Effects of partially replacing barley with sugar beet pulp, with and without roasted canola seeds, on performance, rumen histology and fermentation patterns in finishing Arabian lambs

Abstract

This study investigated the effects of partially replacing barley grains with sugar beet pulp (SBP), with and without roasted canola seed (RCS) on ruminal pH, ruminal volatile fatty acid (VFA) concentrations, ruminal histomorphometric characteristics, and performance in finishing lambs fed a high concentrate diet. Twenty-four Arabian male lambs (23.7 ± 2.5 kg bodyweight, 118 ± 10 days in age) were used for 99 days in a completely randomised design with a 2 × 2 factorial arrangement. Lambs were fed with a high concentrate diet containing (1) 68% barley (B) (2) barley plus 7% RCS (B + RCS) (3) 36% SBP, (4) SBP plus 7% RCS (SBP + RCS). Ruminal fluid pH and VFA concentrations were determined at 0, 2, 4 and 8 h post-feeding 1 day before slaughter day. Tissue samples were collected for histomorphometric study at slaughter day. Average daily gain of the lambs was not affected by partial replacement of barley with SBP, however it was improved by RCS inclusion (P < 0.05). Diets with RCS had significantly lower (P < 0.05) neutral detergent fibre and acid detergent fibre digestibility values than diets without RCS (P < 0.05). Both SBP and RCS increased ruminal pH, molar proportions of acetate, isobutyrate but decreased molar proportion of propionate in rumen content (P < 0.05). The height, width, epithelial thickness and tunica muscularis of rumen papilla and reticulum folds were increased by SBP (P < 0.05). Density of reticulum folds were higher in lambs fed by higher SBP (P < 0.05). Inclusion of RCS significantly increased papillae height and thickness of epithelium (P < 0.05). In conclusion, partially replacing barley with SBP as well as RCS inclusion prevented a drop in the ruminal pH, and improved the morphology of the rumen-reticulum in finishing lambs fed a high concentrate diet.