Utilização de marcadores moleculares na análise da característica de qualidade da carne em caprino (Capra hircus)

Abstract

Goat meat has lower levels of fat than those found in other types of meat such as beef, pork, sheep and deer, but the lack of selection criteria for slaughter, storage and commercialization of meat leads to a low level because of the lack of standardization of the product presenting unpleasant sensory characteristics. A study of polymorphism, variation in gene expression and the association of these variations with the desired phenotype allows to broaden the understanding of the physiological processes, which helps in the strategies aimed at improving the characteristic of interest, resulting in the expected final phenotype. The objective of the present study was to evaluate polymorphisms and gene expression among some of the most promising genotypes of pleiotropic genes, comparing the polymorphism and expression among groups of animals with greater and lesser weight at slaughter to verify if there is any relation with the weight difference Or softness of the flesh. For this purpose, genotypes of 40 goats from the Saanen and Alpina breeds for the growth hormone (GH) gene, diacylglycerol acyltransferase 1 gene (DGAT1), myostatin gene (MSTN), growth factor gene Similar to insulin 1 (IGF1), fatty acid carrier protein (FATP1) gene, nuclear factor 1 (NF1) gene, gamma peroxisome proliferator activated receptor (PPARγ) gene. After analyzing the association of the different genotypes with the slaughter weight (AP), carcass weight (PC) and meat softness expressed in shear force (FC), some genes were selected for the analysis of expression and association with them Variables. The GH, NF1 and PPAR genes were not evaluated for expression, the first for not having presented a good result for the efficiency analysis of the other two primers due to the lack of substantial data for the preparation of the primers. For the softness test, previously performed in another study by the same team, the longissimus lumborum muscle was used. Polymerase chain reaction (PCR) technique was used for the genotyping and later, for some genes, the digestion of the fragments amplified by restriction enzymes, a technique known as PCR-RFLP. Gene expression was conducted using the Real Time PCR technique (qPCR) and the meat tenderness phenotype was analyzed in a texturometer. The data were statistically related using the SAS GLM procedure. The UNIVARIATE procedure was used to verify the normality of residues of expression of the genes under study (expressed as 2-ΔCt) and softness data. The averages were compared by the Tukey test and the Pearson correlations tested by the t test. The polymorphism already described in the GH was also detected in the population studied in the present study, the genotype heterozygous AB presented a mean 2.78kg at slaughter weight more than the AA individuals, for the MSTN the individuals with heterozygous M1M2 genotype presented higher scores for weight at slaughter, while for the IGF1 gene the heterozygous AB animals present less tender meat. The group with lower weight at slaughter showed higher expression of the DGAT1 and FATP genes, which may reflect a higher deposition of fat in the carcass and greater softness, in comparison with the group of higher weight.