Consistent differences in behaviors across contrasting functional contexts, i.e. behavioral syndromes, may have important ecological implications on the relative capacity of individual foragers to cope with familiar and unfamiliar foraging environments. We conducted a pilot field study to test whether social ranks of in a herd of dairy cows explained individual differences in coping styles of animals exposed to an unfamiliar grazing environment. In a first phase, the net displacement behavior (ND = positive-negative) and the time of arrival of individual cows to a freshly delivered familiar feed (TA) was assessed during 6 days in two groups of dairy cows (n=51) housed and managed in a voluntary milking system at the WK Kellogg Biological Station farm. In a second phase, GPS collars were used to monitor the foraging behavior of high (Dominant; n = 6) and low (Subordinate; n= 6) ranking animals during 11 week periods of exposure to a novel grazing environment. Our hypothesis was that dominant cows would consistently show a higher attitude towards feed resources across familiar and unfamiliar foraging environments. Body mass (BM), days in milk (DIM), milk yield (MY), voluntary milking frequency (VMF) and supplement intake rate (IR) were also measured as explanatory variables.
Results/Conclusions
Dominant and subordinate cows differed (P < 0.05) in rate of ND (7 vs. -9 ±2), and TA (9 vs. 21 ± 4 minutes). Compared to subordinate conspecifics, more dominant cows tended to have shorter DIM (56 vs. 109 ±18d; P = 0.08) and higher IR (7 vs. 5 ±1kg/d; P = 0.09), but similar MY (39 vs. 36 ±4 kg), VMF (3.8 vs. 3.1 ±0.4) and BM (578 vs. 537 ±20 kg). After exposing the naïve cows to an increasing weekly gradient of voluntary grazing time on pasture, we detected that dominant cows tended to maintain higher VMF and BM than subordinate cows (P = 0.10). Across weeks, dominant cows consistently traveled longer horizontal distances and showed higher pasture residence time and frequency of pasture foraging bouts than subordinate cows (Behavior group x week = P < 0.03). The prediction that dominant cows would consistently show higher attitude towards feed resources across familiar and unfamiliar foraging environments was supported by the study. Furthermore, our results suggest that the existence of behavioral syndromes in dairy cattle managed in a voluntary milking system could be likely explained by correlated physiological differences in DIM and nutrient requirements between behavioral groups.