Effect of feeding chopped and pelleted lucerne on rumen fungal mass, fermentation profiles and in sacco degradation of barley straw in sheep

The experiment was conducted to study the effects of dietary changes on anaerobic fungal population assessed by rumen chitin content as a marker. Four rumen fistulated sheep were fed different proportions (100:0, 70:30, 30:70 and 0:100) of chopped and pelleted lucerne in a 4 × 4 Latin square design. Samples of whole rumen contents were collected at 0, 4, 8, 16, 22 h post-feeding, and analysed for their particle associated and liquid associated chitin. In addition, rumen pH, VFA concentration and in sacco degradability of barley straw were also measured as some indices of rumen fermentation pattern. The amount of chitin (g/kg DM) in liquid associated fractions (LAF) was about three times higher than that in particle associated fractions (PAF). Changes in the level of chitin (g/kg DM) in LAF and PAF were not significant when different proportions of chopped and pelleted lucerne were included in the diet. Nevertheless, there was a higher level of chitin (g/kg DM) in the rumen of sheep fed a diet of whole chopped lucerne (WCL, 100:0) compared to that of whole pelleted lucerne (WPL, 0:100). The rate of the straw degradability was also higher on WCL diet than that in WPL diet after 8, 16, and 24 h of incubation. The highest concentration of total VFA was observed in WPL diet at 2 h after feeding. However, no significant differences were observed between the diets for the mean pH of rumen fluid, the total concentration of VFA and the molar proportions of individual VFA at different sampling times. From these results, it appears that the mechanical processing of the forage may affect the activity of fungal populations in the rumen.