INFLUENCE OF PROCESSING SUPPLEMENTAL ALFALFA ON INTAKE AND DIGESTION OF DORMANT BLUESTEM-RANGE FORAGE BY STEERS

Four ruminally and duodenally fistulated, 2-yr-old Angus x Hereford st eers (average initial BW = 370 kg) were used to evaluate the effect of method of processing supplemental alfalfa on intake and digestion of dormant bluestem-range forage (2.8% CP, 78% NDF). Treatments (4 x 4 La tin square) were I) control, no supplement; 2) ground and pelleted alf alfa hay (PELLET; 21% CP, 37% NDF); 3) ground and pelleted dehydrated alfalfa (DEHY; 21% CP, 44% NDF); and 4) longstem alfalfa hay (HAY; 20% CP, 37% NDF). All supplements were from a single cutting of alfalfa a nd fed at .5% BW (as-fed basis). Supplementing steers with alfalfa inc reased(P less than or equal to .07) bluestem forage OM intake (FOMI); total OM intake (TOMI); true ruminal OM digestibility; total tract OM digestibility (TTOMD); total N, microbial N, and nonammonia-nonmicrobi al N (NANM) flows to the duodenum; ruminal OM and fluid fill; fluid di lution rates; dietary DE concentration; and ruminal total VFA and NH3 N concentrations. Because of the enhanced FOMI and TOMI associated wit h alfalfa supplementation and the concomitant improvement in TTOMD, di gestible OM intake (DOMI) also increased (P < .01) when supplemental a lfalfa was fed. Method of processing alfalfa had little impact on fora ge utilization, except FOMI (P = .11), TOMI (P = .10), and ruminal OM fill (P = .09) tended to be greater when supplemental alfalfa pellets were dehydrated. Similarly, processing method tended to alter the mola r proportions of some minor VFA. In conclusion, alfalfa supplementatio n exerted a dramatic impact on utilization of low-quality forage. Howe ver, with the relatively high-quality alfalfa used, method of processi ng supplemental alfalfa had minimal impact on utilization of low-quali ty forage by beef cattle.