During the periparturient period, supplementation of rumen-protected choline (RPC) has reduced liver triacylglycerol accumulation and improved animal performance in the dairy cow. Recently milk betaine (Bet) was identified as biomarker for choline bioavailability, making it possible to compare the effectiveness of RPC products at delivering choline for absorption. Our objective was to compare the choline bioavailability of 2 commercial RPC products, ReaShure (RES; Balchem Corporation, New Hampton, NY) and Excential Rumenpass (ERP; Orffa, Werkendam, the Netherlands), using milk betaine as a biomarker for choline absorption. Nine lactating Holstein cows (173 ± 8 DIM) were used in a replicated 5 × 5 Latin square design (one square incomplete), with 7-d treatment periods and a 3-d interval between periods. Treatments were (1) control (0 g/d choline), (2) 12.5 g/d choline fed as RES, (3) 25 g/d choline fed as RES, (4) 12.5 g/d choline fed as ERP, (5) 25 g/d choline fed as ERP. Choline chloride was the choline form for both products; RES and ERP contained 22.2% and 19.8% choline ion, respectively. Cows were fed twice daily and RPC products mixed with 25% of TMR to ensure treatment consumption. Milk samples from d7 were analyzed for Bet using liquid chromatography-stable isotope dilution-multiple reaction monitoring mass spectrometry. No changes in DMI or milk yield were observed with choline treatment (P > 0.40). The concentration and yield of milk Bet increased with ERP relative to RES (P = 0.02). The concentration of milk Bet (control – 83.5 μM) increased linearly (P = 0.05) with ERP (84.8 and 99.6 μM for 12.5 and 25 g/d ERP, respectively). Similarly, the yield of milk Bet (control – 0.42 g/d) increased linearly (P = 0.02) with ERP (0.38 and 0.51 g/d for 12.5 and 25 g/d ERP, respectively). No relationship was found between RES dose and milk Bet concentration (P = 0.44; 78.1 and 74.8 μM for 12.5 and 25 g/d RES, respectively) or RES dose and milk Bet yield (P = 0.76; 0.38 and 0.38 g/d for 12.5 and 25 g/d RES, respectively). Overall, in this experiment the choline bioavailability of ERP was greater than RES when using milk betaine as a biomarker for choline absorption.