PERFORMANCE AND NUTRIENT METABOLISM BY NURSING CALVES SUPPLEMENTED WITH LIMITED OR UNLIMITED CORN OR SOYHULLS

Five-month-old Angus x Hereford reciprocal crossbred nursing steer cal ves on fescue pasture were used to determine the effects of 1) Limitin g supplemental feed intake and 2) soyhulls and corn as sources of supp lemental (creep) feed in an 84-d study. The treatments were 1) control (no creep feed), 2) limited intake of corn (1 kg/d), 3) unlimited int ake of corn, 4) limited intake of soyhulls (1 kg/d), and 5) unlimited intake of soyhulls. Before weaning, there were no differences in suppl emental feed efficiency ([supplemented gain - control gain]/supplement intake) or calf gain between corn or soyhulls. Calf gain before weani ng increased linearly (P <.05) as intake of creep feed increased, but supplemental feed efficiency did not differ between limited and unlimi ted supplements. Feedlot performance by the calves was not affected by any of the previous treatments. Calves that consumed an unlimited lev el of creep feed had greater (P <.05) quality grades than the control group that did not consume creep feed, but no other carcass traits wer e influenced by treatment. In a metabolism study, fescue DM intake dec reased linearly (P <.001) with increasing levels of creep feed, wherea s milk DM intake was not affected by level of creep feed. Digestible D M intake increased linearly (P <.001) with increasing intake of creep feed. No differences (P >.18) were observed in digestible DM intake as a result of creep feed source. Apparent total tract DM digestibility increased (P < .05) with increasing level of creep feed intake but did not differ between sources. Unlimited soyhulls increased (P <.05) tot al tract NDF digestion compared with the corn treatments because of th e high digestibility of soyhull NDF. Creep feeding increased calf wean ing weights and enabled more cattle to achieve Choice quality grade at 14 mo of age. A highly digestible fiber source such as soyhulls can r eplace corn as a supplement for nursing calves.