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M. J. de Veth, V. M. Artegoitia, S. R. Campagna, H. Lapierre, F. M. Harte, C. L. Girard, 1354 Net choline absorption of abomasally infused choline and rumen-protected choline in the lactating dairy cow, Journal of Animal Science, Volume 94, Issue suppl_5, October 2016, Pages 654–655, https://doi.org/10.2527/jam2016-1354
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Abstract
Choline metabolites have a critical role in many biological processes and choline supplementation to the peripaturient dairy cow improves hepatic lipid metabolism. However, variability in responses to choline supplementation has highlighted a lack of understanding of choline absorption and metabolism in the lactating dairy cow. Our objective was to estimate net choline absorption by measuring net portal fluxes of choline and choline metabolites in cows receiving either dietary supplements of rumen-protected choline (RPC) or abomasal infusion of choline (AIC). Five lactating Holstein cows (237 ± 17 DIM) were used in a 5 × 5 Latin Square design, with 5-d treatment periods and a 2-d interval between periods. Treatments were 1) control (0 g/d choline), 2) 12.5 g/d choline fed as RPC, 3) 25 g/d choline fed as RPC, 4) 12.5 g/d choline provided as AIC, 5) 25 g/d choline provided as AIC. Choline chloride (CC) was the choline form for both sources; RPC (Reashure, Balchem Corporation) and AIC (CC70, Balchem Corporation) contained 21.6% and 52.3% choline ion, respectively. Cows were fed every 2 h to minimize post-prandial variation. On the last day of each period 9 blood samples were collected simultaneously from an artery and portal vein at 30-min intervals and analyzed for betaine, free choline (Cho), lysophosphatidylcholine, phosphocholine and sphingomyelin, using liquid chromatography-tandem mass spectrometry. The net portal flux of Cho (control- 1.7 mmol/h) increased linearly (P < 0.001) with AIC (4.0 and 7.1 mmol/h for 12.5 and 25 g/d AIC, respectively) indicating that the net absorption of Cho was 54% (95% confidence interval of 30 to 79%). No relationship was found between dose of RPC and net portal flux of Cho (P = 0.52). Net portal fluxes of the choline metabolites were not altered by choline treatment. However, the plasma arterial concentrations of betaine and phosphocholine increased (P < 0.001) in response to AIC: 30.6, 102.7 and 151.2 μM and 3.47, 4.21 and 4.96 μM for control, 12.5 and 25 g/d. In addition, plasma arterial concentration of phosphocholine increased (P < 0.01) with RPC, averaging 3.47, 3.81 and 4.08 μM for control, 12.5 and 25 g/d, respectively). The results of this study suggests that AIC taken up by the gastrointestinal wall reached the portal circulation only as Cho and the incomplete recovery may indicate that a portion of AIC is metabolized by the portal-drained viscera of the lactating dairy cow.
