Feeding value of corn and corn silage fed at different levels in the diets for young cattle

4 heifers (268 to 400 kg live weight) were fed with four rations containing corn silage and corn flour in ratios of 82:18 (I), 65:35 (II), 45:55 (III) and 25:75 (IV). Urea was added to achieve an N balance. The rations were aimed at a daily weight gain of 700-800 g. The digestibility of the rations, their metabolizable energy, heat production and retained energy were determined. The digestibility of the organic matter was, in the sequence of I-IV = 73.2, 74.3, 75.4 and 75.8%. In the same sequence the energy intake per animal and day in MJ was = 95.9, 92.8, 91.3 and 89,7; the digestibility of the energy was 71.5, 72.2, 73.8 and 74.8%. In urine 3.1, 2.5, 2.7 and 2.9% and in methane 7.6, 7.8, 7.6 and 7.2% of the energy intake were excreted. Metabolizable energy was 60.8, 62.0, 63.5 and 64.7%, heat production 48.7, 48,7, 48.2 and 49.8% of the energy intake. 12.2, 13.2, 14.4 and 14.9% of the energy intake were retained. 51.6, 48.8, 42.4 and 40.1% of the retained energy was protein energy. The energetic feed value of both ration components has been calculated and stated according to various mathematical methods.