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

To enhance sustainable productivity and mitigate methane (CH4) emissions from ruminants, the adoption of herbs in dairy diets has gained increasing attention. Among these, chicory is considered one of the most promising forage options for grazing livestock due to its nutritional and agronomic benefits. Chicory’s taproot structure enables it to access soil moisture in a deeper layer than perennial ryegrass during summer drought, helping to partially offset seasonal declines in ryegrass DM yield and supporting milk production in dairy cows. In the past two decades, its potential for CH4 mitigation has attracted increasing interest as an alternative to ryegrass. The study cited aimed to take this further, the objectives being to compare the effects of feeding chicory versus ryegrass as the sole roughage source on CH4 emissions and dairy cow performance, including feed intake, feeding behaviour, milk production, and milk composition.

Thirty-two Holstein-Friesian cows (130 ± 41.9 days in milk at the start of the trial [DIM]) were assigned to two treatments, based on lactation number, DIM, and fat- and protein-corrected milk (FPCM) yield. The four-week experiment included a two-week adaptation period followed by two weeks of data collection. The 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 gas emissions.

Compared with ryegrass feeding, chicory feeding did not affect the total or roughage dry matter intake (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% with chicory feeding, whereas FPCM, fat, protein, and lactose yields were similar. Methane production (g/day), yield (g/kg DMI), and intensity (g/kg FPCM) compared to ryegrass feeding 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 compared to cows fed ryegrass.

Conclusions: Compared with ryegrass, feeding chicory reduced enteric CH4 emissions and increased H2 emissions, suggesting a shift in rumen fermentation pathways or inhibition of rumen methanogens by secondary metabolites. Chicory maintained comparable DMI but increased eating time and meal duration, while reducing roughage DM intake rate. Feeding chicory decreased milk urea and fat concentrations without affecting total milk fat and FPCM yield. Overall, these findings indicate that chicory may lower the environmental impact of dairy production systems while maintaining milk component yields; however, the observed responses should be interpreted in the context of the forage stages, with chicory at an early vegetative stage and ryegrass at a late vegetative stage.