Effect of feeding calcium salts of long-chain fatty acids, from palm fatty acid distillate or soybean oil, to high producing dairy cows on milk yield and composition, and on selected blood and reproductive parameters

Calcium salts of long-chain fatty acids from palm fatty acid distillate (CaPFAD) and soybean oil (CaSOFA) were compared using 14 first lactation and 26 multiparous Holstein cows housed in a free-stall barn. It was hypothesized that if replacing CaPFAD with CaSOFA, a rich source of linoleic acid, could result in increased conjugated linoleic acid (CLA) content in milk without losing the lactational and reproductive benefits of feeding CaPFAD, this would be beneficial to the dairy industry and public health, as well as potentially enhance the consumption of dairy products. Cows were group-fed one of two total mixed rations (TMR) containing 1.7% CaPFAD or CaSOFA (DM basis) for ad libitum intake following recommendations from the manufacturer of the fat supplements. Fatty acid profiles (g/100 g of fatty acid) of CaPFAD and CaSOFA, respectively, were 16:0: 48.1, 12.1; 18:0: 4.27, 5.34; 18:1: 35.7, 23.9; and 18:2: 8.9, 51.2. Cows spent about 45 days in the fresh group, after which they were moved to high producing group where they stayed up to 10 weeks post-partum within their treatment assignments. The TMR (DM basis) were 50:50 forage:concentrate for both the fresh group and high producing group cows and contained (DM) 28% NDF and 18% CP. There were no treatment differences in milk yield, milk fat percentage, milk CLA content, milk true protein percentage, milk lactose percentage, milk urea N, linear somatic cell count and change in body condition score. Cows fed CaSOFA produced milk containing a higher content of 18:1(t) (P<0.01) and 18:2 (P<0.01) during weeks 8–10 post-partum, and had smaller follicles at ovulation (P=0.03). Cows had similar concentrations of serum nonesterified fatty acids and β-hydroxybutyrate, and similar 30 days uterine score, days to first ovulation, days to first service, first service conception rate and progesterone concentration. In conclusion, while cows fed CaSOFA had similar lactational and reproductive performance to cows fed CaPFAD, the anticipated beneficial effect of enhancing content of CLA in milk was not realized from feeding CaSOFA at 1.7% of expected DM intake.