Objective To prepare and characterize the somatostatin (SS) anti-idiotypic antibody of yolk (SS yolk Ab2 ) on the basis of successful preparation of neutralizing SS mAb1 2E7, and then to further probe the application of SS yolk Ab2 in promoting animal growth. Methods The egg-laying hens were immunized with the neutralizing SS mAb1 2E7. The eggs containing a high titer of SS yolk Ab2 were collected and the egg yolk was separated from the egg white. The SS yolk Ab2 in yolk solution was extracted by water dilution and acidification, and was purified by precipitating with cool ethanol. The titer, concentration and specificity of SS yolk Ab2 was determined by ELISA. The Ab2β property of SS yolk Ab2 was determined by ELISA of competitive inhibition. The effect of SS yolk Ab2 on animal growth was experimented in the mice, chickens and fish. Results The SS yolk Ab2 had a titer of 1×10-5 and a concentration of 8 mg/mL. The SS yolk Ab2 could react with the rabbit antibody against SS, but not react with the rabbit antibody against growth hormone, insulin and gastrin. The immunoreaction between the SS yolk Ab2 and rabbit antibody against SS was inhibited by SS competitively. The SS yolk Ab2 could induce the mouse to produce SS Ab3 and the SS Ab3 could react with SS, which suggest that the SS yolk Ab2 was an Ab2β. The SS yolk Ab2 was used to immunize the mice in different doses of 0.8 μg or 3.2 μg each mouse by subcutaneous injection, and to immunize the chickens in different doses of 0.8 μg or 3.2 μg each chicken through intramuscular injection, and to immunize the Doppelfish in doses of 3.2 μg each Doppelfish by immersing fishes in 2 L of sea water containing Ab2. The control animals were immunized with the same volume of physiological saline and by the same methods. One month later, the SS yolk Ab2 vaccine could increase body weight 33.5% and 37.0% in the mice, 25.6% and 34.1% in chickens, and 24.8% in the Doppelfish compared with the corresponding controls. Conclusion The SS yolk Ab2 was prepared successfully. It had a high titer, concentration and specificity. It is an Ab2β as a vaccine can increase body weight of animals significantly by small-dose immunization only once.