Seasonal variation in some physiological parameters of calves on communal rangeland of North West Province, South Africa

Mineral deficiency of roughages has been widely proven in research to affect productivity in ruminants. Accurate determination of grass minerals and biochemical profile of blood will provide valuable information to assist in diagnosis, prognosis and treatment of nutritional diseases of veterinary importance. This study, therefore, aimed to document the variations in levels of some selected micro and macro mineral concentrations of both grass and blood and blood chemistry as influenced by season of the year (winter, spring, summer and autumn) in selected communal farming locations of the North West Province of South Africa. Blood and Grass samples were collected from herds and areas distributed throughout the North West Province. Areas selected were the Southern region (5 herds, n=48), Bophirima region (8 herds, n=62), Central region (9 herds, n=70) and Bojanala region (6 herds, n=45). The phosphorus (P) and calcium (Ca) concentrations of grass (3.65 and 15.22 mg/g) were increased (P<0.05) during the spring and summer, respectively, compared to other seasons while lower P, Ca and magnesium (Mg) concentrations (0.89, 6.45 and 0.97 mg/g) were obtained during the winter. Serum P, Ca, Mg, Iron (Fe), potassium (K) and copper (Cu) concentration were significantly (P <0.05) influenced by change in season. Higher (P <0.05) serum P, Mg, potassium (K) and copper (Cu) concentration were obtained during the summer compared to other seasons. However, Ca and Iron (Fe) were significantly (P <0.05) increased during the summer, autumn and spring than winter period. Albumin, alanine transaminase (ALT), total bilirubin (TBIL), cholesterol (CHOL), creatinine kinase (CK), glucose (GLU) and lactate dehydrogenase (LDH) concentrations were significantly (P<0.05) reduced in summer compared to other season. Seasonal variations across the year have a great influence on mineral concentration of the grass and subsequently on blood serum concentrations. Therefore, proper documentation and timely evaluation of nutritional quality of available forages is required.