Effect of ensiling pomegranate peels on chemical composition, in vitro gas production kinetics and microbial biomass production

The aim of this study was to compare chemical composition, tannin content, in vitro gas production kinetics, in vitro dry matter and NDF digestibility and microbial biomass production of dried and ensiled pomegranate peel (PP; in four replicates). The crude protein, crude ash, neutral detergent fiber and acid detergent fiber in ensiled pomegranate peel (51, 48.4, 292.9 and 173.7, g/kg DM, respectively) were higher than the dried one(36.5, 37.5, 221.9 and 150.2 g/kg DM, respectively; P<0.05), whereas non-fiber carbohydrates (580 VS. 688.9 g kg- DM) were lower in pomegranate peel silages (P<0.05). Ensiling decreased the total phenolics (191.17 VS. 255.3 g of tannic acid equivalents kg-1 DM), total tannins (162.4 VS.219 g of tannic acid equivalents kg-1 DM) and non-tannin phenols (29.3 VS. 36.2 g of tannic acid equivalents kg-1 DM), pH (3.69 vs. 3.92) and water soluble carbohydrates (24.6 vs. 34.5), but increased the buffering capacity (12.73 vs. 8.79 meq-1 L), ammonia concentration (97 vs. 52 g kg-1 total N) and lactic acid (42.7 vs. 0.162 g kg-1DM) in pomegranate peel (P<0.05). The gas production, metabolizable energy and short chain fatty acids concentration (0.723 vs. 1.023 mmol) in dried PP were higher than those of ensiled PP (P<0.05). The in vitro fiber digestibility, partitioning factor, microbial biomass production, efficiency of microbial biomass production and ruminal ammonia concentration were higher in pomegranate peel (P<0.05). Although ensiling to some extent decreased phenolic contents, but did not improve the nutritive value of PP in comparison with drying.