Authors : Armagan Hayirli, Huzur Derya Umucalilar, Nurettin Gulsen and Ozcan Baris Citil
Abstract: This in vitro experiment was conducted to examine the effects of lactulose (0, 2 or 4%) on ruminal fermentation of mixtures differing in the forage:concentrate ratio (F:C; 20:80, 40:60 or 60:40). Ruminal fluids collected from two Holstein steers were incubated with the mixtures for 48 h. Data were subjected to 2 way ANOVA. Lactulose did not alter ruminal fluid pH, ammonia and lactate concentrations, individual and total Volatile Fatty Acid (VFA) concentrations and gas production. There was a linear increase in ruminal fluid pH from 6.71-6.76 (p<0.0001), a linear decrease in ammonia concentration from 15.84-11.77 mmol L-1 (p<0.0001), a quadratic increase in lactate concentration from 25.51-26.91 mmol L-1 (p<0.04) as the F:C ratio increased from 10:80-60:40. Moreover, increasing the forage level caused linear increases in the acetate (from 53.89-55.69%; p<0.0002) and valerate (from 3.05-3.25%; p<0.003) proportions and a linear decrease in the butyrate proportion (from 19.74-17.32%; p<0.0001) and a linear decrease in cumulative gas production from 41.14-33.54 mL (p<0.0001). The effects of the F:C ratio and lactulose level on gas kinetics parameters were variable. Lactulose addition failed to modify alterations in rumen fermentation characteristics of the mixtures varying in the F:C ratio. In conclusion, lactulose fermentation in ruminal fluids had minimal effects on fermentability of the mixture consisting of different F:C ratios suggesting that lactulose does not modify alterations in rumen fermentation in cattle during their growth and lactation phases.
Armagan Hayirli, Huzur Derya Umucalilar, Nurettin Gulsen and Ozcan Baris Citil, 2010. Role of Lactulose as a Modifier in Rumen Fermentation. Journal of Animal and Veterinary Advances, 9: 2537-2545.