Effect of dietary inclusion of taurine on performance, carcass characteristics and muscle micro-measurements in broilers under cyclic heat stress

Figures & data

Table 1. Mean daily temperature and relative humidity during the experimental period.

Hours	Ambient temperature, °C	Relative humidity, %
08:00	32.23	62.12
12:00	36.65	56.52
16:00	38.34	58.54
20:00	35.89	63.89
24:00	34.23	67.33
04:00	28.44	69.75

Table 2. Composition of basal feed and chemical composition.

Ingredients, % (as fed basis)	Starter phase	Finisher phase
Corn	55.50	56.00
Soybean meal	27.40	26.50
Canola meal	6.50	6.00
Sunflower meal	3.20	3.50
Vegetable oil	1.80	1.90
Molasses	1.00	1.00
Dicalcium phosphate	1.90	1.90
Limestone	1.00	1.00
Sodium chloride	1.00	1.00
Sodium bicarbonate	0.20	0.20
Vitamin mineral premix^a	0.30	0.30
Chemical composition
Metabolizable energy (ME), kcal/kg	3000.00	3150.00
Crude protein, %	23.5	21.30
Methionine, %	0.55	0.44
Lysine, %	1.42	1.23
Sulphur amino acids, %	0.96	0.80
Threonine, %	0.95	0.85
Calcium, %	1.05	0.90
Phosphorus, %	0.50	0.45

^a Vitamin–mineral premix contains in the following per kg: vitamin A, 2,400,000 U; vitamin D, 1,000,000 U; vitamin E, 16,000 U; vitamin K, 800 mg; vitamin B₁, 600 mg; vitamin B₂, 1600 mg; vitamin B₆, 1000 mg; vitamin B₁₂, 6 mg; niacin, 8000 mg; folic acid, 400 mg; pantothenic acid, 3000 mg; biotin, 40 mg; antioxidant, 3000 mg; cobalt, 80 mg; copper, 2000 mg; iodine, 400; iron, 1200 mg; manganese, 18,000 mg; selenium, 60 mg; zinc, 14,000 mg.

Table 3. Effect of different levels of dietary inclusion of taurine on feed intake (g) in broilers under cyclic heat stress.

Weeks	TAN0	TAN2.5	TAN5	TAN7.5	Pooled SEM	p Value
1	146.0	131.0	140.0	142.0	4.32	.381
2	302.0	328.0	316.0	304.0	6.58	.072
3	506.0	498.0	493.0	489.0	7.12	.554
Starter	954.0	956.0	949.0	934.0	11.59	.566
4	754.0	750.0	722.0	730.0	14.50	.293
5	881.0	857.0	880.0	850.0	23.45	.372
Finisher	1636.0	1606.0	1602.0	1580.0	21.55	.202
Overall	2590.0	2563.0	2551.0	2515.0	23.49	.201

TAN0: no supplementation; TAN2.5: 2.5% taurine supplementation; TAN5: 5% taurine supplementation; TAN7.5: 7.5% taurine supplementation.

Table 4. Effect of different levels of dietary inclusion of taurine on weight gain (g) in broilers under cyclic heat stress.

Weeks	TAN0	TAN2.5	TAN5	TAN7.5	Pooled SEM	p Value
1	128.0	114.0	125.0	121.0	2.34	.202
2	252.0	269.0	232.0	246.0	3.56	.132
3	375.0	359.0	367.0	361.0	5.61	.851
Starter	754.0	742.0	724.0	728.0	7.01	.361
4	398.0^b	471.0^ab	489.0^a	495.0^a	2.21	.011
5	417.0^b	474.0^ab	486.0^a	470.0^ab	7.12	.02
Finisher	815.0^b	945.0^a	974.0^a	965.0^a	9.16	<.01
Overall	1569.0^b	1687.0^a	1698.0^a	1693.0^a	11.89	<.01

TAN0: no supplementation; TAN2.5: 2.5% taurine supplementation; TAN5: 5% taurine supplementation; TAN7.5: 7.5% taurine supplementation.

Mean values within each row bearing different superscripts differ significantly (p< .05).

Table 5. Effect of different levels of dietary inclusion of taurine on feed conversion ratio (FCR) in broiler under cyclic heat stress.

Weeks	TAN0	TAN2.5	TAN5	TAN7.5	Pooled SEM	p Value
1	1.15	1.15	1.13	1.18	0.01	.221
2	1.21	1.22	1.36	1.24	0.02	.061
3	1.36	1.39	1.35	1.36	0.01	.921
Starter	1.27	1.29	1.31	1.28	0.03	.221
4	1.90^a	1.60^b	1.49^b	1.48^b	0.03	<.010
5	2.11^a	1.81^b	1.82^b	1.81^b	0.04	.010
Finisher	2.01^a	1.70^b	1.64^b	1.64^b	0.04	<.010
Overall	1.65^a	1.52^b	1.50^b	1.49^b	0.05	<.010

TAN0: no supplementation; TAN2.5: 2.5% taurine supplementation; TAN5: 5% taurine supplementation; TAN7.5: 7.5% taurine supplementation.

Mean values within each row bearing different superscripts differ significantly (p<.05).

Table 6. Effect of dietary inclusion of taurine on carcass characteristics in heat-stressed broiler.

	TAN0	TAN2.5	TAN5	TAN7.5	Pooled SEM	p Value
Dressing, %	62.8	64.5	63.3	63.6	2.55	.324
Eviscerated wt., %	78.4	80.1	79.6	78.8	4.32	.073
Giblet wt., g	89.2	88.0	82.5	78.7	5.67	.062
Abdominal fat wt., %	1.8^a	1.6^ab	1.5^b	1.6^b	0.01	<.010
Breast, %	34.1	31.0	33.2	33.3	3.56	.061
Legs, %	13.7	14.1	15.3	14.1	1.32	.062
Thighs, %	12.6	12.8	14.0	12.7	1.11	.214
Wings, %	3.3	3.4	3.4	3.4	0.03	.565
Mortality, %	4.3	4.1	4.2	4.4	4.30	.074

TAN0: no supplementation; TAN2.5: 2.5% taurine supplementation; TAN5: 5% taurine supplementation; TAN7.5: 7.5% taurine supplementation.

Mean values within each row bearing different superscripts differ significantly (p<.05).

Figure 1. Microstructure of skeletal muscle of heat-stressed (A) and taurine supplementation at the level of 2.5 (B), 5 (C) and 7.5 g/kg (D) in broilers (×40).

Table 7. Effect of different levels of taurine inclusion on muscle histomorphology in broiler birds under cyclic heat stress.

Groups	TAN0	TAN2.5	TAN5	TAN7.5	Pooled SEM	p Value
Muscle fibre diameter, mm	0.050^c	0.064^ab	0.062^b	0.071^a	0.001	.02
Muscle fibre cross sectional area, mm^2	0.002^c	0.003^b	0.003^b	0.004^a	0.001	<.01
Muscle fascial diameter, mm	2.010^c	2.160^b	2.370^b	3.010^a	0.010	.04
Muscle fascial cross-sectional area, mm^2	2.010^c	2.940^b	3.150^b	3.950^a	0.020	.03

TAN0: no supplementation; TAN2.5: 2.5% taurine supplementation; TAN5: 5% taurine supplementation; TAN7.5: 7.5% taurine supplementation.

Mean values within each row bearing different superscripts differ significantly (p<.05).