Among the animals of different species chickens react in greater numbers and more noticeable to a va-riety of growth biostimulators. There are great improvements on their general state, growth spurts and development of internal organs is quicker when they are injected with small portions. Such stimulation has a great influence not only on growth and development of chickens in their first period of life but also on health and productivity later on. The most active peak of reaction is when chicken is two months old. Their internal organs, especially the digestive system, develop earlier, their genitals appear earlier and they begin egg-laying much earlier too, when chickens are being fed those biostimulants. Slaughter meat yield becomes more and quality of meat improves with the influence of stimulators. A major disease pre-vention and healing effect can be reached, since most of the biostimulants raise immune system and re-sistance of the organism. It can be the only thing to justify their usage on animals. Tests show that the most typical growth spurt of birds is from fifteen to twenty percent in normal conditions. Growth spurts are also accompanied with the rise of resistance to different infections and activation of different physio-logical processes. Growth spurts can be twice or more than written here, but those spurts are usually short-timed and often accompanied with the dysfunction of different organs
