ROLE OF BIOLOGICAL ADDITIVES IN SILAGE PRODUCTION FOR IMPROVING FORAGE NUTRIENTS CONSERVATION AND DIGESTIBILITY FOR RUMINANTS NUTRITION

The general aim of this thesis was to study the effect of lactobacillus inoculants and exogenous fibrolityc enzymes on ensiled forages. The thesis includes the results of three experiments. The first experiment investigated the effects of a microbial inoculum containing homofermentative lactobacillus (hoLAB) ( a strain of Pediococcus pentosaceus and a strain of Lactobacillus plantarum) as maize silage additive, alone (L) or in combination with a pool of fibrolityc enzymes (LE) in comparison with untreated silage (C) on fermentative profile at 2, 5, 40 and 110 days of ensiling, dry matter (DM) losses at the same time points, and multiple points in vitro Gas Production (GP) after 110 days of ensiling. Results evidenced that, the hoLAB inoculant and hoLAB+ enzymes treatments determined a significant effects relative to a shifting of silage fermentation: reduced pH, increased lactic acid concentration and decreased ethanol production; dry matter recovery was also positively affected by the treatments. hoLAB inoculum is also able to affect the rumen fermentability of the silage increasing the potential GP and the fractional rate of gas production during in vitro test. The addition of fibrolytic enzymes to hoLAB inoculant seems instead to inhibit this capacity to increase GP. The second study was performed relative to whole crop cereals silages: in a first part of this study we determined fermentative profile, DM losses, chemical composition, in vitro dry matter digestibility (DMD) and neutral detergent fibre digestibility (NDFD) and in vitro GP of whole crop silages made from wheat (var. Artico and var. Sollario) , triticale (var. Magistral) and wheat\u2013barley-triticale mixture (WesternTM) harvested at two different maturity stages (Early vs Late). In the second part the aim was relative to determine the effects, on the same parameters of the first part, of the addition at ensiling of an inoculum of lactobacillus and fibrolitic enzymes mixture on a selected wheat ( var. Artico) harvested at two different maturity stage in comparison with the untreated silage (C). All forages resulted well preserved. Neutral Detergent Fibre (NDF) content was influenced by maturity stage and crop. NDFD was reduced with increasing of maturity stage (50.5 vs 45.0%, P<0.001). Gas production (GP) at 8 h of incubation was positively influenced by maturity stage (P