The effect of rabbit's age on in vitro fermentation of xylan, cellulose and pectin | Vpliv starosti kuncev na in vitro fermentacijo ksilana, celuloze in pektina
2005
Lavrencic, A., Ljubljana Univ. (Slovenia). Biotechnical Fac., Zootechnical Dep | Kermauner, A.
In vitro gas production kinetics for three different substrates, xylan, cellulose and pectin, were determined using the caecum content of weaned rabbits (36 days of age) and of rabbits of slaughter age (78 days) as inoculum. Gas produced was fitted with the Gompertz model and the differences between parameters were calculated. Large differences were observed in the fermentation of xylan: the lag phase (LAG) at slaughter weight rabbits started earlier then in weanlings (6,2 h and 9,0 h, respectively; P0,05). However, the fermentation in slaughter weight rabbits was less intensive (lower maximum fermentation rate (MFR): 14,3 ml/h and 24,4 ml/h, respectively; P0,05) and the MFR was reached later than in weanlings (time of maximum fermentation rate (TMFR): 14,2 h and 13,7 h, respectively; P0,05). There were no differences in total potential gas production of xylans between slaughter weight and weaned rabbits (parameter 'B'). The fermentation of cellulose also started earlier in slaughter weight rabbits (LAG: 24,9 h and 31,2 h, respectively; P0,05) and the total potential gas production was greater than in weanlings (parameter 'B': 155 ml and 115 ml, respectively; P0,05). Total potential gas production of pectin was significantly lower (P0,05) in slaughter weight than in weaned rabbits (parameter 'B': 331 ml and 356 ml, respectively), while other parameters of fermentation did not depend on the age of rabbits. In first 10 hours of fermentation that correspond to the normal retention time of nutrients in the caecum (Gidenne et al., 2000), the highest amount of gas was produced from pectins, followed by xylan and cellulose. However, only with pectins the time of maximum fermentation rate was short enough (TMFR of pectins at 36 days old rabbits was 8,0 hours and at 78 days old rabbits 9,5 hours), that majority of pectinc could be actually fermented in vivo.
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