. 2021 Mar 12;7(2):460–471. doi: 10.1016/j.aninu.2020.09.004

Table 5.

Egg quality of hens fed reduced protein diets from wk 20 to 39.

Hen age, wk	Variable	SP¹	RP²	RP-Arg³	RP-GAA³	RP-Cit³	SEM	P-value
20 to 29	Albumen height, mm	8.34	8.35	8.50	7.74	8.37	0.08	0.167
	Haugh unit	91.55	92.79	93.20	89.29	93.26	0.46	0.140
	Yolk score	11.30^a	10.84^b	10.81^b	10.52^b	10.75^b	0.05	<0.001
	Breaking strength, N	47.83	45.66	45.50	46.70	46.16	0.46	0.547
	Reflectivity, %	24.30	24.48	24.04	26.19	23.56	0.31	0.076
	Shell deformation, μm	0.286^a	0.274^a	0.273^a	0.287^a	0.285^a	0.001	0.030
	Shell thickness, mm	0.410^a	0.403^ab	0.398^ab	0.398^ab	0.393^b	0.002	0.033
30 to 39	Albumen height, mm	7.50	7.65	7.75	7.49	7.77	0.08	0.675
	Haugh unit	86.58	88.32	89.15	87.84	89.39	0.44	0.095
	Yolk score	10.24^a	9.13^b	9.13^b	8.62^b	9.11^b	0.09	<0.001
	Breaking strength, N	44.29	44.45	44.23	44.84	40.88	0.51	0.088
	Reflectivity, %	26.19	27.38	27.14	28.54	26.42	0.34	0.208
	Shell deformation, μm	0.265	0.265	0.265	0.267	0.258	0.002	0.690
	Shell thickness, mm	0.414^a	0.414^a	0.407^ab	0.405^ab	0.397^b	0.002	0.024
20 to 39	Albumen height, mm	7.86	7.93	8.07	7.68	8.02	0.07	0.395
	Haugh unit	88.71	90.10	90.86	88.89	91.01	0.38	0.105
	Yolk score	10.69^a	9.83^b	9.84^b	9.59^b	9.79^b	0.06	<0.001
	Breaking strength, N	45.76	44.98	44.84	45.35	43.14	0.42	0.345
	Reflectivity, %	25.36	26.16	25.87	27.27	25.25	0.30	0.319
	Shell deformation, μm	0.274	0.268	0.268	0.276	0.270	0.002	0.334
	Shell thickness, mm	0.413^a	0.409^ab	0.403^ab	0.401^ab	0.396^b	0.002	0.010

GAA = guanidinoacetic acid; Cit = citrulline.

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

SP: standard protein diet with 17% CP.

RP: reduced protein diet with 13% CP.

l-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.