1. The composition of the vaccine from Salmonella for birds, comprising as an active ingredient a structure containing the O-antigen obtained from Salmonella, provided that the specified structure does not contain a whole cell. A salmonella vaccine composition according to claim 1, wherein the O-antigen containing structure is a lipopolysaccharide. 3. The salmonella vaccine composition of claim 1, wherein Salmonella is one or more selected from the group consisting of Groups O4, O7 and O9.4. A salmonella vaccine composition according to claim 1, wherein Salmonella is one or more selected from the group consisting of Salmonella Enteritidis, Salmonella Typhimurium and Salmonella Infantis. 5. The salmonella vaccine composition of claim 1, wherein the structure comprising the O antigen obtained from Salmonella is a mixture of structures. Containing O-antigen obtained from Salmonella Enteritidis, Salmonella Typhimurium and Salmonella Infantis. 6. A Salmonella vaccine composition according to claim 1, wherein the O-antigen containing structure is an O-antigen containing structure in an amount of at least 5400 EU / ml from each Salmonella in the Salmonella vaccine composition. The vaccine composition of Salmonella according to claim 1, wherein the vaccine composition further comprises an antigen derived from one or more pathogens selected from the group consisting of VirusAnyuscastle disease, avian infectious bronchitis virus, Mycoplasma gallisepticum, VLD virus, and Haemophylus paragallinarum. 8. A method for preparing a Salmonella vaccine composition for birds, comprising, as an active ingredient, a structure comprising an O-antigen obtained from Salmonella, comprising the following steps (1) to (4) :( 1) a stage for culturing Gram-negative bacteria (stage for cultivation)； (2) a step for releasing the aforementioned structure from cells contained in the solution after said cultivation (a release step)； (3) a step for collecting the aforementioned structure from the solu
