Masters Theses

Date of Award

12-1980

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Ronald R. Johnson

Committee Members

Backus, J.W. Holloway

Abstract

The objectives of this study were to determine the influence of sodium diacetate added to whole shelled corn rations fed with and without rumensin to heavy yearling steers. Changes in pH, volatile fatty acid (VFA), and ciliate protozoa concentrations in the rumen, as well as animal performances and carcass characteristics were observed.

Experimental treatments (tmts) were (1) whole shelled corn + supplement(B), (2) B + 5gm Nadiac per day, (3) B + 25gm Nadiac per day, (4) B + 165mg Rumensin(R), per day, (5) B + R + 5gm Nadiac, and (6) B + R + 25gm Nadiac.

Three trials were conducted in which 54 and 60 Angus steers or 84 Hereford steers, were adapted to and finished with these rations for 84, 97 and 112 day periods, respectively.

Performance variables for treatments were not different (P>.05) in any of the trials, although, feed efficiency and average daily gain tended to decrease and increase, respectively, with addition of rumensin but showed some significant affects. Carcass variables were inconsistent between trials and considered of minor importance.

Ruminal parameters were pooled for trials one and two. The effects of day (time on feed) on rumen variables observed within each trial are presented at a 5% level of significance, and the pH and molar percent acetate decreased, (6.94-6.13) and (73.6-51.1), respectively, through day 33. Also total VFA and propionate increased, (78.7-156.3) and (15.2-31.6), respectively. Molar percent propionate increased with rumensin in the ration 27.8 compared to 35.3. The effects of treatment on total VFA were not significant. Although values tended to increase with Nadiac in the rations. In trial 3, total VFA concentration tended to increase (90.8-128.1) through day thirty and leveled off (131.4) by day 63. Molar percent acetate decreased (72.5-44.1) and molar percent propionate increased (16.5-41.0) while molar percent butyrate remained somewhat stable through the finishing period. Changes in protozoa concentration were not significant. Protozoa concentrations, composed primarily of Entodinium, showed a 5 slight decrease (2.04-1.45x105/ml) on day 63 of the finishing period.

There were no significant differences between treatments in trial 3 but molar percent propionate tended to be higher for treatments containing rumensin on day 16, 30 and 63. Total VFA concentrations on day 30 tended to have higher values for treatments containing Nadiac.

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