Heat stress affects dairy cow health status through blood oxygen availability

Table 1 Effects of heat stress on lactation performance of dairy cows

Item¹	Heat stress			SEM	P-value
Item¹	No	Mild	Moderate	SEM	Treat	Linear	Quadratic
Rectal temperature, °C	38.4^c	38.8^b	39.7^a	0.08	< 0.01	< 0.01	< 0.01
Respiratory rate, bpm	43.4^c	49.2^b	76.0^a	2.26	< 0.01	< 0.01	< 0.01
Yield, kg/d
Milk yield	41.4^a	36.8^b	26.8^c	0.70	< 0.01	< 0.01	< 0.01
ECM	49.6^a	35.5^b	26.0^c	1.47	< 0.01	< 0.01	0.22
4%FCM	46.1^a	31.1^b	23.1^c	1.53	< 0.01	< 0.01	0.07
Milk composition, %
Fat	4.02^a	2.88^b	2.65^b	0.28	< 0.01	< 0.01	< 0.01
Protein	3.51^a	3.20^b	3.04^b	0.05	< 0.01	< 0.01	< 0.01
Lactose	5.08^a	5.00^a	4.73^b	0.09	< 0.01	< 0.01	0.24
SCC, × 10³/mL	67.9^b	93.3^b	166.0^a	25.96	< 0.01	< 0.01	0.30
MUN, mg/dL	18.1^a	12.5^b	14.4^b	0.80	< 0.01	< 0.01	< 0.01

¹ECM Energy-corrected milk yield, ECM = 0.3246 × milk yield + 13.86 × milk fat yield + 7.04 × milk protein yield, FCM Fat corrected milk yield, 4%FCM = 0.4 × milk yield + 15 × milk fat yield, SCC Somatic cell counts, MUN Milk urea nitrogen
^a–cMeans within the same row with different superscripts differ (P < 0.05)

ISSN: 2049-1891