The aim of this work was to produce biofloc from the fish breeding system
and study of its effect on in vitro ruminal digestibility and gas production in the
ruminants. In the first phase of the experiment, two hundred common carp fishes
(1gr) in two tanks with capacity 250 liters’ water were used for producing biofloc. In
the second stage, the effect of 0, 0.5, 1, 1.5 and 2% of produced biofloc with ration
70 to 30 concentrate to forage on in vitro gas production and digestibility was
determined. The data were analyzed in a completely randomized design (5
treatments and 4 replicates). The results showed that there was no significant
difference in potential and rate of gas production and dry matter digestibility
between treatments. The highest amount of truly digested organic matter, cell wall
degradability, and NDF digestibility was related to the treatment containing 2%
compared with the other treatments (108.4, 67.8, and 32.5, respectively). The10

microbial biomass efficiency, microbial biomass and PF of treatments containing
biofloc were more than control treatment (P < 0.05). On the base of this trial,
treatments containing biofloc especially the high levels of biofloc had a more
positive effect on digestibility and fermentation of experimental diets, therefore
biofloc produced from the fish breeding system can be used as a useful supplement
in ruminants.