Using Commercial Tannin-Degrading Bacteria, or Isolated from the Rumen of some Ruminants to Improve the Nutritional Value of Pomegranate Peel

Introduction Pomegranate has many secondary metabolites such as tannins and phenolic compounds, which have various properties such as antimicrobial, antioxidant, anti-inflammatory, and immune system stimulating effects. The amount of tannin in pomegranate skin has been reported up to 20.6%. The limiting effects of tannins can be related to reducing the use of nutrients, especially protein, reducing growth and performance, reducing palatability and feed consumption, and reducing the activity of digestive enzymes. In addition to the anti-nutritional effects in high concentration, the positive impact of dense tannins in optimal concentration includes improving live weight gain, preventing flatulence, increasing milk production, reducing intestinal nematodes, and reducing the production of NH3-N and methane in the rumen. Therefore, the present experiment was carried out to improve the nutritional value of pomegranate peel as a tannin-containing edible material by treating it with some tannase-producing bacteria for ruminants.Materials and methods Pomegranate peel was treated with tannin-degrading bacteria including Klebsiella pneumoniae and Acinetobacter (isolated from deer rumen), Lactobacillus fermentum (isolated from Najdi goat rumen), and commercial Lactobacillus fermentum, and its nutritional value including chemical composition, digestibility, and fermentation ability alone (first experiment) or as a combination in a standard fattening lamb diet (second experiment), with two-stage digestion method and gas production test were studied. In the first experiment, five experimental treatments included 1- Pomegranate peel without treatment (control treatment), treatment 2 to 5- Pomegranate peel treated with each of the four tannin-degrading bacteria. The five treatments of the second experiment included 1- Diets containing pomegranate peel without treatment (control treatment), 2-5- Diets containing pomegranate peel treated with each of the four tannin-degrading bacteria.Results and discussion Applying tannin-degrading bacteria reduced the tannin in pomegranate peel (P