Table 6. Least squares means of rumen parameters for high (n = 32) and medium (n = 32) producing dairy cows receiving either calcium salts of fatty acids (Ca-FA) or high-palmitic acid (PA) during a heat stress period

Item	High production		Medium production		SEM	p-value
	PA	Ca-FA	PA	Ca-FA		PL	FS	PL × FS
pH	6.25	6.45	6.31	6.14	0.20	0.67	0.97	0.54
NH3 (mg/dL)	8.05	9.17	10.26	11.70	1.35	0.23	0.55	0.93
Total VFA (mM)	89.78	83.53	89.60	93.79	9.92	0.71	0.94	0.71
Acetate (mol/100 mol)	50.68	47.56	49.81	53.21	4.69	0.71	0.98	0.62
Propionate (mol/100 mol)	25.10	24.73	26.80	26.78	4.39	0.76	0.97	0.97
Butyrate (mol/100 mol)	11.04	8.65	9.61	10.54	0.91	0.85	0.61	0.23
Valerate (mol/100 mol)	1.38	1.14	1.38	1.50	0.22	0.58	0.86	0.58
Iso-butyrate (mol/100 mol)	1.56	1.43	1.98	1.75	0.20	0.22	0.57	0.84
Acetate:Propionate	2.16	2.03	1.94	2.08	0.21	0.78	0.99	0.66

PL, production level; FS, fat source; PL × FS, interaction between production level and fat source.