Abstract The aim of this study was to evaluate the influence of two sub-periods of the calving season and two cow maturity stages on the efficiency of beef cows and their calves. A total of 159 cow-calf pairs were divided by calving time (early or late) within the calving season and maturity stage (young or adult). Calves were weaned at 42 or 63 days after birth and evaluated until 210 days of age. Cows and calves had their development examined based on their weight and body condition score at calving, at weaning, and at 210 days. Reproductive performance was evaluated on the basis of time to become pregnant again. Milk yield was assessed by the direct method on three occasions spaced 21 days apart. Adult cows were heavier than young cows, at calving (398.5 vs 327.5 kg, respectively), weaning (397.3 vs 324.1 kg, respectively) at the end breeding season (424.1 vs 342.1 kg, respectively). Reproductive performance was influenced by calving time. Adult cows had higher pregnancy rates (83.75 and 69.17%, for early and for late calving, respectively) than young cows (57.03 and 35.01% for early and for late-calving, respectively). Calves from early-calving young cows weighed 158.8 kg at 210 days of age vs. 123.7 kg for those born from late-calving adult cows. However, late-calving cows produced 10.7% more milk than those that calved early in the season (227.0 vs 205.0 liters, respectively). Early calving associated with non-requirement of growth determine higher productivity efficiency in beef cows.

A correta avaliação e previsão do tempo de vida útil dos mecanismos que atuam no rompimento do solo, são importantes na análise de equipamentos. O desgaste deste tipo de ferramenta (ponteiras sulcadoras de semeadoras, de escarificadores e de subsoladores) depende de vários fatores, entre eles as condições do solo e características geométricas e construtivas das ferramentas. A taxa de desgaste das ferramentas de mobilização do solo, normalmente é determinada através da sua perda de massa. O objetivo do trabalho foi desenvolver uma metodologia diferenciada, ágil e de fácil execução, para avaliação do desgaste de ferramentas simétricas que promovem a mobilização do solo. A análise da variação da configuração geométrica da ferramenta foi obtida por fotografia digital utilizando-se, posteriormente, um programa computacional para o seu desenho. Utilizaram-se ponteiras sulcadoras de adubo de semeadora de plantio direto como ferramenta de mobilização de solo. Os resultados possibilitaram verificar que o desgaste é melhor determinado pelo método da fotografia digital que pelo método tradicional (perda de massa). A vantagem do método proposto reside basicamente em sua agilidade e precisão.

The correct evaluation and prediction of the durability of soil-engaging mechanisms are important factors in the analysis of the agricultural equipments. The wear of these tools (planters furrow openers, chisel and subsoiler rippers) is dependent on various factors, among them the soil conditions and the geometric and constructive characteristics of the tool. The wear rate of the soil-engaging tools is usually determined through loss of mass. The analysis of the variation of the geometric configuration of the tool was assessed through digital photography, afterwards a software was used to design them. The objective of the study was to use a differentiated, agile methodology of easy execution, for evaluation of the wear of soil-engaging tools. In this study furrow openers of a direct drill planter was employed as the soil-engaging tool. The results show that the wear is best determined by the digital photography than the traditional method (loss of mass). The advantage of the proposed method consists basically in its agility and precision.