Energy Requirements of Zebu Beef Cattle

Projections for beef cattle production in Brazil for the next 10 years forecast an annual increase of about 3.5%. For the same period, a 2.22% growth in the domestic intake of beef cattle and an increase of 3.07% a year in exportation is estimated. This annual increase in exportation could reach 3.4 million tons by 2019, establishing Brazil as the main beef exporting country (MAPA/AGE, 2009). This increase in exports should happen together with improvements in national beef quality and with changes that meet international demands, such as increased tenderness, lower age at slaughter and a better finishing standard, all of which will add value to national beef. With the increase in production and export will come an increase in the cattle finished in feedlot and in the use of industrial crossbreeding. Grain production and poultry, swine and milk production will also show pronounced annual increase rates, improving competitiveness in agribusiness and eliminating those producers that are less effective. Rising concern from environmentalists could limit the progress of livestock farming in new areas, thus making improvements in productivity in existing areas essential for increased production. Therefore, appropriate technologies should be developed and set in place to enable the expansion of beef cattle production. As feeding corresponds to the largest part of operating costs and is one of the main factors affecting animal performance, the search for and the adoption of more rational feed management have the potential to greatly impact both quality and economics in beef cattle production systems. The technologies being adopted in our territory in the field of livestock agriculture should be developed in Brazil, where the cattle herd composition, available feed and climate are typical of a tropical environment. Beef cattle production systems in Brazil are based on pasture covered with tropical grass. The cattle are predominantly zebuine, and the Nellore breed is the most common. More than 80% of the Brazilian herd shows some genetic composition coming from this Zebu breed (Ripamonte, 2002). According to Sainz et al. (2006), the Nellore, with more than 100 million heads spread around the country, has become the main breed due to its adaptability to tropical environments conditions, such as: hot and moist weather; the presence of endoand ectoparasites; and the irregular pattern, qualitative or quantitative, of avaliable feed, Therefore, determining the nutritional requirements of our herd means offering Brazilian society a production technology created under our conditions, which are markedly distinct from those present in countries of temperate climates. The balance of rations and supplements for determined levels of performance, as well as performance estimated from balanced diets, requires the knowledge of nutritional requirements for different functions and for different levels of performance (Boin, 1995).