1. Testing a stratified continuous rumen fermenter system.
- Author
-
Mason, F., Zanfi, C., and Spanghero, M.
- Subjects
- *
RUMEN (Ruminants) , *PROTOZOAN populations , *ANIMAL adaptation , *CONTINUOUS culture (Microbiology) , *ARTIFICIAL saliva , *FERMENTATION of feeds , *ANIMAL feeding behavior , *PHYSIOLOGY - Abstract
The capability of maintaining protozoa populations and reduce the accumulation of undigested material was investigated in two experiments using a stratified continuous-culture rumen fermenter (CCF) at various setting. The CCF consists of 8 × 2 L glass bottles, warmed at 39 °C and placed on a waterproof magnetic stirrer. Bottles are closed with a rubber stopper, with an insert for the inflow of artificial saliva and have the outflow at the base. In Experiment 1 the effect of two stirring frequencies (continuous vs intermittent, S1 and S2) and two dilution rates ( D , 1.29 vs 1.04) on the pH values and on the counts of the protozoa in the fermentation fluid was evaluated. The pH reached a steady state after 4 d of fermentation and S1 bottles had lower pH than those S2 (6.50 vs 6.57, P<0.001). The protozoa in the fermentation fluid (2.92 × 10 5 /ml at the beginning) declined sharply in the first 2 d of fermentation and stabilized at about 13 × 10 3 /ml in the S2 flasks, while the S1 flasks had lower protozoa concentrations (about 0.8 × 10 3 /ml, P<0.001). The D had no effects on pH and protozoa. Experiment 2 aimed to test effects of varying the daily diet ( F ) amount (15, 20, 25, 30 g DM/d of a diet with 50:50 forage: concentrate ratio) on the organic matter (OM) digestibility (OMD) and on the fermentative patterns. In two fermentation runs of 8 d each, bottles were inoculated with 450 ml of rumen fluid and 1050 ml of artificial saliva, which was then pumped at a rate of 78 ml/h. Lowering F reduced the OM accumulated inside the vessels (from 5.06 to 0.68 g/d; P<0.001) but did not affected the OMD for any of the dietary treatments (range between 0.460 and 0.510). The reduction of F led to a linear decrease (P<0.001) in volatile fatty acids concentration (from 65.8 to 45.3 mM) and to an increase of acetate:propionate ratio (from 2.91 to 3.42) and of pH (from 6.0–6.1 to 6.4–6.5). Lowering F tended to increase the number of protozoa (from 72 to 198 × 10 3 /ml, P=0.082). The tested CCF reaches stable conditions of fermentation after some days of adaptation, allows the survival of protozoa population and has a limited accumulation of undigested materials in the glass bottles. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF