The effect of sucrose or starch on fermentation characteristics of some feedstuffs by gas production and in vitro culture

In this experiment the effect of adding different kinds of non-fiber carbohydrates (sucrose, starch, or equal mixture of them) on the amount of produced gas and fermentation characteristics of some feedstuffs were studied. Gas production was recorded for non-supplemented and supplemented (70 mg/g DM) pure cellulose, alfalfa hay and sugar beet pulp. The feedstuffs that were used in in vitro experiment includes: alfalfa hay, wheat bran and unmolassed sugar beet pulp. Non-supplemented or NFC supplemented (70 mg/g DM) samples incubated for 2, 4, 8, 16, 24, 48, 72 and 96 h at 39°C. The results of gas production study showed that (except for 2 h), supplementation of all kinds of non-fiber carbohydrates increased the amount of produced gas significantly (P<0.05). Sucrose supplementation increased the gas production rate of alfalfa hay significantly (P<0.05). In the case of sugar beet pulp, the adding of starch decreased the gas production rate significantly (P<0.05). Also, when the alfalfa hay or sugar beet pulp were used as a basal forage, adding of sucrose, starch or sucrose+ starch increased gas production from fermentable fraction significantly (P<0.05). The source of NFC used in the medium containing alfalfa hay caused a significant decrease in DM disappearance (P<0.01). Fractional rate constant of dry matter disappearance of unmolassed sugar beet pulp and wheat bran was significantly decreased by supplemental non-fiber carbohydrate, except when sucrose was added to wheat bran (P<0.01). The indigestible fraction of dry matter of alfalfa hay was significantly increased when it was supplemented with non-fiber carbohydrate (P<0.05).