Table 4.

Effect of glycerol tributyrate on egg quality of broiler breeders with different egg-laying rate.¹

Item		Eggshell strength, kg/cm3	Albumen height, mm	York color	Haugh unit	Yolk weight ratio, %	Egg shell weight ratio, %	Eggshell thickness, mm−2	Egg white ratio, %
Laying	TRI
AR	−	3.59	6.12b	8.11	74.60b	33.67	9.89	30.57	59.54
AR	+	3.64	6.61a	8.12	78.51a	32.75	9.96	30.18	59.86
LR	−	3.55	6.18b	8.20	76.69b	33.81	9.98	30.16	59.86
LR	+	3.55	6.25b	8.17	77.38b	32.65	9.90	30.08	60.02
SEM		0.19	0.28	0.16	2.03	0.37	0.16	0.49	0.39
P-value		0.29	0.02	0.51	0.05	0.57	0.34	0.12	0.11
P-value
Laying		0.50	0.99	0.31	0.78	0.97	0.52	0.28	0.76
TRI		0.11	0.22	0.69	0.23	0.32	0.37	0.39	0.44
Laying × TRI		0.61	0.02	0.30	<0.01	0.74	0.14	0.20	0.37

Abbreviations: AR, average egg laying rate; LR, low egg laying rate; TRI, 1000 mg/kg tributyrin.

^a,bMeans with different superscripts within a column differ significantly (P ≤ 0.05).

¹Each mean represents 8 layers/replicate, 8 replicates/treatment.