Feed competition reduces heritable variation for body weight in Litopenaeus vannamei

Table 2 Estimates of genetic parameters for body weight (g) based on models without or with indirect genetic effects (IGE) under two feeding regimes in Litopenaeus vannamei

Parameter	Model without IGE		Model with IGE
Parameter	Ad libitum feeding	Restricted feeding	Ad libitum feeding	Restricted feeding
Log likelihood	− 4301.81	− 4027.37	− 4299.40	− 4020.26
\(\sigma_{{a_{d} }}^{2}\)	1.15 ± 0.97	2.26 ± 1.07	0.75 ± 0.86	3.17 ± 1.16
\(\sigma_{{a_{s} }}^{2}\)	–	–	0.0023 ± 0.0013	0.0028 ± 0.0012
\(\sigma_{{a_{ds} }}\)	–	–	0.013 ± 0.017	-0.087 ± 0.028
\(\sigma_{c}^{2}\)	0.76 ± 0.43	0.36 ± 0.38	0.86 ± 0.42	0.38 ± 0.35
\(\sigma_{t}^{2}\)	0.37 ± 0.12	0.46 ± 0.13	0.025 ± 0.13	0.31 ± 0.13
\(\sigma_{TBV}^{2}\)	–	–	5.79 ± 2.57	0.68 ± 1.28
\(\sigma_{e}^{2}\)	8.23 ± 0.54	5.96 ± 0.57	8.46 ± 0.50	5.37 ± 0.63
\(\sigma_{p}^{2}\)	10.53 ± 0.38	9.04 ± 0.39	10.20 ± 0.37	9.35 ± 0.49
\(T^{2}\)	–	–	0.57 ± 0.25	0.07 ± 0.14
\(h^{2}\)	0.11 ± 0.09	0.25 ± 0.11	0.07 ± 0.08	0.34 ± 0.11
\(c^{2}\)	0.07 ± 0.04	0.04 ± 0.04	0.09 ± 0.04	0.04 ± 0.04
\(r_{{a_{{d_{BW} s_{BW} }} }}\)	–	–	0.32 ± 0.47	− 0.93 ± 0.15
Two-environmental analysis model with heterogeneous variance structure for body weight
\(r_{{g_{{d_{BW} d_{BW} }} }}\)	0.94 ± 0.06		0.94 ± 0.07
\(r_{{g_{{s_{BW} s_{BW} }} }}\)	–		0.67 ± 0.20
Two-environmental analysis model with an extended factor analytic variance structure for body weight^a
\(r_{{g_{{d_{BW} s_{BW} }} }}\)	–		− 0.81 ± 0.12
Bivariate model for body weight and survival
\(r_{{a_{{s_{BW} d_{SUR} }} }}\)	–		− 0.12 ± 0.22	− 0.58 ± 0.20
\(r_{{a_{{d_{BW} d_{SUR} }} }}\)	–		0.71 ± 0.10	0.71 ± 0.12

^aCorrelation for body weight between IGE for the ad libitum feeding regime (AF) and DGE for the restricted feeding regime (RF) was not estimated because the model with IGE of body weight for the AF regime did not converge
IGE, indirect genetic effects
\(\sigma_{{a_{d} }}^{2}\), direct genetic variance
\(\sigma_{{a_{s} }}^{2}\), indirect genetic variance
\(\sigma_{{a_{ds} }}\), direct–indirect genetic covariance
\(\sigma_{c}^{2}\), common environmental variance
\(\sigma_{t}^{2}\), variance of the test tank effect
\(\sigma_{TBV}^{2}\), variance of the total breeding value
\(\sigma_{e}^{2}\), residual variance
\(\sigma_{p}^{2}\), phenotypic variance
\(T^{2}\), total heritability
\(h^{2}\), narrow sense heritability
\(c^{2}\), common environmental coefficient
\(r_{{a_{{d_{BW} s_{BW} }} }}\), correlation between DGE and IGE of body weight
\(r_{{a_{{s_{BW} d_{SUR} }} }}\), correlation between IGE of body weight and DGE of survival
\(r_{{a_{{d_{BW} d_{SUR} }} }}\), correlation between DGE of body weight and DGE of survival
\(r_{{g_{{d_{BW} d_{BW} }} }}\), correlation on DGE of body weight between the AF and RF regimes
\(r_{{g_{{s_{BW} s_{BW} }} }}\), correlation on IGE of body weight between the AF and RF regimes
\(r_{{g_{{d_{BW} s_{BW} }} }}\), correlation in body weight between DGE for the AF regime and IGE for the RF regime

ISSN: 1297-9686