Preliminary studies on hepatic carnitine palmitoyltransferase in dairy cattle with or without fatty liver

The hepatic mitochondrial carnitine palmitoyltransferase (CPT) activity was measured by fluorimetric assay in dairy cows with or without fatty liver. CPT activities in 13 lactating cattle and in 6 non-lactating cows were 304.4+/-86.6 micromol CoA/min per g protein and 169.3+/-84.8 micromol CoA/min per g protein, respectively. This difference was significant (p < 0.05). CPT activities in early lactation (0-110 days after calving), mid-lactation (111-220 days after calving) and late lactation (over 220 days after calving) were 278.9+/-68.0, 312.4+/-124.1 and 320+/-59.3 micromol CoA/min per g protein, respectively. There was no significant difference between the values at different stages of lactation. The CPT activity in 10 lactating cows with fatty liver unrelated to calving was 201.3+/-80.0 micromol CoA/min per g protein. CPT activity in 10 cattle with fatty liver was significantly lower than that in normal lactating cattle. Based on these findings, clinical fatty liver unrelated to calving appears to be associated with a decrease in hepatic CPT activity.