In vitro fermentation characteristics of ryegrass-white clover sward containing different proportions of chicory

Chicory (Cichorum intybus) is a deep-rooted grazeable forage used to overcome production and nutritive value shortfalls of perennial ryegrass (Loliun perenne) and white clover (Trifolium repens) swards during summer drought periods in New Zealand. Despite the wide use of chicory, limited data is available on its fermentation characteristics, and how those affect rumen fermentation pattern and, thereby, nutrient supply from ryegrass-white clover based swards including chicory. The objective of this study was to evaluate the in vitro fermentation characteristics of ryegrass-white clover sward containing different proportions of chicory. Herbages containing 100% ryegrass-white clover (Ch0); 25% chicory + 75% ryegrass-white clover (Ch25%); 50% chicory + 50% ryegrass-white clover (Ch50%); and 100% chicory (Ch100%) were incubated using the Daisy II-200/220 incubator (ANKOM Technology, NY). Treatments, Ch0, 25%, 50% and 100%, were randomly assigned to the four fermentation jars over two runs. The pH, volatile fatty acids and ammonia-N concentrations of fermentation liquor were measured at 4, 8, 12, 24 and 48 hours of incubation. Data were analysed using repeated measures ANOVA with chicory proportion as treatment effect, incubation time as time effect and run as replicate. The pH, mean concentration of ammonia-N, propionate, acetate and butyrate were not affected by treatment (P > 0.05), averaging at 6.5 ± 0.02, 19.1 ± 1.98, 5.3±1.12, 20.2 ± 3.37and 3.3 ± 0.66 mmol/l, respectively. Current results showed that fermentation pattern of herbage containing increasing proportions of chicory is similar to the ‘conventional’ ryegrass-white clover, suggesting that including chicory in conventional swards might not alter the nutritive value of herbage