Table 4.

Effects of age on the heterophil-to-lymphocyte (H:L) ratios, serum corticosterone (CORT) concentrations (ng/mL), IRT eye and beak surface temperatures (°C), and core body temperatures (°C) of broilers in pens with light intensities of 2, 5, or 10 lx and after day 29 were raised on litter or wire flooring (N = 6 pens for day 6 through 28; N = 12 pens for day 28 through 56).

Age (D)	H:L1	CORT	Eye temp	Beak temp	Core temp
Study 1
7	-	9.12 ± 1.15b	34.90 ± 0.16a	32.60 ± 0.41b	-
9	-	8.76 ± 0.13b	34.39 ± 0.14b	30.88 ± 0.38c	-
28	0.22 ± 0.15b	11.08 ± 1.13a	32.92 ± 0.14c,d	32.91 ± 0.38a,b	-
30	0.29 ± 0.10b	10.92 ± 0.10a	33.22 ± 0.10c	33.50 ± 0.27a,b	-
38	0.25 ± 0.05b	5.66 ± 0.10c	33.06 ± 0.10c	32.84 ± 0.27b	-
56	0.58 ± 0.11a	6.25 ± 0.10c	32.74 ± 0.10d	33.63 ± 0.27a	-
P value	0.0001	0.0001	0.0001	0.0001	-
Study 2
6	0.09 ± 0.14c	13.08 ± 1.10a	34.94 ± 0.14b	33.65 ± 0.33b,c	41.07 ± 0.05c
8	0.16 ± 0.13b	12.22 ± 1.10a	34.08 ± 0.14c	32.45 ± 0.33d	41.05 ± 0.05c
27	0.19 ± 0.13b	9.02 ± 1.10b	32.79 ± 0.14d	32.26 ± 0.33d	41.44 ± 0.05b
29	0.21 ± 0.10b	6.78 ± 1.08c	33.86 ± 0.10c	33.40 ± 0.23c	41.38 ± 0.04b
40	0.25 ± 0.10b	6.91 ± 1.08c	33.83 ± 0.10c	34.14 ± 0.23b	41.47 ± 0.04b
55	0.37 ± 0.10a	7.17 ± 1.08c	35.58 ± 0.10a	36.65 ± 0.23a	41.88 ± 0.04a
P value	0.0001	0.0001	0.0001	0.0001	0.0001

^a–dMeans not sharing the same superscript letter within each column differ at P ≤ 0.05.

Data are shown as mean ± SEM.

Abbreviation: lx, lux.

¹In study 1 day 7 and 9, H:L ratios were not determined because of equipment malfunction.