Thesis (M. App. Sc.)--University of Adelaide, Dept. of Animal Science, 1997? / Includes bibliographical references (leaves 107-130).

Two silages were prepared from mature orchardgrass ensiled at 19% dry matter. The additive NutroLac Sila-Aid, containing a dry culture, of lactobacilli, was added to one silage at a rate of 0.5 kg per tonne of fresh herbage, the other silage remained untreated. A wooden stave silo of 40-tonne capacity was filled with each silage. Silage effluent was collected daily for 30 days and the silage temperature was recorded daily for 2.5 months. These two silages comprised the only forage in a two-period crossover design feeding trial. The silages were fed ad libitum (10% feed refusal) and grain was fed at a rate of 1 kg per 3.5 kg milk yield. Twelve Holstein cows in early to mid lactation were subdivided in two groups and allocated to the treated or untreated silage. The cows were fed the assigned forage for a 7-day adjustment period and a 7-week experimental period. The treatments were reversed during a 7-day change-over period and the alternate forage fed for a further 6 weeks. Three cows from each group were assigned to a 7-day digestion trial for total collection of feces and urine during the second last week of each experimental period. The herbage ensiled had the same composition for both silos, the dry matter and protein contents being 19.0 and 14.4% respectively. The treated silage lost almost twice as much effluent compared to the control. Dry matter and protein loss accounted for 2.5 and 4.2% of the ensiled dry matter and protein in the treated silage and 1.5 and 2.3% in the control silage. Peak silage temperatures of 30.3 and 29.1°C for treated and untreated silage were recorded on the ninth day after ensiling. The resulting silage had a dry matter and protein content of 22.8 and 13.2% (treated) and 23.8 and 13.0% (untreated). There was no significant difference (P^.05) between the two treatments with regards to intake, body weight change and milk production. On the average the cows consumed 10.1 kg forage and 8.0 kg grain on a dry matter basis and yielded 2 28.0 kg milk containing 3.2% fat. The animals fed NutroLac silage gained an average of 3.7 kg per period whereas the cows on control silage lost 5.6 kg over the same time. The rumen pH and the acetate/propionate ratio of the ruminal fluid was the same for both treatments, the values being 6.6 and 2.4. The apparent dry matter digestibility of the total ration was significantly higher (P≤.05) for the control silage (70.7%) compared to the treated (69.1). The digestibility of organic matter and protein was not different (P≤.05) between treatments, the average being 7 3.3 and 74.4%. The results from the present experiment tended to be in favour of the control silage and indicated that there was no advantage, and perhaps even a disadvantage, in terms of dry matter digestibility and increased ensiling losses when NutroLac was added to the grass at ensiling time. / Land and Food Systems, Faculty of / Unknown

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