Impact of agonistic interactions on feeding behaviours when beef heifers are fed in a competitive feeding environment

Animals housed in intensive production systems typically face a certain level of competition for resources such as feed. In many intensive housing systems animals are forced to actively compete for access to food resources. The aim of this study was to examine the relationship between competition and feeding behaviour, and to describe the variability of this relationship among beef heifers fed in a highly competitive environment. We anticipated that heifers would vary in how they would compete for access to feed. For those engaging in agonistic interactions, those that were competitively successful would feed longer and at a slower feeding rate. Forty-five crossbred (Hereford. Charolais and Angus) beef heifers (520.5 +/- 32 kg body weight; BW) were randomly assigned to 3 pens of 15 animals. Pens were fitted with two radio frequency equipped feed tubs that monitored individual animal dry matter intake (DMI; kg), feed bunk attendance frequency (count), duration of feed bunk attendance (min) and eating rate of the heifers (g/min); all feeding behaviour data was summarized by hour. All agonistic behaviours resulting in successful access or maintenance of a feeding position were recorded from 0900 h to 2200 h on 3 separate days, and summarized per hour. Across the three groups, there was a positive relationship between the number of successful agonistic interactions (SAI) displayed and DMI (y = 0.028x + 0.557, R-2 = 0.26, P<0.003), bunk attendance duration, (y = 0.44x + 1.30, R-2 = 0.45, P<0.001) and bunk attendance frequency (y = 0.30x + 1.95, R-2 = 0.49, P<0.001). With the exception of duration and SAI at mid-day, the strength of these relationships was fairly consistent across the day. The strength of the relationships between SAI and the feeding behaviours varied between individual heifers. This study suggests that beef heifers fed in a competitive environment do access the food resource by engaging in agonistic behaviour; however, the extent to which competition relates to feeding behaviour varies between animals within the same group. Differences between individuals may provide insight into how animals that are less likely to compete for access to feed adapt to highly competitive environments. Crown Copyright (C) 2010 Published by Elsevier By. All rights reserved.