Galgal et al., 2000. Asian-Aust. J. Anim. Sci., 13 (Suppl. July 2000): 261
Beef cattle production from native Imperata cylindrica (Kunai) pastures in Papua New Guinea is limited to a large extent by the inherent low nutritive value for much of the year and particularly during the dry season. Supplementary feeding is required to ensure satisfactory liveweight gains by grazing animals. This experiment examined the response of weaner steers grazing Imperata cylindrica pastures and supplemented with copra and palm kernel meals (bypass protein) alone and with molasses (rumen fermentable energy) and with or without urea (rumen degradable nitrogen, RDN).
Seventy Brahman weaner steers of average liveweight of 147.4 ± 30 kg (± SD) were assigned to 7 treatment groups: control, copra meal (CM), palm kernel meal (PKM), CM + molasses (M), PKM + M, CM + M + urea (U) and PKM + M + U. CM and PKM contained 210 g crude protein/kg dry matter (DM) and 150 g crude protein/kg DM respectively. Supplements were fed in paddocks at 1.0 % body weight (BW) and comprised of 2/3 CM or PKM ± 1/3 M ± 3 % U. The level of daily supplement per animal was adjusted fortnightly and group fed every second day. Urea was dissolved in water and thoroughly mixed into the molasses before mixing with CM or PKM. The steers were grazed on the native Imperata cylindrica pastures during the 1993 dry season (June – November). DM yields and nitrogen content of pasture were estimated at the start, middle and end of trial. Liveweight of steers were measured fortnightly. Average pasture DM on offer and N content were 8.3 t/ha and 9.8 g/kg DM, respectively. The pastures contained mixed legumes, viz. Centrosema pubescens, Stylosanthes spp. Macroptilum atropurpureum, and Calopogpnium mucunoides, at a level of less than 20%.
Supplementation with Copra Meal and Palm Kernel Meal significantly increased liveweight gain by 96 and 154 g/day or 25 and 41 %, respectively. Adding molasses alone to CM did not significantly increase liveweight gain. However, adding both molasses and urea to CM significantly increased liveweight gain by 159 g/day or 34 %. Addition of molasses and/or urea did not produce any effect on PKM supplementation.