RESUMO

The aim of this study was to estimate the (co)variance components and breeding values for birthweight (BW) in Nellore cattle by considering or not identical weights that exhibit a high frequency within the contemporary group (CG). A total of 175,258 BW records of Nellore cattle born between 2002 and 2018 were used. The CG was formed by farm, year of birth, sex and feeding regime at birth. CGs with more than 16% of identical BW values were eliminated, generating a data file called BWd. Another file was created without removing these animals (BWt). A mixed linear model was used for statistical analysis, which included fixed and random effects. In both data files analysed, single-trait analysis was performed by Bayesian inference. The mean direct and maternal heritability for BW and the correlation between direct and maternal effects were 0.27, 0.07 and -0.07 for BWt, respectively, and 0.30, 0.093 and -0.07 for BWd. This method should affect the estimation of genetic merits of animals for BW, providing greater safety in the choice of sires.

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RESUMO

We aimed to evaluate environmental effects on pre-weaning traits of Santa Gertrudis cattle. We used 213 standardized records for adjusted 205-day weight at weaning (W205), average daily gain from birth to weaning (AGD), and number of days to gain 160 kg from birth to weaning (D160), obtained from the Santa Gertrudis Breeders’ Association for animals born between 1990 and 1997. The files were edited with information regarding cow age at calving (CAC) and contemporary group (CG),for which the effects of year and season of birth, animal category, herd, and sex were considered. It was observed that cow age at calving, which had linear and quadratic effects, and effect of contemporary group were significant (P<0.0001) for the evaluated traits. Estimated averages were 198.05 ± 40.64 kg, 0.790 ± 0.198 kg day-1,and 288.05 ± 67.18 days for W205, ADG, and D160, respectively. Males were 4.67 kg heavier (197.17 kg) than females, on average. Regarding the animal category effect, the classified females were 2.3% heavier than the unclassified males, on average. On average, animals born in the dry season were 1.6% lighter than those born in the rainy season (197.18 kg). Thus, environmental effects are important and should be considered in any analysis model.

O objetivo deste estudo foi avaliar os efeitos ambientais sobre as características da pré-desmama em bovinos da raça Santa Gertrudis. Foram utilizados 213 registros de peso à desmama padronizado aos 205 dias (P205), ganho médio diário do nascimento à desmama (GMD) e número de dias para ganhar 160 kg do nascimento até a desmama (D160), oriundos da Associação dos Criadores de Santa Gertrudis, de animais nascidos no período de 1990 a 1997. Os arquivos foram editados com as informações da idade da vaca ao parto (IVP) e grupo de contemporâneos (GC) que considerou os efeitos de ano e estação de nascimento, categoria animal, rebanho e sexo. Por meio dos resultados obtidos observou-se que a idade da vaca ao parto, efeitos linear e quadrático e o grupo de contemporâneos foram significativos (P<0,0001) para as características avaliadas. As médias estimadas foram de 198,05 ± 40,64 kg, 0,790 ± 0,198 kg dia-1e 218,05 ± 67,18 dias para P205, GMD e D160, respectivamente. Os machos foram 4,67 kg mais pesados (197,17 kg) do que as fêmeas. No efeito de categoria animal as fêmeas selecionadas mostraram-se 2,3% superiores aos machos. Animais nascidos na estação da seca foram 1,6% mais leves em relação aos que nasceram nas águas (197,18 kg). Assim, as avaliações dos efeitos ambientais tornam-se importantes e devem ser consideradas no modelo de análise.

Assuntos

RESUMO

We aimed to evaluate environmental effects on pre-weaning traits of Santa Gertrudis cattle. We used 213 standardized records for adjusted 205-day weight at weaning (W205), average daily gain from birth to weaning (AGD), and number of days to gain 160 kg from birth to weaning (D160), obtained from the Santa Gertrudis Breeders Association for animals born between 1990 and 1997. The files were edited with information regarding cow age at calving (CAC) and contemporary group (CG),for which the effects of year and season of birth, animal category, herd, and sex were considered. It was observed that cow age at calving, which had linear and quadratic effects, and effect of contemporary group were significant (P<0.0001) for the evaluated traits. Estimated averages were 198.05 ± 40.64 kg, 0.790 ± 0.198 kg day-1,and 288.05 ± 67.18 days for W205, ADG, and D160, respectively. Males were 4.67 kg heavier (197.17 kg) than females, on average. Regarding the animal category effect, the classified females were 2.3% heavier than the unclassified males, on average. On average, animals born in the dry season were 1.6% lighter than those born in the rainy season (197.18 kg). Thus, environmental effects are important and should be considered in any analysis model.(AU)

O objetivo deste estudo foi avaliar os efeitos ambientais sobre as características da pré-desmama em bovinos da raça Santa Gertrudis. Foram utilizados 213 registros de peso à desmama padronizado aos 205 dias (P205), ganho médio diário do nascimento à desmama (GMD) e número de dias para ganhar 160 kg do nascimento até a desmama (D160), oriundos da Associação dos Criadores de Santa Gertrudis, de animais nascidos no período de 1990 a 1997. Os arquivos foram editados com as informações da idade da vaca ao parto (IVP) e grupo de contemporâneos (GC) que considerou os efeitos de ano e estação de nascimento, categoria animal, rebanho e sexo. Por meio dos resultados obtidos observou-se que a idade da vaca ao parto, efeitos linear e quadrático e o grupo de contemporâneos foram significativos (P<0,0001) para as características avaliadas. As médias estimadas foram de 198,05 ± 40,64 kg, 0,790 ± 0,198 kg dia-1e 218,05 ± 67,18 dias para P205, GMD e D160, respectivamente. Os machos foram 4,67 kg mais pesados (197,17 kg) do que as fêmeas. No efeito de categoria animal as fêmeas selecionadas mostraram-se 2,3% superiores aos machos. Animais nascidos na estação da seca foram 1,6% mais leves em relação aos que nasceram nas águas (197,18 kg). Assim, as avaliações dos efeitos ambientais tornam-se importantes e devem ser consideradas no modelo de análise.(AU)

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RESUMO

In closed rabbit lines selected for prolificacy at the Polytechnic University of Valencia, genetic responses are predicted using BLUP. With a standard additive BLUP model and year-season (YS) effects fitted as fixed, genetic trends were overestimated compared to responses estimated using control populations obtained from frozen embryos. In these lines, there is a confounding between genetic trend, YS effects and inbreeding, and the role of dominance is uncertain. This is a common situation in data from reproductively closed selection lines. This paper fits different genetic evaluation models to data of these lines, aiming to identify the source of these biases: dominance, inbreeding depression and/or an ill-conditioned model due to the strong collinearity between YS, inbreeding and genetic trend. The study involved three maternal lines (A, V and H) and analysed two traits, total born (TB) and the number of kits at weaning (NW). Models fitting YS effect as fixed or random were implemented, in addition to additive genetic, permanent environment effects and non-inbred dominance deviations effects. When YS was fitted as a fixed effect, the genetic trends were overestimated compared to control populations, inbreeding had an apparent positive effect on litter size and the environmental trends were negative. When YS was fitted as random, the genetic trends were compatible with control populations results, inbreeding had a negative effect (lower prolificacy) and environmental trends were flat. The model fitting random YS, inbreeding and non-inbred dominance deviations yielded the following ratios of additive and dominance variances to total variance for NW: 0.06 and 0.01 for line A, 0.06 and 0.00 for line V and 0.01 and 0.08 for line H. Except for line H, dominance deviations seem to be of low relevance. When it is confounded with inbreeding as in these lines, fitting YS effect as random allows correct estimation of genetic trends.

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The objective of this study was to verify the reproductive efficiency expressed by traits, interval from first to second calving (IDP), number of services per conception to the first calving (NSC1), number of services per conception for the second calving (NSC2), service period from the first to the second calving (PS) and gestation lenght (PG) of Holstein heifers. Data from 377 heifers from two herds, one in Santa Cruz do Rio Pardo, São Paulo and another in Rolândia, Paraná were analysed. The statistical model to analyze IDP, NSC1, NSC2, PS and PG included the fixed effect of Contemporary Group (CG). To analyze PG, it was also considered the effect of calf sex. To evaluate the growth performance and age at first calving (AFC), data from 360 Holstein heifers belonging to property in Rolândia were analysed. The model included the fixed effects of contemporary groups (CG) and average daily gain from birth to 15 months (ADG). A similar model was used to analyze weigth at 458 dias (W458) and ADG, therefore considering only CG. The overall means of IDP, NSC1, NSC2, PS and PG, were 14.96 ± 3.94 months; 1.35 ± 0.71 services, 2.86 ± 2.37 services, 178.83 ± 118.73 days; 276.67± 5.65 days, respectively. Correlations were observed between the traits IDP and NSC2 of 72% (P 0.0001), between IDP and PS of 98% (P 0.0001) and between NCS2 and PS of 72% (P 0.0001). The gestation length

Objetivou-se neste trabalho analisar os componentes de eficiência reprodutiva, expressos pelas características, intervalo do primeiro para o segundo parto (IEP), número de serviços por concepção para o primeiro parto (NSC1), número de serviços por concepção para o segundo parto (NSC2), período de serviço (PS) e período de gestação (PG), além da idade ao primeiro parto (IPP) e desenvolvimento ponderal até os 15 meses de idade. Foram utilizados dados de 377 novilhas, de dois rebanhos, sendo um em Santa Cruz do Rio Pardo, São Paulo e outro em Rolândia, Paraná. O modelo estatístico para IEP, NSC1, NSC2, PS e PG incluiu o efeito fixo de Grupo de Contemporâneas (GC). Para analisar PG, além de GC, foi também considerado o efeito de sexo da cria. Para avaliar o peso corrigido para 458 dias (P458), ganho médio diário do nascimento aos 15 meses (GMD) e IPP de 360 novilhas do rebanho pertencente à propriedade em Rolândia, foi utilizado um modelo fixo com efeito (GC). Para avaliar IPP foi utilizado GMD como covariável, além do efeito fixo de GC. As médias estimadas para IEP, NSC1, NSC2, PS e PG, foram respectivamente 14,96 ± 3,94 meses; 1,35 ± 0,71 serviços, 2,86 ± 2,37 serviços; 178,83 ± 118,73 dias; 276,67± 5,65 dias. Foram verificadas correlações entre as variáveis IEP e NSC2 de 72% (P 0,0001), entre IEP e PS de 98% (P 0,0001) e entre NSC2 e PS de 72% (P 0,0001). A duração da g

RESUMO

The objective of this study was to verify the reproductive efficiency expressed by traits, interval from first to second calving (IDP), number of services per conception to the first calving (NSC1), number of services per conception for the second calving (NSC2), service period from the first to the second calving (PS) and gestation lenght (PG) of Holstein heifers. Data from 377 heifers from two herds, one in Santa Cruz do Rio Pardo, São Paulo and another in Rolândia, Paraná were analysed. The statistical model to analyze IDP, NSC1, NSC2, PS and PG included the fixed effect of Contemporary Group (CG). To analyze PG, it was also considered the effect of calf sex. To evaluate the growth performance and age at first calving (AFC), data from 360 Holstein heifers belonging to property in Rolândia were analysed. The model included the fixed effects of contemporary groups (CG) and average daily gain from birth to 15 months (ADG). A similar model was used to analyze weigth at 458 dias (W458) and ADG, therefore considering only CG. The overall means of IDP, NSC1, NSC2, PS and PG, were 14.96 ± 3.94 months; 1.35 ± 0.71 services, 2.86 ± 2.37 services, 178.83 ± 118.73 days; 276.67± 5.65 days, respectively. Correlations were observed between the traits IDP and NSC2 of 72% (P 0.0001), between IDP and PS of 98% (P 0.0001) and between NCS2 and PS of 72% (P 0.0001). The gestation length

Objetivou-se neste trabalho analisar os componentes de eficiência reprodutiva, expressos pelas características, intervalo do primeiro para o segundo parto (IEP), número de serviços por concepção para o primeiro parto (NSC1), número de serviços por concepção para o segundo parto (NSC2), período de serviço (PS) e período de gestação (PG), além da idade ao primeiro parto (IPP) e desenvolvimento ponderal até os 15 meses de idade. Foram utilizados dados de 377 novilhas, de dois rebanhos, sendo um em Santa Cruz do Rio Pardo, São Paulo e outro em Rolândia, Paraná. O modelo estatístico para IEP, NSC1, NSC2, PS e PG incluiu o efeito fixo de Grupo de Contemporâneas (GC). Para analisar PG, além de GC, foi também considerado o efeito de sexo da cria. Para avaliar o peso corrigido para 458 dias (P458), ganho médio diário do nascimento aos 15 meses (GMD) e IPP de 360 novilhas do rebanho pertencente à propriedade em Rolândia, foi utilizado um modelo fixo com efeito (GC). Para avaliar IPP foi utilizado GMD como covariável, além do efeito fixo de GC. As médias estimadas para IEP, NSC1, NSC2, PS e PG, foram respectivamente 14,96 ± 3,94 meses; 1,35 ± 0,71 serviços, 2,86 ± 2,37 serviços; 178,83 ± 118,73 dias; 276,67± 5,65 dias. Foram verificadas correlações entre as variáveis IEP e NSC2 de 72% (P 0,0001), entre IEP e PS de 98% (P 0,0001) e entre NSC2 e PS de 72% (P 0,0001). A duração da g