Effect of Beam electron irradiation on phenolic compound content and ruminal degradability parameters of pomegranat seed pulp

Pomegranate seed pulp (PSP, resulting from squeezing of pomegranate seed) contains remarkable amount of nutrients such as protein and specially oil which in areas that it is accessible can stand in ruminant’s diet instead of some cereal grains, but its tannin content can reduces palatability and nutritive value. Irradiation is one of physical processing methods that can reduce tannins and improve nutritional value of feeds. So, PSP was irradiated with three doses of 10, 15 and 20 KGy of electron beam and then chemical composition, phenolic compounds content and DM ruminal degradability parameters and ruminal, post-ruminal and total tract digestibility of its DM were measured. The data were analyzed based on completely randomized design using Proc GLM of SAS software. The results showed crude protein was significantly increased by irradiation at 15 and 20 KGy while water soluble carbohydrate was reduced by irradiation. Total phenolic compounds and total tannin content were reduced by all irradiation doses while condensed tannin content was not affected by irradiation. Amongst hydrolysable tannins, gallic acid and ellagic acid content were significantly reduced by all three irradiation doses and tannic acid and punicalin were significantly reduced at higher doses of irradiation (15 and 20 KGy) but punicalagin A content was not reduced by irradiation and punicalagin B content was reducted at 10 and 20 KGy irradiation. Irradiation did not change degradability parameters, ruminal digestibility and total tract digestibility of PSP’s DM but post-ruminal digestibility of its DM was significantly reduced by irradiation. From these results it looks that irradiation of PSP at 15 KGy had the best outcome because while it reduced total tannin and detrimental hydrolysable tannins including gallic acid, tannic acid and punicalin, it caused to preserved the hydrolysable tannins with antioxidant properties including punicalagin’s A and B.