Vitamin D concentrations and biological biomarkers of lactating mares and foals in the dry season

Abstract

During the lactation phase, there is an intense mobilization of blood biomarkers in the tissues for milk production by mares, while the foals face challenges and metabolic adaptations essential for their development. To determine variations in the haematological, lipid, protein, and vitamin D (VIT-D) profiles between lactating mares and their foals, blood samples were obtained during the entire lactation period under a semi regime in the Caatinga. Animals were maintained on Buffel grass, mineralized salt, and a mixture of mesquite bran and corn roll, and water was provided ad libitum. In addition, the foals had free access to a creeper-feeder with commercial concentrate. Concentrations of total cholesterol, high- and low-density lipoproteins, triglycerides, VIT-D, erythrocytes, haemoglobin, total plasma protein and albumin, and haematocrit and leukocytometric levels were determined in serum blood samples. No body mass changes were observed in the lactating mares; however, it increased in the foals, the values ranged from 56 kg to 165 kg, in the end of the study. Alterations in lipid biomarkers compatible with the physiological phase were observed. The concentration of lipids in the blood of the foals was higher than that in the mares. Thus, the alterations observed were compatible with the metabolic modifications during the lactation phase in mares and their foals. The concentrations of VIT-D of mares and foals were low; it is important to note during the standardization of these values for horses raised under tropical conditions and exposed to high solar incidence. Therefore, these findings may be useful for the evaluation of animals in tropical climates under conditions of high solar incidence.