Table 4.

Laying performance of hens fed reduced protein diet from wk 20 to 39.

Hen age, wk	Variable	SP1	RP2	RP-Arg3	RP-GAA3	RP-Cit3	SEM	P-value
20 to 29	Egg mass, g/d per hen	53.00	51.03	50.30	49.40	50.80	0.41	0.078
	Egg weight, g/egg	55.41	53.83	54.55	53.25	53.8	0.28	0.133
	Feed intake, g/d	117.1	117.2	117.7	113.8	116.5	0.98	0.762
	FCR, kg feed/kg egg	2.202	2.300	2.330	2.308	2.302	0.02	0.333
	Hen day egg production, %	95.83	94.86	91.85	92.74	94.4	0.58	0.150
30 to 39	Egg mass, g/d per hen	56.82c	50.78b	49.72b	40.81a	48.80b	0.71	<0.001
	Egg weight, g/egg	59.00b	54.80a	55.10a	53.54a	54.65a	0.35	<0.001
	Feed intake, g/d	118.1b	113.0b	111.6b	98.13a	109.1b	1.33	<0.001
	FCR, kg feed/kg egg	2.089a	2.237ab	2.266ab	2.472b	2.261ab	0.033	0.023
	Hen day egg production, %	96.29b	92.74b	90.17b	76.19a	89.20b	1.02	<0.001
20 to 39	Egg mass, g/d per hen	53.85c	50.90bc	49.00ab	45.10a	49.80bc	0.52	<0.001
	Egg weight, g/egg	57.50b	54.31a	54.82a	53.40a	54.23a	0.31	<0.001
	Feed intake, g/d	117.6b	115.1b	114.3ab	106.0a	112.8ab	1.06	0.008
	FCR, kg feed/kg egg	2.145a	2.269ab	2.300ab	2.390b	2.282ab	0.024	0.029
	Hen day egg production, %	96.06c	93.80bc	91.03b	84.46a	91.80bc	0.65	<0.001

GAA = guanidinoacetic acid; Cit = citrulline; FCR = feed to gain ratio.

^{a, b} Differing superscripts indicate significant differences between means.

¹SP: standard protein diet with 17% CP.

²RP: reduced protein diet with 13% CP.

³l-Arg, GAA and l-Cit were added on top of the RP diets at 0.35%, 0.46% and 0.35% in diets, RP-Arg, RP-GAA and RP-Cit, respectively, to the level of Arg in SP.