Polinômios para modelar a trajetória de crescimento de tourinhos em provas de ganho em peso.

Este trabalho foi realizado com o objetivo de identificar o tipo de polinômio e a ordem de ajuste mais adequados para modelagem da trajetória média de crescimento de tourinhos Nelore, MA (21/32 Charolês + 11/32 Nelore) e Canchim em provas de ganho em peso. As trajetórias médias de crescimento foram ajustadas por meio de polinômios ordinários e de Legendre (linear até quíntico) e Bsplines quadráticos (com dois até seis intervalos regulares). Nas comparações envolvendo apenas os modelos com os mesmos números de parâmetros, os B-splines promoveram os melhores ajustes. O modelo com polinômio B-spline com seis intervalos foi considerado como o melhor para as raças Canchim e MA. Para a raça Nelore, o B-spline com quatro intervalos foi o modelo com melhor ajuste de acordo com o Critério de Informação de Akaike Consistente

Estimativas de parâmetros genéticos para características de temperamento em gado Canchim.

Objetivou-se, neste trabalho, a estimação de parâmetros genéticos e fenotípicos de diferentes medidas de temperamento em bovinos da raça Canchim, visando a possibilidade de inclusão dessas características como critério de seleção. Foram avaliadas 2089 informações provenientes de 697 animais, nascidos entre 2012 e 2015, provenientes da fazenda Canchim, pertencente à Embrapa Pecuária Sudeste. O temperamento foi avaliado pelas características: escore composto de temperamento (ECT), tempo de saída (TS) e reatividade (REAT) e o escore total (ET), derivado do ECT. Os registros de temperamento foram obtidos nas fases: desmama (210 dias), ano e sobreano (450 dias). O grupo de contemporâneos (GC) foi formado por sexo e ano de nascimento. As características de temperamento foram analisadas utilizando-se um modelo animal, por análises uni e bi-característica. As medidas de temperamento apresentaram estimativas de herdabilidade que variaram de 0,07±0,142 (TS na desmama) a 0,36±0,240 (TS, ao sobreano). Os resultados demonstram que o temperamento pode vir a ser utilizado como critério de seleção visando obter animais mais dóceis, sugerindo que a seleção tenha efeito a médio e longo prazo

Uncovering sub-structure and genomic profiles in across-countries subpopulations of Angus Cattle.

Highlighting genomic profiles for geographically distinct subpopulations of the same breed may provide insights into adaptation mechanisms to different environments, reveal genomic regions divergently selected, and offer initial guidance to joint genomic analysis. Here, we characterized similarities and differences between the genomic patterns of Angus subpopulations, born and raised in Canada (N?= 382) and Brazil (N = 566). Furthermore, we systematically scanned for selection signatures based on the detection of autozygosity islands common between the two subpopulations, and signals of divergent selection, via FST and varLD tests. The principal component analysis revealed a sub-structure with a close connection between the two subpopulations. The averages of genomic relationships, inbreeding coefficients, and linkage disequilibrium at varying genomic distances were rather similar across them, suggesting non-accentuated differences in overall genomic diversity. Autozygosity islands revealed selection signatures common to both subpopulations at chromosomes 13 (63.77?65.25 Mb) and 14 (22.81?23.57 Mb), which are notably known regions affecting growth traits. Nevertheless, further autozygosity islands along with FST and varLD tests unravel particular sites with accentuated population subdivision at BTAs 7 and 18 overlapping with known QTL and candidate genes of reproductive performance, thermoregulation, and resistance to infectious diseases. Our findings indicate overall genomic similarity between Angus subpopulations, with noticeable signals of divergent selection in genomic regions associated with the adaptation in different environments

Polynomials to model the growth of young bulls in performance tests

The use of polynomial functions to describe the average growth trajectory and covariance functions of Nellore and MA (21/32 Charolais+11/32 Nellore) young bulls in performance tests was studied. The average growth trajectories and additive genetic and permanent environmental covariance functions were fit with Legendre (linear through quintic) and quadratic B-spline (with two to four intervals) polynomials. In general, the Legendre and quadratic B-spline models that included more covariance parameters provided a better fit with the data. When comparing models with the same number of parameters, the quadratic B-spline provided a better fit than the Legendre polynomials. The quadratic B-spline with four intervals provided the best fit for the Nellore and MA groups. The fitting of random regression models with different types of polynomials (Legendre polynomials or B-spline) affected neither the genetic parameters estimates nor the ranking of the Nellore young bulls. However, fitting different type of polynomials affected the genetic parameters estimates and the ranking of the MA young bulls. Parsimonious Legendre or quadratic B-spline models could be used for genetic evaluation of body weight of Nellore young bulls in performance tests, whereas these parsimonious models were less efficient for animals of the MA genetic group owing to limited data at the extreme ages.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Random regression models with B-splines to estimate genetic parameters for body weight of young bulls in performance tests.

The objective of this study was to estimate genetic parameters for body weight of beef cattle in performance tests. Different random regression models with quadratic B-splines and heterogeneous residual variance were fitted to estimate covariance functions for body weights of Nellore and crossbred Charolais × Nellore bulls. The criteria −2 residual log-likelihood (−2RLL), Akaike Information Criterion (AIC), and consistent AIC (CAIC) were used to choose the most appropriate model. For Nellore bulls, residual variance was modeled with six classes of age, and direct additive genetic and permanent environment effects were modeled with quadratic B-splines with two and one intervals, respectively. For crossbred bulls, quadratic B-splines with one interval fitted direct additive genetic and permanent environment effects and nine classes of age were needed to fit residual variance. Pooling classes of age with up to 40% in difference of residual variances does not compromise the fit of the model. Heritability for body weight in performance tests are moderate (>0.25, for crossbred bulls) to high (>0.5, for Nellore bulls) and genetic correlation between weights over the test are also high (>0.65). Then, selection of young bulls in performance test is an efficient tool to increase body weight in beef cattle.Made available in DSpace on 2019-01-11T23:34:49Z (GMT). No. of bitstreams: 1 RamdomRegressionModels.pdf: 1787275 bytes, checksum: f4f686d9435ae56e7939c6f2edc9520c (MD5) Previous issue date: 2018-10-19bitstream/item/184758/1/RamdomRegressionModels.pd

Modelagem das trajetórias médias do peso vivo e do rendimento de carcaça de tilápias do Nilo (Oreochromis niloticus) por meio de funções B-spline

Employing the method of least squares and quadratic B-spline polynomials, different statistical models were tested to identify the most appropriate to model the mean trajectories of live weight and carcass yield of Nile tilapia (Oreochromis niloticus). Data of live weight (8,758) and carcass yield (2,042) of tilapias with ages between 106 and 245 days were obtained from 72 families derived from 36 males and 72 females. The sex and tank variables were considered as classificatory and the coefficients of quadratic polynomials B-spline of two to five intervals of the same size were used as covariables. According to most fit criteria used, the models with quadratic B-spline polynomial with five intervals of the same size presented the best adjustments. The increase in number of intervals of B-spline polynomial improved the fit of the polynomials to the data. The inclusion of classificatory effects from sex, tank, the interaction of these effects and the quadratic polynomial B-spline nested in this interaction indicated that, over time, each sex, grown in different tank, presented different mean trajectory, necessitating the inclusion of nesting time in the interaction sex x tank in order to avoid the under or overestimation of breeding values of the selection candidates in breeding programs of this species.Empregando o método dos quadrados mínimos e polinômios B-spline quadráticos, diferentes modelos estatísticos foram testados para identificar o mais apropriado para modelar as trajetórias médias do peso vivo e do rendimento de carcaça de tilápias do Nilo (Oreochromis niloticus). Dados de peso vivo (8.758) e de rendimento de carcaça (2.042) de tilápias com idades entre 106 e 245 dias foram obtidos de 72 famílias provenientes de 36 machos e 72 fêmeas. As variáveis sexo e tanque de criação foram consideradas como classificatórias, e os coeficientes dos polinômios B-spline quadráticos com dois a cinco intervalos de mesmo tamanho foram utilizados como covariáveis. Segundo a maioria dos critérios de ajuste utilizados, os modelos com polinômio B-spline quadrático com cinco intervalos de mesmo tamanho apresentaram os melhores ajustes. O aumento do número de intervalos do polinômio B-spline melhorou o ajuste dos polinômios aos dados. A inclusão dos efeitos classificatórios de sexo, tanque de criação, interação entre esses efeitos e polinômio B-spline quadrático aninhado a essa interação indicou que, com o decorrer do tempo, cada sexo, cultivado em diferente tanque, apresentou trajetória média diferente, sendo necessária a inclusão do aninhamento do tempo na interação sexo x tanque de criação para que, em programas de melhoramento genético da espécie, os valores genéticos dos candidatos à seleção não sejam sub ou superestimados

Short communication: Variable number of tandem repeat polymorphisms in DGAT1 gene of buffaloes (Bubalus bubalis) is associated with milk constituents

The diacylglycerol-O-transferase 1 gene is a positional and functional candidate for milk composition traits. The objective of this study was to evaluate the segregation of the variable number of tandem repeat polymorphisms in the regulatory region of diacylglycerol- O-transferase 1 gene in a water buffalo herd, and to assess the association of this mutation with milk production traits. For this purpose, 196 Murrah buffalo cows were genotyped by PCR. The association of the marker with total milk, fat, and protein yields at 305 d of lactation, milk fat and protein percentage, and somatic cell scores were evaluated by single-trait analyses using a generalized mixed model. Two segregating alleles were identified in the population. The allele with 2 repeats affected fat percentage favorably. The present results suggest that this polymorphism is an interesting marker to include in the genetic evaluation of buffaloes.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP