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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #296241
Title: Comparison of alfalfa, birdsfoot trefoil, and cicer milkvetch in combination with 25, 50, or 75% tall fescue in a continuous-culture system

Author
item NOVIANDI, C - Utah State University
item NEAL, K - Tuskegee University
item EUN, J - Utah State University
item Peel, Michael
item Waldron, Blair
item ZOBELL, D - Utah State University
item BIN, B - Tuskegee University

Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2013
Publication Date: 2/1/2014
Citation: Noviandi, C.T., Neal, K., Eun, J.S., Peel, M., Waldron, B.L., Zobell, D.R., Bin, B.R. 2014. Comparison of alfalfa, birdsfoot trefoil, and cicer milkvetch in combination with 25, 50, or 75% tall fescue in a continuous-culture system. Professional Animal Scientist. 30:23-32.

Interpretive Summary: An experiment was completed to investigate the ratio (75, 50, or 25%) of tall fescue (TF) with three legumes, alfalfa (AF), birdsfoot trefoil (BT), and cicer milkvetch (CM) on in vitro fermentation characteristics. Nine dietary laboratory culture treatments were tested. Each culture fermentor was offered a total of 15 g DM/d in 4 equal portions at 0600, 1200, 1800, and 2400 h. Average daily culture pH ranged from 6.10 to 6.29 and was affected by both TF-legume ratio and TF-legume mixed diet. Diet treatments did not affect the concentrations of total VFA, acetate, and butyrate, whereas increasing legume proportion in the mixed diets increased propionate concentration. Regardless of TF-legume ratio, feeding the TF+CM resulted in the greatest propionate concentration, while the TF+AF and the TF+BT maintained similar concentration of propionate. The TF+AF had a greater acetate-to-propionate ratio (3.26) than the TF+BT (2.93) and the TF+CM (2.85). Decreases in ammonia-N concentration occurred when the proportion of legume in mixed diets decreased. Ammonia-N concentration of the TF+CM decreased compared with the TF+AF and the TF+BT. Methane production decreased with increasing legume proportion and was most notable in the TF+BT, like due to condensed tannins. In addition, the TF+BT increased the proportion of C18:1 trans-11 and decreased C18:0 fatty acids in the culture, but no effects were observed associated with TF-legume ratio. Overall this study indicates that TF-legume mixed diets with relatively high legume percentage favorably shifted in vitro fermentation pathways to produce more propionate and less methane. Furthermore, the TF+BT mixed diets increased dietary N utilization.

Technical Abstract: A continuous culture experiment was performed to investigate the effects of tall fescue (TF)-to-legume ratios (TF: = 75:25, 50:50, or 25:75 on a DM basis) of 3 different TF-legume mixed diets [TF-alfalfa (TF+AF), TF-birdsfoot trefoil (TF+BT), or TF-cicer milkvetch (TF+CM)] on in vitro fermentation characteristics. Nine dietary treatments were tested in a 3 (TF-legume ratio) x 3 (TF-legume mixed diet) split-plot design. Each culture fermentor was offered a total of 15 g DM/d in 4 equal portions at 0600, 1200, 1800, and 2400 h. Average daily culture pH ranged from 6.10 to 6.29 and was affected by TF-legume ratio and TF-legume mixed diet (P<0.01). Diet treatments did not affect the concentrations of total VFA, acetate, and butyrate (averaged 51.4, 32.3, and 5.68 mM, respectively), whereas increasing legume proportion in the mixed diets increased propionate concentration (P=0.03). Regardless of TF-legume ratio, feeding the TF+CM resulted in the greatest propionate concentration, while the TF+AF and the TF+BT maintained similar concentration of propionate. The TF+AF showed a greater acetate-to-propionate ratio than the TF+BT and the TF+CM (3.26 vs. 2.93 and 2.85 mM, respectively; P = 0.03). Decrease in ammonia-N concentration (P<0.01) was noticed when legume proportion in mixed diets decreased. Ammonia-N concentration of the TF+CM decreased (P<0.01) compared with the TF+AF, and it further decreased in cultures receiving the TF+BT (P<0.01). Methane production decreased by increasing legume proportion in mixed diets, and this result was particularly notable in the case of the TF+BT due to increased condensed tannins. In addition, the TF+BT increased the proportion of C18:1 trans-11 and decreased C18:0 in the culture (P<0.01), but no effects were detected due to TF-legume ratio in the diets. Overall results of this study indicate that TF-legume mixed diets at a relatively high proportion of legume favorably shifted in vitro fermentation pathways by producing more propionate and less methane. The TF+BT mixed diets also increased dietary N utilization and affected biohydrogenation in cultures by increasing C18:1 trans-11 proportion.