Performance of and Nutrient Utilization by Steers Consuming Kenaf, Pearl Millet, or Mixed Grass

Kenaf [Hibiscus cannabinus L.] is primarily used as an industrial fiber. However, during the vegetative phase, nutrients from kenaf may be utilized as cattle feed. To determine animal performance, grazing trials were conducted for 2 consecutive yr. During the first year, 72 steers (214 ± 65 kg) were assigned to one of three forages: kenaf, pearl millet, or a bermudagrass/dallisgrass mix and allowed to graze for 56 d. Average daily gains for steers grazing pearl millet was greater (P < 0.01; 0.80 kg/d) than that for those grazing mixed grass or kenaf (0.65 and 0.67 kg/d, respectively). During the second year, 45 steers (244 ± 35 kg) were allotted to the same three forage groups and allowed to graze for 84 d. Total BW gain for steers differed (P < 0.01) among kenaf, pearl millet, and mixed grass (0.71, 0.50, and 0.17 kg/d, respectively). To determine nutrient utilization, 12 steers were divided into three treatments consisting of greenchop kenaf, pearl millet, or mixed grass and fed while housed in individual metabolism crates. Apparent digestibility of NDF, ADF, and hemicellulose was less (P < 0.01) for kenaf than for mixed grass or pearl millet. More (P < 0.01) protein was retained in steers consuming pearl millet (320 g/d) than in those consuming mixed grass or kenaf (78 and 107 g/d, respectively). Apparent energy retained by steers was different (P < 0.03) among kenaf, pearl millet, and mixed grass (5.2, 16.3, and 9.6 Mcal/d, respectively). Steers consuming pearl millet appeared to digest and utilize nutrients more efficiently than those consuming kenaf or mixed grass.