Effects of silage additives and varieties on fermentation quality, aerobic stability, and nutritive value of oat silage.

Oat is a main feed crop in high- altitude areas of western China, but few studies have been done on its silage making. The aim of this study was to evaluate the effect of silage additives on fermentation, aerobic stability, and nutritive value of different oat varieties (OV) grown in the Qinghai-Tibet Plateau of China. Two OV (Avena sativa L. cv. Longyan No.1 (OVL1) and Avena sativa L. cv. Longyan No.3 (OVL3)) were planted in a randomized complete block design, harvested at early dough stage with 32.6% and 34.1% DM, respectively. The fresh material was chopped to 2-cm length and treated with additives (0, Sila-Mix (MIX), Sila-Max (MAX) in a 2 × 3 factorial arrangement of treatments with three replicates. Both additives contained a mixture of lactic acid bacteria and supplied a final application rate of 2.5 × 108 of lactic acid bacteria per kg of fresh forage weight. After 60 d of ensiling, the number of lactic acid bacteria in treated silages was about 10-fold greater than the control and generally resulted in a lower pH and ammonia-nitrogen (P < 0.001), greater total acids and ratios of lactic acid/acetic acid (P < 0.001), and DM recovery (P = 0.028). Treatment with additives also decreased (P < 0.001) the number of yeasts, which resulted in marked (P < 0.001) improvements in aerobic stability with the effect being greatest with MAX. Both additives improved (P ≤ 0.036) the 48-h in situ DM digestion in OVL1, but not in OVL3 (P ≥ 0.052). Treatment with both additives also increased (P ≤ 0.003) NDF digestion in OVL1 while it was improved (P < 0.001) only by MAX in OVL3. In contrast, the additives did not affect (P ≥ 0.088) in situ hemicellulose digestion in OVL1, but it was improved (P = 0.048) by MIX and further improved (P = 0.002) by MAX in OVL3. Treatment with MAX improved yields of digestible DM and digestible NDF in both varieties. Dry matter recovery was not affected (P = 0.121) by variety. Compared to CTRL, silage treated with MAX had a greater (P = 0.015) DM recovery (96.7% vs. 93.9%). Inoculation improved (P < 0.001) aerobic stability. The MAX was the most effective for both varieties, while MIX was intermediate and was more effective in OVL3 than OVL1 silage. The results also showed that in Qinghai-Tibet Plateau, compared to OVL1, OVL3 resulted in greater (P ≤ 0.002) yields of digestible nutrients; specifically, treated with MAX improved silage fermentation efficiency, DM recovery, and provided excellent aerobic stability for feeding to ruminants.