Effect of season, age and physiological status on body weight and blood metabolites of communal sheep

The study was aimed at investigating temporal changes in body weight and blood profiles of related metabolites in rangeland sheep raised under an extensive production system. Body weight measurements were taken every month using a sheep crate electronic weighing scale and pooled to represent each season. Approximately 5 ml blood samples were collected from 262 ewes for serum biochemical analysis using standard procedures. The data were analyzed by univariate ANOVA in a completely randomized design with year (2012, 2013), age (4, 6, 8 years), and season (autumn, winter, spring, summer) as fixed factors and animal as a random variable. The body weight (BW), glucose, globulin, and albumin/globulin (A/G) ratio levels varied (P<0.05) between years. Older ewes (8 years) showed significantly higher (P<0.05) blood glucose levels compared to younger ewes (4 and 6 years). The total protein (TP), albumin, globulin, calcium and phosphorus contents were all higher (P< 0.05) in winter and spring compared to autumn or summer, while urea was high in spring and summer (P<0.05). The physiological status significantly (P<0.05) influenced BW, glucose, TP, albumin, globulin, cholesterol, calcium, and phosphorus levels of sheep. The BW was negatively correlated to most serum components. It was concluded that autumn and summer seasons are associated with improved body weight gains due to increased forage availability and quality, while higher levels of total protein, albumin, and globulin are observed in winter and spring, reflecting the animals' metabolic adaptations to varying environmental conditions.