Evaluating Chemical Composition, Fatty Acid Profiles, Antioxidant Activity and Nutritive Value of Pomegranate By-Product using in Vitro Gas Production Technique

This study was conducted to determine the important nutritional properties of pomegranate by-product (seed and peel) for evaluating its potential in silage preparation compared to corn forage. At first, enough fresh pomegranate by-products were prepared from a fruit juice factory in the fall season. Then, the chemical composition, fatty acid profiles, phenolic compounds and gas production parameters were measured in dried pomegranate and corn forage samples. Also, the parameters of silage preparation were determined in fresh samples. The results showed that dry matter, crud protein, ether extract, neutral detergent fiber, acid detergent fiber and lignin content of pomegranate seed was higher (P <0.05) than peel. But, the water soluble carbohydrates and ash content of pomegranate seed was lower (P <0.05) than pomegranate peel. The water soluble carbohydrates in pomegranate peel was about two times more than corn forage. Moreover, pomegranate peel had high content of phenolic compounds (6.17%), total tannin (4.5%) and antioxidant activity (99.1%). Pomegranate seed and peel had 88.3% and 77.9% unsaturated fatty acids, respectively and the punicic acid content of pomegranate seed and peel was 64.9% and 46.9% of total fatty acids, respectively. The gas production parameters showed that metabolizable energy, net energy for lactation, short chain fatty acid, and organic matter digestibility in pomegranate seed and peel were lower (P <0.05) than corn forage. The buffering capacity of the mixture of pomegranate seed and peel (1:4) was in the proper range for the preparation of silage. Water storage capacity in the mixture of pomegranate seed and peel was lower (P <0.05) than corn forage. It was concluded that the mixture of pomegranate seed and peel (1:4) has suitable chemical composition for preparation of silage, and due to the antioxidant activity and fatty acids profile, could be considered as a valuable feed ingredient in replacement with the part of ruminant's required silage.