Effect of replacing alfalfa hay with a mixture of cassava foliage silage and sweet potato vine silage on ruminal and intestinal digestion in sheep

This study aimed to investigate the effects of replacing alfalfa hay (AH) with a mixture of cassava foliage silage and sweet potato vine silage (CSP) (1:1 on a dry matter (DM) basis) on ruminal and intestinal nutrient digestion in sheep. Four wethers were fed a control diet containing 35% of AH and two treatment diets containing 15% and 30% of the CSP as substitute for AH at 1.5 times the metabolizable energy required for maintenance. Replacing AH with the CSP silage did not affect DM intake, whereas it linearly increased (P<0.05) the intake of ether extract and acid detergent insoluble nitrogen (ADIN). Increasing the CSP substitution linearly decreased (P<0.05) ruminal DM and neutral detergent fiber (aNDFom) digestibility; however, it did not affect total tract aNDFom digestibility. The CSP substitution did not affect nitrogen (N) intake and duodenal total N flow, whereas it linearly increased duodenal ADIN flow (P<0.01) and decreased ruminal ammonia-N concentration (P<0.01), and intestinal (P=0.08) and total N digestibility (P<0.01). These results indicate that replacing AH with the CSP reduced the ruminal N degradation as well as the digestion of ruminal aNDFom and intestinal N.