Saturation Ratio of Supplemental Dietary Lipid on Production Performance of Holstein Cows

Two experiments were conducted to evaluate the effect of supplemental lipid varying in proportion of unsaturated and saturated fatty acids on lactation performance and milk composition. All diets (45% chopped alfalfa hay and 55% concentrates) contained 12% whole cottonseed (as-fed) and were fed as a TMR. Treatments were no supplemental lipid (control, 3% total fatty acids, DM basis) or the addition of2% supplemental lipid from tallow, yellow grease, or a blend (60% tallow:40% yellow grease). In Exp. 1, 48 cows were assigned to their treatment diets beginning wk 4 and ending wk 18 of lactation. In Exp. 2, 4 cows that completed Exp. 1 were enrolled in a 4 x 4 Latin square with 2-wk periods to further study the effects of saturation ratio of the supplemental lipids on milk composition. In Exp. 1, no treatment effects were observed for DMI, milk production, or milk composition; however, 4% fat-corrected milk tended to increase and fat yield increased for lipid-supplemented treatments. In Exp. 2, DMI, milk production, and percent and yield of milk fat increased in lipid-supplemented treatments. Digestible energy intakes tended to increase when yellow grease was the lipid source compared with tallow. In both experiments, milk fatty acid composition was affected by supplemental lipid as well as the source of supplemental lipid. No effects on lactation performance were evident due to the differences in the un-saturated to saturated fatty acid composition of the supplemental lipid source.