The Effect of Ingested Cod Liver Oil, Shark Liver Oil, and Salmon Oil upon the Com- Position of the Blood and Milk of Lactating Cows

The feeding of cod liver oil to a lactating cow is followed by a reduction of the fat percentage in the milk. Golding et al. (l), who described this effect, found the fat was decreased by about 30 per cent. Results from several other laboratories have confirmed this original observation (2, 3). The phenomenon is so consistent, and the decrease in fat percentage is so large, that few animals need be employed in such studies. Golding and Zilva (4) found that a daily feeding of more than 56 gm. of cod liver oil per cow was necessary to produce either a lowering of the fat per cent or an increase in the fat-soluble vitamins of the milk. Nothing is known concerning the fractions of cod liver oil that are responsible for this interference in fat secretion except that Golding (5) reported that the non-saponifiable fraction from the oil caused no lowering of the milk fat. The changes that take place within the body that may lead to this decrease in the secretion of milk fat are also unknown. In an earlier report the muscular degeneration that accompanies the feeding of cod liver oil to herbivora was described by us (6). The non-saponifiable fraction of the cod liver oil proved much less effective in producing the lesions than the entire oil. This suggested the possibility that the toxic agent here involved and that affecting fat percentage might be similar, or at least that they occurred in the triglyceride fraction in both cases. The purpose of the present study was to determine first if the