Table 4.

Effect of different stocking densities on the blood pH and gas concentrations of meat ducks exposed to heat stress.

	Treatment groups
Items${}^{\mathrm{1}}$	CON	LSD	MSD	HSD
pH	7.08 $\pm$ 0.07${}^{\mathrm{2},\mathrm{c}}$	7.35 $\pm$ 0.06${}^{\mathrm{b}}$	7.37 $\pm$ 0.02${}^{\mathrm{b}}$	7.46 $\pm$ 0.01${}^{\mathrm{a}}$
$p$${\mathrm{CO}}_{\mathrm{2}}$(mmHg)	32.83 $\pm$ 2.07${}^{\mathrm{c}}$	45.32 $\pm$ 1.20${}^{\mathrm{a}}$	44.57 $\pm$ 0.64${}^{\mathrm{a}}$	39.30 $\pm$ 0.25${}^{\mathrm{b}}$
${\mathrm{PO}}_{\mathrm{2}}$(mmol L${}^{-\mathrm{1}}$)	55.10 $\pm$ 1.29${}^{\mathrm{a}}$	47.10 $\pm$ 0.94${}^{\mathrm{b}}$	46.24 $\pm$ 0.59${}^{\mathrm{b}}$	41.58 $\pm$ 0.82${}^{\mathrm{c}}$
BEecf	$-$3.15 $\pm$ 0.09	$-$3.04 $\pm$ 0.09	$-$2.82 $\pm$ 0.14	$-$3.16 $\pm$ 0.45
${\mathrm{HCO}}_{\mathrm{3}}$(mmol L${}^{-\mathrm{1}}$)	18.13 $\pm$ 0.71${}^{\mathrm{c}}$	24.56 $\pm$ 0.62${}^{\mathrm{a}}$	24.61 $\pm$ 0.68${}^{\mathrm{a}}$	22.46 $\pm$ 0.23${}^{\mathrm{b}}$
TCO${}_{\mathrm{2}}$(mmol L${}^{-\mathrm{1}}$)	19.75 $\pm$ 0.77${}^{\mathrm{c}}$	26.86 $\pm$ 0.61${}^{\mathrm{a}}$	26.70 $\pm$ 0.77${}^{\mathrm{a}}$	24.38 $\pm$ 0.49${}^{\mathrm{b}}$

${}^{\mathrm{1}}$ pH represents the hydrogen exponent, $p$${\mathrm{CO}}_{\mathrm{2}}$ represents the partial pressure of carbon dioxide, ${\mathrm{PO}}_{\mathrm{2}}$ represents the partial pressure of oxygen, BEecf represents the base excess in the extracellular fluid, ${\mathrm{HCO}}_{\mathrm{3}}$ represents bicarbonate, $T$${\mathrm{CO}}_{\mathrm{2}}$ represents total carbon dioxide. ${}^{\mathrm{2}}$ Mean values $\pm$ standard errors ($n=\mathrm{15}$). ${}^{\mathrm{a},\mathrm{b},\mathrm{c}}$ represent significant differences among treatment groups at a confidence level of 95 % ($P\mathit{<}\mathrm{0.05}$).