. 2021 Apr 1;11(4):980. doi: 10.3390/ani11040980

Table 4.

Summary of the thresholds of respiration-related data.

Indicator	Threshold for Animal-Based Indicators	Threshold for Environment-Based Indicators	Cow Information	Thermal Condition	Reference
Respiration rate	48 BPM	THI ^a 70	High-producing Holstein dairy cows	Hot climate with a T_a range of 9.5 to 30.8 °C	Li et al. [47]
	37, 39 BPM	THI ^a 70, 65	Standing and lying high-producing Holstein-Friesian dairy cows	Continental climate with a THI range of 17.8 to 85.1	Pinto et al. [19]
	60 BPM	Unknown	Lactating Holstein-Friesian dairy cows	Three summers and two winters in Queensland, Australia	Lees et al. [123]
	30 BPM	BGHI 73.61	½ Holstein dairy cows	BGHI stayed higher than 72	Dalcin et al. [48]
	45 BPM	BGHI 72.29	¾ Holstein dairy cows	BGHI stayed higher than 72	Dalcin et al. [48]
	Unknown	THI ^a 70	Lactating Holstein cows	Unknown	Atkins et al. [53]
	61 BPM	Unknown	Dry cows	Unknown	Toledo et al. [125]
	Unknown	THI ^a 65	Preweaning dairy calves	Averaged THI of 78 with shade only in a subtropical climate	Dado–Senn et al. [49]
	Unknown	THI ^a 69	Preweaning dairy calves	Averaged THI of 78.25 with shade plus fans in a subtropical climate	Dado–Senn et al. [49]
	Unknown	THI ^b 82.4	Preweaning Holstein bull calves	Hot climate with a THI range from 70.3 to 94	Kovács et al. [50]

BPM = breaths per minute; THI = temperature–humidity index; T_a = ambient temperature (°C); BGHI = black globe-humidity index. ^a THI equation from National Research Council [57]; ^b THI equation from Bianca et al. [58].