Exploring the use of residual variance for uniformity of body weight in meat quail lines using Bayesian inference.

1. Uniformity in animal products is an important aspect of the production system. Several studies have reported estimates of genetics on residual variance in different species, indicating that it could be exploited to improve uniformity by selection. Nevertheless, there are no reports about the possibilities of such a selection strategy in meat quail.2. Records of hatching weight (HW) and body weight at 42 days (W42) of female and male birds from two meat quail lines (UFV1 and UFV2) were analysed. A three-step genetic evaluation was used to investigate the effect of genetic variation on residual variance of HW and W42 in both lines. In Step 1, a single-trait model was fitted to the data. In Step 2, log-transformed squared estimated residuals (ln(ê2)) were evaluated for these traits. In Step 3, a multi-trait analysis was performed to estimate the genetic correlation between the additive genetic effects for HW, W42, and their respective ln(ê2).3. The heritability estimates ranged from 0.12 to 0.23 for HW and from 0.22 to 0.35 for W42. The estimated heritabilities for the residual part were low and ranged from 0.0003 to 0.02 for both traits, and the genetic coefficient of variation residual variance estimates ranged from 0.31 to 0.42 for HW and from 0.09 to 0.25 for W42. Genetic correlations between the means (HW and W42) and ln(ê2) values were both positive and did not differ from zero, indicating no association between mean and ln(ê2).4. In conclusion, the uniformity of HW and W42 could be improved by selecting for lower residual variance in both meat quail lines, but the accuracy of selection may be low due to low heritability for uniformity, mainly for W42.

Profile of endoparasites in dairy cattle in the microregion of São João del-Rei, state of Minas Gerais, Brazil / [Perfil de endoparasitas em bovinos leiteiros na microrregião de São João del-Rei, Minas Gerais, Brasil]

The present study provides the first evaluation of the endoparasite profile in dairy cattle from the microregion of São João del-Rei, Minas Gerais, Brazil, including seasonal variations in parasitic infections. Fecal samples were collected directly from rectum of 123 dairy cows and 160 calves on 15 farms. These were kept in insulated boxes and sent for immediate analysis. Using eggs per gram of feces (EPG) we found the following prevalences: Strongyloidea 43.5%, Moniezia sp. 7.6% and both Strongyloides sp. and Trichuris spp. 2.2%, in dairy cows. In calves, the prevalence was Strongyloidea 50.9%, Moniezia sp. 5.6% and Strongyloides sp. 1.9%. The third-stage larvae recovered from coprocultures from cows and calves consisted mainly of Cooperia spp., Haemonchus spp. and Ostertagia spp. EPG counts were significantly higher in calves. Regarding seasonality, the EPG counts and prevalence of Moniezia sp. tended to be higher in the dry period, whereas those of Strongyloidea were higher in the rainy season. Evidence suggests that parasite control and prophylaxis were inadequately managed on the farms studied here. The present parasitological profile correlates with those found by other similar studies, indicating that the main problem is still the inadequate management of parasite control and prophylaxis by farmers.(AU)

O presente estudo representa a primeira avaliação do perfil de endoparasitos em bovinos leiteiros da microrregião de São João del-Rei, Minas Gerais, Brasil, e das variações sazonais das infecções parasitárias. Foram avaliadas amostras fecais de 123 vacas e 160 bezerros de 15 propriedades rurais, coletadas diretamente do reto, mantidas em caixas térmicas isoladas e analisadas imediatamente. A contagem de ovos por grama de fezes (OPG) revelou prevalências de 43,5% de Strongyloidea, 7,6% de Moniezia sp. e 2,2% de Strongyloides sp. e Trichuris spp. em vacas leiteiras. As prevalências de OPG em bezerros foram 50,9% de Strongyloidea, 5,6% de Moniezia sp. e 1,9% de Strongyloides sp. As larvas do terceiro estádio recuperadas de coproculturas de vacas e bezerros foram principalmente de Cooperia spp., Haemonchus spp. e Ostertagia spp. OPG dos parasitos foram significativamente maiores em bezerros. Em relação à sazonalidade, OPG e a prevalência de Moniezia sp. tenderam a ser maiores durante a estação seca, enquanto OPG de Strongyloidea foram maiores na estação chuvosa. Com base nos resultados, é possível concluir que o manejo antiparasitário nas propriedades estudadas não é realizado de maneira plenamente satisfatória. O presente perfil parasitológico se assemelha a outros encontrados em estudos semelhantes, indicando que o maior problema ainda é o manejo antiparasitário inadequado realizado nas propriedades de bovinos leiteiros.(AU)

Genetic parameter and genetic trend estimates for reproductive traits in Wistar rats / [Estimativas de parâmetros genéticos e tendências genéticas de características reprodutivas em ratos Wistar]

The aim of this study was to estimate genetic parameters and genetic trends for reproductive traits in Wistar rats. A total of 1,167 data records from 283 females over six generations of monogamous mating pairs was used. Heritability and genetic correlation were estimated through Bayesian inference and genetic trends were calculated by linear regression of breeding values over generations. Heritability estimates for litter size at birth (LS), calving interval (CI), pup mortality (PM) and maternal cannibalism (CAN) presented low magnitude, ranging from 0.01 to 0.13. CAN presented high and positive genetic correlation with LS and PM (0.77 and 0.78, respectively). On the other hand, all the other estimated genetic correlations were not significant. Genetic trend was positive for LS (+0.0900 pups per generation), and negative for PM and CAN (-1.0085 and -0.5217 pups per generation, respectively). For CI the genetic trend was not significant. It is recommended to increase selection intensity on dams in this Wistar rat population in order to accelerate the genetic progress.(AU)

O objetivo deste estudo foi estimar os parâmetros genéticos e as tendências genéticas de características reprodutivas em ratos Wistar. Foram analisados 1.167 registros coletados em 283 fêmeas ao longo de seis gerações de pares de acasalamentos monogâmicos. Herdabilidade e correlação genética foram estimadas por meio de inferência bayesiana, e as tendências genéticas foram calculadas pela regressão linear dos valores genéticos em função das gerações. As estimativas de herdabilidades para as características número de filhotes nascidos (LS), intervalo de parto (CI), mortalidade de filhotes (PM) e canibalismo materno (CAN) foram de baixa magnitude (0,01 a 0,13). CAN apresentou correlação genética alta e positiva com LS e PM, 0,77 e 0,78, respectivamente. As demais correlações genéticas estimadas foram não significativas. A tendência genética foi positiva para LS (+0,0900 filhote por geração) e negativa para PM e CAN (-1,0085 e -0,5217 filhote por geração, respectivamente). A tendência genética não foi significativa para CI. Recomenda-se aumentar a intensidade de seleção nas fêmeas nessa população de ratos Wistar, a,fim de acelerar o progresso genético.(AU)

Genetic evaluation for latent variables derived from factor analysis in broilers.

1. The aim of this study was to investigate the associations between several carcass, performance and meat quality traits in broilers through factor analysis and use the latent variables (i.e. factors) as pseudo-phenotypes in genetic evaluations.2. Factors were extracted using the principal components method and varimax rotation algorithm. Genetic parameters were estimated via Bayesian inference under a multiple-trait animal model.3. All factors taken together explained 71% of the original variance of the data. The first factor, denominated as 'weight', was associated with carcass and body weight traits; and the second factor, defined as 'tenderness', represented traits related to water-holding capacity and shear force. The third factor, 'colour', was associated with traits related to meat colour, whereas the fourth, referenced as 'viscera', was related to heart, liver and abdominal fat.4. The four biological factors presented moderate to high heritability (ranging from 0.35 to 0.75), which may confer genetic gains in this population.5. In conclusion, it seems possible to reduce the number of traits in the genetic evaluation of broilers using latent variables derived from factor analysis.

A note on transgenerational epigenetics affecting egg quality traits in meat-type quail.

1. The aim of the following experiment was to estimate transgenerational epigenetic variance for egg quality traits using genealogical and phenotypic information in meat-type quail. Measured traits included egg length (EL) and width (EWD), albumen weight (AW), shell weight (SW), yolk weight (YW) and egg weight (EW). 2. A total of 391 birds were evaluated for egg quality by collecting a sample of one egg per bird, during three consecutive days, starting on the 14th d of production. Analyses were performed using mixed models including the random epigenetic effect. Variance components were estimated by the restricted maximum likelihood method. A grid-search for values for the auto-recursive parameter (λ) was used in the variance components estimation. This parameter is directly related to the reset (v) and epigenetic transmissibility (1 - v) coefficients. 3. The epigenetic effect was not significant for any of the egg quality traits evaluated. Direct heritability estimates for egg quality traits ranged in magnitude from 0.06 to 0.33, whereby the higher estimates were found for AW and SW. Epigenetic heritability estimates were low and close to zero (ranging from 0.00 to 0.07) for all evaluated traits. 4. The current breeding strategies accounting for additive genetic effect seem to be suitable for egg quality traits in meat-type quail.

Transgenerational epigenetic variance for body weight in meat quails.

We aimed to estimate transgenerational epigenetic variance for body weight using genealogical and phenotypic information in meat quails. Animals were individually weighted from 1 week after hatching, with weight records at 7, 14, 21, 28, 35 and 42 days of age (BW7, BW14, BW21, BW28, BW35 and BW42, respectively). Single-trait genetic analyses were performed using mixed models with random epigenetic effects. Variance components were estimated by the restricted maximum likelihood method. A grid search for values of autorecursive parameter (λ) ranging from 0 to 0.5 was used in the variance component estimation. This parameter is directly related to the reset coefficient (ν) and the epigenetic coefficient of transmissibility (1-ν). The epigenetic effect was only significant for BW7. Direct heritability estimates for body weight ranged in magnitude (from 0.15 to 0.26), with the highest estimate for BW7. Epigenetic heritability was 0.10 for BW7, and close to zero for the other body weights. The inclusion of the epigenetic effect in the model helped to explain the residual and non-Mendelian variability of initial body weight in meat quails.

Avaliação da imobilidade tônica em codornas de corte via análise de sobrevivência' / Tonic immobility evaluation in meat quail via survival analysis

Tonic immobility (TI) is a way to measure fear, as characterized by the reduced capacity to respond to external stimuli. The time spent in TI indicates the level of fear. Since TI is measured as the time until event occurrence, survival analysis stands out as a suitable statistical method to treat these data. We aimed to investigate the influence of possible factors (lines, sex and age) on fear behavior in meat quail (Coturnix coturnix) measured through TI by using survival analysis (non parametric Kaplan-Meyer method via logrank test). The dataset was composed by TI information provided by 50 animals from each line (UFV1 and UFV2) in each age (14 and 28 days of age), totalizing 200 records. Despite the slight difference between the two evaluated ages, there was no significance for this factor between each studied line, UFV1 (P= 0.1493) and UFV2 (P= 0.2583). The logrank test indicated significant difference (P= 0.0407) between levels of line/sex groups at 14 days of age. We noted that males from UFV2 line presented higher fear behavior in relation to males from UFV1 line. No significant differences were observed for this factor when considering 28 days of age.(AU)