Abstract
Forty-six Japanese Black steers were used to determine the comparative feeding value of whole-shelled corn (WC), cracked corn (CC) and steam-rolled corn (RC). The steers were assigned to 3 groups and fed a total mixed ration (TMR) containing 30% corn-based concentrate (C) of each corn-type, and chopped rice straw (R) with varying ratios for the duration of the trail. From 10 to 18months of age (early phase, 35weeks) a feed ratio of 75% C and 25% R was used. This was then followed by a 92% C and 8% R ratio mix from 18 to 27months of age (late phase, 39weeks). No significant differences were observed among treatments in daily feed intake, final body weight (706kg, 708kg and 724kg for WC, CC and RC group, respectively) and average daily gain (0.76kg, 0.78kg and 0.80kg, respectively). Dry matter digestibility was 69.9, 70.3 and 72.9% for WC, CC and RC group, respectively, in early phase (P<0.05) and 74.5, 75.4 and 77.8%, respectively, in late phase (P>0.10). Starch digestibility was 82.7, 95.7 and 98.3% for WC, CC and RC group, respectively, in early phase (P<0.01) and 93.0, 97.5 and 99.3%, respectively, in late phase (P<0.05). Total amount of corn grain particles excreted into feces was larger for WC group than for the other groups in early phase (19.8, 2.6 and 0.3%, respectively) and late phase (11.7, 5.2 and 0.3%, respectively). There were no significant differences among the treatments in carcass measurements and meat qualities. Hematin content of longissimus muscle was higher for CC group than for the other groups (P<0.05). Linoleic acid contents of longissimus muscle and kidney fat were lower for WC group than for the other groups (P<0.05). In conclusion, we suggest that when feeding a TMR to Japanese Black steers, WC could be used as an alternative of CC and RC for up to 30% of a concentrate during the fattening period of the cattle.
