Table 3.

Effects of supplementation with AA on performance and egg quality in old laying hens

Items	Treatment, g AA/kg diet				SEMb	P-value
	0	0.25	0.5	1		Main effect	Linear	Quadratic
Performance
Laying rate, %	86.0	86.5	86.0	81.9	0.80	0.144	0.075	0.138
Egg weight, g	65.4	64.4	64.6	65.0	0.28	0.597	0.674	0.222
ADFIa, g	117	118	117	119	0.6	0.672	0.492	0.611
FCR	2.13	2.13	2.12	2.20	0.023	0.170	0.097	0.126
Egg quality
Eggshell thickness, mm	0.34	0.34	0.34	0.34	0.002	0.107	0.106	0.798
Eggshell strength, kg/cm3	3.10	3.14	3.03	3.01	0.031	0.773	0.382	0.734
Albumen height, mm	6.39	6.32	6.92	6.39	0.079	0.738	0.761	0.598
Haugh unit	76.7	77.0	76.6	76.4	0.60	0.988	0.807	0.825
Yolk colour	6.82	6.80	6.83	6.85	0.029	0.959	0.653	0.807
Eggshell portion, %	9.88	9.91	9.81	9.73	0.059	0.748	0.322	0.650

Data represent the mean of 30 cages (three old laying hens per cage) per treatment

^aADFI average daily feed intake, FCR feed conversion rate

^bThe SEM values represent the overall standard errors of the mean in each row