The effects of stage of growth and additives with or without cellulase on fermentation andin vitrodegradation characteristics ofLeymus chinensissilage

Abstract

AbstractThis study evaluated the effects of different combinations of added lactic acid bacteria and cellulase applied at two growth stages on chemical composition andin vitrorumen digestibility ofLeymus chinensissilage. Fresh grass was harvested at early heading stage (S1) and late heading stage (S2), respectively, and ensiled with five additives: 200 U cellulase (C) kg−1fresh matter (FM), 1 × 105colony‐forming units (cfu)Lactobacillus plantarum(LP) g−1FM, 1 × 105 cfuLb. casei(LC) g−1FM,LP+C,LC+C and a control (CK). Four replicates of each treatment were weighed into 5‐L plastic buckets, and the mini silos were stored at ambient temperature (~30°C) for 60 d.Leymus chinensisharvested at S2 showed relatively higher neutral detergent fibre content, coliform bacteria count and lower crude protein content than S1. All additives decreased thepHand ammonia nitrogen (NH3‐N) content ofL. chinensissilage (P < 0·001) except C.LP+C andLC+C decreased fibre content and increased water‐soluble carbohydrate content (P < 0·001). The silages were further anaerobically incubatedin vitroat 39°C for 48 h with buffered rumen fluids of lactating cows.Leymus chinensisharvested at S2 showed lowerin vitrodry‐matter disappearance,NH3‐N, total volatile fatty acid (VFA) content and higher average gas production rate (P < 0·05) than S1. In conclusion,Leymus chinensisshould not be harvested too late. Compared with other treatments, a combination ofLb. casei(LC) with cellulase resulted in better fermented silage, but further testing is needed to confirm its efficacy.