Chicory reduces enteric methane emissions and maintains milk yield but decreases milk fat content compared with perennial ryegrass in dairy cows

The effects of chicory (Cichorium intybus) and perennial ryegrass (Lolium perenne) diets on methane (CH₄) emissions, feed intake, feeding behavior, and lactation performance in dairy cows were assessed using a randomized complete block design. Thirty-two Holstein-Friesian cows (130 ± 41.9 DIM at the start of the trial; mean ± SD) were assigned to 2 treatments, based on parity, DIM, and fat- and protein-corrected milk (FPCM) yield. The 4-wk experiment included a 2-wk adaptation period followed by 2-wk of data collection. Cows received either early vegetative chicory or late vegetative ryegrass as their sole roughage source, harvested daily and freshly provided in individual feed bins with automated intake recording. Concentrate was provided during milking and via the GreenFeed system that measured gaseous emissions. Compared with ryegrass feeding, chicory feeding did not affect total or roughage DMI, but increased eating time and meal duration, while reducing roughage DM intake rate. Milk fat content decreased by 11% and milk urea content by 52% upon feeding chicory, while FPCM as well as fat, protein, and lactose yields remained unaffected. Methane production (g/d), yield (g/kg DMI) and intensity (g/kg FPCM) were reduced by 26%, 24%, and 25%, respectively. No dietary effect was observed on GreenFeed visit frequency or its influence on CH₄ estimates. Hydrogen production, yield, and intensity was 63%, 68% and 67% higher, respectively, in cows fed chicory. In conclusion, chicory reduced CH₄ emissions and milk urea content compared with perennial ryegrass, without compromising milk yield, although milk fat content was lowered. Although chicory may serve as a promising forage option to mitigate methane emissions in dairy production systems, the 24 to 26% reduction observed here should be interpreted with caution and require confirmation across diverse conditions before broader generalization.