Effects of stocking density and environmental conditions on performance, immunity, carcase characteristics, blood constitutes, and economical parameters of cobb 500 strain broiler chickens

Figures & data

Table 1. Experimental treatments and arrangement.

Treatment	Climate region	Density, chicks/m^2
1	Mild and humid	10
2	Mild and humid	15
3	Mild and humid	17
4	Mild and humid	20
5	Semi-arid	10
6	Semi-arid	15
7	Semi-arid	17
8	Semi-arid	20
9	Alpine	10
10	Alpine	15
11	Alpine	17
12	Alpine	20
13	Hot and dry	10
14	Hot and dry	15
15	Hot and dry	17
16	Hot and dry	20
Density, chicks/m^2	Chicks per replication (pen)	Chicks per treatment or farm (4 replications)	Chicks per climate (4 farms)	Chicks per 4 climates
10	200	800	3200	12,800
15	300	1200	4800	19,200
17	340	1360	5440	21,760
20	400	1600	6400	25,600
Total	1240	4960	19,840	79,360

Table 2. Geographical characteristics of four studied climates.

Climate	Rainfall, mm/year	Geographical coordinates		Average annual temperature, ˚C	Average annual rainfall, mm	Altitude from the sea, m
		Latitude	Longitude
Mild and humid	More than 400	31.32	53.30	17.9	789.2	48
Semi-arid	Between 250 and 400	36.39	59.38	14.3	250	1077
Alpine	Between 150 and250	38.22	48.12	9.2	295.5	1294
Hot and dry	Less than 150	32.48	51.33	16.3	125	1600

Table 3. Percentage and calculated composition of experimental diets during the starter (1–21 days of age) and grower (22–42 days of age) periods.

Ingredient, g/kg or %	Starter period (1–21 days of age)	Grower period (22–42 days of age)
Corn	62.17	64.27
Soybean meal	31.2	28.50
Soybean oil	2.90	3.40
Dicalcium phosphate	1.45	1.35
Calcium carbonate	1.20	1.10
Salt	0.15	0.13
dl-methionine	0.17	0.15
Vitamin and mineral premix*	0.60	1.00
Lysine HCl	0.16	0.10
Calculated analysis
Energy (kcal ME/kg	3083	3176
Protein (%)	19.0	18.0
Calcium (%)	0.96	0.90
Available phosphorus (%)	0.48	0.45
Methionine (%)	0.40	0.39
Methionine + cysteine (%)	0.84	0.82
Lysine (%)	1.10	1.05

* Calcium pantothenate, 4 mg/g; niacin, 15 mg/g; vitamin B6 (pyridoxine), 13 mg/g; vitamin A, 5000 U/g; vitamin D3, 500 U/g; vitamin E, 1000 mg/g; vitamin K3, 1.5 mg/g; vitamin B2, 1 mg/g; Cu, 3 mg/g; Zn, 15 mg/g; Mn, 20 mg/g; Fe, 10 mg/g; K (potassium), 0.3 mg/g.

Table 4. Effect of environmental conditions and stocking density on body weight gain (BWG) (g/chick/day), feed intake (FI) (g/chick/day), and feed conversion ratio (FCR) (g/g) of Cobb 500 broilers at starter (1–21 days of age), grower (22–42 days of age) and whole (1–42 days of age) periods*.

Treatments	Starter			Grower			Whole
	BWG	FI	FCR	BWG	FI	FCR	BWG	FI	FCR
Climate
Mild and humid	40.03^b	52.53^a	1.31	80.33	169.15^b	2.11	60.18	110.84^b	1.84
Semi-arid	39.98^b	51.48^b	1.29	81.36	172.68^a	2.13	60.67	112.08^a	1.84
Alpine	41.25^a	52.97^a	1.29	80.67	171.33^a	2.13	60.96	112.15^a	1.84
Hot and dry	40.16^b	52.98^a	1.32	80.37	171.42^a	2.14	60.26	112.20^a	1.86
SEM	0.27	0.35	0.01	0.56	0.64	0.01	0.25	0.26	0.00
p Value	.003	.0097	.16	.55	.001	.65	.11	.0006	.19
Mean	40.35	52.49	1.30	80.68	171.15	2.12	60.52	111.82	1.84
Density, chick/m^2
10	40.70	52.05	1.28^b	83.65^a	172.06	2.06^b	62.17^a	112.06	1.80^d
15	40.11	52.48	1.31^ab	81.71^b	170.75	2.09^b	60.91^b	111.62	1.83^c
17	40.73	52.17	1.28^b	79.50^c	171.27	2.16^a	60.11^c	111.72	1.86^b
20	39.88	53.25	1.33^a	77.87^d	170.49	2.19^a	58.88^d	111.87	1.90^a
SEM	0.27	0.35	0.01	0.56	0.64	0.01	0.25	0.26	0.00
p Value	.07	.08	.007	<.0001	.33	<.0001	<.0001	.67	<.0001
Mean	40.35	52.49	1.30	80.68	171.15	2.12	60.52	111.82	1.84

* Means within each comparison column with no common superscript differ significantly at p < .05.

Table 5. Effect of environmental conditions and stocking density on performance and economical parameters of Cobb 500 broilers*.

Treatments	Body weight at 42 days of age, g/chick	Survival rate, %	European production index	Produced body weight in m^2, kg/m^2	Cost, $ (kg/m^2)	Income, $ (kg/m^2)	Profit, $ (kg/m^2)
Climate
Mild and humid	2570	96.52^a	321.2^ab	38.22^ab	37.76^a	40.96^ab	3.19^b
Semi-arid	2590	95.75^c	320.0^ab	38.29^ab	37.87^a	41.02^ab	3.15^b
Alpine	2602	96.09^b	323.9^a	38.57^a	38.00^a	41.33^a	3.32^b
Hot and dry	2573	95.24^d	314.0^b	37.82^b	35.94^b	40.52^b	4.57^a
SEM	10.74	0.09	2.61	0.16	0.12	0.17	0.19
p Value	.12	<.0001	.05	.01	<.0001	.01	<.0001
Mean	2583.57	95.90	319.77	38.23	37.39	40.96	3.56
Density, chick/m^2
10	2653^a	95.52^c	335.0^a	25.33^d	24.38^d	27.14^d	2.75^b
15	2600^b	95.97^b	324.5^b	37.41^c	36.18^c	40.08^c	3.90^a
17	2566^c	96.49^a	317.8^b	42.08^b	41.11^b	45.09^b	3.98^a
20	2515^d	95.62^c	301.7^c	48.09^a	47.91^a	51.52^a	3.61^a
SEM	10.74	0.09	2.61	0.16	0.12	0.17	0.19
p Value	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001
Mean	2583.57	95.90	319.75	38.22	37.39	40.96	3.56

* Means within each comparison column with no common superscript differ significantly at p < .05.

Table 6. Significant interaction effects of environmental conditions and stocking density on body weight gain (BWG), feed conversion ratio (FCR) at starter period (1–21 days of age), economical indices, and plasma constitutes of Cobb 500 broilers*.

Climate	Density, chick/m^2	BWG, g/chick/day	FCR, g/g	Survival rate, %	Cost, $ (kg/m^2)	Profit, $ (kg/m^2)	Total Cholesterol, mg/dL	Triglycerides, mg/dL	VLDL, mg/dL	HDL Cholesterol, mg/dL	LDL/HDL	AST, U/L	ALT, U/L
Mild and humid	10	40.38^bc	1.29^ab	96.43^a–d	24.48^g	2.95^b	159.3^a–d	59.64^b	11.92^b	73.39^a–d	1.21^abc	293.7^abc	534.6^de
	15	40.61^bc	1.29^ab	96.64^ab	36.51^e	3.19^b	164.2^a	54.85^bcd	10.97^bcd	71.57^a–e	1.24^abc	294.7^abc	559.2^abc
	17	39.30^c	1.34^a	96.85^a	41.41^c	3.33^b	163.9^a	59.12^bc	11.82^bc	72.63^a–d	1.19^bc	296.6^ab	548.3^a–e
	20	39.85^c	1.32^a	96.15^b–e	48.62^a	3.31^b	164.4^a	52.72^d	10.54^d	69.19^de	1.26^ab	292.2^bc	526.5^e
Semi-arid	10	39.96^c	1.29^ab	95.12^gh	24.36^g	2.64^b	161.8^ab	56.39^bcd	11.27^bcd	73.91^ab	1.19^bc	296.2^ab	541.8^b–e
	15	39.43^c	1.31^ab	96.02^cde	36.67^e	3.70^b	164.4^a	59.59^b	11.92^b	71.09^b–e	1.22^abc	294.6^abc	535.2^cde
	17	40.78^bc	1.23^b	96.61^abc	41.81^c	3.34^b	159.5^abc	52.89^cd	10.57^d	75.60^a	1.13^c	293.6^abc	524.3^e
	20	39.73^c	1.31^ab	95.26^fg	48.64^a	2.93^b	161.4^ab	66.07^a	13.21^a	69.66^cde	1.24^abc	297.8^a	528.8^e
Alpine	10	41.87^ab	1.23^b	95.87^def	24.49^g	2.85^b	157.7^bcd	56.42^bcd	11.28^bcd	69.82^b–e	1.28^ab	293.2^abc	557.5^b–e
	15	39.97^c	1.33^a	96.10^cde	36.75^e	3.71^b	161.9^ab	52.67^d	10.53^d	71.63^a–e	1.23^abc	292.7^bc	543.3^a–e
	17	43.13^a	1.23^b	96.70^ab	41.84^c	3.78^b	161.8^ab	59.60^b	11.92^b	71.74^a–e	1.26^ab	295.7^ab	545.1^a–e
	20	40.01^c	1.35^a	95.67^efg	48.94^a	2.93^b	154.9^cd	60.15^b	12.03^b	73.42^abc	1.19^bc	292.0^bc	557.4^a–d
Hot and dry	10	40.59^bc	1.30^ab	94.65^h	24.18^g	2.58^b	162.7^ab	59.80^b	11.96^b	68.31^e	1.31^a	296.2^ab	525.1^e
	15	40.42^bc	1.30^ab	95.12^gh	34.79^f	4.98^a	153.9^d	58.81^bcd	11.76^bcd	71.64^a–e	1.19^bc	290.6^c	539.7^b–e
	17	39.69^c	1.33^a	95.80^ef	39.36^d	5.45^a	160.4^abc	58.31^bcd	11.66^bcd	73.13^a–d	1.22^abc	295.1^abc	560.0^ab
	20	39.95^c	1.35^a	95.39^fg	45.43^b	5.27^a	157.1^bcd	56.32^bcd	11.26^bcd	71.14^b–e	1.21^abc	296.4^ab	567.2^a
SEM		0.54	0.02	0.19	0.24	0.39	1.77	1.94	0.38	1.25	0.03	1.46	7.38
p Value		.004	.04	.04	<.0001	.02	.0004	<.0001	<.0001	.006	.03	.03	<.0001
Mean		40.35	1.30	95.90	37.39	3.56	160.59	57.71	11.54	71.74	1.22	294.44	543.40

* Means within each comparison column with no common superscript differ significantly at p < .05; VLDL: Very low density lipoprotein; HDL: High Density Lipoproteins; AST: Aspartate amino-transferase; ALT: Alanine aminotranferase.

Table 7. Effect of environmental conditions and stocking density on plasma constitutes (lipids and glucose) of Cobb 500 broilers at 42nd day of age*.

Treatments	Glucose, mg/dL	Total cholesterol, mg/dL	Triglycerides, mg/dL	VLDL (Very low density lipoprotein), mg/dL	HDL Cholesterol (High Density Lipoproteins), mg/dL	LDL Cholesterol (Low Density Lipoproteins), mg/dL	LDL/HDL
Climate
Mild and humid	195.3^b	163.0^a	56.58	11.31	71.70	87.48	1.22
Semi-arid	192.1^c	161.8^a	58.74	11.74	72.57	86.63	1.20
Alpine	198.0^a	159.1^b	57.21	11.44	71.65	88.51	1.24
Hot and dry	194.0^bc	158.5^b	58.31	11.66	71.06	87.34	1.23
SEM	0.83	0.88	0.97	0.19	0.62	0.65	0.01
p Value	<.0001	.0008	.37	.3789	.40	.24	.24
Mean	194.85	160.59	57.71	11.54	71.74	87.49	1.22
Density, chick/m^2
10	193.6^b	160.4	58.06	11.61	71.36^b	88.67	1.25
15	194.6^b	161.1	56.48	11.59	71.48^b	86.93	1.22
17	194.0^b	161.4	57.48	11.49	73.28^a	87.74	1.20
20	197.3^a	159.5	58.82	11.46	70.85^b	86.62	1.22
SEM	0.83	0.88	0.97	0.19	0.62	0.65	0.01
p Value	.006	.41	.38	.38	.03	.12	.19
Mean	194.87	160.59	57.71	11.54	71.74	87.49	1.22

* Means within each comparison column with no common superscript differ significantly at p < .05.

Table 8. Effect of environmental conditions and stocking density on plasma constitutes (enzymes, proteins and uric acid) of Cobb 500 broilers at 42nd day of age*.

Treatments	Uric acid, mg/dL	Aspartate amino- transferase (AST), U/L	Alanine amino- transferase (ALT), U/L)	Total protein, g/dL	Albumin, g/dL	Globulin, g/dL
Climate
Mild and humid	4.44	294.3	542.1^ab	3.92	1.10^b	1.47^a
Semi-arid	4.69	295.5	532.6^b	3.90	1.15^a	1.40^ab
Alpine	4.69	293.4	550.8^a	3.97	1.15^ab	1.36^b
Hot and dry	4.64	294.5	548.0^a	3.93	1.17^a	1.35^b
SEM	0.12	0.73	3.69	0.03	0.01	0.02
p Value	.45	.23	.003	.53	.03	.005
Mean	4.61	294.44	543.38	3.93	1.14	1.40
Density, chick/m^2
10	4.80^a	294.8	539.8	3.94^ab	1.16	1.37
15	4.39^b	293.1	544.4	3.90^b	1.11	1.37
17	4.44^b	295.3	544.4	4.03^a	1.16	1.45
20	4.83^a	294.6	545.0	3.86^b	1.14	1.40
SEM	0.12	0.73	3.69	0.03	0.01	0.02
p Value	.02	.20	.72	.004	.11	.07
Mean	4.61	294.44	543.40	3.93	1.14	1.40

* Means within each comparison column with no common superscript differ significantly at p < .05.

Table 9. Effect of environmental conditions and stocking density on immunity of Cobb 500 broilers at 28th and 42nd day of age (when inoculated with sheep red blood cells on days 15 and 35, respectively)*.

Treatments	28 day of age			42 day of age
	Immunoglobulin G antibody (IgG)	Immunoglobulin M antibody (IgM)	Total antibody (IgT)	Immunoglobulin G antibody (IgG)	Immunoglobulin M antibody (IgM)	Total antibody (IgT)
Climate
Mild and humid	1.81^b	0.81^b	2.62^b	3.37	2.65^c	6.03^b
Semi-arid	2.10^a	1.21^a	3.32^a	3.50	3.46^a	6.96^a
Alpine	2.15^a	1.20^a	3.35^a	3.48	3.09^b	6.57^a
Hot and dry	2.25^a	1.12^a	3.37^a	3.43	3.07^b	6.51^ab
SEM	0.10	0.09	0.19	0.10	0.09	0.17
p Value	.02	.01	.01	.83	<.0001	.003
Mean	2.08	1.08	3.17	3.44	3.07	6.52
Density, chick/m^2
10	2.03	1.00	3.03	3.42	2.96	6.39
15	2.09	1.10	3.20	3.50	3.12	6.62
17	2.07	1.10	3.18	3.40	3.09	6.50
20	2.12	1.14	3.26	3.46	3.10	6.57
SEM	0.10	0.09	0.19	0.10	0.09	0.17
p Value	.93	.75	.85	.91	.65	.80
Mean	2.08	1.08	3.17	3.44	3.07	6.52

* Means within each comparison column with no common superscript differ significantly at p < .05.

Table 10. Effect of environmental conditions and stocking density on carcase components of Cobb 500 broilers at 42nd day of age*.

Treatments	Live body weight, g	Defeathered body weight, g	Full GIT carcase weight, g	Empty GIT carcase weight, g	Eviscerated carcase, %
Climate
Mild and humid	2545	2322	2107^b	1587^b	75.42^b
Semi-arid	2541	2327	2127^a	1599^b	75.42^b
Alpine	2545	2328	2120^ab	1623^a	76.62^a
Hot and dry	2530	2317	2107^b	1588^b	75.42^b
SEM	6.78	6.36	6.36	7.30	0.32
p Value	.39	.57	.05	.0015	.01
Mean	2540.15	2323.43	2115.34	1599.04	75.73
Density, chick/m^2
10	2551	2333	2123^a	1604	75.62
15	2545	2330	2124^a	1602	75.47
17	2531	2315	2104^b	1600	76.15
20	2533	2315	2110^ab	1590	75.46
SEM	6.78	6.36	6.36	7.30	0.32
p Value	.10	.06	.05	.57	.40
Mean	2540.00	2323.25	2115.25	1599.00	75.74

* Means within each comparison column with no common superscript differ significantly at p < .05. GIT: gastrointestinal tract.

Table 11. Effect of environmental conditions and stocking density on relative weight (% of live weight) of carcase components of Cobb 500 broilers at 42nd day of age*.

Treatments	Breast	Drumsticks (thighs)	Wings	Abdominal fat weight	Gizzard (ventriculus)	Heart	Neck	Head
Climate
Mild and humid	33.44	30.51^b	4.44	2.55	2.86	0.62	2.36	2.92^b
Semi-arid	33.44	31.68^a	4.53	2.58	2.93	0.63	2.43	3.01^a
Alpine	33.27	31.69^a	4.53	2.46	2.89	0.62	2.41	3.00^a
Hot and dry	33.22	31.50^a	4.48	2.53	2.89	0.63	2.45	3.01^a
SEM	0.24	0.23	0.03	0.04	0.03	0.00	0.02	0.01
p Value	.85	.0008	.19	.27	.56	.46	.07	.0004
Mean	33.35	31.35	4.50	2.53	2.89	0.62	2.41	2.98
Density, chick/m^2
10	33.36	31.18	4.48	2.49	2.86	0.61	2.42	2.97
15	33.24	31.48	4.47	2.61	2.85	0.63	2.41	2.98
17	33.47	31.36	4.54	2.51	2.98	0.62	2.38	2.98
20	33.35	31.36	4.49	2.50	2.87	0.62	2.44	3.00
SEM	0.24	0.23	0.03	0.04	0.03	0.01	0.02	0.01
p Value	.93	.84	.43	.14	.07	.54	.52	.73
Mean	33.35	31.35	4.50	2.53	2.89	0.62	2.41	2.98

* Means within each comparison column with no common superscript differ significantly at p < .05.

Table 12. Effect of environmental conditions and stocking density on relative weight (% of live weight) of carcase components of Cobb 500 broilers at 42nd day of age*.

Treatments	Back thoracic vertebrae (notarium)	Crop	Proventriculus	Pancreas
Climate
Mild and humid	3.03	0.48	0.42	0.29
Semi-arid	3.06	0.47	0.43	0.28
Alpine	3.12	0.48	0.42	0.29
Hot and dry	3.10	0.47	0.43	0.28
SEM	0.03	0.01	0.00	0.00
p Value	.18	.68	.84	.20
Mean	3.08	0.48	0.43	0.29
Density, chick/m^2
10	3.03	0.49	0.43	0.29
15	3.08	0.47	0.42	0.29
17	3.14	0.48	0.43	0.28
20	3.06	0.47	0.43	0.28
SEM	0.03	0.01	0.00	0.00
p Value	.10	.30	.87	.60
Mean	3.08	0.48	0.43	0.29

* Means within each comparison column with no common superscript differ significantly at p < .05.