Table 2.

Rectal temperature, feed intake, milk yield and milk composition, feed efficiency, and tissue gain of cows exposed to either heat stress (HS) or cooling (CL) during the postpartum period

Item	Treatment (T)			P-value
	HS	CL	SE	T	Week (W)	T × W
N	23	23	—	—	—	—
Rectal temperature, °C	39.8	39.1	0.17	0.04	0.78	0.73
DMI, kg/d	19.8	21.3	0.26	<0.001	0.07	0.03
NEL intake, Mcal/d	32.4	35.0	0.43	<0.001	0.07	0.03
Yields of milk and milk composition, kg/d
Whole lactation milk, kg	9,173	10,615	172	<0.001	—	—
Raw milk	31.2	38.6	1.28	<0.001	<0.001	0.04
FPCM1	32.1	35.7	1.18	0.03	<0.001	0.02
Fat	1.26	1.43	0.04	0.01	0.009	0.01
Protein	0.99	1.16	0.04	0.006	<0.001	0.14
Lactose	1.44	1.76	0.05	<0.001	<0.001	0.01
SNF	2.63	3.19	0.11	0.001	<0.001	0.03
Milk composition, %
Fat	4.31	3.59	0.04	<0.001	<0.001	<0.001
Protein	3.25	3.06	0.02	<0.001	<0.001	0.70
Lactose	4.73	4.58	0.02	<0.001	0.001	<0.001
SNF	8.63	8.38	0.04	<0.001	0.05	<0.001
SCS2	3.49	2.13	0.06	<0.001	<0.001	0.003
Feed efficiency
Raw milk/DMI	1.58	1.81	0.03	0.002	0.001	0.31
FPCM/DMI	1.62	1.68	0.04	0.16	0.09	0.25
Tissue gain
BCS	2.36	2.62	0.09	0.06	<0.001	0.04

¹FPCM yield = fat- and protein-corrected milk [(0.337 + 0.116 × fat % + 0.06 × protein %) × milk yield (kg/d)] (Heuer, 2004; Kargar et al., 2014).

²Somatic cell score = [log₁₀(SCC/12.5)]/log₁₀(2) (Karimi et al., 2015).