Abstract
Farmers are understandably concerned that many proposed improvements to broiler chicken welfare such as 'enrichments' lead to the birds being more active, eating more and therefore result in financially detrimental effects on Feed Conversion Ratio (FCR). The current evidence is inconclusive, but most research so far has relied on small-scale pen studies, not flocks studied under commercial conditions. We measured the life-long activity of 34 commercial flocks of Cobb broilers using smart camera technology and analyzed the data using four statistical descriptors of the patterns made by flock movements - mean, variance, skew and kurtosis of optical flow. For each day, we scored each flock by its scaled deviation from the median for each of the four descriptors and gave it 4 overall activity scores, based on its average lifetime deviation from median ([average optical flow value - median]/√median). The results showed that, contrary to widespread concerns, FCR was no higher in more active flocks and that on average more active flocks tended to have lower (i.e. more efficient) FCR (p = 0.060). There were positive correlations between FCR and the lifetime activity score using both the skew of optical flow (r = 0.608, p < 0.001) and kurtosis (r = 0.603, p < 0.001), both suggesting that increasing numbers of active birds within a flock were associated with lower FCR. There were also positive correlations between skew and kurtosis of optical flow and mortality (r = 0.388, p = 0.023 and r = 0.454; p = 0.007) respectively), as well as an even higher correlation between FCR and mortality (r = 0.698; p < 0.001), which suggests that the favorable effect of activity on FCR may at least in part, be via decreased mortality. While not all welfare improvement may result in improvements in FCR, these results show that increased flock activity is not itself the problem that might be feared.