Wider slot in pens with fully slatted rubber mat flooring for fattening bulls: Effects on animal hygiene, health and welfare

•A 4%-increase of drainage area in slatted rubber pens did not improve bull hygiene.•Season of the year had the greatest influence on the hygiene of the bulls.•Wider slots did not prevent against claw shape defects or infectious diseases.•Very few atypical standing up/lying down movements were recorded on both floorings.•Wider slots allowed bulls to adopt comfortable postures during lying.