Effect of laying month on egg quality in the Utrerana chicken breed (Partridge variety) during the first laying period

Figures & data

Table 1. Nutrient composition (as feed basis) of the balanced feed supplied to the hens (Ponemax®, Cereales Maestre; Los Palacios y Villafranca, Spain)^a.

Item	Content
Dry matter (%)	89.1
Crude protein (%)	17.0
Crude fibre (%)	2.6
Crude fat (%)	4.2
Ash (%)	13.5
Total Calcium (%)	4.09
Total Phosphorus (%)	0.55
Sodium (%)	0.16
Lysine (%)	0.93
Methionine (%)	0.41
Metabolizable energy (kcal/kg)	2822

^a Additives per kg of balanced feed contains: vitamin A: 7875 IU; vitamin D₃: 1575 IU; copper (cupric sulphate pentahydrate): 4.2 mg; iodine (potassium iodide): 2 mg; canthaxanthin: 2 mg; butylated hydroxytoluene (BHT): 0.231 mg; ethoxyquin: 0.034 mg; Butylated hydroxyanisole (BHA): 0.021; sepiolite: 1 g.

Table 2. Hen-day egg production and estimated marginal means of external quality traits of eggs from the Partridge variety of the Utrerana chicken breed during the first laying period.

Trait	Laying Month^A						Whole period (n = 378)	Pooled SEM	p-value
	1^st (n = 67)	2^nd (n = 81)	3^rd (n = 67)	4^th (n = 59)	5^th(n = 63)	6^th(n = 41)
Hen-day egg production (%)	47.9	61.4	50.7	43.6	46.4	30.7	46.8	–	–
Egg Weight (g)	61.46	62.54	61.98	61.62	61.29	61.10	61.66	0.178	0.166
Egg Length (mm)	60.41^bc	59.34^d	60.15^c	60.82^ab	61.03^a	60.85^ab	60.43	0.088	<0.001
Egg Width (mm)	42.45^c	42.66^bc	42.90^a	42.77^ab	42.62^bc	42.85^ab	42.71	0.036	0.003
Shape Index (%)	70.33^c	71.95^a	71.41^ab	70.47^bc	69.98^c	70.51^bc	70.77	0.154	0.001
Specific Gravity (g/cm^3)	122.19^a	119.09^b	106.55^e	113.98^c	110.19^d	108.99^de	113.50	0.426	<0.001
Eggshell Weight (g)	7.44	7.62	7.26	8.19	6.71	6.43	7.28	0.197	0.178
Eggshell Ratio (%)	12.06	12.34	11.77	13.19	10.86	10.41	11.77	0.309	0.162
Eggshell Thickness (mm)	0.50^a	0.45^b	0.46^b	0.43^c	0.40^d	0.36^e	0.43	0.002	<0.001
Eggshell Colour:
L*	89.57^b	89.54^b	90.90^a	90.49^ab	90.87^a	89.45^b	90.14	0.166	0.011
a*	0.19^ab	0.26^a	0.21^ab	0.06^bc	−0.16^d	−0.15^c	0.07	0.029	<0.001
b*	8.78^ab	8.87^a	7.90^abc	7.44^bc	6.63^c	8.32^ab	7.99	0.202	0.007
C*	8.80^ab	8.90^a	7.92^abc	7.45^bc	6.64^c	8.33^ab	8.01	0.203	0.006
H*	20.05^a	20.37^a	8.10^a	−3.56^a	−43.09^b	−47.02^b	−7.52	4.363	<0.001

^a-e Estimated marginal means in the same row sharing different superscript letters are different (p < 0.05). SEM: Standard error of the mean.

^A Laying months: 1^st: 16 March − 11 April; 2^nd: 12 April − 9 May; 3^rd: 10 May − 6 June; 4^th: 7 June − 4 July; 5^th: 5 July − 1 August; 6^th: 2 August − 29 August.

Table 3. Quality traits of the egg yolk from the Partridge variety of the Utrerana chicken breed during the first laying period (estimated marginal means).

Trait	Laying Month^A						Whole period (n = 378)	Pooled SEM	p-value
	1^st (n = 67)	2^nd (n = 81)	3^rd (n = 67)	4^th (n = 59)	5^th (n = 63)	6^th (n = 41)
Yolk Weight (g)	18.06^c	18.41^c	19.74^b	20.08^ab	20.19^ab	20.66^a	19.52	0.076	<0.001
Yolk Ratio (%)	29.23^c	29.88^c	31.99^b	32.54^b	32.74^ab	33.48^a	31.64	0.121	<0.001
Yolk Height (mm)	18.34^a	18.46^a	17.03^b	16.92^b	16.14^c	15.56^d	17.08	0.066	<0.001
Yolk Diameter (mm)	43.81^c	43.49^c	46.01^b	45.58^b	46.82^a	47.36^a	45.51	0.110	<0.001
Yolk Index (%)	41.98^a	42.50^a	37.18^b	37.34^b	34.65^c	33.02^d	37.78	0.198	<0.001
Yolk pH	6.13^a	5.99^b	6.01^b	5.91^c	6.00^b	5.99^bc	6.00	0.012	<0.001
Yolk Colour – Roche Fan	11.25^a	11.22^a	11.14^ab	11.46^a	9.42^bc	8.85^c	10.56	0.276	0.038
Yolk Colour:
L*	54.01^b	54.48^b	56.00^a	56.68^a	56.58^a	56.43^a	55.70	0.132	<0.001
a*	7.49^ab	7.91^a	7.39^b	5.62^c	5.77^c	5.71^c	6.65	0.073	<0.001
b*	36.56^bc	38.09^a	37.38^ab	34.02^d	36.01^c	35.37 ^cd	36.24	0.208	<0.001
C*	37.35^bc	38.92^a	38.13^ab	34.48^d	36.48^c	35.84 ^cd	36.87	0.211	<0.001
H*	78.32^b	78.25^b	78.79^b	80.61^a	80.90^a	80.88^a	79.62	0.099	<0.001

^a-d Estimated marginal means in the same row sharing different superscript letters are different (p < 0.05). SEM: Standard error of the mean.

^A Laying months: 1^st: 16 March − 11 April; 2^nd: 12 April − 9 May; 3^rd: 10 May − 6 June; 4^th: 7 June − 4 July; 5^th: 5 July − 1 August; 6^th: 2 August − 29 August.

Table 4. Quality traits of the egg albumen from the Partridge variety of the Utrerana chicken breed during the first laying period (estimated marginal means).

Trait	Laying Month^A						Whole period (n = 378)	Pooled SEM	p-value
	1^st (n = 67)	2^nd (n = 81)	3^rd (n = 67)	4^th (n = 59)	5^th (n = 63)	6^th (n = 41)
Albumen Weight (g)	36.24^a	35.71^ab	34.73^bc	33.46^c	34.84^bc	34.66^bc	34.94	0.212	0.004
Albumen Ratio (%)	58.71^a	57.78^ab	56.24^bc	54.27^c	56.41^bc	56.11^bc	56.59	0.332	0.003
Albumen Height (mm)	6.69^a	5.84^b	5.01^c	4.83^c	4.73^c	4.97^c	5.35	0.087	<0.001
Haugh Units	85.66^a	72.48^b	65.64^c	62.96^c	63.29^c	64.70^c	69.12	0.733	<0.001
Albumen pH	9.23^c	9.18^c	9.35^b	9.42^ab	9.37^ab	9.48^a	9.34	0.016	<0.001

^a-c Estimated marginal means in the same row sharing different superscript letters are different (p < 0.05). SEM: Standard error of the mean.

^A Laying months: 1^st: 16 March − 11 April; 2^nd: 12 April − 9 May; 3^rd: 10 May − 6 June; 4^th: 7 June − 4 July; 5^th: 5 July − 1 August; 6^th: 2 August − 29 August.

Data availability statement

The data supporting the findings of this study are available from the corresponding author, P.G.-R., upon reasonable request.