The social environment is very important for the welfare of animals in loos
e housing daily production systems. This article reviews recent literature
on the effect of animal density (AD) and regrouping (RG) on the welfare of
cattle and describes the development of feasible indicators for the social
environment. Special emphasis is given to the methodological problems that
arise when AD and RG are used as welfare indicators in a welfare assessment
at the herd level. Various factors affecting estimates of AD were consider
ed, including the size of the animals, correction for very high AD values,
pen shape and how best to aggregate the results at herd level and over time
. The examination of RG is centred around the effect of early social experi
ence of the animals, the stability of social relationships, and the effect
of pen changes.
A range of parameters is suggested for the evaluation of AD and RG as possi
ble welfare indicators. These are based on observational data from 10 Danis
h dairy herds and related to clinical records from the herd farms. It is co
ncluded that mean AD is not feasible as a welfare indicator at the herd lev
el but the 25th percentile of AD) corrected for the liveweight of the anima
ls should be used instead. The two most promising parameters for evaluation
of RG are the frequency of combined pen and group changes for a sample of
the herd, and the probability of a certain duration of inter-animal relatio
nships. Results from clinical observations correlated with neither AD nor R
G.