Comparison of alfalfa and fenugreek (Trigonella foenum-graecum) silages supplemented with barley grain on performance of growing steers

Abstract

To compare nutritive value of alfalfa and fenugreek silages for weaned back-grounding feedlot steers, isonitrogenous diets of alfalfa or fenugreek silage, supplemented with three levels of steam-rolled barley (0, 15 and 30% DM) were fed ad libitum to 60 steers (initial weight of 237 ± 18 kg). The study was conducted in individual pens for 105 d using a 2 × 3 factorial experiment. Fenugreek was cut 17 wk after seeding while the alfalfa was cut at mid-bloom. Both fenugreek and alfalfa silages were prepared in plastic tube silos after wilting to 38 and 35% DM, respectively. After ensiling for 40 d, silage tubes were opened and a feeding trial was conducted. Alfalfa and fenugreek silage contained similar levels of CP (18.0 and 17.2%, respectively) while fenugreek silage contained a lower level of NDF (38.2%) than alfalfa silage (40.4%). Dry matter intake (DMI) and average daily gain (ADG) of steers increased (P < 0.001) and feed efficiency (FE) improved linearly (P < 0.001) with increasing grain level in the diet. Dry matter intake (6.4 vs. 6.2 kg d−1), ADG (0.82 vs. 0.84 kg d−1), FE (8.1 vs. 7.8), total rumen volatile fatty acids (103.4 vs. 105.3 mM), rumen fluid pH (6.9 vs. 6.9) and rumen ammonia concentration (9.6 vs. 10.4 mg dL−1) in steers were similar for both alfalfa- and fenugreek-silage-based diets, respectively. Although in vitro rate of gas production was different at 12.6 and 17.4% h−1 for alfalfa and fenugreek diets, respectively, potential gas production at the end of 72 h of fermentation was similar (21.6 vs. 22.3 mL 100 mg−1 DM). The presence of steroidal saponins in fenugreek plants did not affect steer performance or hormonal status when fed as silage. Results from this study indicate that the nutritive value of fenugreek silage is comparable to that of mid-bloom alfalfa silage, and that fenugreek, a high-DM yielding annual legume, has potential to be a valuable forage in feedlot diets. Key words: Alfalfa silage, fenugreek silage, annual legume, feedlot, steer, barley