Abstract #M169

# M169
Feeding rumen-protected choline to prepartum Holstein cows in negative energy balance increases circulating lipoprotein phosphatidylcholine and triglyceride levels while preventing hepatic triglyceride accrual.
W. A. Myers*1, M. G. Zenobi2, B. A. Barton3, C. R. Staples2, J. W. McFadden1, 1Cornell University, Ithaca, NY, 2University of Florida, Gainesville, FL, 3Balchem Corp, New Hampton, NY.

Rumen-protected choline (RPC) supplementation may increase hepatic phosphatidylcholine (PC) synthesis to promote triglyceride (TG) secretion within very-low density proteins. To assess whether RPC enhances lipoprotein PC and TG levels in dairy cows, 41 pregnant, nonlactating, multiparous Holstein cows were fed a RPC (ReaShure, Balchem Corp., New Hampton, NY) that provided 0 (control), 6.5, 12.9, 19.4, and 25.8 g/d of choline ions, respectively. Diets were fed to exceed nutrient requirements for 5 d, then cows were restricted to consume ~31% of their net energy requirements for 9 d. Preprandial plasma and liver were collected on d 9 of feed restriction. Plasma TG-rich and low-density lipoprotein (LDL) fractions were isolated using liquid chromatography. Lipoprotein fraction total TG, cholesterol and phospholipids were quantified. Lipoprotein fractions and liver were processed for lipidomics. Statistical analyses were done using the Mixed procedure of SAS. Birth weight of the calves and number of days prepartum at enrollment were covariates. Normalized omic data were natural log-transformed. A significant linear increase (P < 0.01) in TG-rich lipoprotein total TG levels was observed with choline ion supplementation. Likewise, RPC linearly increased TG levels within LDL fractions (P = 0.02). Total LDL fraction phospholipids tended to be modified by treatment (quadratic, P = 0.09). The majority of PC within the TG-rich lipoprotein fraction increased linearly with increasing RPC (40 PC out of 45 PC detected; e.g., PC 38:5; P < 0.01). A similar linear outcome was observed for select TG-rich lipoprotein TG (168 TG out of 317 TG detected; P < 0.05). In LDL, RPC increased majority of PC detected (control vs. RPC [all levels], P < 0.05); however, TG was not overtly modified. In liver, RPC increased a limited number of PC (<15% detected; control vs. RPC, P < 0.05). Hepatic total TG was lowered by RPC (17.5 vs. 13.6% of tissue DM; control vs. RPC, P < 0.05). We conclude that RPC increased lipoprotein PC and TG concentrations, and reduced hepatic TG deposition in dairy cows.

Key Words: choline, liver, phosphatidylcholine