Table 3.

Variance components, genetic parameters, model statistic criteria, and rate of decline of the absolute growth rate (AGR) in Thai native chickens (Pradu Hang dum) at various temperature and humidity indices (THI)

Items	Absolute growth rate
	THI72	THI74	THI76	THI78	THI80
Parameters
Va0	602.48	627.22	644.76	658.50	672.20
Va1	15.31	18.33	25.72	28.34	33.09
Cova0,a1	−58.38	−64.12	−78.44	−79.15	−82.75
Vp0	776.62	789.12	838.44	876.62	893.46
Vp1	9.69	9.68	10.55	16.12	19.23
Covp0,p1	−68.58	−72.44	−78.12	−98.71	−112.55
Ve	846.63	846.63	846.63	846.63	846.63
h2 (±SE)	0.25±0.02	0.26±0.02	0.25±0.02	0.26±0.02	0.26±0.03
pe2 (±SE)	0.33±0.01	0.32±0.01	0.34±0.01	0.34±0.02	0.33±0.03
rg	−0.61	−0.60	−0.61	−0.58	−0.55
rp	−0.79	−0.83	−0.83	−0.83	−0.86
Rate of decline of AGR (gram/THI)
Male	0	0	−15.21	−21.45	−34.41
Female	0	0	−10.10	−16.21	−28.95
Statistic criteria
−2logL	4	21	0	59	81
AIC	4	21	0	59	81
BIC	4	21	0	59	81

THI, temperature and humidity indices; V_a0, additive variance of animal; V_a1, additive variance of heat stress effect; Cov_a0a1, covariance between additive variance of animal and heat stress effect; V_p0, permanent environmental variance of animal; V_p1, permanent environmental variance of heat stress effect; Cov_p0p1, covariance between permanent environmental variance of animal and heat stress effect; V_e, residual variance; h², heritability; SE, standard error; r_g, genetic correlation between animal and heat stress effect; r_p, correlations between the intercept and slope of the permanent environmental effects; AGR, absolute growth rate; −2logL, minus twice the logarithm of the likelihood; AIC, Akaike’s information criterion; BIC, Bayesian information criterion.