Comparison of non-encapsulated and encapsulated active dried yeast on ruminal pH and fermentation, and site and extent of feed digestion in beef heifers fed high-grain diets

• Published in: Animal feed science and technology 2017-06, Vol.228, p.13-22
• Main Authors: Jiao, P.X., Wei, L.Y., Walker, N.D., Liu, F.Z., Chen, L.Y., Beauchemin, K.A., Yang, W.Z.
• Format: Article
• Language: English
• Subjects: Beef heifer; Rumen pH and fermentation; Rumen protected live yeast; Site and extent of digestion
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2017.04.001

•Live yeast (LY) and rumen protected (RP-LY) were evaluated in high-grain fed beef heifers.•Supplementation of LY or RP-LY did not affect DM intake and OM flow to omasum.•Feeding RP-LY improved postruminal and total digestibility of OM.•These results indicated benefits to feeding RP-LY on improving digestibility of nutrients. The objective of this study was to determine whether feeding ruminally protected active dried yeast (ADY) exhibits postruminal activity in comparison with feeding non-protected ADY assessed by measuring feed intake, ruminal pH and fermentation, and site and extent of feed digestion in finishing heifers. A combination antibiotic was used as a positive control. Five Angus beef heifers with ruminal cannulas (body weight of 650±48.8kg) were used in a 5×5 Latin square design with 21-d periods and 1 week of washout between each period. The five treatments were: 1) control (no ADY and no antibiotics), 2) antibiotics (ANT; 300mg monensin+110mg tylosin/d), 3) ADY (1.5g ADY/d), 4) encapsulated ADY (EDY; 3.5g/d containing 1.5g ADY and 2g capsule), and 5) mixture of ADY and EDY (MDY; 1.5g ADY+3.5g EDY/d). The ADY was encapsulated using barley hordein and glutelin extracted from barley grain. The stability of encapsulated yeast in the rumen and its release in the intestine were validated in vitro. Intake (kg/d) of dry matter (DM) was not affected by treatments. Ruminal pH, total volatile fatty acid (VFA) concentration, and NH3-N concentration did not differ among treatments, whereas molar proportion of acetate and ratio of acetate to propionate were greater with yeast addition than ANT. No treatment effects on flows of organic matter (OM) and starch to the omasum were observed, whereas flows of neutral detergent fibre (NDF) were greatest with ANT, lowest with EDY and intermediate with control, ADY and MDY (P