. 2019 Dec 17;98(12):6684–6692. doi: 10.3382/ps/pez541

Table 4.

Effect of a 4-wk long, daily, cyclic heat stress over time on select blood chemistry parameters in laying hens.¹

	pH	PCO₂²	PO₂³	HCO₃⁻⁴	TCO₂⁵	sO₂⁶	iCa⁷
Time period		(mm Hg)	(mm Hg)	(mmol/L)	(mmol/L)	(%)	(mmol/L)
Control⁸	7.39^c	42.8^a	44.8^b	25.7^a	27.0^a	78.9^b	1.41^a
Acute	7.45^a	30.2^d	43.1^c	20.7^d	21.6^d	80.6^a	1.09^d
2 wk Chronic	7.44^b	33.2^c	42.6^c	22.4^b	23.4^b	79.2^b	1.36^b
4 wk Chronic	7.37^d	37.5^b	46.9^a	21.6^c	22.7^c	80.9^a	1.28^c
Pooled SEM	0.003	0.32	0.29	0.11	0.12	0.35	0.011
P-value	≤0.01	≤0.01	≤0.01	≤0.01	≤0.01	≤0.01	≤0.01
Reference range⁹	7.23–7.37	41.6–59.8	39.1–52.7	22.0–27.6	23.5–29.3	65.8–84.2	1.55–1.83

^¹

Means values of data from 398 individual hens in both rooms combined.

^²

Partial pressure of carbon dioxide in the blood.

^³

Partial pressure of oxygen in the blood.

^⁴

Concentration of bicarbonate ions in the blood.

^⁵

Total concentration of carbon dioxide in the blood.

^⁶

Saturation of oxygen in the blood.

^⁷

Concentration of ionized calcium in the blood.

^⁸

Control values were measured the day before first exposure to HS.

^⁹

Blood chemistry reference ranges calculated from mean values plus or minus one standard deviation determined by Schaal et al. (2016) for first cycle Hy-Line W-36 laying hens.

^{^a-d}

Values without similar letters within parameter are significantly different (P ≤ 0.05).