Suckling Rat Pup Model: Do Caprine Milk Lactoferrin and Immunoglobulins Have Different Digestion and Absorption Properties from That of Human and Bovine Species?

This study aimed to investigate the digestion and absorption properties of caprine milk serum proteins in comparison to human and bovine species by using rat pups to mimic preterm infants. The results indicate that caprine lactoferrin (LTF) had a shorter retention time in the intestine and released a greater number of fragments, resembling human milk LTF more closely. In contrast, caprine immunoglobulins (Igs) were similar to bovine Igs and both exhibited a longer retention time in the intestine. For absorption, caprine Igs could be absorbed intact, which was similar to human and bovine Igs, whereas caprine LTF fragments were found in jejunum but not in plasma of rat pups. This is similar to bovine LTF but differed from human LTF as human LTF could be absorbed intact in plasma of rat pups at 20 min. In addition, the absorption rate of peptides and amino acids from caprine milk serum was similar to that of human milk serum, which was higher than that from bovine milk serum. This study aimed to enhance our understanding of the differences in bioavailability of LTF and Igs derived from caprine, human milk, and bovine milk, thereby offering guidance for selecting protein sources for premature infants.