Our objective was to evaluate in vitro rumen fermentation of carinata meal from different processing methods (cold pressed or solvent extracted) and compare it to other common protein sources. Treatments were: 1) solvent extracted carinata meal (CAR-SE) 2) cold pressed carinata meal (CAR-CP) 3) solvent extracted linseed meal (LIN-SE), 4) cold pressed linseed meal (LIN-CP), 5) solvent extracted soybean meal (SOY-SE) and 6) cold pressed soybean meal (SOY-CP). The 24 h in vitro trial used the Ankom RF gas production system, with rumen fluid from 3 dry dairy cows. Duplicate samples were weighed in F57 fiber bags and placed in triplicate bottles. Samples for VFA analysis were collected at 24 h. Data were analyzed with MIXED procedures in SAS 9.4. Orthogonal contrasts were used to evaluate processing. The DM degradation and gas production were greatest for SOY meals (Table 1). Total VFA and isovalerate were greatest for SOY-CP. Solvent extracted meals had greater acetate. Cold pressed meals had greater propionate. Greater butyrate was found for SOY-CP and CAR-CP. Solvent extracted meals had greater acetate to propionate ratio. Differences in rumen utilization and fermentation of the different plant sources were found, with varied impacts within meal source related to oil extraction methods. Table 1 (Abstr. M180).

Item	Feedstuff						SEM	P-value
CAR-SE	CAR-CP	LIN-SE	LIN-CP	SOY-SE	SOY-CP	Feed	SE vs. CP1
DM deg, %	46.3c	49.3b	30.8d	50.4b	58.9a	61.4a	0.74	<0.01	<0.01
24-h gas production, mL/100 mg of DM	41.8b	38.8bc	27.0c	45.5b	72.4a	77.3a	4.506	<0.01	0.28
Total VFA, mM/g of DM	16.8c	14.2c	15.9c	19.6ab	18.8b	26.1a	1.32	<0.01	0.05
Acetate, %2	63.2ab	57.3d	64.8a	58.5b	62.6a	58.1bc	0.90	<0.01	<0.01
Propionate, %2	25.2b	29.5a	25.4b	30.6a	26.3b	28.9a	0.64	<0.01	<0.01
Butyrate, %2	8.4b	9.4a	8.0b	8.4b	8.2b	9.3a	0.18	<0.01	<0.01
Isovalerate, %2	2.55bc	2.37d	1.80e	2.40dc	2.76b	3.56a	0.097	<0.01	<0.01
Valerate, %2	0.68	0.18	0.08	0.13	0.14	0.18	0.210	0.36	0.44
Acetate:propionate	2.77a	1.95b	2.84a	2.09b	2.75a	2.01b	0.134	<0.01	<0.01

^a–dValues with unlike superscripts differ by P < 0.05 using Tukey’s test. ¹Contrast P-value for solvent-extracted versus cold-pressed processing. ²% of Total VFA.