Influence of dietary supplementation of vitamin A (retinol) on haematology and oxidative stress biomarkers pregnant of West African Dwarf ewes

Vitamin A plays a crucial physiological role in pregnant ewes; it has been documented to be a limited mineral during seasons when pastures are scarce and/or lignified. This study investigated the influence of dietary supplementation of vitamin A (retinol) on haematology and oxidative stress biomarkers of pregnant West African dwarf ewes. A total of eighteen (18) matured ewes of averaged 15 kg were used for the experiment. The ewes were synchronized using Synchromate, a follicle stimulating hormone (FSH), at the end of 4 weeks of acclimatization to bring all eighteen (18) ewes to ovulation at the same period. The eighteen matured ewes were randomly assigned to three (3) treatment groups consisting of six (6) ewes per group Each group was randomly allotted to the three (3) experimental diets having treatment 1 (control) with basal diet without vitamin A, treatment 2 supplemented with 140,000 IU vit A/kg and treatment 3 supplemented with 280,000 IU vitamin A/kg of the diet arranged in a completely randomized design (CRD). Data were collected for packed cell volume (PCV), haemoglobin concentration (Hb), red blood cells (RBCs), white blood cell count (WBCs) and white blood cell differentials while the serum biochemical (total proteins, albumin, glucose, creatinine, total bilirubin, uric acid, cholesterol, alkaline phosphatase) and oxidative stress biomarkers (catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH) and glutathione peroxidase (GPx)) were analyzed using one-way analysis of variance, and Tukey’s test was used to separate significantly different means. Significant differences (p < 0.05) were observed across the treatments at the end of the study for most of the parameter, except for eosinophils, basophils, mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCHC) while the control diet and those fed 280,000 IU vitamin A similarly elevated the packed cell volume, haemoglobin, red blood cell and lymphocytes when compared to those offered 140,000 IU. Serum indices measured at the final phase were not significantly (p > 0.05) affected except cholesterol. Cholesterol was reduced with the increase in inclusion level of vitamin A. Malondialdehyde, glutathione and glutathione peroxidase were significantly (p < 0.05) influenced by the dietary supplementation of vitamin A. Ewes diet containing 280,000 IU had the highest MDA concentrations (12.13 µmol/l) compared to others. The highest glutathione peroxidase value of 11.03 U/g Hb was observed in ewes on the control diet while those fed diet containing 280,000 IU vit A had the lowest with a value of 8.68 U/g Hb. This study therefore concluded that the dietary supplementation of vitamin A can be recommended for health maintenance and oxidative stability with reference to normal haematological profile (PCV, Hb and RBC), reduced malondialdehyde and GPX (U/g Hb) concentration of West African Dwarf ewes.