Scielo RSS <![CDATA[Revista Brasileira de Zootecnia]]> vol. 44 num. 6 lang. es <![CDATA[SciELO Logo]]> <![CDATA[Kinetics of transit and degradation of the fiber from guinea grass silages enriched with waste from soybean pre-cleaning]]> The objective was to study the kinetics of transit and degradation of the fiber from guinea grass and the waste from soybean pre-cleaning (WSPC), ensiled with different proportions of mass (0, 100, 150, and 200 g WSPC/kg total mass). Four crossbred (Gyr × Holstein), fistulated cattle with an average body mass of 400±50 kg were organized in a 4 × 4 Latin square experimental design. The fiber utilized in the study of the transit kinetics was stained with chromium mordant, whereas the in situ technique was adopted for the degradation kinetics. The level of inclusion of WSPC only affected the true digestibility and the mean retention time. The addition of waste from soybean pre-cleaning to the silage of guinea grass is beneficial, in terms of kinetics of digestion and passage, at up to levels close to 100 g/kg, because after this quantity the fiber digestion and passage in and through the reticulo-rumen are impaired and there may be alterations in the ruminal environment that will affect the use of silage by animals. <![CDATA[Milk composition and its relationship with weaning weight in Charolais catte]]> To determine the effects of a number of non-genetic factors on milk components and estimate their indirect relationships with weaning weight (WW205), the percentages of protein, fat, lactose and solids non-fat in Charolais cows from Mexico were estimated. Lactation period (LP) and calving season (CS) had significant effects on protein and fat, whereas lactose and solids non-fat were only affected by the LP. Sire line and age of the dam had significant effects on calf birth weight, while CS affected WW205. Residual correlations between milk components and WW205 suggest a low but significant correlation with lactose. These results demonstrate the importance of several non-genetic factors on the composition of milk from Charolais cows managed under extensive cow-calf production systems and the indirect relationships between these factors and the weaning weight of a calf. <![CDATA[Conceptual model to identify factors with influence in Brazilian beef consumption]]> The complexity of the consumers' behavior has taken the food industry to a new level of dynamism. Therefore, understanding the factors that influence this behavior is decisive for the differentiation of products to niche markets and even to adjust the supply according to consumers' expectancy. This article proposes a conceptual model to identify the factors influencing beef consumption in Brazil. The methodological approach was characterized by a systematic review through a synthesis of research related directly to this topic. Therefore, 76 papers published during the 2000-2014 period, including official documents (statistics), full research papers, abstracts, proceedings, and reports, were selected. Four main factors were related to influences in consumer behavior and/or directly in beef consumption: sociocultural, economic, health/food, and environmental. Among these dimensions, there was an emphasis on recent publications related to health/food and the environment. The compilation and analysis of these papers enabled the conception of the proposed model and suggests the consideration of four main dimensions in beef consumption. <![CDATA[Economic and socio-environmental performance assessment of beef cattle production systems: a data envelopment analysis (DEA) approach with weight restrictions]]> This study evaluated the performance of 21 beef cattle modal production systems that conduct only the raising phase. These production systems were developed in 21 municipalities in seven Brazilian states. We used two different DEA BCC models, corresponding to different points of view. Firstly we used an economic model that measured the ability of a production system to generate revenue with the preservation of native forest, using labor, capital, and current spending as inputs. The socio-environmental approach, corresponding to the second BCC model, uses the production factor labor as an output. In that model our interest was to assess whether the capital costs generate economic, environmental, and social benefits. Weight restrictions were imposed on the output variables of each model to explain the proposed viewpoints and to avoid inconsistent results. The results pointed out sources of inefficiency in terms of labor with low qualification, and use of bulls of questionable quality, factors that are common in extensive systems. These are some of the major bottlenecks in animal production systems as a whole. <![CDATA[Methodology to estimate the cost of delayed pregnancy for dairy cows. An example for Argentina]]> The objectives of the present study were to develop a methodology that implies the use of an electronic spreadsheet to calculate the financial losses of involuntary days open (IDO; every additional day open beyond an optimal calving-to-conception interval) and to show an example of the cost of days open using the proposed methodology. The costs accounted for in the methodology were: milk yield loss, calf crop loss, additional reproductive interventions, and cow replacement costs due to infertility. An example for Argentinean dairy cows in grazing year-round calving systems is presented. Results suggest that milk yield loss and cow replacement due to infertility are the main components determining the final cost of the delayed pregnancy. The methodology presented in this study is simpler than previous methodologies, and can be applied in a wide range of scenarios, using different cow types and regional costs.