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Objective: The genetic evaluation of Santa Inês sheep was performed for resistance to gastrointestinal nematode infection (RGNI) and body size using different relationship matrices to assess the efficiency of including genomic information in the analyses.Methods: There were 1,637 animals in the pedigree and 500, 980, and 980 records of RGNI, thoracic depth (TD), and rump height (RH), respectively. The genomic data consisted of 42,748 SNPs and 388 samples genotyped with the OvineSNP50 BeadChip. The (co)variance components were estimated in single- and multi-trait analyses using the numerator relationship matrix (A) and the hybrid matrix H, which blends A with the genomic relationship matrix (G). The BLUP and single-step genomic BLUP methods were used. The accuracies of estimated breeding values and Spearman rank correlation were also used to assess the feasibility of incorporating genomic information in the analyses.Results: The heritability estimates ranged from 0.11±0.07, for TD (in single-trait analysis using the A matrix), to 0.38±0.08, for RH (using the H matrix in multi-trait analysis). The estimates of genetic correlation ranged from –0.65±0.31 to 0.59±0.19, using A, and from –0.42±0.30 to 0.57±0.16 using H. The gains in accuracy of estimated breeding values ranged from 2.22% to 75.00% with the inclusion of genomic information in the analyses.Conclusion: The inclusion of genomic information will benefit the direct selection for the traits in this study, especially RGNI and TD. More information is necessary to improve the understanding on the genetic relationship between resistance to nematode infection and body size in Santa Inês sheep. The genetic evaluation for the evaluated traits was more efficient when genomic information was included in the analyses.

The aim of this study was to evaluate the influence of different non-genetic effects on indicator traits for maternal ability in Santa Inês ewes. Data included performance records of 100 lambs (males and females) born from 59 dams, from 2009 to 2012. The analyzed traits were birth weight (BW), weaning weight (WW), average daily gain from birth until weaning (ADGBW), total litter weight at birth (TLWB), and total litter weight at weaning (TLWW). The effects analyzed were the year of birth of the lamb, birth season, dam age at lambing, dam weight at lambing, sex of the lamb, lamb birth type, interaction between sex and birth type, and interaction between sex and birth season. SAS® software (SAS University Edition, USA) was used for calculation of the analysis of variance, means, and Pearson correlation coefficients. With the exception of the birth season, all the other environmental effects evaluated had a significant influence on at least one of the studied traits. The correlation estimates ranged from low to high and were either positive or negative. Birth weight was negatively correlated with the birth type and influenced positively all the other performance traits evaluated. The maternal ability of Santa Inês ewes was more clearly influenced by the age and weight of the dam at lambing, and the lamb birth type.

Objetivou-se descrever o quantitativo, distribuição e estrutura do rebanho de ovino da raça Santa Inês no estado do Piauí. Foram analisados dados de registros genealógicos da raça Santa Inês, mantidos pela Associação Brasileira de Criadores de Ovinos (ARCO), referentes ao período de 1992 a 2012. Foram realizadas análises estatísticas descritivas de modo a conhecer como o rebanho Santa Inês está estruturado. Foi realizada a classificação do rebanho quanto a sua estrutura organizacional, determinada com base na origem e uso dos reprodutores, utilizando-se o programa ENDOG. v.4.8. O registro dos animais da raça Santa Inês, no Piauí, teve inicio em 1990, e a maior representatividade foi verificada no período de 1993 a 2001. Quanto à estrutura dos rebanhos, 56,8% foram classificados como rebanhos multiplicadores (estrato intermediário da pirâmide) e 43,2% como rebanhos comerciais (base da pirâmide), sendo que não se observou nenhum rebanho núcleo e nem isolado. A falta de rebanhos núcleo da raça no Estado pode ser uma das causas da redução do número de animais registrados nos últimos anos no Piauí.