Table 1.

Effect of age at photostimulation on sexual maturity variables of White Leghorn breeder hens.

Item	Age at photostimulation (wk)				SEM	P-value
	16	18	20	22
BW at sexual maturity, g	1372.39	1381.40	1438.77	1454.57	16.15	0.18
Age at 5% egg production, D	134.00	132.50	141.00	141.00	1.85	0.21
Age at 50% egg production, D	149.50	148.50	154.50	154.00	1.32	0.28
Photostimulation to 5% egg production interval, D	28.00a	12.50b	7.00b	−7.00c	4.86	0.01
5% to 50% egg production interval, D	15.50	16.00	13.50	13.00	1.07	0.79
Age at peak of laying, D	176.00	179.50	186.50	179.50	4.17	0.90
Peak of laying, %	91.96a	93.37a	88.91a	78.81b	2.26	0.02

Data are the mean of 2 replicates.

¹Age at sexual maturity was defined as age at 5% egg production.

^a–cValues within a row with different superscripts differ significantly at P < 0.05.