Effects of pulse-dosing an essential oil blend to dairy cows on enteric methane emissions and productivity

The objective was to investigate the effects of pulse-dosing the essential oil blend, Agolin Ruminant (EOB), to dairy cows on methane (CH₄) production (g/d) and intensity (g/kg milk or energy-corrected milk (ECM)), as well as lactation performance, on a commercial farm. Seventy-two multiparous, mid-lactation cows were blocked by days in milk, parity, and milk yield and housed in a single pen. After a 2-wk covariate period, cows within each block were randomly assigned to one of two treatments for 10 wk: Control (blank pellets) and EOBP (blank pellets and EOB pellets). The pellets were delivered through double-hopper GreenFeed (GF) units. Hopper 1 of each GF unit contained EOB pellets, formulated to supply ~1 g EOB from the first daily drop of pellets for each EOBP cow. Hopper 2 dispensed blank pellets for the remaining daily drops to EOBP cows and for all drops to Control cows. Enteric gases were measured via the GF units. Milk yields and components were obtained twice weekly, and dry matter intake (DMI) was calculated weekly using milk data, body weight, and body condition score. Overall, cows receiving EOB tended to have lower milk lactose concentration. In week 7, EOBP cows outperformed Control cows in milk yield, ECM, yields of milk protein, lactose, and solids-nonfat, modeled DMI, and CH₄ intensity. Inherent limitations of administering EOB through the GF units, as well as a low number of CH₄ measurements occurring after peak fermentation, may have contributed to the lack of consistent treatment differences. Our efforts to administer a feed additive to individual cows, and our consideration of how farm management practices influenced the results, contribute to the progress of on-farm CH₄ research.