Yara Braga Amancio, M.S. student
Sha Tao, Ph.D., Associate Professor | stao@uga.edu |706-542-0658
Methane (CH₄) is one of the primary greenhouse gases associated with dairy production systems and has become an increasingly important topic as the dairy industry seeks to improve environmental sustainability. Enteric methane is produced naturally during ruminal fermentation and represents a loss of dietary energy that could otherwise be utilized for productive purposes. Consequently, strategies that reduce methane emissions have received considerable attention because they may simultaneously decrease the environmental footprint of dairy production and improve nutrient utilization efficiency.
Methane is produced during microbial fermentation of feed in the rumen. Bacteria, protozoa, fungi, and archaea degrade dietary carbohydrates into volatile fatty acids (VFA), primarily acetate, propionate, and butyrate, which provide most of the metabolizable energy used by the cow (Van Soest, 1994; Russell and Wallace, 1997). During this process, hydrogen is generated as a fermentation byproduct. Accumulation of hydrogen can impair microbial metabolism, making its removal essential for maintaining efficient ruminal fermentation (Janssen, 2010). Methanogenic archaea utilize hydrogen and carbon dioxide to form methane, which is subsequently released through eructation. Because methane production depends on hydrogen availability, fermentation pathways that favor acetate production generally increase methane formation, whereas propionate-producing pathways compete with methanogenesis for hydrogen utilization and may reduce methane emissions (Janssen, 2010; Hook et al., 2010).
Although nutrition is the primary factor influencing methane emissions, breed-related differences in digestive physiology may also influence methane production by altering ruminal fermentation and nutrient utilization. Holstein and Jersey cattle differ in body size, feed intake, milk production, and nutrient utilization. In a comparison of lactating cows, Olijhoek et al. (2018) reported average body weights of 663 kg for Holsteins and 487 kg for Jerseys, respectively. In the same study, Holsteins consumed more feed and produced more milk than Jerseys. Because methane production is closely related to feed intake, larger cows would be expected to produce more methane on an absolute basis.
However, breed differences extend beyond body size and feed consumption. Aikman et al. (2008) observed that Jersey cows spent more time eating and ruminating per unit of feed consumed and exhibited greater neutral detergent fiber (NDF) digestibility than Holsteins. Interestingly, Jerseys achieved greater fiber digestibility despite a faster rate of digesta passage through the gastrointestinal tract. The authors suggested that increased chewing activity and more extensive particle size reduction may improve the accessibility of fiber to ruminal microorganisms. Feed intake was also distributed more evenly throughout the day in Jerseys, potentially creating a more stable ruminal environment for microbial fermentation.
The physiological differences described by Aikman et al. (2008) may help explain subsequent observations regarding methane emissions. Olijhoek et al. (2018) reported greater methane yield (g CH₄/kg DMI) in Jerseys than in Holsteins across dietary treatments despite lower daily methane production. Jerseys also exhibited greater total-tract NDF digestibility and a greater acetate-to-propionate ratio than Holsteins, supporting the hypothesis that breed-related differences in nutrient digestion and ruminal fermentation contribute to methane yield.
Additional evidence that breed influences methane yield was provided by Islam et al. (2021), who compared Holstein and Jersey steers fed the same total mixed ration. Despite receiving identical diets, Jersey steers produced substantially greater methane yield than Holsteins, averaging 16.89 and 9.69 g CH₄/kg DMI, respectively. Because dietary effects were minimized, these results suggest that factors beyond diet contribute to differences in methane yield between breeds.
To investigate potential mechanisms underlying these differences, Islam et al. (2021) evaluated ruminal microbial populations. Although microbial richness and diversity indices were similar between breeds, principal coordinate analysis demonstrated a clear separation of microbial communities between Holstein and Jersey steers, indicating that breed influenced microbial composition even when animals received the same diet. Differences were also observed among methanogenic archaea. Jersey steers exhibited a greater relative abundance of Methanobrevibacter millerae, whereas Holsteins were characterized by a greater abundance of Methanobrevibacter olleyae. These microorganisms belong to a group of archaea directly involved in methane production within the rumen. Previous research has reported positive associations between the abundance of M. millerae and methane emissions in cattle, suggesting that differences in methanogenic populations may contribute to breed-related variation in methane yield (King et al., 2011; Islam et al., 2021).
Breed differences may also influence the effectiveness of methane mitigation strategies. Olijhoek et al. (2018) reported that increasing dietary concentrate concentration reduced methane yield by approximately 27% in Holsteins but only 14% in Jerseys. Similar responses were later observed by Olijhoek et al. (2022), where increasing concentrate inclusion from 49 to 91% of dietary dry matter reduced methane yield by approximately 48% in Holsteins compared with 22% in Jerseys. These findings indicate that nutritional strategies developed to reduce methane emissions may not produce equivalent responses across breeds.
While Jerseys appear to exhibit greater methane yield, evaluating environmental sustainability requires consideration of productive output. Methane intensity expressed relative to milk production is generally regarded as a more meaningful indicator of environmental efficiency than methane production per animal or methane yield alone.
Interestingly, Olijhoek et al. (2018) reported no significant breed differences when methane emissions were expressed per kilogram of energy-corrected milk (ECM). Although Jerseys exhibited greater methane yield, they also produced milk with greater concentrations of fat and protein. This observation is consistent with findings from a recent meta-analysis comparing Holstein and Jersey cattle. Almeida et al. (2026) reported that Jerseys consumed less dry matter and produced less milk and ECM than Holsteins. However, feed efficiency expressed as ECM per unit of dry matter intake did not differ between breeds. Jerseys produced milk with greater fat and protein concentrations, whereas Holsteins produced greater milk volume. Consequently, differences observed in methane yield became substantially less important when emissions were evaluated relative to productive output.
Current evidence indicates that Holstein and Jersey cattle differ in several biological characteristics associated with methane production, including fiber digestibility, ruminal fermentation patterns, microbial populations, and responses to dietary interventions. Holsteins generally produce more methane on a daily basis because they consume more feed, whereas Jerseys tend to produce more methane relative to feed intake. Nevertheless, when methane emissions are evaluated relative to milk production, breed differences become considerably smaller. Therefore, although breed influences methane production and methane yield, available evidence suggests that differences between Holstein and Jersey cattle become considerably smaller when emissions are expressed relative to milk production. Production efficiency, nutritional management, forage quality, and overall herd productivity are likely to exert a greater influence on environmental sustainability than breed selection alone.