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Deoiled soy lecithin is a feed additive enriched in phospholipids. Our study evaluated the effects of dietary deoiled soy lecithin supplementation on (1) milk production and composition, (2) plasma and milk fatty acid (FA) content and yield, and (3) apparent FA digestibility and absorption in lactating dairy cows fed fractionated palm fat. In a split-plot Latin square design, 16 Holstein cows (160 ± 7 days in milk; 3.6 ± 1.2 parity) were randomly allocated to a main plot receiving a corn silage and alfalfa haylage-based diet with palm fat containing either moderate (MPA) or high palmitic acid (HPA) content at 1.75% of ration dry matter (72 or 99% palmitic acid, respectively; n = 8/palm fat diet). On each palm fat diet, deoiled soy lecithin was top-dressed at 0, 0.12, 0.24, or 0.36% of ration dry matter in a replicated 4 × 4 Latin square design. Following a 14-d covariate period, lecithin supplementation spanned 14 d, with milk and blood collected during the final 3 d. Milk composition and pooled plasma markers were measured. The statistical model included the fixed effects of palm fat type, lecithin dose, period, and the interaction between palm fat type and lecithin dose. The random effect of cow nested within palm fat group was also included. Lecithin linearly decreased dry matter intake. In cows fed HPA, lecithin feeding reduced milk fat content and tended to decrease milk fat yield. Although no changes in milk yield were observed, a quadratic reduction in 3.5% fat-corrected milk was observed with increasing lecithin dose. Lecithin linearly increased energy-corrected milk efficiency in cows fed MPA. Lecithin supplementation also decreased milk urea nitrogen, relative to unsupplemented cows. The proportion of 16-carbon FA in milk fat decreased linearly with lecithin dose, whereas 18-carbon FA increased linearly. Lecithin reduced de novo FA (16-carbon) content and tended to increase preformed FA (16-carbon) content in a linear manner. Compared with MPA, HPA diets reduced apparent total and 16-carbon FA digestibility and absorption. Deoiled soy lecithin feeding did not modify FA digestibility or absorption. Our observations suggest that soy lecithin feeding modifies rumen digestion to reduce dry matter intake and change milk composition.

Recombinant bovine somatotropin (rBST) changes metabolism to spare glucose for milk synthesis in cows. Ceramides inhibit insulin responsiveness in bovine adipocytes and are associated with insulin resistance and milk production in cows. The mechanisms by which rBST supports lactation may involve ceramide. Eight multiparous lactating Holstein cows were enrolled in a 2 × 2 replicated Latin square design with 14-d periods. Cows received a single rBST injection (Posilac; Elanco Animal Health, Indianapolis, IN; 0.062 mg/kg BW) or no injection (CON). An epinephrine challenge, insulin tolerance test, and liver biopsy were performed. Somatotropin enhanced the conversion of feed nutrients into milk components and increased plasma free fatty acid (FFA) concentrations (P < 0.01). Area-under-the-curves for FFA in response to epinephrine and insulin were greater in rBST-treated cows. In response to insulin, glucose concentrations (20- and 30-min post-challenge) and insulin area-under-the-curve were higher with rBST treatment (P < 0.05

Our objectives were to (1) determine whether the abomasal infusion of behenic acid (C22:0) elevated hepatic ceramide relative to palmitic acid (C16:0) or docosahexaenoic acid (C22:6n-3) infusion; (2) assess whether the abomasal infusion of choline chloride or l-serine elevated hepatic phosphatidylcholine (PC) in cows abomasally infused with C16:0; and (3) characterize the PC lipidome in cows abomasally infused with C22:6n-3, relative to C16:0 or C22:0 infusion. In a 5 × 5 Latin square design, 5 rumen-cannulated Holstein cows (214 ± 4.9 DIM; 3.2 ± 1.1 parity) were enrolled in a study with 6-d periods. Abomasal infusates consisted of (1) palmitic acid (PA; 98% C16:0); (2) PA + choline chloride (PA+C; 50 g/d choline chloride); (3) PA + l-serine (PA+S; 170 g/d l-serine); (4) behenic acid (BA; 92% C22:0); and (5) an algal oil rich in docosahexaenoic acid (DHA; 44% C22:6n-3). Emulsion infusates provided 301 g/d of total fatty acids containing a minimum of 40 g/d of C16:0. Cows were fed a corn silage-based diet. Milk was collected on d -2, -1, 5, and 6. Blood was collected and liver biopsied on d 6 of each period. Although we did not detect differences in milk yield, milk fat yield and content were lower in cows infused with DHA relative to PA. Plasma triacylglycerol concentrations were lower with DHA treatment relative to PA or BA. Cows infused with DHA had lower plasma insulin concentrations relative to cows infused with PA only. For objective 1, hepatic ceramide-d18:2/22:0 was highest in cows infused with BA relative to other treatments. For objective 2, plasma free choline concentrations were greater in PA+C cows relative to PA; however, we did not observe this effect with PA+S. Plasma total PC concentrations were similar for all treatments. Regarding the hepatic lipidome, a total of 18 hepatic PC were higher (e.g., PC-16:1/18:2) and 25 PC were lower (e.g., PC-16:0/22:6) with PA+C infusion relative to PA. In addition, 17 PC were higher (e.g., PC-20:3/22:5) and 21 PC were lower (e.g., PC-18:0/22:6) with PA+S infusion relative to PA. For objective 3, hepatic concentrations of many individual saturated PC (e.g., PC-18:0/15:0) were lower with DHA relative to other treatments. Hepatic concentrations of highly unsaturated PC with very-long-chain fatty acids (e.g., PC-14:0/22:6) were higher in DHA-infused cows relative to PA, PA+C, PA+S, or BA. The abomasal infusion of emulsions containing palmitic acid, palmitic acid with choline chloride or serine, behenic acid, or docosahexaenoic acid influence the hepatic ceramide and PC profiles of lactating cows.