Comparison of genetic parameters and estimated breeding values for worm resistance in meat sheep obtained using traditional and genomic models.

Gastrointestinal nematode infections have caused expressive losses in sheep production worldwide. The improvement of host genetic resistance to worms has been used as a strategy to mitigate this problem. In this sense, the inclusion of genomic information has shown potential to increase the accuracy of prediction of breeding values and speed up selection. In this study, we aimed to compare estimates of genetic parameters and breeding values for traits that indicate the resistance to gastrointestinal nematode infection in Santa Inês sheep using the pedigree-based BLUP or including genomic information. There were 1478 animals in the pedigree, of which 271 were genotyped using the OvineSNP50 BeadChip (Illumina, Inc.). The host resistance was assessed using the following traits: fecal nematode egg counts (FEC); FAMACHA score (FAMACHA); and resistance to gastrointestinal nematode infection (RGNI) as a combination of FEC, FAMACHA, body condition score, and hematocrit. The genetic parameters and breeding values were estimated using single- and multi-trait analyses. For RGNI, the heritability estimates ranged from 0.25 using the single-trait genomic model (S-H) to 0.54 using the traditional multi-trait model (M-A). The heritability estimates for FEC ranged from 0.06 to 0.36, using the single-trait pedigree-based model (S-A) and the multi-trait genomic model (M-H), respectively. For FAMACHA, the heritability estimates ranged from 0.46 (M-H) to 0.54 (M-A). Estimates of genetic correlation ranged from 0.22 to 0.69. The inclusion of genomic information provided gain in accuracy for all traits. All estimates of predictive ability obtained using genomic data in a multi-trait setting were higher than those obtained using single-trait models. The estimates of predictive ability ranged from 0.03 (S-A) to 0.46 (M-H). The heritability estimates obtained using genomic information showed that all traits evaluated are suitable for genomic selection. Despite the low accuracies obtained, the use of the genomic model provided more accurate estimates of breeding values in comparison to the pedigree-based model.

Genetic parameters for marbling and body score in Anglonubian goats using Bayesian inference via threshold and linear models.

OBJECTIVE: The aim of this study was to estimate (co) variance components and genetic parameters for categorical carcass traits using Bayesian inference via mixed linear and threshold animal models in Anglonubian goats. METHODS: Data were obtained from Anglonubian goats reared in the Brazilian Mid-North region. The traits in study were body condition score, marbling in the rib eye, ribeye area, fat thickness of the sternum, hip height, leg perimeter, and body weight. The numerator relationship matrix contained information from 793 animals. The single- and two-trait analyses were performed to estimate (co) variance components and genetic parameters via linear and threshold animal models. For estimation of genetic parameters, chains with 2 and 4 million cycles were tested. An 1,000,000-cycle initial burn-in was considered with values taken every 250 cycles, in a total of 4,000 samples. Convergence was monitored by Geweke criteria and Monte Carlo error chain. RESULTS: Threshold model best fits categorical data since it is more efficient to detect genetic variability. In two-trait analysis the contribution of the increase in information and the correlations between traits contributed to increase the estimated values for (co) variance components and heritability, in comparison to single-trait analysis. Heritability estimates for the study traits were from low to moderate magnitude. CONCLUSION: Direct selection of the continuous distribution of traits such as thickness sternal fat and hip height allows obtaining the indirect selection for marbling of ribeye.

Genetic parameters for carcass traits and body size in sheep for meat production.

The aim was to estimate the covariance components and genetic parameters of carcass traits and body size of meat sheep by employing animal models for single and multi-trait analyses. Data were collected from herds of adult Santa Ines sheep. The ribeye area, subcutaneous fat thickness, and rump fat thickness, evaluated in vivo by ultrasound images of the carcass; and morphometric traits: fat depth, rump height, chest circumference, chest depth, body length, and rump length were measured. The covariance components and genetic parameters for these traits were estimated by restricted maximum likelihood methodology, considering the random additive direct-genetic effects of the animal and errors associated with each observation, and the fixed effects of the contemporary group, the type of birth, and the age of the animal classes. Heritability estimates for carcass traits and animal size were higher in the three-trait analyses than in the single-trait analyses. The magnitudes of the values obtained indicate that genetic progress can be achieved by selection based on the traits studied.

Nonlinear mixed models for characterization of growth trajectory of New Zealand rabbits raised in tropical climate.

OBJECTIVE: The identification of nonlinear mixed models that describe the growth trajectory of New Zealand rabbits was performed based on weight records and carcass measures obtained using ultrasonography. METHODS: Phenotypic records of body weight (BW) and loin eye area (LEA) were collected from 66 animals raised in a didactic-productive module of cuniculture located in the southern Piauí state, Brazil. The following nonlinear models were tested considering fixed parameters: Brody, Gompertz, Logistic, Richards, Meloun 1, modified Michaelis-Menten, Santana, and von Bertalanffy. The coefficient of determination (R2), mean squared error, percentage of convergence of each model (%C), mean absolute deviation of residuals, Akaike information criterion (AIC), and Bayesian information criterion (BIC) were used to determine the best model. The model that best described the growth trajectory for each trait was also used under the context of mixed models, considering two parameters that admit biological interpretation (A and k) with random effects. RESULTS: The von Bertalanffy model was the best fitting model for BW according to the highest value of R2 (0.98) and lowest values of AIC (6,675.30) and BIC (6,691.90). For LEA, the Logistic model was the most appropriate due to the results of R2 (0.52), AIC (783.90), and BIC (798.40) obtained using this model. The absolute growth rates estimated using the von Bertalanffy and Logistic models for BW and LEA were 21.51g/d and 3.16 cm2, respectively. The relative growth rates at the inflection point were 0.028 for BW (von Bertalanffy) and 0.014 for LEA (Logistic). CONCLUSION: The von Bertalanffy and Logistic models with random effect at the asymptotic weight are recommended for analysis of ponderal and carcass growth trajectories in New Zealand rabbits. The inclusion of random effects in the asymptotic weight and maturity rate improves the quality of fit in comparison to fixed models.

Avaliação ultrassonográfica dos tendões flexores dos membros anteriores em equinos de vaquejada na microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil / Ultrasound evaluation of the flexor tendons of the forelimbs in horses in vaquejada horses in theAlto Médio Gurgueia, South of Piauí, Brazil

Objetivou-se com este estudo demonstrar a influência do tipo de treinamento sobre as medidas dos tendões flexores palmares em equinos de vaquejada que correm à direita do boi na microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil. Foram utilizados oito animais, da raça quarto de milha e seus mestiços, de diferentes idades, peso e sexo, selecionados e questionados sobre o tempo que exerciam a atividade de vaquejada e o tipo de treinamento a qual eram submetidos, que refere-se a maneira como praticavam a prova correndo de que lado do boi, em uma prova de vaquejada no município de Cristino Castro, Sul do Piauí, Brasil, onde os participantes eram provenientes de diferentes haras da Microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil. Em cada animal foi realizada ultrassonografia das zonas IB, IIB e IIIB dos tendões flexores digital superficial (TFDS) e digital profundo (TFDP), obtendo-se as medidas dos diâmetros médio lateral (DML) e dorso palmar (DDP) através do plano transverso em cada uma das diferentes zonas. Os dados foram submetidos a análise estatística (ANOVA), utilizando-se o teste t a nível de significância de (p<0,05), observando-se que não houve diferença significativa entre as medidas avaliadas. De acordo com os resultados obtidos, cavalos atletas que correm a direita do boi não apresentam diferença significativa nos diâmetros médio lateral e dorso palmar dos tendões flexores entre os antímeros direito e esquerdo do membro torácico.

The objective of this study was to demonstrate the influence of the type of training on the measurements of the palmar flexor tendons in vaquejada horses that run to the right of the ox in the microregion of the Alto Médio Gurgueia, South of Piauí, Brazil. Eight animals of the quarter-mile breed and their crossbreed, of different ages, weight and sex, were selected and asked about the time they were engaged in the activity of the vaquejada and the type of training they were submitted to as they practiced running on which side of the ox, in a vaquejada test in the municipality of Cristino Castro, South of Piauí, Brazil, where the participants came from different farms of the microregion of the Alto Médio Gurgueia, South of Piauí, Brazil. The ultrasonography of the IB, IIB and IIIB zones of the superficial digital (TFDS) and deep digital flexor tendons (TFDP) were performed in each animal, obtaining the measurements of the lateral diameters (DML) and palmar dorsum (DDP) through the transverse plane in each of the different zones. Data were submitted to statistical analysis (ANOVA), using the t test at the significance level of (p <0.05), observing that there was no significant difference between the measures evaluated. According to the results, horses for vaquejada athletes do not present significant difference in the lateral diameters and palmar dorsum of the flexor tendons between the right and left thoracic limb antimeres.

Avaliação ultrassonográfica dos tendões flexores dos membros anteriores em equinos de vaquejada na microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil / Ultrasound evaluation of the flexor tendons of the forelimbs in horses in vaquejada horses in the Alto Médio Gurgueia, South of Piauí, Brazil

Objetivou-se com este estudo demonstrar a influência do tipo de treinamento sobre as medidas dos tendões flexores palmares em equinos de vaquejada que correm à direita do boi na microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil. Foram utilizados oito animais, da raça quarto de milha e seus mestiços, de diferentes idades, peso e sexo, selecionados e questionados sobre o tempo que exerciam a atividade de vaquejada e o tipo de treinamento a qual eram submetidos, que refere-se a maneira como praticavam a prova correndo de que lado do boi, em uma prova de vaquejada no município de Cristino Castro, Sul do Piauí, Brasil, onde os participantes eram provenientes de diferentes haras da Microrregião do Alto Médio Gurgueia, Sul do Piauí, Brasil. Em cada animal foi realizada ultrassonografia das zonas IB, IIB e IIIB dos tendões flexores digital superficial (TFDS) e digital profundo (TFDP), obtendo-se as medidas dos diâmetros médio lateral (DML) e dorso palmar (DDP) através do plano transverso em cada uma das diferentes zonas. Os dados foram submetidos a análise estatística (ANOVA), utilizando-se o teste t a nível de significância de (p<0,05), observando-se que não houve diferença significativa entre as medidas avaliadas. De acordo com os resultados obtidos, cavalos atletas que correm a direita do boi não apresentam diferença significativa nos diâmetros médio lateral e dorso palmar dos tendões flexores entre os antímeros direito e esquerdo do membro torácico.

The objective of this study was to demonstrate the influence of the type of training on the measurements of the palmar flexor tendons in vaquejada horses that run to the right of the ox in the microregion of the Alto Médio Gurgueia, South of Piauí, Brazil. Eight animals of the quarter-mile breed and their crossbreed, of different ages, weight and sex, were selected and asked about the time they were engaged in the activity of the vaquejada and the type of training they were submitted to as they practiced running on which side of the ox, in a vaquejada test in the municipality of Cristino Castro, South of Piauí, Brazil, where the participants came from different farms of the microregion of the Alto Médio Gurgueia, South of Piauí, Brazil. The ultrasonography of the IB, IIB and IIIB zones of the superficial digital (TFDS) and deep digital flexor tendons (TFDP) were performed in each animal, obtaining the measurements of the lateral diameters (DML) and palmar dorsum (DDP) through the transverse plane in each of the different zones. Data were submitted to statistical analysis (ANOVA), using the t test at the significance level of (p <0.05), observing that there was no significant difference between the measures evaluated. According to the results, horses for vaquejada athletes do not present significant difference in the lateral diameters and palmar dorsum of the flexor tendons between the right and left thoracic limb antimeres.

Effect of racial crossing on the seminal parameters of rams submitted to heat stress / Efeito do cruzamento racial nos parâmetros seminais de carneiros submetidos ao estresse de calor

The aim of this study was to evaluate the effect of racial crossing on seminal parameters of eight Santa Inês and crossbred (Santa Inês x Dorper) rams submitted to heat stress, and to monitor the return of these parameters to previously reported. Before to place the insulation bags, two collects of semen through electroejaculation were performed. The insulation pouches were made with double-layer plastic, internally lined with cotton, and fixed around the spermatic funiculus and scrotum with adhesive tape and bandage remaining on the testes of the animals for seven days. The first collect was performed on the day that the pouches were taken (day 0) and thereafter, every seven days, totalizing 15 measurements. Data were submitted to analysis of variance (ANOVA). The analyzed variables were subjected to Dunnett test at 5% probability to compare the values obtained before treatment with those obtained in the following days. In this study it was found that the animals restored normal seminal parameter after the insulation effects, however, the return rate differed slightly among the studied breeds. The crossbred animals restored the seminal patterns, on average, a week before Santa Inês. It is concluded that the racial crossing influences the semen parameters of rams submitted to heat stress.

O objetivo deste estudo foi avaliar o efeito do cruzamento racial sobre parâmetros seminais de oito carneiros Santa Inês e mestiços, submetidos ao estresse térmico e monitorar o retorno desses parâmetros aos relatos anteriormente. Antes de colocar as bolsas de insulação, foram realizadas duas coletas de sêmen por meio de eletroejaculação. As bolsas de insulação foram confeccionadas com plástico de camada dupla, revestidas internamente com algodão, fixadas ao redor do funículo espermático e escroto com fita adesiva e bandagem, permanecendo nos testículos dos animais por sete dias. A primeira coleta foi realizada no dia em que as bolsas foram retiradas (dia 0) e a partir daí, a cada sete dias, totalizando 15 coletas. Os dados foram submetidos à análise de variância (ANOVA). As variáveis analisadas foram submetidas ao teste de Dunnett a 5% de probabilidade para comparar os valores obtidos antes do tratamento com aqueles obtidos nos dias seguintes. Neste estudo verificou-se que os animais restauraram os parâmetros seminais normais após os efeitos da insulação, porém, a taxa de retorno diferiu ligeiramente entre as raças estudadas. Os animais mestiços restauraram os padrões seminais, em média, uma semana antes da Santa Inês. Conclui-se que o cruzamento racial influencia os parâmetros seminais de carneiros submetidos ao estresse térmico.