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Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 52-64). Also available on the World Wide Web.

Monensin was fed at levels of 0 and 33 ppm in a series of experiments to determine its effect on nitrogen (N) utilization by steers fed diets high in sorghum grain (76%, steam-processed, flaked) and corn (90%, whole shelled). Total ruminal volatile fatty acid (VFA) concentrations measured 3 hr postprandially were not affected by monensin addition to either diet. Molar proportion of acetic acid decreased (P < .05) was observed with monensin addition to the sorghum grain-based diet. Monensin had no effect on apparent total tract digestibility of dry matter or energy in either diet, but consistently improved apparent total tract digestibility of crude protein (CP) in both diets. Improvement was greater (P < .05). Retention of N tended (P > .05) to improve in response to monensin with the sorghum grain-based diet (24 vs 20% of N intake; 41 vs 36% of N absorbed). Ruminal ammonia concentrations measured 3 hr post-prandially were decreased (P < .10) ruminal digestion of feed N (44 vs 51%) for steers fed monensin. Monensin decreased (P < .05) the contibution of bacterial N (42 vs 50%) and increased (P < .05) that of ruminally undegraded feed (bypass) N (58 vs 50%) to total N digested postruminally, resulting in less (P < .10) bacterial N (23 vs 28 g/day) and a tendency (P > .10) for more feed bypass N (32 vs 27 g/day) to be digested in the intestines of steers fed monensin with the corn-based diet. That monensin caused a greater proportion of feed OM and N to be digested and absorbed in the intestines than in the rumen (with possibly greater resultant metabolic efficiency) may account for some of the benefit of feeding this compound with high grain diets, as losses incurred in the ruminal transformation of feed nitrogen to bacterial nitrogen appear to be partially eliminated.

No description available.

Studies were conducted to: (1) examine an in situ technique with sorghum grain substrates using monofilament nylon bags, (2) evaluate in vitro various reconstituted sorghum grain treatments, (3) determine digestibility and nitrogen balance of steers fed reconstituted sorghum grain and (4) evaluate sorghum grain processing methods on performance of finishing steers. Dry matter efflux, DME (water bath) and in situ dry matter disappearance, ISDMD (ventral sac of rumen) from nylon bags were higher (P < .05) as bag porosity (5 to 80 um) and incubation time (4 to 24 h) increased, and as substrate weight: bag surface area ratio (7 to 56 mg/cm²) decreased. High linear correlations were obtained between DME and ISDMD, and also between nitrogen efflux and in situ nitrogen disapperance. No permanent influx of ruminal dry matter into nylon bags were detected. In vitro dry matter digestibility (mixed rumen inoculum) of reconstituted whole sorghum grain was influenced (P<.001) by grain moisture level (18 to 31%), constant or variable temperature during storage (-18 to 41 C) and length of storage time (3 to 28 d). All interactions of these three factors were significant (P<.05 or higher). Short term flushing with O₂, CO₂ and N₂ did not affect (P>.10) the digestibility of reconstituted whole sorghum grain. With reconstituted whole sorghum grain, grain pH could be used as a satisfactory measure of quality control. Apparent digestion coefficients for dry matter, organic matter, protein and energy were similar (P>.05) for steers fed 90% concentrate diets containing reconstituted whole or flaked sorghum grain. Nitrogen retention as a percent of nitrogen intake was 35% higher (P<.05) for steers fed reconstituted than flaked sorghum grain diets. In two finishing trials with steers, feed intake and feed conversion were higher (P<.05) for dry rolled than for flaked or reconstituted sorghum grain.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

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Typescript (photocopy). / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1979 G462 / Master of Science

Call number: LD2668 .T4 1979 M94 / Master of Science