Table 7.

Effects of heat stress and dietary betaine on meat quality of yellow-feathered broilers *.

Dietary Betaine Levels (mg/kg)	Temperature	Breast Muscle				Leg Muscle
		Cooking Loss, %	Shear Force, kgf	pH45min	pH24h	Cooking Loss, %	Shear Force, kgf	pH45min	pH24h
0	TN	38.2	2.83	5.75	5.30	40.3	1.99	5.78	5.71
0	HS	36.3	2.92	5.59	5.37	38.2	1.85	5.82	5.47
500	HS	32.5	2.46	5.87	5.55	35.0	1.55	5.76	5.64
1000	HS	38.4	2.20	5.74	5.45	39.1	1.72	6.00	5.50
2000	HS	34.8	2.77	5.58	5.45	38.4	2.12	5.97	5.40
SEM		2.51	0.259	0.143	0.130	2.15	0.264	0.102	0.139
Contrast		p-value
TN vs. HS		0.545	0.809	0.726	0.413	0.509	0.698	0.233	0.818
Linear		0.913	0.521	0.773	0.802	0.618	0.438	0.153	0.605
Quadratic		0.969	0.052	0.107	0.522	0.558	0.215	0.930	0.396

* TN, thermoneutral zone; HS, heat stress; SEM, standard error of means; TN vs. HS, TN group vs. HS control (0 mg/kg betaine) group.