Publications
Recent Publication: Nitrate—Not Tannins—Delivers Gains in Efficiency and Methane Intensity
We’re thrilled to share the first PhD publication from student Rong Peng in the Journal of Dairy Science.
This study tested whether supplementing a low-CP, corn-silage–based diet with nitrate (0.67% of dietary DM), tannins from Acacia mearnsii bark extract (3% DM; AMT), and/or additional rumen-protected rapeseed meal (RPR) could improve nitrogen use efficiency (NUE) and reduce enteric methane emissions in dairy cows. Nitrate supplementation (vs. isonitrogenous urea) clearly stood out: it increased milk yield by 12%, improved NUE by 11%, and reduced methane intensity (g CH₄/kg ECM) by 12%, without changing methane yield (g CH₄/kg DMI) or daily methane production, and without negative effects on milk composition, blood methemoglobin, or milk nitrate.In contrast, tannin supplementation (3% AMT) did not reduce methane production, yield, or intensity. Instead, it reduced energy-corrected milk yield by 8%, slightly lowered NUE, and markedly decreased nutrient digestibility, while shifting nitrogen excretion from urine to feces—an environmentally favorable change in N partitioning, but at the cost of productivity and efficiency. Adding RPR increased dietary CP intake but did not mitigate these negative effects of AMT on digestibility, milk yield, or NUE; rather, it further reduced NUE and increased both urinary and fecal N excretion, suggesting inefficient utilization of the additional protein and some energy dilution.Conclusion: Under these low-CP conditions, only nitrate effectively improved NUE and reduced methane intensity without compromising animal health indicators or milk safety, whereas tannins—with or without extra rumen-protected protein—failed to mitigate methane and impaired digestibility and efficiency, offering no synergistic advantage when combined with nitrate.
Recent Publication: Methane inhibitor 3-NOP works differently across dairy cow breeds, while tannins improve nitrogen use
Researchers at ETH Zürich Animal Nutrition investigated how the methane-reducing feed additive 3-nitrooxypropanol (3-NOP) and a tannin extract from Acacia mearnsii affect dairy cow emissions and productivity. In a controlled feeding study, 3-NOP reduced methane emissions substantially, with a stronger response in Holstein Friesian cows (about 22%) than in Brown Swiss cows (about 13%).
Tannins, in contrast, had little effect on methane emissions but significantly improved nitrogen utilisation by shifting nitrogen excretion from urine to faeces, a change that may help reduce environmental nitrogen losses from dairy farming. Importantly, combining 3-NOP and tannins did not lead to additional methane reductions, showing that the additives act independently. Milk production was not negatively affected by either additive.
Implications: The findings highlight the importance of understanding how different mitigation strategies work together - and across breeds - to support more targeted and effective climate solutions for dairy production.
external page Link to full text
Recent Publication: Invited Review Underscores Need for Proper Power Analysis in Dairy Research
A recent invited review in the Journal of Dairy Science highlights a major gap in rigorous power analysis: only 4.73% of 4,376 reviewed publications reported conducting a power analysis, with 59% lacking methodological details. Most reported power analysis relied on non-open-source tools such as SAS, which do not automate degrees-of-freedom (DF) approximation, a limitation for mixed models requiring covariance adjustments, making them challenging to be implemented effectively. In contrast, many R packages fail to support complex designs frequently used in dairy science. To address these issues, the authors developed pwr4exp, an open‑source R package for model‑based power analysis. Built on linear mixed model theory, pwr4exp automates DF approximation and enables power calculations for standard designs (e.g., randomized block, split-plot, and Latin Square) while supporting custom experimental designs tailored to diverse study objectives. Validation against SAS confirmed its accuracy, with pwr4exp resolving DF challenges and offering an intuitive interface.
external page Link to full text
Meta-Analysis Highlights Benefits of Niacin Supplementation During Lactation
In our recent publication in the Journal of Dairy Science, we conducted a comprehensive meta-analysis evaluating the effects of niacin supplementation on dairy cow performance. Using data from 41 experiments including 1,992 cows, we found that supplementing with either rumen-unprotected or protected niacin during the lactating period significantly increased dry matter intake, which led to increase in yields of milk and milk components. Interestingly, niacin supplementation during the transition period did not result in performance gains. These findings support the targeted use of niacin during lactation to enhance dairy cow productivity.
A sampling method for differentiating breath and ruminal exhaled volatile organic compounds in dairy cows using methane as a marker
We’re thrilled to share the first PhD publication from student Mario Barrientos-Blanco in the Journal of Dairy Science Communications. This milestone work, conducted here at in the Animal Nutrition Group, ETH Zurich, presents a novel sampling method that distinguishes between volatile organic compounds (VOCs) exhaled through the breath and those originating from the rumen in dairy cows.
By using methane as a biological marker, the method significantly improves the accuracy of VOC profiling, which is an important step forward in monitoring cow health, metabolism, and feed efficiency. The findings lay a strong foundation for future research in precision livestock farming and metabolic monitoring.