In vivo and in vitro growth-stimulatory effects of pigeon milk

Pigeon milk (PM) was tested for its effect on growth in vivo and in vitro. Eleven-day-old mice sucklings given a supplementary feeding of 125 mg PM per day for 3 days showed a significant increase in the weight of stomach and distal intestine, and the length of small intestine; there was, however, a significant decrease in heart size. In PM-fed animals the protein content of stomach, and RNA content of stomach, caecum and distal intestine increased whereas protein content of testes and distal intestine and DNA content of stomach decreased. Crude homogenates of PM stimulated 3H-thymidine incorporation both in quiescent mouse embryo fibroblasts and Chinese hamster ovary cells. Addition of PM homogenates to cell cultures increased cell number but not protein content. The extent of in vitro growth-stimulation by 1% (v/v) PM homogenate was comparable to that by 2% (v/v) foetal bovine serum but was greater than that by 0.1 ng mouse epidermal growth factor. It appears that in mammalian test systems the in vitro growth-stimulatory effects of pigeon milk outweigh those observed in mice.