While comprehensive farm level models for the dairy, beef and cereal sectors have previously been developed, to date, relatively little research has been conducted on the economics of the sheep sector at farm level. Nationally representative farm level data from Teagasc’s National Farm Survey (NFS) is used to develop a model examining the economic factors of concentrate usage on Irish sheep farms informed by the current body of literature on pastoral based production systems research. Results from a 2 step random effects panel regression of a demand function for concentrate use with log linear functional form support the established production literature. The demand for concentrates on Irish sheep farms was found to be elastic and thus sensitive to price changes. Farm labour input, fertiliser application, subscription to an extension and research provider and date of lambing were found to be significantly associated with concentrate demand on sheep enterprises. Results from a second model specification indicate the presence of spatially heterogeneous effects of lambing on concentrate demand across regions.