Genetic and environmental heterogeneity of residual variance of weight traits in Nellore beef cattle

Table 2 Results of variance component estimation according to trait, sex ^* and residual variance structure ^**

Trait/Sex	Model	σ²_a	σ²_e	h²_d	σ²_m	σ²_c	AIC	BIC	MSE
GBW/M	HOM	44 (9)	226 (8)	0.12 (0.02)	113 (7)		157113	157137	380.54
GBW/M	HET	44 (8)	225 (8)	0.11 (0.02)	120 (7)		156986	157748	381.22
GBW/F	HOM	31 (6)	193 (6)	0.10 (0.02)	78 (5)		155334	155358	305.67
GBW/F	HET	31 (6)	192 (7)	0.10 (0.02)	84 (5)		155163	155992	305.51
GBW/B	HOM	44 (7)	209 (4)	0.12 (0.02)	53 (12)	47 (12)	346263	346298	337.94
GBW/B	HET	42 (6)	212 (7)	0.12 (0.02)	58 (12)	47 (12)	345807	347105	338.17
YW/M	HOM	308 (58)	292 (44)	0.51 (0.08)			64302	64316	569.00
YW/M	HET	312 (58)	268 (18)	0.54 (0.05)			64267	64593	569.19
YW/F	HOM	177 (24)	281 (18)	0.39 (0.05)			82970	82985	439.54
YW/F	HET	183 (24)	279 (12)	0.40 (0.03)			82907	83386	439.97
YW/B	HOM	220 (15)	310 (11)	0.42 (0.03)			202426	202443	499.54
YW/B	HET	218 (15)	306 (10)	0.42 (0.02)			202249	203229	500.04

^*GBW = weight gain from birth to weaning; YW = long-yearling weight; M = males; F = females; B = both sexes; ^**HOM = model with homogeneous residual variance; HET = model allowing for differences between sire families in residual variance; σ²_a = estimated variance for additive direct genetic effect for the mean of each trait; σ²_e = estimated residual variance (average residual variance among sire families), in the case of model HOM (HET); σ²_m = estimated variance due to maternal additive genetic effects for the mean of GBW; σ²_c = estimated variance due to maternal permanent environmental effects for the mean of GBW; AIC = Akaike Information Criterion; BIC = Bayesian Information Criterion. MSE = average mean squared error of prediction based on a 10-fold cross-validation; standard errors are presented between brackets.

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