The social environment is very important for the welfare of animals in loose housing dairy production systems. This article reviews recent literature on the effect of animal density (AD) and regrouping (RG'j 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 considered, 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 experience 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 possible welfare indicators. These are based on observational data from 10 Danish dairy herds and related to clinical records from the herd farms. It is concluded that mean AD is not feasible as a welfare indicator at the herd level but the 25th percentile of AD corrected for the liveweight of the animals 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 relationships. Results from clinical observations correlated with neither AD nor RG.

In the context of determining the sustainable carrying capacity of dry-Mediterranean herbaceous rangelands, we examined the effect of animal density on cattle nutrition, which is fundamental to animal performance and welfare. The effects on dietary components of low (0.56 cows/ha; L) and high (1.11 cows/ha; H) animal densities were monitored for three consecutive years in grazing beef cows. In the dry season (summer and early autumn), cows had free access to N-rich poultry litter (PL) given as a dietary supplement. In each season, near-IR spectroscopy (NIRS) was used to predict the chemical composition of herbage samples (ash, NDF, CP, in vitro dry matter digestibility (IVDMD) and metabolizable energy (ME) content from IVDMD). Near-IR spectroscopy was applied also to faecal samples to determine the chemical composition of the diet selected by the animal, as well as the contents of ash, NDF and CP in the faeces themselves. A faecal-NIRS equation was applied to estimate the dietary proportion of PL. Seasonal categories were green, dry without PL supplementation and dry with it. We found no effects of animal density on nutrition during the green season but effects were apparent when cows consumed dry pasture. Ash content predicted by faecal NIRS was higher in the diet than in plant samples clipped from pasture, which infers that cows ingested soil. Dietary and faecal ash contents were higher (P<0.05) at the H, implying greater soil intake in these animals. During the dry period, dietary contents of ME were higher in L than in H (P<0.05). Poultry litter supplementation was associated with a marked increase (P<0.01) in dietary and faecal CP contents. Poultry litter represented 0.45 and 0.59 of the diet in treatments L and H, respectively (P<0.05). Consequently, treatment H had higher faecal protein (P<0.05). A tendency of higher dietary protein (P=0.08) and lower dietary NDF (P=0.10) in treatment H was probably related to greater PL ingestion. Given that high and sustained rates of poultry litter consumption are detrimental to animal health, the above results cast doubts on the long-term sustainability of the higher of the animal densities tested. Although it may be sustainable vis-à-vis the vegetation, treatment H may have exceeded the boundaries of what is acceptable for cow health. Chemical information revealed with NIRS can be used to evaluate whether animal densities are compatible with animal health and welfare standards and can play a role in determining the carrying capacity of Mediterranean rangelands.