Table 3.

Devices for automatic temperature monitoring for calving prediction, with performance and references.

Parameter	Sensor Type	Device	N	Application	TI	Device Performance	Factory	References
Temperature	Rumen temperature	SmartStock	30	Rumen bolus	48–24 h	n.a.	SmartStock, LLC, Pawnee, OK https://www.smartstock-usa.com	Cooper-Prado et al. [43]
		Phase IV	266	Rumen bolus	24 h	Cut-off = −0.2 °C Se = 68–69%; Sp = 67–69%; AUC = 73–74%	Fase IV Ingegneria, Boulder, CO https://www.phaseivengr.com/solutions-demos/animal-health-identification/	Costa et al. [44]
					12 h	Cut-off = −0.2 °C Se = 69–70%; Sp = 64%; AUC = 71–72%
	Rumen temperature and pH	SmaXtec	10	Rumen bolus	Eutocic delivery −0.48 °C at 20 h	n.a.	Animal Care GmbH, Graz, Austria https://smaxtec.com/en/	Kovàcs et al. [45]
			8		Dystocic delivery −0.23 °C at 32 h
	Vaginal temperature	Minilog II-t	42	Vaginal canal	24 h	Se = 74%; Sp = 74%; PPV = 51%; NPV = 89%; AUC = 0.80	Vemco Ltd., Halifax, Canada https://support.vemco.com/s/ (NS)	Ouellet et al. [29]
					12 h	Se = 69%; Sp = 69%; PPV = 26%; NPV = 93%; AUC = 0.74
					6 h	Se = 68%; Sp = 67%; PPV = 13%; NPV = 97%; AUC = 0.68
	Tail base temperature	Thermistor Prototype: 103JT-025	35 22	Ventral tail surface	24 h	Se = 80–89%; Sp = 89–91%; PPV = 19–20%; NPV = 99%	SEMITEC Corporation, Tokyo, Japan http://www.semitec.co.jp/english/ (NS)	Koyama et al. [46], Miwa et al. [47]
					18 h	Se = 83–92%; Sp = 87–88%; PPV = 55–56%; NPV = 97–98%
					12 h	Se = 84–90%; Sp = 82–85%; PPV = 35–38%; NPV = 98–99%
					6 h	Se = 83–90%; Sp = 79–82%; PPV = 19–20%; NPV = 99%
			108 (validation set)	Ventral tail surface + machine learning	24 h	Se = 84.3%; Pr = 70.5%		Higaki et al. [48]
	Vaginal temperature	Gyuonkei	625	Vaginal canal	~22 h	n.a.	Remote Inc., Oita, Japan http://www.gyuonkei.jp/	Sakatani et al. [49]
	Vaginal temperature	Vel’Phone®	211	Vaginal canal	24 h	Cut off = 38.2 °C Se = 86%; Sp = 91%; PPV = 80%; NPV = 88%; AUC = 0.89 Cut off = −0.21 °C Se = 66%; Sp = 76%; PPV = 67%; NPV = 69%; AUC = 0.72	Medria, Châteaugiron, France https://www.medria.fr/en/solutions/velphone/	Ricci et al. [50]

N: number of animals; NS: not specific, means that devices was self-assembled by researchers starting from data logger and sensor available in the market. This means that there are no commercially available products specific for use in cow. TI: time interval between calving alarm and parturition. Se: sensitivity; Sp: specificity; Acc: accuracy; PPV: positive predictive value; NPV: negative predicting value; AUC: area under curve; n.a.: not available.