Repeatability of rumen volatile fatty acid concentrations in sheep under field conditions

Short-term studies with grazing sheep have shown that the concentration of volatile fatty acids (VFA) in the rumen is correlated with VFA production rate (Leng et al., 1968), which is stoichiometrically linked with enteric methane production rate. These associations may present an opportunity to predict daily methane production of grazing sheep from the concentration of VFA in the rumen. Such a method could have application in genetic improvement of methane traits, but a better understanding of the repeatability of VFA concentrations is required to assess the usefulness of a single VFA measurement in predicting daily methane production. A study was undertaken to determine between-animal and between-day variation in VFA concentrations in grazing sheep.