Abstract:

Insulin-like growth factors play important roles in the cell differentiation, animal growth, development, reproduction and metabolism, and are largely present in the bovine colostrums. In present study, insulin-like growth factor-Ⅰ(IGF-Ⅰ) was separated from bovine colostrums by using ultra-filtration, and the degreasing and ultra-filtration conditions were optimized. The IGF-Ⅰand total protein concentrations were detected by radio-immunoassay(RIA) and coomassie blue staining, respectively. The results showed that the optimum degreasing conditions were as follows: centrifugation temperature 36 ℃, centrifugation speed 4000 r/min and centrifugation time 15 min. Macromolecular impurities protein and lactose could be removed after ultra-filtration with molecular weight cut-off 10－20 kD and 6 kD membrane, respectively. The relative concentration of IGF-Ⅰwas 3660 times higher than that in colostrums after ultra-filtration.

Key words: colostrums, insulin-like growth factor- Ⅰ(IGF- Ⅰ), lipid extraction, ultra-filtration, technological conditions