Document Type : Research Paper
In order to investigate the effect of partial replacement of barley starch with neutral detergent soluble fiber with or without roasted canola seed on histomorphometry of lamb rumen, reticulum and rumen fermentation parameters, 24 Arabian male lambs were used for 84 days in a completely randomized design with a 2×2 factorial arrangement of treatments. Dietary treatments were, 1) starch of barley, 2) starch of barley with roasted canola seed 3) beet pulp and 4) beet pulp with roasted canola seed. Forage:conceantrat ratio was 10: 90 for all diets. Partial replacement of starch with beet pulp led to increase thickness of the epithelium, tunica muscularis and the rumen wall (p<0.01). Interactions between carbohydrate source with roasted canola seed were significantly associated with villus height and thickness of the epithelium, and addition of the roasted canola seed to the diet with high soluble fiber lead to significant increases in both parameters compared with high starch diets. Partial replacement of starch with soluble fiber increased height, thickness and number of folds, the thickness of the epithelium, muscular floor and the reticulum wall (p<0.01). Addition of canola seed was followed by increase in the number of folds, the thickness of the epithelium and muscular wall in the reticulum. High starch diets decreased rumen pH and addition of canola seed increased this parameter. Partial replacement of starch with soluble fiber and addition of roasted canola seed increased acetate concentration and decreased concentration of propionate, butyrate, and isobutyrate. The results of this study showed that partial replacement of starch with neutral detergent soluble fiber and addition of fat from roasted canola seed could affect the histological structure of reticulo- rumen and increased absorption of volatile fatty acids, prevent their accumulation in the rumen and provide a more favorable pH when animals fed by high concentrate diets.