Effects of the palmitic-to-oleic ratio in the form of calcium salts of fatty acids on the production and digestibility in high-yielding dairy cows

Abstract

The form of fat supplements, degree of saturation, and the fatty acid (FA) profile influence cows' production response. The objective was to determine the effects of supplemental fats in the form of calcium salts (CS) of FA (CSFA) with different ratios between palmitic (PA) and oleic (OA) acids on nutrient digestibility and cow performance. Forty-two dairy cows were assigned to 3 groups and fed (for 13 wk) rations that contained 2.2% CSFA (on a DM basis) with increasing PA-to-OA ratios as follows: (1) CS45:35, 45% PA and 35% OA; (2) CS60:30, 60% PA and 30% OA; and (3) CS70:20, 70% PA and 20% OA. Rumen and fecal samples were taken for VFA and digestibility measurements, respectively. Increasing the PA-to-OA ratio linearly decreased the milk and ECM yields, whereas a quadratic effect was observed for milk fat concentration (3.55%, 3.94%, and 3.87% in the CS45:35, CS60:30, and CS70:20 groups, respectively) and fat yield. Dry matter intake was highest in the CS60:30 group (33.7 kg/d) and lowest in the CS70:20 group (31.6 kg/d), and a tendency of quadratic effect was observed for calculated energy balance with no difference in BW gain among the groups. The milk-to-DMI ratio was decreased, and the ratio of ECM-to-DMI tended to decrease when the PA-to-OA ratio increased. The highest apparent total-tract digestibilities of DM, OM, and protein were observed in the CS60:30 cows, and NDF tended to decrease with increasing PA-to-OA ratio; however, digestibility of the total FA and FA subgroups (16- and 18-carbon FA) were not different among groups. Across treatments, the 18-carbon FA digestibility was higher than the 16-carbon FA digestibility. Under the current study conditions, the CS60:30 cows had the highest fat concentration and fat yield; energy output in milk; DMI; and digestibility of DM, OM, and protein. However, further research is required to fine tune the optimal FA ratio in supplemental fat sources to maximize production and efficiency under various conditions, such as production level, stage of lactation, and diet composition.