ABSTRACT
This study investigated the effects of genotype-environment interaction on yearling weight, age at first calving and post-weaning weight gain in Nellore cattle using multi-trait reaction norm models. The environmental gradient was defined as a function of the mean yearling weight of the contemporary groups. A first-order random regression sire model with four classes of residual variance was used in the analyses and Bayesian methods were applied to estimate the (co)variance components. The heritability estimates ranged from 0.284 to 0.547, 0.222 to 0.316 and 0.256 to 0.522 for yearling weight, age at first calving and post-weaning weight gain, respectively. The lowest genetic correlations between environment groups for each trait were 0.38, 0.02 and 0.04 for yearling weight, age at first calving and post-weaning weight gain, respectively. Differences in the correlation estimates were observed between traits in the same environments, with the magnitude of the estimates tending toward zero as the environment improved. The results highlight the importance of including genotype-environment interactions in genetic evaluation programs considering the differences observed between environmental groups not only in terms of heritability, but also of genetic correlations.
Subject(s)
Bayes Theorem , Breeding , Cattle/genetics , Cattle/physiology , Gene-Environment Interaction , Genotype , Quantitative Trait, Heritable , Reproduction/physiology , Age Factors , Animals , Body Weight , Female , Male , Weaning , Weight GainABSTRACT
Beef cattle producers in Brazil use body weight traits as breeding program selection criteria due to their great economic importance. The objectives of this study were to evaluate different animal models, estimate genetic parameters, and define the most fitting model for Brahman cattle body weight standardized at 120 (BW120), 210 (BW210), 365 (BW365), 450 (BW450), and 550 (BW550) days of age. To estimate genetic parameters, single-, two-, and multi-trait analyses were performed using the animal model. The likelihood ratio test was verified between all models. For BW120 and BW210, additive direct genetic, maternal genetic, maternal permanent environment, and residual effects were considered, while for BW365 and BW450, additive direct genetic, maternal genetic, and residual effects were considered. Finally, for BW550, additive direct genetic and residual effects were considered. Estimates of direct heritability for BW120 were similar in all analyses; however, for the other traits, multi-trait analysis resulted in higher estimates. The maternal heritability and proportion of maternal permanent environmental variance to total variance were minimal in multi-trait analyses. Genetic, environmental, and phenotypic correlations were of high magnitude between all traits. Multi-trait analyses would aid in the parameter estimation for body weight at older ages because they are usually affected by a lower number of animals with phenotypic information due to culling and mortality.
Subject(s)
Body Weight/genetics , Breeding/methods , Cattle/growth & development , Cattle/genetics , Models, Genetic , Multifactorial Inheritance/genetics , Phenotype , Age Factors , Animals , Body Weight/physiology , Brazil , Likelihood Functions , Linear Models , Multifactorial Inheritance/physiology , WeaningABSTRACT
A work was done at "Centro de Biologia Aquática - Universidade Católica de Goiás", from August 16 to November 6, 1995, to evaluate the use of brewery by-products as feed for fish growth. Six outdoor tanks (60 m2) were stocked with Colossoma macropomum fingerlings weighing 1.12 ± 0.8 g and at a density of one fish/m2. Feeding pattern was kept in a 6% biomass proportion of each tank daily. A 34% Crude Protein commercial ration was used as control (Treatment II) resulting in a mean final weight of 24.42 g with an average daily gain of 0.34 g against 17.84 g and 0.24 g for treatment I; brewery by-products with 36% Crude Protein, respectively. There was no statistical difference (P>0.05) in apparent feed conversion and mean final weight between treatments, which approves the use of brewery by-products as a partial ingredient in rations for fishes.
Um experimento foi conduzido no Centro de Biologia Aquática da Universidade Católica de Goiás no período de 16 de agosto a 6 de novembro de 1995. Foram utilizados seis viveiros de 60 m2, escavados em terreno natural e povoados com alevinos de tambaqui na densidade de 1 peixe/m2 e peso médio inicial de 1,12 ± 0,8 g. Utilizaram-se, nos tratamentos I e II, resíduo de cervejaria contendo 36% de proteína bruta (I) e ração comercial com 34% de proteína bruta (II), fornecidos na proporção de 6% da biomassa de cada viveiro. Os peixes apresentaram peso médio final de 24,42 g com a ração comercial e 17,84 g com o resíduo de cervejaria e conversão alimentar de 1,15 e 1,29, respectivamente. O resultado demonstra a viabilidade do uso do resíduo de cervejaria na alimentação de tambaqui.
ABSTRACT
A work was done at "Centro de Biologia Aquática - Universidade Católica de Goiás", from August 16 to November 6, 1995, to evaluate the use of brewery by-products as feed for fish growth. Six outdoor tanks (60 m2) were stocked with Colossoma macropomum fingerlings weighing 1.12 ± 0.8 g and at a density of one fish/m2. Feeding pattern was kept in a 6% biomass proportion of each tank daily. A 34% Crude Protein commercial ration was used as control (Treatment II) resulting in a mean final weight of 24.42 g with an average daily gain of 0.34 g against 17.84 g and 0.24 g for treatment I; brewery by-products with 36% Crude Protein, respectively. There was no statistical difference (P>0.05) in apparent feed conversion and mean final weight between treatments, which approves the use of brewery by-products as a partial ingredient in rations for fishes.
Um experimento foi conduzido no Centro de Biologia Aquática da Universidade Católica de Goiás no período de 16 de agosto a 6 de novembro de 1995. Foram utilizados seis viveiros de 60 m2, escavados em terreno natural e povoados com alevinos de tambaqui na densidade de 1 peixe/m2 e peso médio inicial de 1,12 ± 0,8 g. Utilizaram-se, nos tratamentos I e II, resíduo de cervejaria contendo 36% de proteína bruta (I) e ração comercial com 34% de proteína bruta (II), fornecidos na proporção de 6% da biomassa de cada viveiro. Os peixes apresentaram peso médio final de 24,42 g com a ração comercial e 17,84 g com o resíduo de cervejaria e conversão alimentar de 1,15 e 1,29, respectivamente. O resultado demonstra a viabilidade do uso do resíduo de cervejaria na alimentação de tambaqui.