Weighted single-step genome-wide association study and functional enrichment analyses for gastrointestinal nematode resistance traits in Santa Ines sheep.

This study aimed to identify genomic regions, pathways, and putative candidate genes associated with resistance to gastrointestinal nematode in Santa Ines sheep. The phenotypic information comprised 5529 records from 1703 naturally infected animals. After genomic data quality control, 37,511 SNPs from 589 animals were available. The weighted single-step approach for genome-wide association study was performed to estimate the SNP effects and variances accounted by 10-SNP sliding windows. Confirming the polygenic nature of the studied traits, 20, 22, 21, and 19 genomic windows that explained more than 0.5% of the additive genetic variance were identified for fecal egg counts (FEC), Famacha© (FAM), packed cell volume (PCV), and total plasma protein (TPP), respectively. A total of 81, 122, 106, and 101 protein-coding genes were found in windows associated with FEC, FAM, PCV, and TPP, respectively. Several protein-coding genes related to the immune system and inflammatory response functions were identified within those genomic regions, such as ADCY9, ADRB2, BRAF, CADM1, CCL20, CD70, CREBBP, FNBP1, HTR4, IL16, IL22, IL26, MAPK8, NDFIP1, NLRC3, PAK5, PLCB1, PLCB4, ROCK1, TEK, TNFRSF12A, and VAV1. Functional enrichment analysis by DAVID tool also revealed many significant (P < 0.05) pathways and Gene Ontology terms that could be related to resistance to gastrointestinal nematode in Santa Ines sheep, such as chemokine signaling pathway (oas04062), cAMP signaling pathway (oas04024), cGMP-PKG signaling pathway (Oas04022), platelet activation (Oas04611), Rap1 signaling pathway (oas04015), and oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen (GO:0016705). These results contribute to improving the knowledge of the genetic architecture of resistance to gastrointestinal nematode in Santa Ines sheep.

Cluster analysis to explore additive-genetic patterns for the identification of sheep resistant, resilient and susceptible to gastrointestinal nematodes.

Infection caused by gastrointestinal nematodes is an important issue for animal health and production. Controlling worm infections improves the sustainability of the sheep industry. Genetic selection of animals that are resistant to gastrointestinal nematodes is another strategy to render sheep production more sustainable by decreasing the use of anthelmintics. The aims of this study were (1) to explore the additive-genetic pattern of EBVs for Famacha© (FAM), packed-cell volume (PVC), and fecal egg counts (FEC) of Santa Ines sheep, (2) to propose a classification of animals that are resistant, resilient and susceptible to gastrointestinal nematodes based on their additive-genetic patterns, and (3) to identify the most suitable animals for selection based on their genetic pattern. A dataset of 2,241 records from 747 animals was used to predict the breeding values for indicator traits of resistance to gastrointestinal nematodes with THRGIBBS1F90 and to carry out cluster analyses was used R software. Three clusters of animals were found in the population using hierarchical cluster analysis of the breeding values for FAM, PCV and FEC. Each cluster was characterized by different additive-genetic patterns identified by k-means non-hierarchical cluster analysis. Among a total of 747 animals, 196 were classified as resistant, 288 as resilient, and 263 as susceptible. Cluster analysis is a valuable tool for data screening that permits to evaluate only selection candidates based on their additive-genetic pattern for gastrointestinal nematode resistance. EBVs for FEC were decisive to divide the population into resilient, resistant and susceptible animals. It is also important to include the EBVs for PCV and FAM to adequately distinguish resistant from resilient animals. Finally, the resistant cluster consisted of the most desirable animals to be used as selection candidates in order to genetically improve resistance to infection with gastrointestinal nematodes. This cluster contained animals with the most appropriate additive-genetic pattern to achieve the breeding goal, with positive breeding values for PCV and negative breeding values for FAM and FEC.

Identification of polymorphisms in the myostatin and leptin genes of santa inês breed and crossbreed sheep and association with carcass traits / Identificação de polimorfismo nos genes da miostatina e leptina em ovinos santa inês e cruzados e associação com características de carcaça

The objective of this study was to identify polymorphisms in the myostatin and leptin genes in Santa Inês (SI) and crossbreed (SI x Dorper) sheep, to verify the effect of these polymorphisms on carcass traits. We evaluated seventy sheep of 8-month-old at the Federal Institute of Espírito Santo, Brazil. Data collected were slaughter weight (SW), hot carcass weight (HCW), cold carcass weight (CCW), loin weight, tenderloin weight and fat thickness (FT). The hot carcass yield (HCY) was calculated by the formula (HCW/SW) x 100. We collected hairs from each animal for DNA extraction by the alkaline protocol. The animals were genotyped for the G>A mutation in nucleotide 9827 of the myostatin gene and for three polymorphisms in exon 3 of the leptin gene, by the PCR-RFLP technique. The amplicons the myostatin and leptin gene were cleaved with restriction enzyme for allelic discrimination. The alleles were recorded for each animal and analysis of variance was performed to check the influence of the mutations on the carcass traits. The mutant allele of the myostatin gene showed association with increased measures of CCW, FT and with reduced HCY. Among the three alleles of the leptin gene, only one showed an effect (increased CCW). The other alleles were not associated with any traits.

O objetivo deste estudo foi identificar os polimorfismos nos genes da miostatina e leptina em Santa Inês (SI) e mestiças (SI x Dorper) ovelhas, para verificar o efeito desses polimorfismos sobre características de carcaça. Foram avaliadas setenta ovelhas com oito meses de idade, do Instituto Federal do Espírito Santo, Brasil. Os dados coletados foram o peso de abate (PA), peso de carcaça quente (PCQ), peso de carcaça fria (PCF), peso de lombo, peso lombinho e espessura de gordura de cobertura (ECG). O rendimento de carcaça quente (RCQ) foi calculado pela fórmula (PCQ/PA) x 100. Foram coletados pelos de cada animal para a extração de DNA pelo protocolo alcalino. Os animais foram genotipados para a mutação G>A no nucleotídeo 9827 do gene da miostatina e para três polimorfismos no exon 3 do gene da leptina, através da técnica PCR-RFLP. Os produtos de amplificação do gene da miostatina e da leptina foram clivados com a enzima de restrição para diferenciação alélica. Os alelos encontrados foram registrados para cada indivíduo e então foi realizada a análise de variância para verificar os efeitos das mutações sobre as características de carcaça pelo procedimento GLM do SAS. O alelo mutante do gene da miostatina mostrou associação com o aumento das médias PCF e ECG e com a redução do RCQ. Entre os três alelos do gene da leptina, apenas um apresentou efeito com aumento do PCF. Os demais alelos e as demais características não apresentaram associação.

Sugarcane and mulberry silage supplementation of sheep during the peripartum period.

The aim of this study was to evaluate the effects of supplementation with silage made from sugarcane alone or mulberry and sugarcane on the gastrointestinal nematodes and hematological parameters in peripartum Santa Inês ewes. Three groups, each of 15 ewes, were supplemented with either 100 % sugarcane silage or sugarcane silage and mulberry at ratios of either 75:25 or 50:50. The variables analyzed were weight, body condition, packed cell volume, total plasma protein, hemoglobin, total leukocytes, eosinophils, and number of parasite eggs per gram of feces. All variables were measured individually every 14 days, making ten samples per ewe. Diets with sugarcane added to different proportions of mulberry branches did not influence the blood and parasitological parameters of Santa Inês sheep naturally infected in the peripartum period.

Morphometric indices in Santa Ines sheep / Índices morfométricos en ovejas Santa Ines

The aim of this study was to evaluate the effect of period of the year, year of the birth, sex and age on morphometric indices, such as body capacity, body indices, body side indice, anamorphosis indice, compactness indice and body proportionality indice. The correlation between these characteristics was calculated. Santa Ines sheep offspring from the birth to 12 months-old, at the Estado do Rio de Janeiro were used. Measurements were obtained from animals under an extensive scheme within three years of study totaling 2,601 observations. In this work, the year of birth, sex, animal age and triple interaction between these effects have influenced (P<0.05) morphometric indices. According to body and compactness indices averages also was verified that the animals tended for a more compact conformation. Males were higher than females in all measurements and weight. Correlations between all measures were high and positive. The studied animals show a longilinear conformation, tending to compact.

Los efectos de la estación, año de nacimiento, edad y sexo sobre índices morfométricos como: capacidad del cuerpo, índice corporal, índice del cuerpo, índice de anamorfosis, índice de compacidad y índice de proporcionalidad corporal fueron evaluados y fueran estimadas las correlaciones entre ellos. Se utilizaron ovejas Santa Inés desde el nacimiento hasta los 12 meses de edad, criadas en el norte del Estado de Río de Janeiro. Las evaluaciones fueron realizadas durante un período de tres años, totalizando 2.601 observaciones. El año de nacimiento, el sexo, la edad del animal y la interacción entre ellos tuvo efectos (P<0,05) sobre los índices estudiados. A partir de las medidas corporales y de los niveles de compacidad se observó que los animales tienden a presentar conformación más compacta. Las correlaciones entre las medidas fueron altas y positivas. Los animales estudiados muestran una conformación longilínea, tendiendo a compacto.