Crop Physiological Structure At Different Reproductive Cyclesand The Mechanism Of Milk Protein Synthesis Of Domestic Pigeon(Columba Livia)

With the development of economic, people's demand for pigeon becomes more and more vigorous, and pigeon whole industry is expanding at 15% annual growth rate. Then squabs are the main forms of the consumption of pigeon, however, the growth of the young pigeon relies on feeding of the breeding pigeons. Young pigeon, out of it shell, is unable to take the initiative to gather the food, and needs to be fed by the breeding pigeons as a mouth to mouth way. Crop milk is the only source of food for 1-7 days age squab, and is rich in amino acids, Ig A, Ig G, and so on. Therefore, crop milk plays an extremely important rolein the process of growth of the young pigeons. The experiment with king pigeon at different reproductive cycles as the research object, through analyzing for nutrient content ofcrop milk collected from 30 squabs,and during the non-breeding and the first day of the lactation, blood samples were collected from ten pairs of breeding pigeons and the levels of prolactin and insulin were determined. Additionally, at the 14 th and 16 th day of the incubation period and the 1st, 3rd, and 7th day of the lactation period, crop samples were collected from five pairs of breeders, respectively. Crop samples were evaluated for changes in crop physiology structure, as well as changes in the expression patterns of IRS1/Akt/TOR signaling pathway-related proteins, aimed at providing theoretical basis for crop milk protein synthesis and the nutrition regulation of the young pigeon growth.The results showed that,(1) on a dry matter basis, crude protein content of crop milk at the day 1, 3, 7 of the lactation decreased significantly(P<0.05), and the contents of crude fat and crude ash were no difference.(2) Compared with the non-breeding, the relative weight and thickness of pigeon crop increased gradually, and climbed the peak on the third day of lactation.H&E staining with crops found that crop inner wall leaved the basic smooth during the non-breeding period, the surface had a few small spikes called rete pegs, from the incubation to the lactation, the thickness of crop tissue and the rete pegs increased gradually, then in the end of incubation period, these adjacent hyperplasia rete pegs became to combine together, and the phenomenon was strengthened in the early lactation, and then in the seventh day of lactation, the adjacent rete pegs separated gradually.(3) The serum prolactin and insulin level of the lactation pigeon were20.34 ng/m L, 1.41 nmol/m L respectively, and theywere higher than those of the non-breeding period(9.72 ng/m L, 0.29 nmol/m L) significantly(P<0.05).(4)Compared with the pigeons of the non-breeding period, the expressions of phosphorylated insulin receptor substrate 1, phosphorylated Akt, phosphorylated TOR, phosphorylated ribosomal protein S6 kinase, phosphorylated eukaryotic initiation factor 4E binding protein 1, phosphorylated ribosomal protein S6, and eukaryotic initiation factor 4E proteins were up-regulated significantly in crop tissue of pigeon in lactation period(P<0.05).It can be concluded that, at different reproductive cycles, the structure and morphology of pigeon crop change gradually, and it forms the physiology structure basis of crop milk synthesis. The production of crop milk protein may be regulated through the IRS1/Akt/TOR signaling pathway.