Four trials were conducted to evaluate the effects of ensiling whole plant maize with wet distillers grains with solubles (WDGS) on its preservation and nutritive value. In the first study, WDGS was blended with whole maize plants at 0% (control), 10%, 20%, 30% and 40%, and ensiled for 120 days in bottle silos in a complete randomized design. Fermentation was monitored by taking samples at day 0, 7, 21, 42 and 120. Results showed a steady decrease (P<0.05) in dry matter (DM) concentration with increasing level of WDGS inclusion. Final silage pH was lowest (P<0.05) for the 40% WDGS treatment (pH 3.62) and highest for the 10% WDGS treatment (pH 3.79). There was no effect (P>0.05) of level of WDGS inclusion on initial buffering capacity (day 0), as well as for day 42 and 120 samples. Lactic acid was higher (P<0.05) at day 120 for the control treatment than those blended with WDGS, which did not differ significantly. The concentration of acetic acid was higher value (P<0.05) for silage treatments blended with WDGS than the control, with that of 40% WDGS level of inclusion recording the highest (P<0.05). The control and 40% WDGS treatments had lower (P<0.05) ammonia nitrogen concentration (g/kg N) than the other treatments at day 120. The second trial involved monitoring ruminal fermentation characteristics of cannulated sheep fed three experimental diets. Formulated diets contained maize silage mixed with 24% dried distillers grains with solubles (MS DDGS treatment ), maize silage mixed with 19.5% sunflower oilcake meal (MS SOM treatment), and silage blend of 91% of whole maize plant/9% WDGS (WDGSMS treatment), all on a DM basis, to obtain iso-nutrient diets. The mean value for rumen pH, NH3N and total VFA concentrations among diets did not differ (P>0.05) among treatments. The individual VFA were similar with only butyric acid being lower (P<0.05) in sheep fed WDGSMS. There were no differences in the acetic:propionic acid ratio among treatments. The third trial involved the determination of DM degradability of the three formulated experimental diets using the nylon bag technique. Effective degradability was measured at two outflow rates, 2% and 5%. The diets did not differ (P>0.05) for washing losses (avalue), slowly degradable DM fraction (b-value) and rate of degradation of DM (c-value). Treatment MS SOM recorded the highest effective degradability with MS DDGS having the lowest at 2% outflow rate. The effective degradability value at 5% outflow rate for WDGSMS was not significantly different from that of MS SOM and MS DDGS, which differed significantly. In the final study, experimental diets were fed to three groups of eight lambs in a growth performance trial. The groups offered MS DDGS and MS SOM had superior (P<0.05) final mass (g/head), average daily intake (gDM/kg0.75) and average daily gain (g/head/day), than those offered WDGSMS. The feed conversion ratio did not differ (P>0.05) among all treatments. / Dissertation (MSc(Agric))--University of Pretoria, 2010. / Animal and Wildlife Sciences / unrestricted