Table 3.

Least Squares Means (± Standard Error) of aromatic amino acids, kynurenine and nitrite in birds at 10, 14 and 32 weeks of age (woa) (n of birds: UC = 119, LFP = 119, HFP = 116, whereby LFP low feather pecking line; HFP high feather pecking line; UC unselected control line).

	Genetic line
	UC (n = 119)	LFP (n = 119)	HFP (n = 116)
10 woa
Tryptophan (TRP) (µmol/L)	94.3 ± 0.95 a	98.2 ± 0.95 a	88.2 ± 0.96 b
Tyrosine (TYR) (µmol/L)	156 ± 2.1 a	162 ± 2.1 ab	127 ± 2.1 c
Phenylalanine (PHE) (µmol/L)	97 ± 1.1 a	97 ± 1.2 a	91 ± 1.2 b
TRP:(PHE + TYR)	0.38 ± 0.005 a	0.38 ± 0.005 a	0.41 ± 0.005 bc
KYN:TRP (µmol/mmol)	2.6 ± 0.11 a	2.9 ± 0.11 ab	2.9 ± 0.12 ab
PHE:TYR (µmol/µmol)	0.63 ± 0.009 a	0.60 ± 0.009 a	0.72 ± 0.010 b
Kynurenine (KYN) (µmol/L)	0.25 ± 0.010 a	0.28 ± 0.010 ab	0.25 ± 0.010 a
Nitrite (µmol/L)	34 ± 2.2 a	33 ± 2.2 a	31 ± 2.2 a
14 woa
TRP (µmol/L)	96.9 ± 0.95 a	103.2 ± 0.96 c	96.5 ± 0.98 a
TYR (µmol/L)	162 ± 2.1 ab	170 ± 2.2 b	140 ± 2.2 d
PHE (µmol/L)	100 ± 1.1 ac	100 ± 1.2 ac	96 ± 1.2 ab
TRP:(PHE + TYR)	0.37 ± 0.005 a	0.39 ± 0.005 ab	0.41 ± 0.005 c
KYN:TRP (µmol/mmol)	3.5 ± 0.11 c	3.5 ± 0.12 c	3.5 ± 0.12 c
PHE:TYR (µmol/µmol)	0.63 ± 0.009 a	0.59 ± 0.009 a	0.69 ± 0.010 b
KYN (µmol/L)	0.34 ± 0.010 cd	0.36 ± 0.010 c	0.33 ± 0.011 cd
Nitrite (µmol/L)	61 ± 2.2 b	65 ± 2.2 bc	57 ± 2.3 b
32 woa
TRP (µmol/L)	80.7 ± 1.02 d	81.9 ± 1.04 d	80.4 ± 1.05 d
TYR (µmol/L)	122 ± 2.3 ce	123 ± 2.3 ce	117 ± 2.3 e
PHE (µmol/L)	103 ± 1.2 c	103 ± 1.2 c	103 ± 1.2 c
TRP:(PHE + TYR)	0.36 ± 0.005 a	0.37 ± 0.006 a	0.37 ± 0.006 a
KYN:TRP (µmol/mmol)	3.8 ± 0.12 c	3.8 ± 0.12 c	3.4 ± 0.13 bc
PHE:TYR (µmol/µmol)	0.86 ± 0.010 c	0.85 ± 0.010 c	0.89 ± 0.010 c
KYN (µmol/L)	0.31 ± 0.011 bd	0.32 ± 0.011 bcd	0.27 ± 0.011 ab
Nitrite (µmol/L)	77 ± 2.4 d	76 ± 2.4 d	75 ± 2.4 cd

Different letters indicate statistically significant differences across lines within each time point and across time points within each line for each variable (P < 0.05).