Avaliação do modelo NRC para predição do consumo de matéria seca por vacas leiteiras manejadas em pastos tropicais / NCR Model Evaluation for prediction of dry matter intake by dairy cows managed in tropical pastures

Objetivou-se avaliar o poder preditivo do modelo do National Research Council (NRC) para gado leiteiro em estimar o consumo de matéria seca (CMS) por vacas mestiças, em pastagens tropicais. Foi efetuada uma análise conjunta de cinco estudos, contemplando três forrageiras. Foram avaliadas 132 estimativas individuais do CMS observado (CMSObs), obtidas por meio do indicador externo Cr2O3. O CMS também foi predito por meio do software do NRC (CMSPred), que, por sua vez, foi abastecido com inputs referentes aos animais e ao ambiente de criação. Os valores de CMSPred (12,7±1,6kg/d) foram semelhantes aos de CMSObs (12,3±3,3kg/d). Foram obtidas as seguintes estimativas da avaliação do poder preditivo do modelo: viés médio (-0,419kg/d), coeficiente de determinação (0,029), coeficiente de correlação (0,17; P=,051), quadrado médio do erro de predição (11,844±20,034), fator de eficiência do modelo (-0,081), coeficiente de determinação do modelo (4,1032) e fator de correção do viés (0,767). A comparação entre CMSObs e CMSPred permitiu identificar a tendência de superestimação das predições se considerado o ajuste por meio de regressão robusta para o modelo linear simples sem intercepto. Nas condições avaliadas, o modelo produz predições de CMS com satisfatória exatidão, porém com baixa precisão.(AU)

The aim of the present study was to evaluate the predictive power of estimating the dry matter intake (DMI) of crossbred cows on tropical pastures by the National Research Council (NRC) equation for dairy cattle. A joint analysis of five studies covering three forages was performed in which 132 individual estimates of observed DMI obtained through Cr2O3 as a marker. DMI was also predicted from the NRC (DMIPred) software with inputs concerning animals and breeding environment of the studies used. Predicted DMIPred average values (12.7±1.6kg/d) were similar to the observed DMIObs ones (12.3±3.3kg/d). We obtained the following estimates of the evaluation of the predictive power of the model: average bias (- 0.419kg/d), coefficient of determination (0.029), Person's correlation coefficient (0.17, P= 0.051), mean square error of prediction (11,844±20,034), model efficiency factor (- 0.081), coefficient of determination (4.1032), and bias correction factor (0.767). The comparison between DMIObs and DMIPred values allowed the identification of the overestimating tendency of the predictions demonstrated by the robust regression fit of the simple linear no intercept model. Nevertheless, the model yields predictions with satisfactory accuracy, but with low precision.(AU)

Carbohydrate binding modules enhance cellulose enzymatic hydrolysis by increasing access of cellulases to the substrate.

Plant biomass is a low-cost and abundant source of carbohydrates for production of fuels, "green" chemicals and materials. Currently, biochemical conversion of the biomass into sugars via enzymatic hydrolysis is the most viable technology. Here, the role of carbohydrate binding modules (CBMs) in the disruption of insoluble polysaccharide structures and their capacity to enhance cellulase-promoted lignocellulosic biomass hydrolysis was investigated. We show that CBM addition promotes generation of additional reducing ends in the insoluble substrate by cellulases. On the contrary, bovine serum albumin (BSA), widely used in prevention of a non-specific protein binding, causes an increase in soluble reducing-end production, when applied jointly with cellulases. We demonstrate that binding of CBMs to cellulose is non-homogeneous, irreversible and leads to its amorphisation. Our results also reveal effects of CBM-promoted amorphogenesis on cellulose hydrolysis by cellulases.

Alignment of the human body in standing.

Alignment of the body in typical symmetrical standing was studied by photographing fifteen subjects in profile on a reaction board. Two aspects of alignment were studied: (1) the anteroposterior position of the body landmarks of knee joint, hip joint, shoulder joint, and ear, compared to the ankle joint; and (2) the positions of the partial centers of gravity above the knee and hip, as a measure of how the body is balanced above these joints. The knee, hip, shoulder, and ear were forward of the ankle in all subjects. On average, the knee was 3.8 (+/- 2.0), the hip 6.2 (+/- 1.3) the shoulder 3.8 (+/- 1.9), and the ear 5.9 (+/- 1.6) cm (+/-S.D.) anterior to the ankle. The positions of landmarks were positively correlated with one another but not highly. The position of the center of gravity could be predicted well from the positions of the landmarks within individual subjects' data, but not across subjects. The centers of gravity above the knee and hip were calculated by subtracting the mass and position of the segments below the joint from the whole-body center of gravity. The center of gravity above the knee was located on average 1.4 (+/- 1.1) cm in front of the joint, and that of the hip 1.0 (+/- 1.6) cm behind the trochanter. Thus, at both knee and hip in typical standing, there exist slight gravitational torques tending to extend the joints.