Breed and early postpartum stage shape the physicochemical, rheological, and microstructural properties of Indonesian goat colostrum for sustainable dairy development

Abstract Colostrum is the first mammary secretion produced after parturition and represents a biologically active fluid essential for neonatal survival, immune maturation, and early growth. Despite its importance, breed-related and temporal variations in goat colostrum remain insufficiently characterized, particularly within indigenous production systems. This study comprehensively evaluated the physicochemical, rheological, and microstructural properties of colostrum from four Indonesian goat breeds—Kacang, Local Gorontalo, Saanen crossbreed, and Etawa crossbreed—during the first three days postpartum. Standardized analytical techniques were applied, including proximate composition, amino acid and fatty acid profiling, sodium dodecyl sulfate–polyacrylamide gel electrophoresis, high-performance liquid chromatography, gas chromatography, particle size and zeta potential analysis, rheometry, and confocal laser scanning microscopy. Significant effects of breed and postpartum day were observed. On Day 1, Saanen crossbreeds exhibited the highest crude protein (16.5 ± 0.3%) and fat (6.7 ± 1.5%), whereas indigenous breeds showed higher lactose concentrations. Crossbreeds were enriched in essential amino acids and polyunsaturated fatty acids, including conjugated linoleic acid. Rheological measurements demonstrated higher viscosity (1.95 × 10⁵ Pa·s) and yield stress (418 Pa) in crossbreeds compared with indigenous goats. Confocal microscopy confirmed denser protein–fat matrices in crossbreeds and looser, more heterogeneous microstructures in indigenous breeds. Principal component analysis clearly differentiated breeds and postpartum stages, supporting genotype–phenotype–function relationships. Beyond neonatal nutrition, these results contribute directly to Sustainable Development Goals 2 (Zero Hunger), 3 (Good Health and Well-Being), 12 (Responsible Consumption and Production), and 15 (Life on Land) by improving kid survival, promoting functional dairy innovation, enhancing resource efficiency, and supporting conservation of indigenous genetic resources in sustainable dairy systems.