Effect of Feeding Cod Liver Oil and Unsaturated Fatty Acids on Rumen Volatile Fatty Acids and Milk Fat Content

Abstract

Feeding 150 ml of cod liver oil, oleic acid or linoleic acid twice daily as additives to normal rations for dairy cows resulted in (1) a decrease in molar proportion of rumen acetic acid, (2) an increase in molar proportion of propionic acid, and (3) a greater concentration of total volatile fatty acids(VFA) per ml of rumen liquor. When fed to cows that had received milk fat depressing diets, linoleic acid had the greatest effect on rumen VFA being complimentary to the basal diet in decreasing the acetate and increasing the propionate proportions while increasing the total concentration of ruminal VFA, cod liver oil and oleic acid feeding reflected a change in the rumen VFA but to a lesser degree. The effect of feeding oleic acid was further shown by a decrease in the short chain fatty acids of butterfat with a resulting increase in iodine number, and a decrease in the fat content of milk similar to that produced by feeding cod liver oil.