Abstract
An experiment was conducted to study the comparative performance of cattle fed young or mature guinea grass (Panicum maximum Jacq. ecotype A) and urea supplemented rice straw. Evaluation was based on intake and digestibility parameters. Twelve crossbred bulls calves weighing $90{\pm}15$ kg were offered young (4 weeks regrowth) or mature (9 weeks regrowth) grass in the long or chopped (10-15 cm) form, and rice straw supplemented with urea. The diets were offered 30-60% in excess of voluntary intake, and the experiment consisted of two periods. The crude protein content of the young grass, mature grass and the straw offered were 12.2, 5.4 and 7.7%, respectively, and the refusal was 10.1, 3.9 and 7.0%, respectively. The organic matter digestibility of the young grass (69%) was significantly higher than the mature grass (62.5%) and straw (55.8%) diets. The organic matter intake (kg/100 kg LW/day) of the unchopped and chopped grass diets were 2.6 and 3.3 respectively, and these values were significantly higher (p < 0.01) than the young grass (2.3) and straw (2.1) diets. The digestible organic matter intake (DOMI) of the mature grass diet offered in the chopped form (2.1 kg/100 kg LW/day) was significantly higher (p < 0.01) than the other three diets. The DOMI of the young and mature grass offered in the long form was similar (1.6 kg/100 kg LW/day), but were significantly better (p < 0.01) than the urea supplemented straw diet.