Dairy cow fertility is already poor: first service conception
rates in most herds are below 50%. Furthermore, there
has been a steady downward trend in conception rates in
some countries over the past 30 years coupled with
increasing milk yields (Lamming et al., 1998). As cows are
managed more intensively, there has been a decreased
dependence on grass as forage and a subsequent increase in
the n-6:n-3 ratio (Pike and Barlow, 2000). It is therefore
important to understand how changing the composition of