Abstract: In this experiment, the appearance quality, energy and protein concentrations, digestive enzyme activitties, immunoglobulin levels and growth factor concentrations of pigeon milk in squabs at different periods were determined, and the dynamic changes of these factors at different days were analyzed, so as to provide theoretical basis for systematically understanding the nutritional and physiological needs of squabs. Twelve healthy White King pigeons aged 0, 7, 14, 21 and 28 days were randomly selected respectively. After being fed by parent pigeons, squabs were slaughtered and all contents of their crops were taken out. One part was diluted with normal saline, then the supernatant was isolated for the determination of digestive enzyme activity, immunoglobulin activity and growth factor concentration. The other part was made into air-dried samples for detection of routine nutrient levels. The results showed that:The pigeon milk of 0-day-old showed a milky, oily, cheesy-like appearance, and it was a mixture of cheesy-like crop milk and feed at 7-day-old. After 14 days of age, the pigeon milk was gradually transformed into softened feed. The energy and protein concentrations of pigeon milk were affected by age significantly (P<0.05), and they were significantly higher at 0-day-old than those in later periods (P<0.05). The energy and protein concentrations of pigeon milk after 7 days of age were very similar. The activities of amylase, trypsin and chymotrypsin in pigeon milk at different periods were significantly different (P<0.05), and showed a linear increasing relationship (P<0.05). The levels of immunoglobulin A (IgA), immunoglobulin M (IgM) and immunoglobulin G (IgG) in pigeon milk at different periods had significant differences (P<0.05), and showed a quadratic curve relationship that first decrease and then increase (P<0.05). The levels of insulin growth factor-1(IGF-1) and epidermal growth factor(EGF) in pigeon milk at different periods were significantly different (P<0.05), and showed a significant trend of decreasing first and then increasing (P<0.05). In conclusion, during 0-7 days, the exfoliation and cell debris of the mucosa epithelial cells from the parents’ were the main contents of pigeon milk, and the energy, protein, immune factors and growth factors were at the highest levels. From 8-14 days, the energy and protein levels of pigeon milk tended to be flat, while the immune factors and growth factors decreased to the minimum. The nutrients levels of pigeon milk of squabs from 15 to 28 days were similar to the feed of parent pigeons, and the digestive capacity of squabs gradually increased.

Key words: pigeon milk; nutrients levels; immunoglobulin; growth factor