Abstract

Background and Aim: Dairy goats exhibit distinct physiological adaptations during pregnancy and lactation, necessitating breed-specific biochemical reference values for accurate health assessment. The Thuringian Forest goat, an important regional dairy breed managed under organic systems, remains insufficiently characterized in this regard. This longitudinal study aimed to evaluate clinical-chemical profiles and metabolic dynamics across reproductive stages and to determine the influence of lactation number, milk yield, and litter size on biochemical parameters.

Materials and Methods: A total of 25 clinically healthy Thuringian Forest dairy goats were monitored over one production cycle under standardized organic farming conditions. Blood samples were collected monthly from late gestation (−3 to −1 months) through 12 months of lactation, yielding 300 serum samples. Analyses included enzyme activities (alkaline phosphatase, gamma-glutamyl transferase, aspartate aminotransferase, glutamate dehydrogenase, and creatine kinase), electrolytes (sodium, potassium, calcium, phosphate, and magnesium), and metabolic indicators (glucose, cholesterol, β-hydroxybutyrate, urea, creatinine, total protein, triglycerides, and free fatty acids). Repeated measures analysis of covariance was used to assess the effects of time, lactation number, milk yield, and litter size.

Results: Marked physiological variations were observed across reproductive stages. Sodium and potassium decreased slightly prepartum and fluctuated significantly during lactation, while calcium, phosphate, and magnesium showed stage-dependent changes. Enzyme activities exhibited clear lactation-related patterns, with alkaline phosphatase increasing progressively, gamma-glutamyl transferase peaking in early lactation, and aspartate aminotransferase declining over time. Metabolic parameters demonstrated adaptive responses, including increased glucose, total protein, and cholesterol during lactation, and elevated β-hydroxybutyrate in early lactation without exceeding clinical thresholds. Milk yield significantly influenced several biochemical markers, including sodium, creatine kinase, triglycerides, and β-hydroxybutyrate, whereas litter size had minor effects, primarily on sodium and urea concentrations. No evidence of pathological alterations was detected.

Conclusion: The study provides comprehensive longitudinal data on biochemical and metabolic adaptations in Thuringian Forest dairy goats under organic management. Lactation stage and milk yield are the primary determinants of biochemical variation, while litter size plays a limited role. These findings support the development of breed-specific reference intervals and highlight the importance of considering physiological and production factors for accurate clinical interpretation and improved herd management.

Keywords: biochemical profile, dairy goats, lactation, metabolic adaptation, milk yield, organic farming, pregnancy, Thuringian Forest goat.