Effect of the data family structure, tank replication and the statistical model, on the estimation of genetic parameters for body weight at 28 days of age in the Pacific white shrimp (Penaeus (Litopenaeus) vannamei Boone, 1931)

Abstract

Real and simulated data sets were analysed to estimate the effect of data structure (i.e. the number of dams mated to one sire and the number of tanks per dam) and the model used for analysis on the bias of genetic parameter estimates of the square root of 28-day body weight (BW28) in Penaeus vannamei. Estimated parameters used were 0.13 for the heritability (h 2 ); 0.16 for the proportion of the variance of the maternal and common environmental effects (c 2 ); 0.15 for the proportion of the tank effect variance (t 2 ) and 0.56 for the proportion of the environmental variance (e 2 ). Total variance for the BW28 was 2.36 mg. Simulated data involved a total of 9000 sires and 1 444 000 offspring. Exclusion of maternal and common environmental effects inflated estimates of heritability both in real and simulated data. Exclusion of tank effects from the model inflated the estimates of heritability in real, but not in simulated data, indicating the presence of non-random effects affecting individual tanks. We conclude that replication of dams per sire is necessary for obtaining unbiased estimates of heritability. Use of replicated tanks may help in reducing overestimation of heritability if tank and genetic effects are confounded.

Heritability and genetic correlations for infectious hypodermal and hematopoietic necrosis virus load, body weight at harvest, and survival rate in Pacific white shrimp (Litopenaeus vannamei)

“…In that study, heritability was also moderate (0.41). These values were higher than our findings, but unlike our estimates based on the sire component, which may better isolate the additive genetic variation, the figures reported by these authors may have been inflated by common full‐sib environmental effects (Montaldo, Castillo‐Juárez, Campos‐Montes, & Pérez‐Enciso, ), including the effects caused by vertical transmission (Phuthaworn et al, ).…”

Genetic parameters for spawning and growth traits in the Pacific white shrimp (Penaeus (Litopenaeus) vannamei)

“…() estimated it for body weight at 130 days of age averaging 0.07. It is important to include this effect in the models when estimating genetic parameters for body weight at reproductive and harvesting ages, as neglecting it leads to an overestimation of the additive genetic effects in shrimp breeding populations (Montaldo, Castillo‐Juárez, Campos‐Montes & Pérez‐Enciso ).…”

Inbreeding Effects on Body Weight at Harvest Size and Grow‐out Survival Rate in a Genetic Selected Population of Pacific White Shrimp Penaeus (Litopenaeus) vannamei

“…To estimate the effect of inbreeding on BW at harvest size and grow‐out SR, data were analyzed using mixed linear model methodology and restricted maximum likelihood (REML) methods with ASReml software (Gilmour et al ). Model specification was based on results from previous research made on the same population for the studied traits (Castillo‐Juárez et al ; Campos‐Montes et al ; Montaldo et al ; Campos‐Montes et al ). Single trait mixed linear models used in the analysis of BW and SR were:…”