Performance and feed intake of beef heifers on rotational grazing of natural grassland receiving protein and energy supplement in cool season

The aim of this study was to evaluate the performance and feed intake of grazing beef heifers on two grazing intervals determined by thermal sum related to leaf elongation duration during cool season on natural grasslands. A complete randomized block design experiment with two treatments and three replications was conducted from May to September 2011 in the central part of the state of Rio Grande do Sul, Brazil. The treatments were two thermal sums calculated at 375 and 750 degrees-days (DD) to determine the intervals between grazing periods in a rotational grazing system. Thirty six beef heifers with average age of 18 months old and (initial body weight = 220 +/- 14kg) were used, all heifers received ground corn supplement at a rate of 5g kg(-1) of body weight per day, at 2p.m., throughout the experiment and had free access to mineral and protein supplementation (450g kg(-1) of CP). Similar average daily gain (ADG), beef production gain (BPG) and feed intake (FI), were obtained in both treatments. Leaf elongation duration is an alternative grazing management tool for improved animal production and to increase animal stocking rate.