Rumen-Protected Choline Improves Metabolism and Lactation Performance in Dairy Cows

Simple Summary: Choline is a nutrient that plays a vital role in cell structure and functions as a component of phospholipids. In dairy cows, particularly during early lactation, there is often a shortage of essential amino acids such as methionine, which can impact the production of cell components such as phosphatidylcholine. A shortage of choline can further reduce phospholipid availability that might lead to an imbalance in lipid metabolism, resulting in excessive fat accumulation in the liver and potential health issues. To address this, we have explored whether supplementing choline in a rumen-protected form (RPC) helps reduce fatty liver. While some studies suggest that choline supplementation reduces triacylglycerol in the liver prepartum, the results have been inconsistent with postpartum cows. In the present experiment, we investigated the effects of supplementing dairy cows with RPC before and/or after calving on metabolism and lactation performance. Our findings revealed that feeding cows with RPC improved milk production, reduced hyperketonemia (a condition associated with elevated concentrations of ketone bodies in blood), and minimized hepatic lipidosis (excessive fat accumulation in the liver). Choline is required for the synthesis of phosphatidylcholine, an important constituent of lipoproteins. Early lactation cows presumably synthesize insufficient phosphatidylcholine, and choline supplementation in a rumen-protected form might benefit metabolism and lactation. The objectives of this study were to determine the effects of feeding rumen-protected choline (RPC) on lactation and metabolism in dairy cows. In experiment 1, 369 nulliparous and parous Holstein cows housed in four pens per treatment were fed 12.9 g/day of choline as RPC from 25 days prepartum until 80 days postpartum. In experiment 2, 578 nulliparous cows housed in five pens/treatment were fed 12.9 g/day of choline as RPC in the last 22 days of gestation only. In both experiments, blood was sampled and analyzed for concentrations of nonesterified fatty acids (NEFAs) and glucose at 1, 14, and 21 days postpartum and of choline at 1 and 14 days postpartum. Blood from all cows was sampled and analyzed for concentrations of beta-OH butyrate (BHB) at 1 and 14 days postpartum. Cows with BHB > 1.2 mmol/L were classified as having hyperketonemia. Hepatic tissue was collected from 46 cows from the eight pens in experiment 1 at 9 days postpartum and analyzed for concentrations of glycogen and triacylglycerol. Milk yield and components were measured for 80 days postpartum in experiment 1, whereas only milk yield was measured in experiment 2. The pen was the experimental unit of analysis. Supplementing RPC tended to increase dry matter intake (DMI) prepartum in experiments 1 and 2 and postpartum in experiment 1. Feeding cows with RPC increased yields of 3.5% fat-corrected milk (42.8 vs. 44.8 kg/day), energy-corrected milk (38.5 vs. 40.3 kg/day), milk fat (1.52 vs. 1.61 kg/day), and true protein (1.16 vs. 1.21 kg/day) in experiment 1. Milk yield tended to be greater with RPC (26.4 vs. 27.4 kg/day) in experiment 2. Supplementing RPC increased plasma choline concentrations on day 14 postpartum in experiment 1 (3.32 +/- 0.27 vs. 4.34 +/- 0.28 mu M) and on day 1 in experiment 2 (3.35 +/- 0.16 and 13.73 +/- 0.15 mu M). Treatment did not affect the concentrations of glucose, NEFAs, or BHB in plasma, but the incidence of hyperketonemia was less in multiparous cows fed RPC than those fed the control in experiment 1. Feeding cows with RPC reduced hepatic triacylglycerol content and tended to reduce the ratio of triacylglycerol to glycogen and the risk of hepatic lipidosis in cows in experiment 1. The concentrations of hepatic triacylglycerol on day 9 postpartum were inversely related to those of choline in plasma on day 1 postpartum. Feeding cows with RPC improved lactation and metabolism, but more benefits were noted when it was fed before and after calving.