Rumen size of sheep: difference between a modern and a native Norwegian sheep breed

Abstract

ABSTRACT Breed differences in rumen size may be one factor explaining differences in feed intake and enteric methane (CH4) emissions. In this study, we investigated rumen weight (n = 64 ewes and lambs) of two breeds with contrasting selection history; the Norwegian White (NWS; long-tailed) and the Old Norwegian Spæl (ONS; Nordic short-tailed). For adult ewes, rumen weight corrected for carcass weight, was lower (P < 0.05) for ONS compared to NWS (LSMEANS 1371 vs. 1665 g). Our results suggest that previously observed breed differences between ONS and NWS in feed intake and enteric CH4 emissions (lower feed intake and enteric CH4 emissions per kg body weight, for ONS) may be linked to differentiation in rumen size. This should however be investigated further, by measuring feed intake, enteric CH4 emissions and rumen size on the same individuals. Understanding breed-specific factors associated with enteric CH4 emissions is relevant for selection practices aimed at reducing greenhouse gases.