In France, most young bulls from beef breeds are produced by cow-calf-breeders and finished by specialized fatteners. After weaning the young bulls are transported to sorting facilities and grouped to body-weight-homogeneous groups for the start of fattening. Does this practice really make sense? In pig fattening, it has already been proven that forming bodyweight-homogenous groups has no or even a negative effect on performance. The trend here is often towards housing groups from as few origins as possible and have short transport distances. 
In a recent study in France (Herve, L. et al. 2020), for which data from 19.055 young bulls were analyzed, negative effects of exclusively weight-based group composition are evident. Grouping animals into weight-homogeneous groups is intended to simplify management, but is detrimental to animal welfare and does not guarantee higher performance or uniform gains.
Grouping leads to mixing of animals from different farms, which increases the health risk due to different pathogenetic backgrounds. This is also confirmed by Morel-Journel, t. et al. (2021) after the study of 137,726 weaned calves, in which it was clearly shown that the BRD risk is reduced by fewer origins per group. In addition, a new group hierarchy must be established, which is associated with aggressive behavior or social pressure. In weight-homogeneous groups, it takes even longer to establish a hierarchy.
Other factors affecting fattening performance are transport distance, group size, age of the animals and vaccination status with respect to Bovine Respiratory Disease (BRD). Mixing animals has been shown to affect the homogeneity of average daily weight gain negatively . And also, that the animals from the most uniform groups had the lowest gains at the end of the fattening period. 


This Research Innovation has an impact on:

  • Animal health and welfare, as mixing increases the chance of BRD.
  • Production efficiency and meat quality: As described the batch conformation impacts on average daily gain. The increased duration of rank fights in weight homogeneous groups may influence carcass quality.