Table 3.
The effects of different level of energy and nutrient density on egg quality in laying hens¹

Items	CON	TRT1	TRT2	TRT3	SEM2	P value3
Pre-peak (Week 9)
Haugh unit	70.85	61.04	67.38	64.76	4.84	0.5375
Yolk color	10.31	10.13	10.44	10.13	0.17	0.4853
Eggshell strength, kg/cm2	5.20	4.56	4.70	4.71	0.20	0.1268
Eggshell thickness, mm	35.33b	38.60a	38.81a	39.04a	0.45	0.0003
Pre-peak (Week 11)
Haugh unit	77.39	76.90	78.78	82.73	6.40	0.9160
Yolk color	9.75b	9.88ab	10.13a	10.19a	0.11	0.0383
Eggshell strength, kg/cm2	4.67	5.21	4.76	5.19	0.19	0.1051
Eggshell thickness, mm	37.73b	37.96b	44.88a	46.69a	0.64	<0.0001
Peak (Week 13)
Haugh unit	66.84	73.97	77.05	77.07	4.35	0.3080
Yolk color	9.10	8.70	8.95	8.95	0.20	0.5611
Eggshell strength, kg/cm2	5.35	5.49	5.40	5.07	0.18	0.3688
Eggshell thickness, mm	38.38	38.40	38.38	38.58	0.30	0.2001
Peak (Week 15)
Haugh unit	77.59	83.70	80.74	78.47	4.60	0.7884
Yolk color	8.50	8.75	8.25	8.50	0.15	0.1336
Eggshell strength, kg/cm2	4.59	4.65	4.70	4.51	0.20	0.9125
Eggshell thickness, mm	38.88	38.83	39.25	40.62	0.48	0.1856

Abbreviation: 1-7 weeks - CON, TRT1, TRT2, TRT3, CP: 14.5% (M+C: 0.56)/ ME: 2,710; 7-13 weeks - CON, CP: 14.5% (M+C: 0.56)/ ME: 2,710; TRT1, CP: 19% (M+C: 0.85)/ ME: 2,850; TRT2, CP: 19% (M+C: 0.85)/ ME: 2,870; TRT3, CP: 19% (M+C: 0.85)/ ME: 2,890; 13-15 weeks - CON, TRT1, TRT2, TRT3, CP: 18% (M+C: 0.80)/ ME: 2,850.
Standard error of means.
Means in the same row with different superscripts differ (P<0.05).