Dominance pattern in free grazing zebu cattle.

摘要

Dominance hierarchy was studied in 15 free-grazing Rathi cows under arid conditions in Bikaner from 1987 to 1989. A herd of 12 calves was also introduced into the study during 1989. Cows were maintained together on 7-8 ha and allowed to graze on Lasiurus scindicus pasture during the study period except during calving and illness. During the dry period (December to June) they were supplemented with grass hay and pelleted cattle feed according to the stage of production. Their behaviour (antagonisticinteractions) was recorded during grazing, feeding on grass hay or drinking water. On the basis of these interactions each cow was ranked in a rank order ranging from 15 (top rank) to 1 (bottom rank) and dominance hierarchies were formed. Body weight plays a predominant role in determining social ranks in zebu cows brought from different sources and managed together. Separation of cows from the herd for about 16 days changed social ranks within the herd. Dominance ranks were highly correlated (P<0.01)with heart girth and height at withers in addition to body weight. Dominance ranks were also correlated (P<0.05) with first lactation milk yield indicating higher social ranks in high producers. Rank order in calves was established when they neared the yearling stage at which time males, regardless of size, became dominant over female counterparts; by 23 months of age, male calves were dominating all females (cows and heifers) in the herd. A combination of body weight and age was responsible for dominance ranking within the sexes. Rank orders of cows and their calves were closely related.