Estimates of (co)variance components and genetic parameters for reproductive traits in Santa Inês sheep breed using linear and threshold models / Estimativas de componentes de (co)variância e parâmetros genéticos para características reprodutivas em ovinos da raça Santa Inês utilizando modelos linear e de limiar

AUTOR(ES)

Cristiane Leite Figueiredo

DATA DE PUBLICAÇÃO

2008

RESUMO

The aims of this study were evaluated genetic parameters with sire and animal mixed models, to continuous and discreet reproductive traits, as well as predict sires breeding values to continuous and discreet reproductive traits in Santa Inês ewes breed. The traits analyzed in this study were lambing interval (LI, N = 1,066), fertility (FR, N = 1,006) and number of lambs born (NLB, N = 3,593) of ewes with birth occurred among 1998 to 2005. The FR trait was expressed in form of delivered females in respect to sheltered females, been codified as "1" delivered and "0" otherwise. The NLB trait represented the number of fully formed lambs born per ewe lambing, codified as "1" (simple) and "2" (multiples). The sire model showed super estimate comportment in respect to animal model for reproductive traits heritabilities. The estimates of heritability obtained by linear animal model were 0.12, 0.23 and 0.16 for NLB, FR and LI, respectively. The estimates of heritability obtained by threshold animal model were 0.16, 0.15 and 0.10 for NLB, FR and LI, respectively. The estimates of genetic correlations using linear animal model were 0.13 (between NLB and FR) and -0,21 (between NLB and LI). However, the estimates of genetics correlations using threshold animal model were 0.81 (between NLB and FR) and -0,52 (between NLB and LI). The Pearson correlations between predicted breeding values for 258 sires varying by 0.4835 to 0.8561 between sire and animal models obtained by linear and threshold methodology. This fact suggest the existence of significative changes on sires predicted breeding values classifications by virtue of model type and used methodology on genetic evaluation.

ASSUNTO(S)

ovinocultura de corte fertilidade número de cordeiros ao parto intervalo de partos number of lambs born lambing interval avaliação genética genetic evaluation meat sheep fertility

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