Estimates of energy requirements for maintenance and gain of Holstein x Gyr crossbred yearling bulls using comparative slaughter and respiration chambers techniques.

Brazil has its own nutrient requirement system for cattle; however, information about crossbred cattle is little due to the database being constituted of zebu cattle in general. Regarding energy requirements, different techniques are available to measure the retained energy (RE) of animals and then estimate the requirements. Comparative slaughter (CS) and respiration chambers (RC) are two of them. Each one has its specific advantages and disadvantages. The CS is able to measure RE directly, but it is very laborious and precludes the use of animals of high commercial value. On the other hand, RC prevents the slaughter of animals but it precludes the use of grazing ruminants and it is very expensive. The objective of this study was to compare the estimates of energy requirements for maintenance and gain of Holstein × Gyr crossbred yearling bulls using CS and RC techniques

Unexpected effects of pigeon-peas (Cajanus cajan) in the restoration of rupestrian fields Efeito inesperado do feijão-guandu (Cajanus cajan) na restauração de campos rupestres

Several degraded areas can be found along the Highway MG-010 that crosses the Espinhaço Mountain Biosphere Reserve in the Brazilian state of Minas Gerais. Restoration by planting the legume Cajanus cajan was implemented in some of these areas. The present study compares plant species richness, diversity, abundance, equitability, similarity, and soil composition between restored and non-restored areas, in an attempt to evaluate the effectiveness of the use of C. cajan in the restoration process in the mountain environment. Each treatment (restored and non-restored) had four sampling areas, each with three 300 m² plots. We counted and identified every individual plant found within these plots. We also collected soil from the superficial layer (0-10 cm) of each sampling area in both treatments. The areas where C. cajan was planted revealed lower species richness, diversity, and plant abundance. The soil of these areas also contained higher levels of Phosphorus and Magnesium. Plant equitability and similarity between plots and other soil components (pH, Nitrogen, Aluminum, Calcium, Potassium, H+Al, sum of bases - SB, cation exchange capacity - CTC, base saturation - V%, aluminum saturation - M%) did not differ between the two treatments. Contrary to the expectations, soil enhancement in the quartzitic soil poor in nutrients in the rupestrian fields can facilitate the invasion by exotic plants, which are not adapted to the lack of nutrients. As it appears, the use of C. cajan in restoration projects represents a mistake and future restoration plans should avoid the use of exotic species, given that they may cause negative effects on the native plant community, as demonstrated here in the rupestrian fields.<br>Várias áreas degradadas podem ser encontradas ao longo da rodovia MG-010, que corta a Reserva da Biosfera da Cadeia do Espinhaço, em Minas Gerais, Brasil. Algumas dessas áreas foram restauradas através do plantio da leguminosa Cajanus cajan. O presente trabalho compara a riqueza, diversidade, abundância, equitabilidade e similaridade da comunidade de plantas, e composição do solo de áreas degradadas restauradas e não restauradas, a fim de avaliar a efetividade do uso de C. cajan no processo de restauração. Cada tratamento (áreas restauradas e não-resturadas) teve quatro áreas amostrais, as quais, por sua vez tiveram três parcelas de 300 m². Em cada parcela, todos os indivíduos de planta foram contados e identificados. Além disso, foi coletado o solo da camada superficial em todas as quatro áreas amostrais de ambos os tratamentos. As áreas onde C. cajan foi plantado apresentaram menores riqueza, diversidade e abundância de plantas. O solo dessas áreas também apresentou níveis mais altos de Fósforo e Magnésio. Equitabilidade e similaridade e outros componentes do solo (pH, Nitrogênio, Alumínio, Cálcio, Potássio, H+Al, Soma de Bases - SB, Capacidade de Troca Catiônica- CTC, Saturação de Bases - V%, Saturação de Alumínio - M%) não variaram entre os tratamentos. Ao contrário do esperado, o enriquecimento dos solos quartzíticos pobres em nutrientes dos campos rupestres pode facilitar a invasão desses ambientes por espécies exóticas não adaptadas à falta de nutrientes. Portanto, foi concluído que a restauração com o uso de C. cajan foi um equívoco e que os próximos planos de restauração nesse tipo de ambiente devem evitar o uso de espécies exóticas, já que o uso destas pode ter um efeito pior do que manter a área sem nenhuma ação