Parâmetros genéticos para características de crescimento e reprodução de bovinos da raça Canchim

Abstract

Resumo -O objetivo deste trabalho foi estimar parâmetros genéticos para idades ao primeiro (IPP) e segundo partos (ISP), idades ao primeiro (IPP PEN ) e segundo partos penalizadas (ISP PEN ), e a ocorrência de parto até os 38 meses de idade (PP 38 ), em bovinos da raça Canchim, bem como estimar as relações genéticas entre essas características e o peso (PE 420 ) de machos e femêas e a circunferência escrotal (CE 420 ) de novilhos, medidos aos 420 dias de idade. Foram estimados parâmetros genéticos em análises bicaracterísticas, por meio de inferência bayesiana. As análises foram realizadas entre CE 420 e PE 420 e as características reprodutivas medidas em fêmeas. As características reprodutivas das fêmeas devem apresentar baixa resposta à seleção, e mudanças no manejo e nas condições ambientais melhoram tais características. A seleção quanto ao maior peso aos 420 dias de idade não deve provocar mudanças nas características reprodutivas em fêmeas, enquanto a seleção para o aumento da circunferência escrotal, na mesma idade, contribui para melhorar tais características.Termo para indexação: bovinos de corte, circunferência escrotal, idade ao parto, ocorrência de parição, peso. Genetic parameters for growth and reproductive traits of Canchim breedAbstract -The objective of this work was to estimate genetic parameters for age at first (AFC) and at second (ASC) calvings, penalized age at first (AFC PEN ) and at second (ASC PEN ) calvings, and occurrence of calving until 38 months of age (PP 38 ) in Canchim breed, as well as to estimate the genetic correlations between these traits with weight (PE 420 ) of males and females, and scrotal circumference (CE 420 ) measured at 420 days of age. Genetic parameters were estimated by two-trait analyses using the Bayesian inference. The analyses were performed between CE 420 and PE 420 , and the reproductive traits measured in the females. The female reproductive traits should show low response to selection, and changes in the management and environmental conditions improve these traits. Selection for the higher weight at 420 days of age does not change female reproductive traits, while selection to increase scrotal circumference, at the same age, contributes to improve such traits.

Genetic analyses on bodyweight, reproductive, and carcass traits in composite beef cattle

“…The observed average for bodyweight, reproductive, and carcass traits (Table 2) are in agreement with previous studies of the Canchim breed (Andrade et al 2008;Baldi et al 2010;Barichello et al 2010;Buzanskas et al 2010;Meirelles et al 2010;Borba et al 2011). The variance components and heritabilities estimated in single-trait analyses are presented in Table 3.…”

“…A substantial proportion of the variation in the bodyweights, scrotal circumferences and carcass traits was associated with the additive genetic term indicating that these traits may respond to selection in Canchim cattle. For BW, WW, YW, and SCW the direct heritability estimates were in the range found in the literature for the Canchim breed, which ranged from 0.25 to 0.41 (BW), 0.23 to 0.48 (WW), 0.24 to 0.29 (YW), and 0.17 to 0.52 (SCW) (Alencar et al 1993;Silva et al 2000;Gianlorenço et al 2003;Andrade et al 2008;Baldi et al 2010;Buzanskas et al 2010;Borba et al 2011). Direct heritability estimates for BW obtained by Boligon et al (2011), El-Saied et al (2006), and Meyer (1995) were equal to 0.30 AE 0.01, 0.36 AE 0.04, and 0.38 for Nellore, Charolais, and Australian Angus cattle.…”

“…For SCW, Boligon et al (2011) and Morris et al (2000) found heritability estimates of 0.39 AE 0.01 and 0.37 AE 0.06, respectively for Nellore and Angus breeds. Alencar et al (1993) and Borba et al (2011) found lower heritability estimates for SCY in Canchim. According to Silva et al (2013a) and Garmyn et al (2011), heritability estimates for SCY in Nellore and Angus, respectively, were equal to 0.40 AE 0.02 and 0.46 AE 0.08…”

Genetic parameters for carcass traits and body weight using a Bayesian approach in the Canchim cattle

“…Previous studies in Canchim cattle reported heritability for BW ranging from 0.23 to 0.54 (Alencar et al,1993;Mascioli et al, 1996;Meirelles et al, 2010;Borba et al, 2011), which was similar to the heritability estimated in this study (0.44). Our results also agreed with a number of studies investigating heritability of growth traits, which showed that these traits have moderate to high heritability in most beef cattle breeds (Marshall, 1994;Gregory et al, 1995;Utrera and Van Vleck, 2004).…”

Mixing models and stable isotopes as tools for research on feeding aquatic organisms

“…The convergence evaluated by the method of GEWEKE (1992) performed a division of variables generated by simulation, with respect to the two means in the quantiles (0.1 and 0.5). Thus, this test used the comparison of the initial and final values of the Markov chain to verify convergence faults; Moraes & Henry-Silva. therefore, with the hypothesis of nullity tested, values of probability below 0.05 indicated evidence contrary to the convergence of chains (BORBA et al, 2011).…”