Incidence and severity of fatty liver in dairy cows.

A survey of the incidence and severity of post-parturient fatty liver in high yielding dairy cows was carried out on 151 cows and 46 heifers from four Friesian herds and one Guernsey herd. In Friesian and Guernsey cows from the second lactation onwards fat occupied a significant proportion (15 to 32 per cent) of the hepatic parenchyma at one week after calving but decreased to low values at eight weeks after calving. Fatty liver was insignificant in heifers of either breed. When the fatty liver was classified according to the amount of fat at one week after calving, 66 per cent of Friesian cows and 33 per cent of Guernsey cows had a moderate or severe fatty liver. The severity of the fatty liver was related to the loss of condition score after calving but not the condition score at calving.