Effects of distiller's dried grains with solubles on enteric methane emissions in dairy and beef cattle: a meta-analysis.

INTRODUCTION

Distiller's dried grains with solubles (DDGS), a by-product of grain fermentation for ethanol production, are extensively used in livestock feed. Given their nutrient composition, DDGS could potentially influence methane (CH) emissions, a significant greenhouse gas concern in ruminant production systems. This study utilized a multilevel random-effects meta-analysis to assess the impact of DDGS inclusion in cattle diets on CH production and yield.

METHODS

The literature search was conducted on 23 July 2024. Studies reporting CH emissions and dry matter intake (DMI) in cattle fed DDGS-based diets were identified, and data extraction was performed. The meta-analysis calculated the mean difference (MD) for DMI and CH yield and the relative mean difference (RMD) for CH production across the selected studies.

RESULTS

A total of  = 25 effect sizes from 10 studies were included in the DMI meta-analysis. DDGS had no significant effect on DMI in dairy or beef cattle ( = 0.770, MD = 0.070, 95% confidence interval [CI] from -0.420 to 0.561). For CH production,  = 24 effect sizes from 10 studies were analyzed, revealing no significant effect ( = 0.759, RMD = -1.045, 95% CI: from -8.025 to 5.935). Similarly, the meta-regression model indicated that the diet's ether extract (EE) had no significant influence ( = 0.815, 95% CI from -1.121 to 1.409) on CH production. For CH yield,  = 23 effect sizes from 10 studies were included, with results showing no significant effect ( = 0.475, MD = -0.434 g/kg DMI, 95% CI: from -1.673 to 0.805). The regression model for the EE content of the diet also showed no significant impact on CH yield ( = 0.311, 95% CI: from -0.366 to 0.122).

DISCUSSION

The findings suggest that the inclusion of DDGS does not significantly affect DMI, enteric CH production, or CH yield in cattle. Moreover, the EE content in DDGS-containing diets does not significantly influence CH outcomes. These results indicate that DDGS can be incorporated into cattle diets without exacerbating CH emissions, contributing to sustainable livestock feeding practices.