Masters Theses

Date of Award

8-1982

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Richard N. Heitmann

Committee Members

J.W. Holloway, W.R. Backus

Abstract

Two total collection trials were utilized to determine the digestibility of whole stillage ensiled with mature, chopped fescue hay and to observe the effects on ruminal pH, ciliate protozoa population and volatile fatty acid concentration. Three silages were made using corn whole stillage and mature, chopped fescue hay in different ratios. The ratio of whole stillage to fescue hay was 75:25 in silage 1, 70:30 in silage 2, and 65:35 in silage 3. Each silage was fed to a group of six mature crossbred wethers randomly assigned to metabolism stalls during trial 1. The 75:25 and 70:30 silages were similar in digestibilities with a dry matter digestibility of 60%. The 65:35 silage appeared to be less digestible (P < .05) for all nutrients. Dry matter digestibility was approximately 46% for the 65:35 silage. The 75:25 silage experienced heavy weepage and supported heavy mold growth and therefore was considered undesirable. During trial 2, the 70:30 and 65:35 silages were each fed to a group of four mature crossbred wethers in an attempt to duplicate the digestibility results from trial 1. Ruminal pH, protozoa population and VFA concentration were monitored daily as the animals adapted from an all fescue hay diet to one of the whole stillage fescue hay silages. No effect was noticed upon ruminal pH as a result of feeding the silages, however, the total ciliate protozoa population decreased (P < .05) due to the virtual elimination of the holotrichs and a diminishing of the diplodinia. Total VFA concentration (in mM/1) increased (P < .001) as a result of feeding the WS/fescue hay silages. Molar percent of acetate tended to decrease while propionate, butyrate and valerate increased (P < .01). The digestibilities obtained through trial 1 were not repeated in trial 2. The 65:35 silage had a dry matter digestibility of 59% while the 70:30 silage had a dry matter digestibility of 47%.

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