Effect of Unsaturated Oils on Rumen Fermentation, Blood Components, and Milk Composition

Abstract

Two lactating cows each of the Guernsey (G), Holstein (H), and Jersey (J) breeds were placed on a normal ration to which 250 ml of safflower oil (S) or cod-liver oil (C) were added once daily. The influence of breed or type of oil on treatment response was minor. Milk fat percentages with respective iodine numbers in parentheses during preliminary, experimental, and post-experimental periods were G-S : 4.3(29), 3.4(40), 3.5(28) ; G-C : 4.0(31), 3.6(50), 3.1(28); H-S: 2.8(31), 2.6(39), 2.4(28); H-C: 2.9(29), 1.8(49), 2.4(29); J-S: 5.0(30), 4.2(40), 4.0(29); J-C: 4.4(33), 4.1(43), 3.9(27). Changes in milk protein and solids-not-fat percentages, daily yield, and body weight were not statistically significant. There was a small but statistically significant drop in the percentage of acetate, as well as increases in the percentages of propionate, butyrate, isovalerate, and valerate in the rumen fluid. Changes in rumen fluid pH were not significant. The levels of jugular blood plasma acetate increased significantly. Total levels of plasma phospholipids or cholesterol esters did not show any significant change. The concentrations of plasma free cholesterol and free fatty acids rose, whereas those of total plasma triglycerides dropped. Arteriovenous differences for plasma phospholipids, cholesterol esters, free cholesterol, and free fatty acids were small and inconsistent. The major change associated with the depression in milk fat test was a significant decrease in the arteriovenous differences for total plasma triglycerides. © 1968, American Dairy Science Association. All rights reserved.