Factors of diversity of domestication-related behavior in farm animals of different species

Fear response and domestic behavior of sheep, cattle, horses, and pigs were studied using four different variants of experimental stress conditions. A s standard aversive stimulus, the factor of human presence during the feedi ng time was used under the following conditions: animals were starved for 1 2-14 or 2 h before the exposure and fed individually or in a group. In the animal species studied, these conditions were found to reveal phenotypic an d genotypic differences in fear response to humans, which is correlated wit h feeding behavior by regulatory mechanisms. A comparative qualitative and quantitative study of the discrete variation of the associated passive-defe nsive responses and feeding behavior (as related to domestic behavior) was conducted with regard to the effect of the breed and individual genotypes a nd the feeding and zoosocial deprivation. A classification scheme of the in dividual diversity of this behavior in farm animal species is proposed, in which ontogenetic and evolutionary relationships earlier found in sheep wer e taken into consideration. It is suggested that the progressive ecological and zootechnical specialization alters adaptive reaction norms of stress r esponse in breeds and leads to the formation of the homologous variation in a set of coadapted traits, i.e., constitutional types of animals genetical ly marked by their behavior. A conclusion is made that heritable polymorphi sm of domestic behavior represents a new source of adaptive variation for i mproving fitness, welfare, and productivity of farm animals by breeding.