Table 4.

Effects of Lys supplementation on serum biochemical parameters in growing Holstein heifers.

Item	Months of age	Treatments1		SEM	P-value
		LD	LA
TC, mmol/L	7	1.90	1.91	0.089	0.98
	9	2.79	2.62	0.165	0.63
TG, mmol/L	7	0.17	0.15	0.011	0.50
	9	0.18	0.19	0.010	0.59
SUN, mmol/L	7	3.61	3.34	0.115	0.27
	9	5.03	4.15	0.219	0.03
Glucose, mmol/L	7	4.75	4.62	0.064	0.32
	9	5.12	5.26	0.134	0.63
NEFA, μmon/L	7	346.45	350.39	3.588	0.61
	9	353.07	340.20	4.142	0.13
AST, U/L	7	53.69	53.67	0.740	0.99
	9	51.21	43.07	1.793	0.01
ALT, U/L	7	14.06	16.07	0.623	0.11
	9	17.06	16.67	0.321	0.57
AST/ALT	7	3.83	3.40	0.141	0.14
	9	3.00	2.59	0.103	0.03

TC = total cholesterol; TG = triglyceride; SUN = serum urea nitrogen; NEFA = non-esterified fatty acid; ALT = enzyme activity of alanine aminotransferase; AST = enzyme activity of aspartate aminotransferase.

¹LD group: growing heifers fed a Lys-deficient diet; LA group: growing heifers fed a Lys-adequate diet. (n = 5).