood parameters, and rumen growth and health were not affected by treatment. There was evidence that degradation of Blend may support rumen function. Methylene blue reduction time of Blend calves tended to be decreased by 30% compared to LDPE calves, which indicates the rumen microbiome of Blend calves may better ferment feeds. Papillae length of Blend calves were also 50% longer than those of Control animals, which would improve the absorption of nutrients. Byproduct formation from Blend degradation could explain this; however, studies are needed to specifically elucidate the production of byproducts and their relationship to rumen function. Polymer accumulation and residue length differed among treatments. Calves dosed with LDPE retained 6.7% of the dosed polymer, undegraded, while Blend calves retained 0.4% of the dosed polymer. The polymer residues in Blend calves were 10% of their original size. Single-use agricultural plastics developed from PBSA:PHA may be a suitable alternative to polyethylene-based products in the case of ingestion in ruminants due to no short-term health inflictions, the reduced polymer size within 1d, and improved clearance from the rumen. As such, utilization of these materials may reduce the incidences of plastic impaction in ruminants in commercial operations. Further long-term feeding studies are needed to evaluate specific byproduct production of PBSA:PHA and their potential influences on rumen function and animal health and production in normal commercial conditions.

Dado o poder agropecuário nacional e sabendo que a pastagem tem papel fundamental na nutrição animal, torna-se primordial o estudo dos mecanismos da digestão ruminal das forragens, para um aproveitamento mais racional das pastagens pelos animais, propiciando uma fermentação ruminal ótima e possibilitando o balanceamento de rações de forma mais adequada. Esta abordagem é possível por meio dos modelos de degradação ruminal, que são classificados como modelos de regressão não lineares. Neste trabalho são abordadas as metodologias clássica e bayesiana para ajustar os modelos que descrevem a cinética de degradação ruminal por meio da técnica de produção de gases. Na abordagem clássica foram considerados os modelos não sigmoidal proposto por Orskov&McDonald (1979), o Logístico proposto por Schofield (1994) e o Gompertz proposto por Lavrencic (1997), considerando a necessidade de fatores autorregressivos de primeira e segunda ordem mediante o teste de razão de verossimilhança (TRV); os modelos foram avaliados por meio dos critérios de Akaike (AIC), coeficiente de determinação ajustado (R2 aj) e quadrado médio residual (QMR). Em uma segunda etapa realizou-se o ajuste do modelo não sigmoidal sem fator autorregressivo utilizando a abordagem bayesiana, em que a condição de convergência das cadeias foi analisada por meio dos critérios de Geweke (1992), Heidelberger&Welch (1993), Raftery& Lewis (1992) e o Erro de Monte Carlo (EMC). Dentre os modelos utilizados, o que melhor se ajustou aos dados analisados foi o modelo não sigmoidal proposto por Orskov e McDonald (1979), sem o fator autorregressivo, obtendo estimativas condizentes com a realidade do fenômeno. Os resultados obtidos por meio da abordagem bayesiana também foram satisfatórios, mostrando que a técnica, apesar de pouco difundida em estudos de degradação ruminal é uma metodologia bastante viável e tem muito a agregar em estudos da área. / Given the national agricultural power and knowing that grazing plays an important role in animal nutrition, it becomes primordial to study the mechanisms of ruminal digestion of forages, for a more rational use of pastures by the animals, providing an optimal rumen fermentation and allowing a more adequate and balanced feed. This approach is possible by using the rumen degradation models, which are classified as non-linear regression models. This essay discusses the classical and Bayesian methods to adjust the models that describe the kinetics of degradation by rumen gas production technique. In the classical approach, the \"Non Sigmoidal models\", proposed by Orskov& McDonald (1979), the \"Logistic\", proposed by Schofield (1994), and \"Gompertz\", proposed by Lavrencic (1997), were considered, taking into account the need for autoregressive factors of first and second order, by the \"likelihood ratio test \" (TRV). These models were evaluated using the Akaike criteria (AIC), the coefficient of determination adjusted (R2aj) and \"the residual average square\" (QMR). In the following stage, the adjustment of the non sigmoidal model without the autoregressive factor were performed, using the Bayesian approach. For these matters, the condition of the convergence of chains was analyzed using Geweke (1992), Heidelberger & Welch (1993), Raftery& Lewis (1992) and Monte Carlo error(EMC) criteria.Among the models used, the one that best settle to the data analyzed was the non sigmoidal model without the autoregressive factor, proposed by Orskov and McDonald (1979), obtaining consistent estimates with the reality of the phenomenon. The results obtained through the Bayesian approach were also satisfactory, showing that the technique, although less diffused in studies of rumen methodology, is very viable and has a lot to add in these area studies.

Made available in DSpace on 2015-03-26T13:54:50Z (GMT). No. of bitstreams: 1 texto completo.pdf: 526815 bytes, checksum: 0f1a8d5fba2922105d942fb71cd87da7 (MD5) Previous issue date: 2010-02-23 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this work was to evaluate the lignin contents in tropical forage using the methods of acid sulfuric lignin (ASL), potassium permanganate lignin (PL), Klason lignin (KL) and acetyl bromide soluble lignin obtained from cell wall (ABLcw) and from acid detergent residue (ABLad) and their association with parameters of neutral detergent fiber (NDF) degradation. It were evaluated ten grass samples: elephant grass (Pennisetum purpureum), signal grass (Brachiaria decumbens), torpedo grass (Panicum repens), Korovinia grass (Brachiaria humidicula), gamba grass (Andropogon gayanus), aruana grass (Panicum maximum cv. Aruana), mombaça grass (Panicum maximum cv. Mombaça), xaraés grass (Brachiaria brizantha cv. Xaraés), tifton-85 (Cynodon sp.), and massai grass (Panicum maximum cv. Massai); and ten legume samples: perennial peanut (Arachis pintoi), alfafa (Medicago sativa), leucaena (Leucaena leucocephala), galactia (Galactia striata), lablab bean (Dolichos lablab), butterfly pea (Centrosema pubescens), glycine (Glycine weghtii), gliricidia (Gliricidia sepium), Brazilian lucerne (Stylosantes guianenensis) and guandu (Cajanus cajan). All samples were taken through a cutting near to ground in December of 2008. The plants were 45-days regrowth. The lignin contents obtained by gravimetric methods were also estimated corrected for nitrogenous compounds. In this case, they were assigned as ASLp, PLp, and KLp. The indigestible NDF (iNDF), the fractional degradation rate of potentially degradable NDF (kd), and the discrete lag of NDF degradation were obtained by an in vitro assay. The correction for nitrogenous compounds decreased (P<0.05) the contents of ASL, KL and PL. The differences between corrected and crude values were more prominent for KL. The protein contents of KL were found similar (P>0.05) to neutral detergent insoluble protein. There was interaction effect (P<0.05) between analytical method and forage group on lignin contents. Considering the contents as g/kg DM, differences between grasses and legumes were pointed out (P<0.05) by ASLp and PLp, being the higher values associated with legumes, and by ABLcw, which caused higher values in grasses. For grasses, highest lignin contents (P<0.05) were obtained with KLp, which was followed by PLp and ABLcw, that did not differ each other (P>0.05), ASLp, and ABLad. For legumes, highest contents (P<0.05) were obtained with KLp, followed by LPp, ASLp, ABLcw, and ABLad. These last two were not different (P>0.05). The lignin estimates obtained by ASLp and PLp shown similar association pattern (P<0.05) with iNDF, kd, and LAG. There was no difference in both methods for grasses and legumes regarding intercept and slope of adjusted regression (P>0.05). Stronger correlations were observed between PLp and degradation parameters of NDF compared to ASLp. The KLp estimates did associate with alldegradation parameters (P<0.05). However, there were differences between grasses and legumes regardingintercept of adjusted regression (P<0.05). Legumes presented higher iNDF and LAG, and lower kd. The strongest correlation coefficients were obtained using LPp and KLp estimates. The ABLcw contents did not did not presented functional relationships with NDF degradation parameters (P>0.05), where only the average differences between forage groups were detected. It was verified relationship (P<0.05) between ABLad contents and iNDF. However, no difference between grasses and legumes was pointed out by adjusted regression (P>0.05). Nevertheless, the correlation coefficient was weaker compared to ones obtained using ASLp, KLp, and PLp. There were no functional relationships between ABLcw and degradation parameter of NDF (P>0.05). In this case, it was only detected the average difference between forage groups. It was concluded that gravimetric methods ASL, PL and KL produce residues that contain significant contaminant nitrogenous compounds. More accurate estimates of lignin content could be obtained when correction for residual nitrogen is done. This is particularly necessary for KL. Associations between lignin and degradation parameters of NDF are better recognized when KLp and PLp methods are employed. / Objetivou-se avaliar os teores de lignina em forragens tropicais pelos métodos lignina em ácido sulfúrico (LAS), lignina em permanganato de potássio (LPER), lignina Klason (LK) e lignina solúvel em brometo de acetila obtida a partir da parede celular (LBApf) e do resíduo em detergente ácido (LBAfda) e sua associação com parâmetros da degradação da fibra em detergente neutro (FDN). Foram avaliadas amostras de dez gramíneas: capim elefante (Pennisetum purpureum), capim braquiária (Brachiaria decumbens), grama castela (Panicum repens), quicuio da amazônia (Brachiaria humidicola), capim andropogon (Andropogon gayanus), capim aruana (Panicum maximum cv. Aruana), capim mombaça (Panicum maximum cv. Mombaça), capim xaraés (Brachiaria brizantha cv. Xaraés), capim tifton-85 (Cynodon sp.) e capim-massai (Panicum maximum cv. Massai); e dez leguminosas: amendoim forrageiro (Arachis pintoi), alfafa (Medicago sativa), leucena (Leucaena leucocephala), galactia (Galactia striata), lab lab (Dolichos lablab), centrosema (Centrosema pubescens), soja perene (Glycine weghtii), gliricidia (Gliricidia sepium), estilosantes (Stylosantes guianenensis) e guandu (Cajanus cajan). Todas as amostras foram obtidas por corte rente ao solo no mês de dezembro de 2008. As plantas apresentavam aproximadamente 45 dias de rebrotação. Os teores de lignina obtidos pelos métodos gravimétricos foram estimados também na forma corrigida para compostos nitrogenados, sendo referenciados como LASp, LPERp e LKp. Foram estimados por intermédio de ensaio in vitro os teores da fração indegradável da FDN (FDNi), a taxa de degradação da fração potencialmente degradável da FDN (kd) e a latência discreta para degradação da FDN (LAG). A correção para compostos nitrogenados implicou reduções significativas (P<0,05) nos teores de LAS, LK e LPER. Evidenciaram-se diferenças mais proeminentes entre valores corrigidos e brutos (não corrigidos) para LK. Os teores de proteína associados à LK foram considerados similares (P>0,05) aos teores de proteína insolúvel em detergente neutro. Verificou-se interação (P<0,05) entre método analítico e grupo de forrageiras para os teores de lignina. Considerando-se a unidade g/kg MS, diferenças entre gramíneas e leguminosas foram obtidas (P<0,05) com os métodos LASp e LPERp, que indicaram maiores valores para leguminosas, e LBApc, o qual, por sua vez, indicou maior estimativa para gramíneas. Considerando-se somente gramíneas, maior estimativa (P<0,05) foi conferida pelo método LKp, seguido de LPERp e LBApc, que não diferiram (P>0,05), LASp e LBAfda. Para leguminosas, as maiores estimativas (P<0,05) foram conferidas por LKp, seguidas por LPERp, LASp e LBApc e LBAfda, sendo estes últimos similares (P>0,05). As estimativas dos teores de lignina obtidas pelos métodos LASp e LPERp apresentaram comportamento similar, associando-se significativamente (P<0,05) com os teores de FDNi e com kd e LAG. Contudo, para ambos os métodos, não se detectou comportamento diferenciado para gramíneas e leguminosas quanto ao intercepto ou coeficiente de inclinação da função ajustada (P>0,05). Correlações mais fortes foram observadas entre LPERp e os parâmetros de degradação da FDN em relação àquelas obtidas com o método LASp. Os teores de LKp se associaram (P<0,05) com todos os parâmetros de degradação da FDN. No entanto, diferente dos métodos LASp e LPERp, verificou-se diferenciação entre gramíneas e leguminosas quanto ao intercepto da função ajustada (P<0,05), observando-se valores superiores de FDNi e LAG e inferiores de kd para as leguminosas. Os mais fortes coeficientes de correlação entre todos os métodos avaliados foram obtidos com LPERp e LKp. Os teores de lignina estimados pelo método LBApc não apresentaram relação (P>0,05) funcional com nenhum dos parâmetros da dinâmica de degradação da FDN. Para todos estes, apenas percebeu-se a diferença média entre grupos de forrageiras. Verificou-se relação (P<0,05) entre os teores de lignina estimados pelo método LBAfda e os teores de FDNi, observando-se, contudo, nenhuma diferenciação entre gramíneas e leguminosas (P>0,05). Contudo, o coeficiente de correlação foi menos forte em comparação àqueles verificados para os métodos LASp, LKp e LPERp. Não foram verificadas relações funcionais (P>0,05) entre as estimativas obtidas pelo método LBApc e os parâmetros de degradação da FDN, detectando-se somente a diferença média entre grupos de forrageiras. A partir dos resultados obtidos conclui-se que os métodos gravimétricos LAS, LPER e LK produzem resíduos contaminados por compostos nitrogenados. A correção para estes contaminantes é sugerida, notadamente para LK, para que os teores de lignina sejam expressos com maior exatidão. Associações entre lignina e os parâmetros de degradação ruminal da FDN são mais bem estabelecidas utilizando-se as estimativas produzidas pelos métodos LKp e LPERp.

Dado o poder agropecuário nacional e sabendo que a pastagem tem papel fundamental na nutrição animal, torna-se primordial o estudo dos mecanismos da digestão ruminal das forragens, para um aproveitamento mais racional das pastagens pelos animais, propiciando uma fermentação ruminal ótima e possibilitando o balanceamento de rações de forma mais adequada. Esta abordagem é possível por meio dos modelos de degradação ruminal, que são classificados como modelos de regressão não lineares. Neste trabalho são abordadas as metodologias clássica e bayesiana para ajustar os modelos que descrevem a cinética de degradação ruminal por meio da técnica de produção de gases. Na abordagem clássica foram considerados os modelos não sigmoidal proposto por Orskov&McDonald (1979), o Logístico proposto por Schofield (1994) e o Gompertz proposto por Lavrencic (1997), considerando a necessidade de fatores autorregressivos de primeira e segunda ordem mediante o teste de razão de verossimilhança (TRV); os modelos foram avaliados por meio dos critérios de Akaike (AIC), coeficiente de determinação ajustado (R2 aj) e quadrado médio residual (QMR). Em uma segunda etapa realizou-se o ajuste do modelo não sigmoidal sem fator autorregressivo utilizando a abordagem bayesiana, em que a condição de convergência das cadeias foi analisada por meio dos critérios de Geweke (1992), Heidelberger&Welch (1993), Raftery& Lewis (1992) e o Erro de Monte Carlo (EMC). Dentre os modelos utilizados, o que melhor se ajustou aos dados analisados foi o modelo não sigmoidal proposto por Orskov e McDonald (1979), sem o fator autorregressivo, obtendo estimativas condizentes com a realidade do fenômeno. Os resultados obtidos por meio da abordagem bayesiana também foram satisfatórios, mostrando que a técnica, apesar de pouco difundida em estudos de degradação ruminal é uma metodologia bastante viável e tem muito a agregar em estudos da área. / Given the national agricultural power and knowing that grazing plays an important role in animal nutrition, it becomes primordial to study the mechanisms of ruminal digestion of forages, for a more rational use of pastures by the animals, providing an optimal rumen fermentation and allowing a more adequate and balanced feed. This approach is possible by using the rumen degradation models, which are classified as non-linear regression models. This essay discusses the classical and Bayesian methods to adjust the models that describe the kinetics of degradation by rumen gas production technique. In the classical approach, the \"Non Sigmoidal models\", proposed by Orskov& McDonald (1979), the \"Logistic\", proposed by Schofield (1994), and \"Gompertz\", proposed by Lavrencic (1997), were considered, taking into account the need for autoregressive factors of first and second order, by the \"likelihood ratio test \" (TRV). These models were evaluated using the Akaike criteria (AIC), the coefficient of determination adjusted (R2aj) and \"the residual average square\" (QMR). In the following stage, the adjustment of the non sigmoidal model without the autoregressive factor were performed, using the Bayesian approach. For these matters, the condition of the convergence of chains was analyzed using Geweke (1992), Heidelberger & Welch (1993), Raftery& Lewis (1992) and Monte Carlo error(EMC) criteria.Among the models used, the one that best settle to the data analyzed was the non sigmoidal model without the autoregressive factor, proposed by Orskov and McDonald (1979), obtaining consistent estimates with the reality of the phenomenon. The results obtained through the Bayesian approach were also satisfactory, showing that the technique, although less diffused in studies of rumen methodology, is very viable and has a lot to add in these area studies.

Made available in DSpace on 2015-03-26T13:55:30Z (GMT). No. of bitstreams: 1 texto completo.pdf: 481163 bytes, checksum: dff710e12faa7426a857bca7ddcd71a4 (MD5) Previous issue date: 2007-03-20 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Diets formulated with protein sources presenting different resistance to ruminal degradation were compared by evaluating intake, total and partial digestibility, nitrogen balance, fluxes of nutrients to omasum, production and microbial efficiency and ruminal parameters in goats. Eight rumen cannulated non-lactating, non- pregnant goats were distributed in a 4 x 4 Latin square design with two repeats. Treatments consisted of four diets where different source of plant protein account for the major protein source named soybean meal (SM), roasted soybean (RS), corn gluten meal (CGM), and cottonseed cake (CC). No difference was found as both intake and apparent digestibility of dry matter and nutrients were compared among diets. Reduction of ruminal digestibility for dry matter, crude protein and non fiber carbohydrates by using ration with RS, CGM and CC. Biological values and true digestibility for diets were similar. Amount of rumen protein were similar among rations, however fluxes of dry matter, protein and non fiber carbohydrate to omasum were higher for rations using roasted soybean, corn gluten meal and cottonseed cake. Ammonia nitrogen concentration was higher for ration with soybean meal as major protein source. Values of pH higher values were obtained for rations with RS and CC. Regarding kinetic of transit similar values were found among rations. Rations containing RS, CGM and CC as major protein source presented degradability smaller than diet using soybean meal as the major source of protein, but no difference among rations were found as availability and use by animals were compared. Diets with protein sources presenting reduced ruminal degradation do not compromised the bacterial growth, increasing flux of nutrients to omasum. Although pH and rumen ammonia are altered no compromise is observed in both production and microbial efficiency as those sources are used for dairy goats, which grant their use with similar efficiency to rations using source of more degradable protein. / Objetivou-se com este estudo, avaliar o efeito do uso de fontes protéicas apresentando diferentes graus de resistência à degradação ruminal sobre o consumo, digestibilidade total e parcial, balanço de compostos nitrogenados, fluxo de nutrientes para o omaso, produção e eficiência microbiana e características ruminais. Foram utilizadas oito cabras fistuladas no rúmen, não-gestantes e não lactantes, distribuídas em um delineamento em quadrado latino 4 x 4, duplicado. Foram utilizadas quatro dietas com diferentes fontes de proteína: farelo de soja (FS), soja grão tostada (SGT), farelo de glúten de milho (FGM) e torta de algodão (TA). As rações contendo FS, SGT, FGM e TA como fontes principais de proteína não influenciaram o consumo, a digestibilidade aparente total da matéria seca e dos nutrientes. Houve redução da digestibilidade ruminal da matéria seca, da proteína bruta e dos carboidratos não-fibrosos com o uso das rações contendo SGT, FGM e TA. Os valores biológicos e a digestibilidade total das dietas contendo diferentes fontes de proteína foram semelhantes, independente do perfil da degradação ruminal. As rações com diferentes fontes protéicas não apresentaram diferença na quantidade de proteína presente no rúmen, porém as rações contendo SGT, FGM e TA promoveram um maior fluxo de matéria seca, de proteína e de carboidratos não-fibrosos para o omaso. Maiores valores para a concentração de nitrogênio amoniacal foram obtidos com a ração contendo farelo de soja como principal fonte principal de proteína. Na avaliação de pH foram obtidos maiores valores para as rações contendo SGT e TA. Não houve diferença entre as rações com diferentes fontes de protína quanto à cinética de trânsito. As rações contendo SGT, FGM e TA como principais fontes protéicas apresentam menor degradabilidade ruminal comparativamente ao FS, no entanto as mesmas não diferem entre si, quanto sua disponibilidade e aproveitamento pelos animais. O uso destas fontes de proteína de menor degradabilidade ruminal promovem aumento no fluxo de nutrientes para o omaso e alteram parâmetros digestivos (como nitrogênio amoniacal e pH), sem comprometer a produção e eficiência microbiana, podendo ser utilizadas na alimentação de cabras leiteiras, o que garante o seu uso com eficiência similar à rações utilizando fontes protéicas com maior degradabilidade.