Summary:In order to test the hypothesis that donkeys, housed in different management systems, present minimal variations in the concentration of various blood values, an experiment was carried out to evaluate blood values in Northeastern donkeys at maintenance, of both sexes, in different management systems. Sixty-two Northeastern donkeys were used, of both sexes, adults, healthy and housed in three management systems: Limoeiro (LIM), Natal (NAT) and Mirandiba/Salgueiro (MS), three different regions in the Northeast of Brazil. Body condition score, red blood cell count, haemoglobin, hematocrit, MCV, MCHC, leukocytes, lymphocyte, other white cells, RDW-CV, RDW-SD, platelets, MPV, total plasma protein, albumin, urea, creatinine, uric acid, glutamine, glutamate, triglycerides, total cholesterol, nonesterified fatty acids, AST, ALT, AP, CK, GGT, Ca, P, Cl, Fe, Na, K and Se were evaluated. Results were submitted to ANOVA with two factors (sex and rearing site) and to Tukey test, considering p<0.05. Results showed no difference in body score (p>0.05) and, in blood biomarkers, it was observed that RDW-CV and MPV were higher in females (p<0.05). In G-MS, red blood cells, Hb, HT and lymphocytes were lower than in G-LIM and G-NAT (p<0.05). In G-LIM, MCV and RDW-SD were lower (p<0.05). In relation to metabolic biomarkers, high concentrations of UA, TRIG, TC, NEFA, Ca and P (p<0.05) were observed in females. Higher concentrations of UA, TRIG, TC, P and Cl were detected in G-LIM (p<0.05), and G-NAT had the highest values for URE, GLU and CK (p<0.05). Results indicated that, even when kept under different management systems, donkeys may present some haematological and blood chemistry values with similar concentrations, and the few differences found may not present clinical significance for the evaluation of these animals. It was concluded that donkeys may present significant variations in different blood and metabolic parameters, when they are of different sexes and/or housed in different management systems. The red series, electrolytes and trace elements were not very sensitive to identify variations related to gender and/or rearing site groups. However, the count of lymphocytes, the combination of MVC with RDWs, CK, as well as concentrations of NEFA and triglycerides, can be used to better understand the adaptations of different management conditions or breeding systems, since they can be modified by the evaluated conditions, contributing to a better understanding of the state of health or disease of the animals of that species.

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.

Ovulation inducers are routinely used in domestic horses, especially when assisted reproduction technologies are applied, with the purpose of modulating hormonal activity. The objective of this study was to evaluate the variation of the sex hormones and the lipid profile of empty and single mares, subjected to the use of medicine regulators of the estrous cycle. We used 30 Mangalarga Marchador mares, aged between three and twelve years which were kept in the municipality of Limoeiro, Pernambuco, Brazil. In the presence of a follicle of ≥ 35 mm in diameter and endometrial oedema grade ≥ 2, the mares were randomly separated into three experimental groups of ten animals each, which were treated with different ovulation inducers: i) G-HCG, 1,000 IU of human chorionic gonadotropin, intravenously; ii) G-Deslo, 1.0 mg deslorelin acetate, intramuscularly; iii) G-Combo, 1.0 mg COMBO®, intramuscularly. All mares were artificially inseminated with chilled semen from one stallion. Blood samples were collected before the experiment and 2, 3, 9, and 15 days after ovulation by jugular venopuncture using vacuum system tubes without an anticoagulant. After centrifugation, serum was separated to measure the concentrations of luteinizing hormone (LH) and progesterone (P4) using an ELISA, and concentrations of triglycerides (TRIG), total cholesterol (COLE), high-density lipoproteins (HDL), and low-density lipoproteins (LDL) were measured using semi-automated equipment. The use of oestrus cycle regulators produced significant variations in P4 and COLE whereas no significant effect was observed on LH, HDL, LDL, TRIG, and total plasma proteins (TPP). This likely resulted from endogenous mobilization required for metabolic adaptations at the onset of gestation, as the reproductive success rate of the three groups indicated that the treatments effectively induced and synchronized ovulation.