Effect of different dietary carbohydrate sources on in vitro utilization efficiency of corn steep liquor

This study was carried out to evaluate the effects of supplementing corn steep liquor (CSL), as a nitrogen source, with different dietary carbohydrate sources on in vitro gas production, fermentation parameters, digestibility and activity of rumen microbial enzymes of male lamb's diets. The 8 experimental diets contained different energy sources (including different levels of barley, corn and molasses), in which a constant level of CSL was used (13% of diet dry matter (DM)), incubated in vitro. Experimental diets were 1) corn, 2) barley, 3) mixture of corn/barley and replacing the former with4) 5, 5) 10, 6) 15, 7) 20 and 8) 25% molasses. The maximum and minimum gas production at 72 and 96 (h) of incubation, and potential of gas production (b) were obtained by incubation of diet containing15% molasses and corn diets, respectively (P<0.05). However, the greatest and lowest values for fractional rate of gas production (c) and microbial protein synthesiswere observed in the diets containing 10 and 25% molasses, respectively (P<0.05). The concentration of NH3-N was greatest by supplementing CSL with 25% molasses, while it was lowest in the diet containing 10% molasses (P<0.05). The addition 10% molasses along with CSL increased the activity of carboxymethyle cellulase and microcrystalline cellulase compared with the other treatments (P<0.05). The highest activity of filter paper-degrading (FDP) was obsereved with the diet in which CLS was supplemented with 5% molasses, while supplementing CSL conating diet with 25% molasses led to the lowest FPD activity (P<0.05). In conclusion, the results of present study showed that supplementing CSL containing diet with 10% of molasses improved nutrient digestion, rumen fermentation and nitrogen metabolism in vitro.