Social interactions in N'dama cows during periods of idling and supplementary feeding post-grazing

Abstract

Thirty N'dama cows were observed post-grazing, during periods of idling (NF) and periods of supplementary feeding (F), over a 1-year period to determine the frequency and pattern of social interactions during 1 h each of feeding and idling. Agonistic interactions (butting, threatening and avoidance) were 1.4 times higher ( P<0.01) in the F than the NF. In contrast, amicable behaviours (rubbing, sniffing and grooming) were significantly ( P<0.05) higher in the NF than F. The frequency of agonistic interactions was highest during the first 30 min of the F when feed was available. There was no trend in the frequency of either agonistic or amicable behaviours during the NF. During the first 15 min of the F, animals initiated no amicable behaviours, but thereafter amicable behaviours sharply increased until the end of the period. Season (dry and rainy) had no influence on frequency of agonistic behaviours but grooming, and thus all amicable behaviours combined, were significantly ( P<0.05) higher in the rainy rather than dry season. As butting areas, animals preferred the sides (39–42%) and rear of companion animals (25–28%). Social dominance was highly correlated with liveweight ( r=0.828−0.884) and age ( r=0.664−0.754); this was not linear, and tended to be complex. High-ranking animals initiated most, but received few, agonistic interactions. Agonistic interactions were generally between animals close in rank or with subordinates. There was no significant ( P>0.05) relationship between number of animals dominated and amicable behaviours initiated or received.