Observações sobre o consumo e a digestibilidade de nutrientes e de energia por bovinos arraçoados com níveis crescentes de fibra

• Autor(a) principal: Virginio Júnior, Gercino Ferreira
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5822
• topic: Nutrição animal; Bovino - Nutrição - Fibra; Modelos matemáticos; Animal nutrition; Cattle - Nutrition - Fiber; Mathematical models; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL::EXIGENCIAS NUTRICIONAIS DOS ANIMAIS

The basic objective established for this study was to quantify the consumption of dry matter, nutrients and digestible energy of cattle depending on the supply of fiber in the diet. The experiment was conducted in two latin square and balanced for four treatments. Four levels of daily supply of insoluble neutral detergent fiber (3, 6, 9 and 12 g / (kg.dia)), scaled to the body mass of animals were used. Eight crossbred steers, four with 298 ± 27 kg and four with 219 ± 16 kg, were randomly divided, at the beginning of the experiment, as columns in latin squares. Consecutive experimental periods lasted for 21 days, as follows: adjustment period of 14 days and the collection period of seven days. Samples of diets offered, orts and feces were dried, ground and analyzed for dry matter, crude fat, ash, crude protein, neutral detergent insoluble fiber and gross energy. The nutrient intake, digestible nutrients, digestible energy and the amount of feces produced daily were scaled to metabolic size. The exceptions were for the intake of fiber and lignin, corrected for W1 (g/(kg.dia). The linear mixed model was fitted to the variables described staggered, after logarithmic transformation. The statistical model was fitted using the Proc Mixed of SAS, using the method of restricted maximum likelihood (REML). The probability likelihood of the different structures of variance and covariance was assessed using the Akaike information criterion, corrected for small samples. Null hypotheses on the treatment factor and the respective linear and quadratic components were rejected when P < 0.05. The relationship between digestible energy intake and fiber intake, and intake of digestible protein and fiber intake were analyzed considering the allometric model and five hypotheses. The models in these assumptions were adjusted using Proc Mixed of SAS. The same variance and covariance structures listed above were considered and employed the same criteria of verisimilitude already described for the choice (s) best (s) event (s) represent the reality of the data. The adjustment of the variables, using different structures of covariance showed that the structure of variance components was the best choice for most variables, followed by unstructured variance-covariance, heterogeneous structure composed symmetry, Spatial and Spatial power. The variables FAsh , RAsh , RLig , FLig , FFC e DFC showed a quadratic effect, while the other variables showed a linear effect, which can be seen by their equations. With the increase of fiber content in the diet, there is a growing incidence of observed values for variables neutral detergent fiber, dry matter, ash and lignin. However, close to the level of 12 g, there is a tendency of stabilization of the predicted values. In terms of these variables, just the curve of mineral matter excretion in feces presents different behavior, being more stable to level 3 g up to 6 g, and growing from this level. Variables compounds neutral detergent soluble, organic matter, dry matter, crude protein and gross energy showed predicted values with linear growth, which indicates a non-limiting consumption of these variables by increasing the fiber content in the diet. However, the nonfiber carbohydrates and crude fat results showed constant intake and digestibility, indicating that increasing the fiber content in the diet did not influence these data. The relationship between digestible energy intake and fiber intake was analyzed according to the assumptions described in the methodology, and the one that most fit to the data of the present study was the hypothesis 5, whatever they are &#945;1 , &#945;2 , &#946;1 and &#946;2 . The variance-covariance structure that best fit the hypothesis was variance components, with a significant quadratic effect of level of NDF actually consumed. The relationship between consumption of digestible protein and fiber intake was also analyzed and showed similar results to the assumptions previously tested and the variance- covariance structures. Therefore, it can be concluded that the consumption of fiber per dairy crossbred cattle exhibits a tendency towards stabilization, near the level of supply of NDF in the diet of the order of 10.9 ± 2.6 g/(kg.day). The intake and excretion of lignin are coincident within the range of 3 to 7 g/(kg.day) supply of NDF in the diet. This may explain why lignin be characterized as a nutritional entity digestion trials conducted maintenance level, whose offer of NDF find yourself situated within the limits of the present study.