Insulin and IGF-1 in goat milk : Influence of the diet

Sixteen Saanen lactating goats were fed a diet based on mixed hay, maize, barley and soybean meal (40:60 forage to concentrate ratio) containing 17% (LS) or 33% starch (HS) at 9.00 h and 17.00 h, and milked at 8.00 h and at 18.00 h. High starch (HS) diet increased plasma IGF-1, plasma insulin and insulin post-feeding changes. Milk insulin, but not milk IGF-1, was significantly increased by HS diet. The levels of IGF-1 in plasma was seventy-five times higher than insulin levels, but milk IGF-1 is only 13% of blood level, whereas milk insulin level was two/three times higher than plasma level. In the present study we conclude 1) that insulin and IGF-1 are present in goat milk and 2) that it is possible to influence the level of milk insulin through the maternal diet. Further research is needed to determine whether intraspecific or interspecific transfer can occur and whether these components from goat milk can maintain their biological activity in the gastrointestinal tract of the neonate.