Effect of Group Size on Performance and Egg Quality of Laying Hens During 20 to 36 Weeks of Age

Figures & data

Figure 1. Effect of the interaction between the two tested effects on live weight and feed conversion ratio of laying hens. *P<0.05; **P<0.01.

Figure 2. Effect of the interaction between the two tested effects for egg production. **P<0.01.

Table 1. Ingredients and chemical-nutritional characteristics of the diets for laying hens.

	Pre-laying diet (16 to 20 weeks of age)	Early-laying diet (21 to 36 weeks of age)
Ingredients, %
Corn	55.00	52.00
Soybean meal (44%)	24.00	28.00
Wheat middling	12.00	5.00
Calcium carbonate	5.00	9.00
Soybean oil	2.00	4.00
Bicalcium phosphate	1.00	1.00
Vitamin and mineral mix	0.44	0.45
Salt	0.30	0.30
Sodium bicarbonate	0.10	0.10
DL-methionine	0.16	0.15
Chemical-nutritional characteristics
Crude protein^°, %	17.5	18.0
Ether extract^°, %	3.8	5.2
Ash^°,%	9.5	13.0
Crude fibre^°, %	4.2	3.2
DL-methionine^#, %	0.42	0.42
L-lysine^#, %	0.8	0.85
Ca^#, %	2.2	3.6
P^#, %	0.6	0.6
ME^#, MJ/kg	11.50	11.60

Ca, calcium; P, total phosphorus; ME, metabolisable energy.

°Analysed chemical composition;

^#estimated values according to National Research Council (1994).

Table 2. Effect of group size and week of age on live weight, feed intake and feed conversion ratio of laying hens.

	Live weight, g	Feed intake, g/d	FCR
Group size
S25	1764.0	113.26	2.25^b
S40	1751.1	112.58	2.70^a
Week of production
20	1715.2^b	113.6^ab	3.73^a
22	-	113.8^ab	3.03^ab
24	1743.5^b	119.0^a	2.66^bc
26	-	114.2^ab	2.25^bc
28	1737.9^b	106.7^c	2.20^c
30	-	106.6^c	2.09^c
32	1752.5^b	110.9^bc	2.04^c
34	-	116.04^ab	2.06^c
36	1884.9^a	116.0^ab	2.07^c
P
Group effect	0.1339	0.3408	<0.0001
Week effect	<0.0001	<0.0001	<0.0001
Group x week effect	0.0249	0.9979	0.0389
RMSE	121.6	2.30	0.31

FCR, feed conversion ratio; RMSE, root mean square error.

^a-cMeans within the same column having different letters are significantly different at P<0.01.

Table 3. Effect of group size and week on laying rate and percentage of eggs laid out of the nest.

	Laying rate, %	Eggs laid out of the nest, %
Group size
S25	88.90^a	2.61^a
S40	81.91^b	1.89^b
Week of production
20	64.23^c	2.33^abc
22	77.12^bc	2.50^ab
24	85.03^ab	3.67^a
26	94.88^a	3.21^a
28	88.28^ab	2.62^ab
30	89.71^ab	2.11^abc
32	93.25^ab	2.13^abc
34	93.54^ab	1.32^bc
36	88.35^ab	0.74^c
P
Group effect	0.0016	0.0034
Week effect	<0.0001	<0.0001
Group x week effect	0.0455	0.0529
RMSE	6.51	0.67

RMSE, root mean square error.

^a-cMeans within the same column having different letters are significantly different at P<0.01.

Table 4. Effect of group size and week of production on some qualitative characteristics of eggs.

	Egg weight, g	Shell weight, g	Shell index, %	Yolk weight, g	Yolk index, %	Albumen weight, g	Albumen index, %
Group size
S25	57.29	6.55	11.46	12.40	21.60	38.34	66.94
S40	56.20	6.50	11.35	12.48	22.23	37.97	66.49
Week of production
20	49.27^c	5.50^c	11.93	10.64^d	21.67^abc	31.28^c	67.77^a
22	51.32^bc	5.98^bc	11.64	10.52^d	20.51^bc	34.82^bc	67.85^a
24	55.84^abc	6.43^ab	11.52	11.37^cd	20.49^c	38.05^ab	67.99^a
26	55.84^abc	6.42^ab	11.51	11.38^cd	20.48^c	38.07^ab	67.93^a
28	57.71^ab	6.40^ab	11.09	12.35^bcd	21.40^abc	38.96^ab	67.51^a
30	58.42^a	6.65^ab	11.37	13.04^abc	22.29^abc	38.80^ab	66.34^ab
32	61.30^a	6.80^ab	11.09	14.30^ab	23.36^ab	40.21^a	65.55^ab
34	60.68^a	7.01^a	11.58	14.38^a	23.75^a	39.28^ab	64.61^b
36	62.29^a	6.99^a	11.25	14.56^a	23.37^ab	40.74a	65.38^ab
P
Group effect	0.4099	0.0896	0.7381	0.6142	0.1981	0.0854	0.4021
Week effect	<0.0001	<0.0001	0.1620	<0.0001	0.0003	<0.0001	<0.0001
Group x week effect	0.1743	0.7889	0.9016	0.1809	0.7778	0.5309	0.7095
RMSE	4.72	0.56	0.67	1.43	2.39	3.41	1.86

RMSE, root mean square error.

^a-cMeans within the same column having different letters are significantly different at P<0.01.

Table 5. Effect of group size and week of production on shell thickness, shape index and Haugh unit.

	Shell thickness, mm	Shape index	Haugh unit
Group size
S25	0.39	1.28	77.09
S40	0.39	1.28	75.57
Week of production
20	0.41^a	1.28	71.78^B
22	0.40^ab	1.28	71.25^B
24	0.40^ab	1.25	76.70^AB
26	0.40^ab	1.25	74.97^B
28	0.35^b	1.28	78.25^AB
30	0.40^ab	1.28	73.72^B
32	0.38^ab	1.31	73.32^B
34	0.41^a	1.27	79.80^AB
36	0.36^ab	1.28	86.45^A
P
Group effect	0.6057	0.7116	0.6547
Week effect	0.0420	0.3616	<0.0001
Group x week effect	0.5587	0.9476	0.2373
RMSE	0.050	0.064	7.89

RMSE, root mean square error.

^A,BMeans within the same column having different uppercase letters are significantly different at P<0.01;

^a,bmeans within the same column having different lowercase letters are significantly different at P<0.05.

National Research Council, 1994. Nutrient requirements of domestic animals. Nutrient requirements of poultry. 9th ed., National Academy Press, Washington, DC, USA.

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