Evaluation of posture rating curves of a female line of broilers

Objetivou-se com este trabalho estimar os par?metros gen?ticos e fenot?picos dos par?metros da curva de produ??o de ovos, pelo o modelo de polin?mios segmentados (x p- idade das aves ao pico de postura, P- n?vel de produ??o no pico, s - taxa de decr?scimo semanal na produ??o de ovos ap?s o pico e t - tempo entre o in?cio da postura e o pico de produ??o de ovos). Foram utilizados dados da produ??o de ovos semanal da 25? at? 64? semanas de idade, provenientes de 2.398 matrizes de uma linhagem de frangos de corte. A estima??o dos componentes de covari?ncias, herdabilidade e correla??es para esses par?metros da curva de postura foram obtidas por m?xima verossimilhan?a restrita. As tend?ncias gen?ticas foram estimadas com as m?dias dos valores gen?ticos dos par?metros da curva em fun??o do ano de nascimento das matrizes. As m?dias das herdabilidades foram de baixa a m?dia magnitudes, 0,25 (x p), 0,18 (P), 0,17 (s) e 0,10 (t). As correla??es gen?ticas entre o par?metro t e os demais par?metros da curva foram positivas, variando de 0,21 at? 1,00, sendo menor entre t e s e maior entre os par?metros x p e t. Entre os par?metros x p e P, a correla??o tamb?m foi positiva, de magnitude m?dia (0,39). As correla??es foram negativas entre os par?metros s e x p e s e P, apresentando-se menor entre s e x p (-0,17) e maior entre s e P (-0,91). As tend?ncias gen?ticas encontradas para os par?metros indicaram uma redu??o no tempo entre o in?cio e pico de produ??o e idade ao pico de postura. O n?vel de produ??o apresentou uma queda no valor gen?tico ao longo do per?odo avaliado. Pode-se observar poss?vel ganho gen?tico para os par?metros da curva de produ??o de ovos, contudo, deve-se atentar para as correla??es gen?ticas positivas entre os par?metro x p e P, o que pode levar a um aumento do n?vel de produ??o e a um aumento na idade ao pico de produ??o. O mesmo caso acontece com os par?metros x p e s, indicando que as aves mais precoces ao pico poder?o apresentar menor persist?ncia.Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)The objective of this study was to estimate genetic parameters and phenotypic parameters of egg production curve, using the segmented polynomial model(x p- the peak age of the birds in attitude, P - at peak production level, s - rate of decline in weekly egg production after peak, and t - time between the onset of lay and peak egg production). We used data from the weekly egg production from 25 to 64 weeks of age from 2,398 arrays of a lineage of broilers chickens. Estimation of covariance components, heritability and correlations for these parameters curve posture were obtained by restricted maximum likelihood. Genetic trends were estimated with the average breeding values the of parameters of the curve as a function of birth year of the arrays. The mean heritabilities were low to medium magnitude, 0.25 (x p), 0.18 (P), 0.17 (s) e 0.10 (t). Genetic correlations among the parameter t and the other parameters of the curve were positive ranging from 0.21 to 1.00, being lower between t and s, and higher between the parameters x p and t. Between the parameters x p and P the correlation was also positive, of an average magnitude (0.39). Correlations were negative between parameters s and x p, and s and P, presenting itself lower between s and x p (-0.17) and higher between s and P (-0.91). The genetic trends found for the parameters of the model indicated a reduction in time between the production's onset and peak, and age at production's peak. The level of production showed a decline in breeding value over the period evaluated. It can be observed a potential genetic gain for the egg's production parameters' curve; however, it must be paid special attention to the positive genetic correlations between the parameter x p and P. What can lead to an increase in the level of production and may lead to an increase in age at peak production. The same applies to the parameters x p indicating that birds with earlier peaks may present lower persistence

Simulation study of linear mixed models with contaminated normal distribution in animal breeding

Objetivou-se com esse trabalho comparar estimativas de componentes de vari?ncias obtidas por meio de modelos lineares mistos Gaussianos e Robustos, via Amostrador de Gibbs, em dados simulados. Foram simulados 50 arquivos de dados com 1.000 animais cada um, distribu?dos em cinco gera??es, em dois n?veis de efeito fixo e tr?s valores fenot?picos distintos para uma caracter?stica hipot?tica, com diferentes n?veis de contamina??o. Exceto para os dados sem contamina??o, quando os modelos foram iguais, o modelo Robusto apresentou melhores estimativas da vari?ncia residual. As estimativas de herdabilidade foram semelhantes em todos os modelos, mas as an?lises de regress?o mostraram que os valores gen?ticos preditos com uso do modelo Robusto foram mais pr?ximos dos valores gen?ticos verdadeiros. Esses resultados sugerem que o modelo linear normal contaminado oferece uma alternativa flex?vel para estima??o robusta em melhoramento gen?tico animal.Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)The objective of this study was to compare Gaussian and Robust linear mixed models for the estimation of variance components by REML and Gibbs Sampling, using data from fifty simulated populations consisting of 1,000 animals distributed in 5 generations. Two levels of fixed effect and three hypothetical phenotypic values for a trait, with different levels of contamination were used in the simulations. Additive and residual variance estimates were similar for both REML and Bayesian inference using the Gaussian and Robust model. The best estimates of residual variance in the presence of contaminants were obtained by the Robust model. Estimates of heritability were similar for all models, but regression analyses indicated that predicted genetic values obtained by the robust model were more similar to real breeding values. These results suggest that the contaminated normal linear model is a flexible alternative for robust estimation in animal breeding

Performance, carcass characteristics and non-carcass components of Texel ? Santa In?s lambs fed fat sources and monensin

Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)Performance, carcass, non-carcass and commercial cuts and components of Texel ? Santa In?s crossbred lambs, managed in confinement and fed diets based on soybean oil, soybeans and a conventional diet, with or without the use of monensin (78 ppm dry matter basis) were evaluated. Thirty-six Texel ? Santa In?s lambs (18 males and 18 females) were managed in intensive systems. Animals were slaughtered after 87 days of confinement, and performance, carcass characteristics, weight and percentages of carcass and non-carcass components were evaluated. The animals fed the control diet had heavier carcass and parts than animals fed soybean, while the oil diet did not differ from the controls in most parameters. The animals fed soybean showed lower intake kg dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and metabolizable energy (ME) compared with animals fed the control diet, increased ether extract (EE) intake in kg, % body weight (BW) and metabolic weight (MW) and did not differ from the soybean oil diet. Animals receiving monensin had lower DM intake, OM, CP, EE, NDF, gross energy (GE) regardless of the expression, % kg BW, or % PM, than the animals that did not receive the additive. Males produced better and had heavier cuts than the females; the latter deposited subcutaneous fat earlier. Animals that received oil or soybean showed greater body weight and small intestine percentage. Soybean oil intake did not improve performance, carcass weights or parts of Santa Ines ? Texel lambs in confinement. Soybeans at 15% dry matter reduced energy intake and lamb performance. The use of monensin at 78 ppm on a dry matter basis is not recommended for lambs in confinement, especially if associated with oil or soybeans that may harm animal performance

Generalized linear mixed models for the genetic evaluation of binary reproductive traits: a simulation study

Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)The objective of this study was to evaluate the use of probit and logit link functions for the genetic evaluation of early pregnancy using simulated data. The following simulation/analysis structures were constructed: logit/logit, logit/probit, probit/logit, and probit/probit. The percentages of precocious females were 5, 10, 15, 20, 25 and 30% and were adjusted based on a change in the mean of the latent variable. The parametric heritability (h?) was 0.40. Simulation and genetic evaluation were implemented in the R software. Heritability estimates (h^2) were compared with h? using the mean squared error. Pearson correlations between predicted and true breeding values and the percentage of coincidence between true and predicted ranking, considering the 10% of bulls with the highest breeding values (TOP10) were calculated. The mean h^? values were under- and overestimated for all percentages of precocious females when logit/probit and probit/logit models used. In addition, the mean squared errors of these models were high when compared with those obtained with the probit/probit and logit/logit models. Considering (h^2), probit/probit and logit/logit were also superior to logit/probit and probit/logit, providing values close to the parametric heritability. Logit/probit and probit/logit presented low Pearson correlations, whereas the correlations obtained with probit/probit and logit/logit ranged from moderate to high. With respect to the TOP10 bulls, logit/probit and probit/logit presented much lower percentages than probit/probit and logit/logit. The genetic parameter estimates and predictions of breeding values of the animals obtained with the logit/logit and probit/probit models were similar. In contrast, the results obtained with probit/logit and logit/probit were not satisfactory. There is need to compare the estimation and prediction ability of logit and probit link functions

Performance and carcass characteristics of lambs fed diets with fat and vitamin E

Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)This experiment aimed to determine the influence of diets with inclusion of protected fat and vitamin E on performance, yield and carcass characteristics of feedlot lambs with different weights. Thirty-two non-castrated Santa Ines lambs were fed diets with a ratio of 40% forage and 60% concentrate ad libitum, with presence or absence of protected fat and/or vitamin E, in a total of four diets. Two weights of early containment were also considered: between 20 and 25 kg and between 30 and 35 kg. All animals were slaughtered at 84 days of confinement. Animals fed diets without addition of protected fat, regardless of the use of vitamin E, had the highest intakes of dry matter, crude protein, neutral detergent fiber and ash, and decreased intake of ether extract. The variables investigated did not affect daily weight gain and total gain. Feed conversion was better for the lighter confined animals not fed protected fat. The heavier feedlot lambs fed diets with vitamin E showed higher cold carcass. The warm carcass for the lighter animals confined fed with vitamin E, and the heavier ones, fed with protected fat and vitamin E, showed the best yields of cold carcass. Objective measures of the carcass cold had the highest mean for heavier feedlot lambs. The addition of fat in the diet reduces the intake of dry matter and increases the ether extract. Although the inclusion of vitamin has no effect on intake of nutrients, it protects the carcasses from losses during cooling, and weight differences at containment directly reflect the measures of the carcasses