title: Effect of condensed tannin extract supplementation on growth performance, nitrogen balance, gas emissions, and energetic losses of beef steers.
abstract: Condensed tannins (CT) may decrease greenhouse gas emissions and alter the site of N excreted by ruminants. We evaluated the effect of top-dressing a steam-flaked corn-based finishing diet (14.4% CP and NEg 1.47 Mcal/kg) for beef cattle with a commercially available CT extract at 3 levels (0, 0.5, and 1.0% of diet, DM basis). Angus-crossbred steers ( = 27; 350 ± 32 kg initial BW) were individually fed via Calan gates for 126 d. Diet digestibility and N balance were estimated after 34 and 95 d on feed (Phase 1 and Phase 2, respectively) using titanium dioxide as a marker of fecal output and the creatinine:BW ratio as a marker for urine output. Ruminal CH and metabolic CO fluxes were measured using a GreenFeed system (C-Lock Inc., Rapid City, SD) for 2 sampling periods that coincided with fecal and urine sampling. Urine energy loss was estimated from urine N excretion, assuming all excreted N was urea. Oxygen consumption was estimated from CO production assuming a respiratory quotient of 1.05. Average daily gain (2.08, 2.14, and 2.08 kg/d for 0, 0.5, and 1.0% CT, respectively) and G:F did not differ ( = 0.88) among treatments. Starch intake and OM intake did not differ ( ≥ 0.42) among treatments during each phase. Apparent total tract starch digestibility during Phase 1 linearly decreased ( = 0.04) with inclusion of CT. Apparent total tract digestibility of OM and starch were not different among treatments ( ≥ 0.13) during Phase 2. Nitrogen intake did not differ ( ≥ 0.16) among treatments during each phase, but fecal N excretion linearly increased ( = 0.05) with inclusion of CT during Phase 1. Urinary N excretion was not different ( ≥ 0.39) among treatments during both phases, but urinary N as a proportion of total N excretion linearly decreased ( = 0.01) when CT was included in the diet during Phase 1. Retained N was not different ( ≥ 0.27) among treatments during each phase. Fluxes of CO were similar ( ≥ 0.37) among treatments during both phases. No differences ( ≥ 0.23) were observed for percentage of GE intake lost as CH (2.99, 3.12, and 3.09% in Phase 1 and 3.54, 3.55, and 4.35% in Phase 2) for 0, 0.5, and 1.0% CT, respectively. No difference ( ≥ 0.42) was observed for heat production lost as a percent of GE intake during both phases. Growth performance, gas emissions, and energetic losses were not affected by the inclusion CT in a steam-flaked corn-based finishing diet.
authors.forename: P J
authors.initials: PJ
authors.lastname: Ebert
authors.forename: E A
authors.initials: EA
authors.lastname: Bailey
authors.forename: A L
authors.initials: AL
authors.lastname: Shreck
authors.forename: J S
authors.initials: JS
authors.lastname: Jennings
authors.forename: N A
authors.initials: NA
authors.lastname: Cole
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D002248:Carbon Monoxide / Q000378:metabolism; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004063:Digestion / Q000187:drug effects; D005243:Feces / Q000737:chemistry; D005285:Fermentation / Q000187:drug effects; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D044945:Proanthocyanidins / Q000302:isolation & purification / Q000494:pharmacology*; D012417:Rumen / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013227:Steam; D014508:Urea / Q000378:metabolism; D014556:Urine / Q000737:chemistry; D003313:Zea mays
chemical_list: D044945:Proanthocyanidins; D013227:Steam; D002248:Carbon Monoxide; D014508:Urea; D013213:Starch; D009584:Nitrogen; D010100:Oxygen