Suplementação de bovinos de corte em pastagens : forragem, época do ano e tipo de suplemento

The present study used meta-analysis to assess the effects of supplementation on beef cattle performance in pastures in Brazil, classifying data by forage type, period of the year and supplement type. There were reviewed articles published in journals indexed by "Scielo" using internet searching tools, from 1999 to 2007. There were used 70 articles and information from material and methods and results sections, of each article, were set to a database. Data were grouped according to forage type (Tropical and Temperate), period of the year (Rainy, Drought, Transition Rainy/Drought and Transition Drought/Rainy) and supplement type (Energy/Protein, Protein Salt, Protein and Energy). It was done comparisons between animals without supplement (control) and supplemented animals, to determine the real effect of supplementation on performance and to find the corrected daily gain in each study. A meta-analysis was performed using three sequential analyses: graphic, correlation and variance. The regression equations were obtained through the covariance, and correlation and significance level, between dependent and independent variables were obtained using the SAS statistical program PROC CORR, with a significance level of 1%, and the final selection of variables was based on R2 value. It was observed that 27.4% of animals grazing forage growing in Brazil, showed a corrected daily gain between 0.11 and 0.20 kg/d, and 85.2 % of corrected gain are positive, with a range between 0.02 and 0.40 kg/d. Animals grazing tropical grasses showed a gain positively correlated (P