Efeitos da condição corporal e suplementação materna com fontes de cobalto, ácido fólico e metionina no controle imunometabólico de bezerros neonatos

Abstract

Managing body condition in dairy cows during the dry period can alter the availability of nutrients to the fetus in the final stages of growth in utero. Furthermore, maternal exposure to different metabolic stressors at late pregnancy might contribute to immune dysregulation in offspring and influence disease susceptibility. On the other hand, the inclusion of methyl donors in the maternal diet can provide positive responses in energy metabolism, inflammation, antioxidant status, and offspring performance. The aim of this thesis was to evaluate the effects of body condition and maternal supplementation with methyl donors during late pregnancy on immunological and metabolic parameters of newborn calves. To understand the influence of maternal body condition score (BCS) on neonate immune function, in a first study we evaluated gene expression in whole blood of calves born from a larger cohort of cows and retrospectively divided according to prepartum maternal BCS (4 weeks) in normal BCS (≤ 3.25; n = 22; NormBCS) or high BCS (≥ 3.75; n = 16; HighBCS), through an ex vivo lipopolysaccharide (LPS) challenge at birth, 21, and 42 days of age. The genes evaluated by RT-qPCR were associated with immune response, antioxidant function, and 1-carbon metabolism. Upregulation of genes associated with inflammatory and antioxidant response in calves born from cows with high BCS suggested greater immune stimulation in these animals. Furthermore, the differential regulation of genes related to 1-carbon metabolism in calves born from cows with high BCS underscored the potential role of methyl donors in the innate immune response of neonates. Thus, in a second study, through both an ex vivo LPS and enteropathogenic bacteria challenges, we evaluated the innate immune response in whole blood of calves born from cows supplemented during the last 30 days of pregnancy with two different cobalt sources [cobalt glucoheptonate (CoPro ) or cobalt pectin (CoPectin)], folic acid (FOA), and rumen-protected methionine (RPM). Groups were (n = 12 calves/group) CoPro, FOA+CoPro, FOA+CoPectin, and FOA+CoPectin+RPM. Our results underscored that the maternal supplementation modulated few biomarkers of the innate immune system at plasma and molecular levels, e.g. lower plasma concentration of haptoglobin in calves born from cows fed with additional folic acid. These calves also had differential regulation of genes related to inflammation and pathogen recognition. The lack of effects in the most evaluated target genes and on the functional capability of immune cells suggests that the increased maternal supply of these nutrients had little impact on immunometabolic control of the offspring.