Epigenetic Investigation Related to Gastrointestinal Helminth Resistance and Performance in Cattle

The objective was to characterize a herd of 73 Nellore heifers, identifying resistant, resilient, and susceptible animals to gastrointestinal helminths, relating the global methylation of the DNA of these animals with the degree of helminthiasis and factors that interfere with performance. Individual count of eggs per gram of feces (EPG), fecal culture for gender identification, weighing and blood sampling were carried out to determine PCV, STP, EOS, IgG, followed by DNA extraction and methylation analysis. The results were: 47% resistant animals, 34% resilient, and 19% susceptible to gastrointestinal helminth infections, with EPG counts of 53, 216, and 841, respectively, showing a statistical difference between all groups. The quantification of DNA methylation was 0.311, 0.245 and 0.178, respectively, for resistant, resilient, and susceptible animals, with a correlation being found between resistance to gastrointestinal helminths and overall DNA methylation. For weight gain, resistant and resilient animals showed higher values than susceptible ones, with a correlation between weight gain and EPG. The same was observed for VG; however, there was no statistical difference to the EOS, PPT, and IgG values. A significant correlation was found between PCV and EPG; quantifications of PCV and methylated DNA, STP and EPG; VG and STP. Therefore, the methodologies used made it possible to identify the animals regarding the degree of infection by gastrointestinal nematodes, making it possible to correlate the resistance of cattle to helminths with the amount of global DNA methylation and its performance.