Objectives were to evaluate effects of feeding rumen-protected methionine (RPM; Smartamine M) from 3 wk prepartum until 150 DIM (67 d of pregnancy) on first service pregnancy per AI (P/AI) and pregnancy loss. In addition, cyclicity, concentrations of progesterone (P4) and pregnancy specific protein-B (PSPB) in pregnant cows were evaluated. Multiparous Holstein cows at Cornell University (CU; n = 235) and the University of Wisconsin (UW; n = 233) were randomly assigned to a control (CON) or RPM group. Diets were isoenergetic with similar lysine amounts but RPM included Smartamine M pre- (PreP) and postpartum (PostP; CU: Met as 2.09 vs. 2.68% and UW: 2.10 vs. 2.59 as percent of metabolizable protein). Cows were allocated to pens (12 pens at CU and 6 pens at UW with 16 cows per pen PostP), and diets were fed to pens. Cows received first timed-AI (TAI) at 80 ± 3 DIM after the Double-Ovsynch protocol (GnRH-7d-PGF-3d-GnRH-7d-GnRH-7d-PGF-24h-PG-32h-GnRH-16h-TAI). Pregnancy was evaluated at d 25 (by PSPB), 32, and 67 (by transrectal ultrasonography) after TAI. Cyclicity was based on plasma P4 concentrations (≥1 ng/mL) at 35 and 49 ± 3 DIM. Quantitative and binary outcomes were analyzed by ANOVA with repeated measurements and logistic regression, respectively. Treatment (TRT) and location were fixed effects and PEN(TRT) was included as random effect. Pen was the experimental unit and cow was the observational unit. There were no differences (P > 0.10) in P/AI (Table 1), cyclicity (CON = 84.0%; RPM = 80.2%), P4 (CON = 6.8 ± 0.3; RPM = 6.6 ± 0.3 ng/mL d 8-d 29), or PSPB concentration (CON = 1.59 ± 0.06; RPM = 1.65 ± 0.06 ng/mL; d 22–67) for pregnant cows, with a numerical reduction in pregnancy loss (38% lower). Thus, RPM fed pre- and postpartum had no significant effect on measured reproductive values up to d 67. The numerical reduction in pregnancy loss in cows fed RPM warrants further investigation. Table 1. Reproductive outcomes

Item	CON	RPM	P-value
P/AI at 1st TAI, % (n)	55.7 (212)	56.1 (214)	0.48
d 25 (based on PSPB)	48.6 (212)	49.1 (214)	0.46
d 32	43.1 (211)	45.8 (214)	0.28
d 67
Pregnancy loss	12.7 (118)	12.5 (120)	0.49
d 25 to d 32	22.2 (117)	18.3 (120)	0.23
d 25 to d 67	10.8 (102)	6.7 (105)	0.16
d 32 to d 67	55.7 (212)	56.1 (214)	0.48