Effect of storage duration on frozen inoculum to be used for the in vitro gas production technique in rabbit

Abstract

The present study aimed to investigate the effect of storage duration of frozen inoculum on fermentation parametersobtained with the in vitro gas production technique. Two non-predigested diets differing in chemical composition andespecially crude fibre content (low fibre diet: 13.8%; high-fibre diet: 22.6%) were ground to pass a 1 mm screen andsubjected to fermentation with the same inoculum frozen for different periods: after 1 month (inoculum 1), after 2months (inoculum 2) and after 3 months (inoculum 3). The inoculum used was obtained from the caecal content of 75-day-old NZW rabbits. After defrosting, the caecal content was diluted with the medium 1:1 (V/V) and squeezed throughsix layers of gauze to obtain the inoculum. The substrate affected several fermentation parameters. In particular, thehigh-fibre diet had lower potential and cumulative gas production (A = ml/g 220 vs 256; P vs 221; P acids (mmol/g 56.2 vs 49.8; P P values of degraded organic matter (62.4%, 62.7% and 62.7% respectively for inocula 1, 2 and 3) and similarproduction of VFA (54.0, 52.2 and 52.8 mmol/g, respectively for inocula 1, 2 and 3). This research showed it is possibleto use frozen inoculum for at least 3 months and in this time interval obtain the same parameters of in vitro fermentation.

Keywords

• Gas production, In vitro fermentation, Rabbits, Caecal content