The fatty acid composition of bovine milk fat can be substantially alt
ered by feeding lipid sources which alter the fatty acid profile of li
pid entering the intestine from the rumen. As long-chain fatty acids o
f dietary origin can be incorporated directly into milk fat the opport
unity exists to alter the ratio of short and long-chain fatty acids as
well as the degree of saturation of milk fat. In practice our ability
to alter the fatty acid profile of milk fat is limited not by the syn
thetic capacity of the mammary gland, but rather by the challenge of a
chieving effective protection of unsaturated dietary fatty acids from
biohydrogenation in the rumen, as well as keeping the level of polyuns
aturated fatty acids within the range where the organoleptic quality a
nd shelf-life of milk and dairy products are not compromised. The fatt
y acid composition of oilseeds such as canola are considered desirable
from a human health perspective and thus their inclusion in the diet
of dairy cattle as a means of achieving a more desirable fatty acid pr
ofile in milk fat may enhance the nutritive quality of milk.