Correlation between liver fat and dry matter

Liver function is highly influenced by the feed. Investigating the consequences of different feed compositions on growing mink kits, often makes it interesting to see if there are any fat infiltration in the livers. In investigations on the protein requirement of mink in the growing period, we often observed an increased fat content in the liver, with reduced protein / increased fat content in the feed (Damgaard et al., 1994; 1998a & 1998b).
A chemical analysis of the fat content is slow and expensive. In order to screen livers from many animals, we searched for a fast and cheap method to determine the liver fat content.
A semiquantitative test (Herdt et al., 1983), has been used at the Research Center (Clausen, 1992; Damgaard et al, 1994; 1998a & 1998b). Liver samples were submerged into water and copper sulphate solutions with specific gravities of 1.000, 1.025 or 1.055. Based on buoyancy, liver samples were classified as containing > 34 % fat, 25 – 34 % fat, 13 – 25 % fat, or less than 13 % fat. The method is cheap but rather inaccurate. Furthermore the liquid can only be used for a few liver samples before it has to bee replaced.
The dry matter (DM) content of fat is almost 100 percent. In this investigation we analysed dry matter and crude fat content of the livers and estimated the correlation between these two variables.