Table 3. Least squares means of milk yield and composition 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
Milk (kg/d)	47.48	47.36	44.87	43.78	0.95	0.05	0.69	0.72
3.5% FCM1) (kg/d)	41.66	40.17	35.71	34.65	1.16	<0.01	0.44	0.89
Fat (%)	2.90	2.89	2.75	2.45	0.08	0.03	0.17	0.21
Fat (kg/d)	1.46	1.38	1.21	1.11	0.05	<0.01	0.28	0.89
Protein (%)	2.85	3.01	2.90	3.06	0.03	0.32	0.01	0.87
Protein (kg/d)	1.40	1.44	1.26	1.35	0.02	0.02	0.11	0.57
MUN (mg/dL)	12.20	10.08	13.63	12.07	1.25	0.43	0.95	0.49
BCS	2.60	2.54	2.59	2.66	0.04	0.41	0.93	0.29
Back fat thickness (mm)	24.84	25.53	25.22	24.33	0.94	0.76	0.94	0.57

3.5% FCM = (0.432 × milk yield) + (16.23 × fat yield).
PL, production level; FS, fat source; PL × FS, interaction between production level and fat source; FCM, fat corrected milk; MUN, milk urea nitrogen; BCS, body condition score.