Review: Production and prediction of enteric methane in dairies in the Texas Panhandle and surrounding areas

Purpose

We reviewed the current understanding of methane production, prediction, and mitigation strategies in dairy cattle located in the Texas Panhandle and surrounding High Plains region.

Sources

Peer-reviewed literature was the primary source of information.

Synthesis

The dairy industry in the Texas Panhandle and surrounding High Plains region has expanded greatly in recent decades, reflecting a geographic shift from historically significant dairy production areas in Central and Northeast Texas and states in the Western United States. Along with this geographic shift, the US dairy cattle population has decreased 4.5% since 1990. Nonetheless, enteric CH₄ emissions increased 13% from 1990 to 2022. Enteric CH₄ emissions can be affected by numerous diet- related factors including feed intake, diet composition, and feed additives (hydrogen sinks and direct inhibitors) that alter CH₄ production in the gastrointestinal tract. Accurate, direct estimates of enteric CH₄ emissions are challenging and costly to measure from individual animals, which has resulted in the use of mathematical models as a means to predict CH₄ emissions in dairy cattle. We evaluated commonly used equations to predict CH₄ emissions in lactating cows, nonlactating cows, and growing heifers when applied to diets and performance typical of dairies in the Texas Panhandle. The CH₄ emissions (g/d) among the 3 equations used with 3 lactating cow diets ranged from 431 to 507 g/d. Additionally, the CH₄ emissions among the 2 equations used with 3 dry cow diets ranged from 251 to 278 g/d. For dairy heifers, CH₄ emissions among the 2 equations used with 3 growing heifer diets ranged from 157 to 175 g/d. Predicted CH₄ yield for equations and diets used ranged from 17.8 to 20.9 g/kg of DMI for lactating cows, 17.9 to 19.8 g/kg of DMI for dry cows, and 14.6 to 20.2 g/kg of DMI for growing heifers.

Conclusions and Applications

Dietary factors affecting enteric CH₄ production are generally well defined. Moreover, potential mitigation strategies exist to decrease CH₄ emissions, but our ability to accurately and precisely predict feed intake and digestibility, which are major factors affecting CH₄ production, needs improvement. Future research measuring enteric CH₄ emissions from cows fed diets typical of those used in the Texas Panhandle and High Plains region across a range of DMI would be useful to validate and potentially improve existing prediction equations for their utility in these regions. Improvement in predicting enteric CH₄ emissions will allow dairies to address potential regulatory challenges and understand practical effects of mitigation approaches.