The effect of different types of inoculants on the characteristics of alfalfa, ryegrass and red clover/ryegrass/timothy silage

Abstract

An in vitro laboratory study using 3 L mini silos was conducted in 2012–2013 to observe the effects of 8 inoculants on silage nutrient composition, pH, volatile fatty acids concentration, dry matter loss, and aerobic stability. Alfalfa (Medicago sativa L.) in early-flower stage (first harvest, 355 g kg -1 DM), perennial ryegrass (Lolium perenne L.) in early-boot stage (first harvest, 322 g kg -1 DM) and mixture of red clover (Trifolium pratense L.), perennial ryegrass (L. perenne) and timothy (Phleum pratense L.) at a ratio 60:25:15 of fresh matter, in early bloom stage of red clover (first harvest, 343 g kg -1 DM) were used. The trials were conducted as a randomized complete block design, with five replicates per crop per treatment. Each trial had 9 treatments (uninoculated control and 8 inoculants – Feedtech products (F10, F18, F22 and F3000), and products Sil-All 4 × 4 (ISA), Lalsil Dry (LD), Bonsilage (IBO) and Bio-sil Stabil (BS), with 5 silos per treatment. The mini silos were filled to a target density of 0.2 kg L -1 DM. After a 90-day storage at 20°C, silages were sampled and analyzed. All the eight microbial inoculant products improved many aspects of silage quality across the range of silage analytes examined and across the three forage types tested. Inoculant treated alfalfa, perennial ryegrass and red clover/ryegrass/timothy silage had significantly lower pH values, ammonia-N concentration and dry matter losses, but significantly higher lactic acid concentration compared to untreated silage. Inoculants F18, F22, F3000 and ISA gave significantly lower pH value than F10, LD, IBO and BS in alfalfa silage and in perennial ryegrass silage. The pH value for the red clover/ryegrass/timothy silage treated with inoculants F10, F22 and F3000 was significantly lower compared to F18, ISA, LD, IBO and BS inoculants treated silages. Lactate was significantly higher in perennial ryegrass silage for F18 and F22 inoculants compared with F10, F3000, ISA and LD inoculants and in red clover/ryegrass/timothy silages for F10, F22, F3000 and ISA inoculants versus (vs) F18, LD, IBO and BS inoculants. Dry matter loss was lower (P < 0.05) in perennial ryegrass silages for F10, F18, F22 and F3000 inoculants compared with ISA, LD and IBO inoculants, and in red clover/ryegrass/timothy silages for F10, F18, F3000 and ISA inoculants compared with F22, LD, IBO and BS inoculants (4.02% vs 4.18%, P < 0.05). Addition of the inoculants improved aerobic stability of alfalfa silages by 126–204 h, of perennial ryegrass silages by 18–216 h and of red clover/ryegrass/timothy silages by 30–138 h compared to the uninoculated control. The results suggest that the lactic acid bacteria inoculants were effective in improving the silage quality in moderately difficult and difficult to ensile forage.