Effects of replacing 50% of grass clover silage with whole-crop wheat silage on feed intake, growth, and enteric methane emissions in dairy heifers

Replacement heifers contribute substantially to greenhouse gas emissions from dairy systems, yet information on emissions from heifers fed diets containing whole-crop cereal silage as an alternative forage remains limited. This study evaluated feed intake, growth, and enteric methane emissions in Swedish Holstein and Nordic Red heifers fed either grass-clover silage or a 50:50 mix of grass-clover and whole-crop wheat silage. Twenty-two pregnant heifers (mean age ± SD; 18.3 ± 1.16 mo) were randomly assigned to treatments in a randomized complete block design. Feed intake and methane emissions (GreenFeed system) were monitored throughout the covariate (2 wk), adaptation (1 wk), and experimental (4 wk) periods, whereas body weight and backfat thickness were measured at the start and end of the study. Dry matter intake, methane emissions, and average daily gain or backfat thickness did not differ between diets. These findings suggest that whole-crop wheat silage can partially replace grass-clover silage in the diets of pregnant dairy heifers without affecting feed intake, growth rate or enteric methane emissions.