EFFECTS OF INCREASING LEVELS OF CORN OR BEET PULP ON UTILIZATION OF LOW-QUALITY CRESTED WHEATGRASS HAY BY LAMBS AND INVITRO DRY-MATTER DISAPPEARANCE OF FORAGES

Two trials were conducted to evaluate the effects of corn or dried bee t pulp on intake and digestibility of forage by lambs and on IVDMD. In Trial 1, 16 lambs (average BW = 41 +/- .9 kg) were used in a randomiz ed complete block design with eight lambs per block. Lambs were fed a crested wheatgrass hay (7.5% CP) and received either no supplement (NS ), a protein supplement (PS), or protein supplements with various leve ls of corn or beet pulp. Corn supplements supplied 1.75 (PCL), 3.5 (PM C), and 5.25 (PHC) g of corn/kg of BW, whereas beet pulp supplements s upplied 2.1 (PLBP), 4.2 (PMBP), and 6.3 (PHBP) g of beet pulp/kg of BW . All supplemented lambs received .128 g of CP/kg of BW. Hay DMI decre ased linearly (P < .03) as the level of corn and beet pulp increased i n the supplement. Total DMI decreased linearly (P = .013) as the level of corn increased; however, beet pulp did not affect total DMI (P > . 71). Supplemental corn increased (P = .03) apparent diet DM digestibil ity (DMD), whereas supplemental beet pulp did not affect (P > .32) die t DMD. Lambs whose diet was supplemented with beet pulp had greater (P = .010) estimated hay DMD than lambs whose diet was supplemented with corn. In Trial 2, 48-h IVDMD was determined on each of three forages mixed with either corn or beet pulp. The crude protein content of the three forages was 4.9, 9.4, and 12.2% for low-, medium-, and high-qual ity forages, respectively. Both beet pulp and corn had a quadratic eff ect (P < .042) on IVDMD of low-quality forage. Corn had a quadratic ef fect (P = .002) on medium-quality forage, whereas beet pulp linearly i ncreased (P < .001) IVDMD of medium-quality forage. Beet pulp also had a linear effect (P < .001) on high-quality forage, whereas corn had a cubic effect (P = .06). In summary, hay intake was decreased by both types of supplements, but only corn decreased total intake. When corn or beet pulp replaced low-quality forage, IVDMD increased quadraticall y. With medium- and high-quality forages, replacing forage with beet p ulp increased IVDMD linearly, whereas replacing forage with corn had q uadratic and cubic effects on IVDMD.