We aimed to assess whether solvent extracted camelina meal (SCAM) could replace canola meal (CM) in lactating dairy cows’ diets, and its effects on ruminal fermentation in a dual-flow continuous culture system. Diets were isonitrogenous (16%CP) and randomly assigned to 6 fermentors in a replicated 3 × 3 Latin square with three 10-d experimental periods consisting of 7 d for diet adaptation and 3 d for sample collection. Treatments were 0 (20.6% CM), 50 (10.3% CM), and 100% SCAM (0% CM) inclusion, replacing CM as the protein supplement. Diets contained 55:45 forage:concentrate, and fermentors were fed 72 g of DM/d. On d 8, 9, and 10 of each period samples were collected for analyses of pH, VFA, NH_3, digestibility, and AA flow. Statistical analysis was performed using the MIXED procedure of SAS, and linear and quadratic effects of SCAM inclusion were assessed. Partial data are presented in Table 1. Total VFA and pH were not affected by treatments. Acetate concentration decreased (P = 0.01), while propionate increased (P = 0.01) with SCAM inclusion. Concentration of NH₃-N decreased (P = 0.01), and NAN increased (P = 0.05) with SCAM inclusion. Bacterial efficiency tended (P = 0.06) to be greater on 100% SCAM diet. Arg increased (P = 0.02) with SCAM inclusion. Overall AA flow was not affected by diet. Replacing CM with SCAM changed ruminal fermentation, increasing propionate and NAN, and decreasing NH₃-N, which may improve energy status and nitrogen utilization. Inclusion of SCAM did not change most AA flow, indicating that it can be a potential replacement for canola meal. Table 1.

Item	Camelina (%)			SEM	P-value
0	50	100	Treat	Linear	Quadratic
VFA, % of total
Acetate	63.7	57.2	54.9	1.01	0.01	0.01	0.01
Propionate	19.4	25.9	27.9	0.81	0.01	0.01	0.01
Butyrate	14.1	13.6	14.2	1.08	0.35	0.83	0.16
Valerate	1.56	1.72	1.72	0.10	0.01	0.01	0.05
Total BCVFA1, mM	0.79	0.99	0.81	0.13	0.01	0.82	0.01
Flow, g/d
NAN	1.53	1.60	1.68	0.06	0.05	0.04	0.94
Bacterial N	0.71	0.67	0.73	0.06	0.36	0.61	0.19
NANMN2	0.79	0.86	0.88	0.06	0.32	0.16	0.67
Arg	0.53	0.59	0.62	0.02	0.02	0.01	0.60
His	0.21	0.22	0.22	0.01	0.69	0.45	0.70
Lys:Met	3.03	2.97	3.05	0.02	0.07	0.76	0.03

¹BCVFA = branched-chain VFA. ²NANMN = nonammonia nonmicrobial nitrogen.