Table 4. Effects of dietary crude protein levels and cysteamine (CS) supplementation on plasma metabolite and hormone concentrations of finishing pigs.

Item	Normal protein		Low protein		P value
	Control	Cysteamine	Control	Cysteamine	P	CS	P × CS
Insulin (μIU/mL)	12.22±0.52	13.61±0.82	13.52±0.42	12.94±0.35	0.581	0.475	0.097
IGF-1 (ng/mL)	56.79±2.39	72.62±1.01	53.37±1.13	71.42±0.90	0.139	<0.001	0.465
SS (pg/mL)	659.25±17.17	500.72±25.71	572.47±17.61	450.43±16.38	0.003	<0.001	0.365
Leptin (ng/mL)	2.79±0.02	2.55±0.06	2.79±0.05	2.60±0.02	0.571	<0.001	0.637
PUN (mmol/L)	5.65±0.25	4.61±0.15	4.44±0.14	3.77±0.07	<0.001	<0.001	0.283

IGF-1, insulin-like growth factor 1; SS, somatostatin; PUN, plasma urea nitrogen. Values are means ± SEM. Values within a row with different letters differ (P<0.05). All traits in this table were analysed with pen as the experimental unit (n = 5). P, main effect of dietary protein levels; CS, main effect of cysteamine supplementation; P×CS, interaction between main effects of dietary protein levels and cysteamine supplementation.