Supplementation on beef cattle performance in pastures: season of the year

The present study used meta-analysis to assess the effects of supplementation on beef cattle performance in pastures in Brazil, classifying data by season of the year. There were reviewed articles published in journals indexed from 1999 to 2007. There were used 70 articles and data were grouped according to season of the year (Rainy, Drought, Transition Rainy/Drought and Transition Drought/Rainy). 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 the correlation and significance level, between dependent and independent variables were obtained using the SAS statistical program PROC CORR. In rainy season (n=49) 45.8 % of corrected daily gain ranged between 0.11 and 0.20 kg/day and for drought season (n = 54) it was observed that 21.2 % of the data were under 0.02 kg/d and 21.2% above 0.40 kg/day. Correlation between corrected daily gain during drought and consumption of protein supplement was 0.598 (P < 0.01), and with the TDN/PB ratio of forage this correlation was 0.612 (P < 0.01). The evaluated data that supplementation increases the adjusted daily gain of animals on pasture.