Modulation of Milk Source Differences on Immunity, Nutritional Physiology and Intestinal Microbiota in Neonatal Piglets

Milk sources directly influence digestion, absorption, and overall nutrient utilization during early infant nutrition. Goat milk features a nutritional composition and digestive properties that are more similar to human breast milk. This study aimed to investigate the effects of different milk sources on the immunity, amino acid and fatty acid metabolism, and intestinal microbiota in neonatal piglets. Sixteen 7-day-old suckling piglets were randomly allocated into two groups (eight replicates/group, one piglet/replicate) and fed with standard formula milk powder (CON) and goat milk formula powder (GMF). The formal experiment lasted for 14 days. Results showed that compared with the CON group, the GMF group showed a significant increase (<i>p</i> < 0.05) in the final weight, the serum levels of immunoglobulin A (IgA), IgG, IgM and C-reactive protein (CRP4), and intestinal trypsin content. Additionally, the GMF group had higher (<i>p</i> < 0.05) serum essential and non-essential amino acid and fatty acid levels, and had trends toward upregulation (0.05 < <i>p</i> < 0.1) in hepatic mRNA expression of spermine N1-acetyltransferase 1 (<i>SAT1</i>), duodenal peptide transporter 1 (<i>PePT1</i>), and jejunal cationic amino acid transporter 1 (<i>CAT1</i>). Microbiome sequencing revealed that GMF enhanced intestinal microbial richness and diversity and increased concentrations of acetic and propionic acids (<i>p</i> < 0.05). In conclusion, GMF suggests a potential improvement in the growth performance by enhancing immunity, amino acid and fatty acid metabolism and optimizing intestinal microbiota composition in neonatal piglets. These findings further support the favorable nutritional properties and tolerability of GMF in early-life nutrition.