Efeito da incorporação da covariância entre os efeitos direto e materno sobre a análise para a característica dias para ganhar 160 Kg

O objetivo deste trabalho foi estudar o efeito da covariância entre os efeitos direto e materno sobre as estimativas dos parâmetros genéticos e nas predições dos valores genéticos, direto e materno, para a característica dias para ganhar 160 kg (D160) na fase pré-desmama. Os parâmetros e as predições dos valores genéticos foram estimados utilizando o aplicativo MTDFREML. O modelo 1 incluiu os efeitos genéticos direto e materno e de ambiente permanente, além do efeito fixo de grupo contemporâneo e da covariável idade da vaca ao parto, assumindo a covariância entre o efeito direto e materno (sigmaam;¹;0); o modelo 2, considerou os mesmos efeitos do modelo 1, mas a covariância entre os efeitos direto e materno foi considerada nula (sigmaam=0). As estimativas de correlação de classificação dos animais pelos valores genético foram realizadas utilizando a correlação de Spearman. As estimativas de herdabilidade direta e materna para D160 foram respectivamente, 0,12 ± 0,01 e 0,09 ± 0,02, sob o modelo 1, e 0,12 ± 0,01 e 0,07 ± 0,02, sob o modelo 2. A correlação genética entre os efeitos direto e materno foi de -0,14 ± 0,12 (modelo 1). A inclusão da covariância entre os efeitos direto e materno nos modelos de análises não alterou a estimativa dos parâmetros genéticos e a classificação dos animais pela ordem dos valores genéticos estimados, quando se considerou toda a população. Entretanto, verificou-se que à medida que diminui a proporção de animais selecionados diminui a correspondência entre a classificação dos animais obtida pelos dois modelos.The aim of this work was to study the effect of the covariance between maternal and direct effects on estimatives of genetic parameters and on predictions of breeding values for days to gain 160 kg in the pre-weaning period (D160). The analysis were carried out using the MTDFREML software. The model 1 included the direct and maternal genetic effects and permanent environmental effect and the fixed effects of the contemporaneous group and the covariable age of dam at calving, assuming the covariance between maternal and direct effect (sigmaam;¹;0); the model 2 included the same effects of model 1, but the covariance between maternal and direct effects was considered zero (sigmaam=0). The rank correlations were obtained using Spearman correlation. The direct and maternal heritabilities for D160, were respectively, 0.12 ± 0.01 and 0.09 ± 0.02, for the model 1, and 0.12 ± 0.01 and 0.07 ± 0.02, for the model 2. The correlation between maternal and direct effects was -0.14 ± 0.12 (model 1). The inclusion of the covariance between maternal and direct effects in the analysis models had no influence on the genetic parameters and on the rank of the animals classified by breeding values, when all population was considered. However, as it reduced the proportion of selected animal was reduced there was a corresponding reduction on ranking animals through the two models

Differentially transcribed genes in skeletal muscle of lambs

The objective of this study was to compare gene transcription profiles in Longissimus dorsi muscle of the following four hair sheep genetic groups, Morada Nova (MO), Brazilian Somali (SO), Santa Inˆes (SI) and 1⁄2Dorper  1⁄2Morada Nova (F1). These groups all display different postnatal muscle growth. The transcriptomes of the skeletal muscle of the lambs (at 200 days of age) were profiled by using oligonucleotide microarrays and reverse transcription- quantitative real-time PCR (RT-qPCR). The microarray experiment identified 262 transcripts that were differentially expressed when transcription levels were compared between the different breeds. A total of 23 transcripts among which those involved in skeletal muscle development (MyoD1 and IGFBP4), lipogenesis and adipogenesis (C/EBP d , PPAR g and PGDS) were differentially expressed in at least in one comparison. Clustering analysis showed that there is greater similarity in gene expression between the MO and SI breeds and between F1 and SO genetic groups. The SO breed has the most distinct expression pattern. The RT-qPCR results confirmed the findings from the microarray study. A positive correlation was observed between the expression of MyoD1 and the cold carcass yield. The negative correlations between the weight and yield of cold carcass with the expression of C/EBP d mean that the selection for adipogenesis could lead to a lower carcass weight. The GLUT3 and PYGL gene transcripts were negatively correlated with fat thickness, but ATP5G1 was positively correlated with this trait. Interestingly, many genes negatively correlated with PUFA were positively correlated with cold carcass yield. In conclusion, the present work demonstrated that there are breed-specific expression patterns in Brazilian hair sheep genetic groups. The differences in gene expression among genetic groups were consistent with their phenotypic differences. The positive correlation of the MyoD1 expression with the cold carcass yield suggests that this gene is important for tissue growth in sheep. Thepositive correlation of the C/EBP d expression with PUFA provides an opportunity to select for lipid deposition in meat animals

Effect of 0.9% saline solution and phosphate buffer saline at different temperatures and incubation times on the morphology of goat preantral follicles

The present work investigated the efficiency of 0.9% saline solution and Phosphate Buffered Saline (PBS) in the preservation of goat preantral follicles in situ at different temperatures and incubation times. The ovarian pair of each animal was divided into 19 fragments. One ovarian fragment was taken randomly and fixed (control). The other 18 fragments were randomly distributed in tubes containing 0.9% saline solution or PBS at 4, 20 or 39 ºC for 4, 12 or 24 h. A total of 5,921 preantral follicles were examined. The quality of preantral follicles was evaluated by classical histology. The storage of ovarian fragments in 0.9% saline solution or PBS at 4 ºC did not reduce significantly the percentage of morphologically normal follicles when compared with the control, except after preservation in 0.9% saline solution for 24 h. The storage of ovarian fragments at 20 or 39°C reduced the percentage of normal preantral follicles when compared to the control, except after preservation in PBS at 20°C for 4 h. In conclusion, this study showed for the first time that goat preantral follicles can be stored in situ successfully at 4 ºC in 0.9% saline solution for 12 h and in PBS for 24 h, and at 20 ºC in PBS for 4 h.O presente trabalho investigou a eficiência da solução salina 0,9% e tampão fosfato salina (PBS) na conservação de folículos pré-antrais caprinos in situ a diferentes temperaturas e tempos de incubação. O par ovariano de cada animal foi dividido em 19 fragmentos. Um fragmento foi escolhido aleatoriamente e fixado (controle). Os outros 18 fragmentos foram distribuídos aleatoriamente em tubos contendo solução salina 0,9% ou PBS a 4, 20 ou 39 °C por 4, 12 ou 24 h. Um total de 5.921 folículos pré-antrais foram analisados. A qualidade dos folículos pré-antrais foi avaliada através de histologia clássica. A incubação de fragmentos ovarianos em solução salina 0,9% ou PBS a 4 ºC não reduziu significativamente a percentagem de folículos morfologicamente normais quando comparados com o controle, exceto após a conservação em solução salina 0,9% por 24 h. A incubação de fragmentos ovarianos a 20 ou 39°C reduziu a percentagem de folículos pré-antrais normais quando comparados com o controle, exceto após conservação em PBS a 20°C por 4 h. Em conclusão, este estudo mostrou pela primeira vez que folículos pré-antrais caprinos podem ser conservados in situ com sucesso a 4 ºC em solução salina 0,9% por 12 h e em PBS por 24 h, e a 20 ºC em PBS por 4 h

Aromatase gene and its effects on growth, reproductive and maternal ability traits in a multibreed sheep population from Brazil

We determined the polymorphism C242T of the aromatase gene (Cyp19) and its allelic frequency, as well as the effect of the variants on productive and reproductive traits in 71 purebred Santa Inês sheep, 13 purebred Brazilian Somali sheep, nine purebred Poll Dorset sheep, and 18 crossbred 1/2 Dorper sheep. The animals were genotyped using the PCR-RFLP technique. The influence of the animal's genotype on its performance or on the performance of its lambs was analyzed by the least square method. Another factor assessed was the importance of the animal's genotype in analysis models for quantitative breeding value estimates, and whether there were differences among the averages of breeding values of animals with different genotypes for this gene. In the sample studied, no AA individuals were observed; the AB and BB frequencies were 0.64 and 0.36, respectively. All Brazilian Somali sheep were of genotype BB. All 1/2 Dorper BB animals presented a lower age at first lambing, and the Santa Inês BB ewes presented a lower lambing interval. In these same genetic groups, AB ewes presented higher litter weight at weaning. This is evidence that BB ewes have a better reproductive performance phenotype, whereas AB ewes present a better maternal ability phenotype. However, in general, animals with genotype AB presented better average breeding values than those with genotype BB