Yep, you have to have them under EU regulation 1/2005
Chapter III Section 1.3
Facilities and procedures
1.3. Facilities for loading and unloading, including the flooring, shall be designed, constructed, maintained and operated so as to:
(a) prevent injury and suffering and minimise excitement and distress during animal movements as well as to ensure the safety of the animals. In particular, surfaces shall not be slippery and lateral protections shall be provided so as to prevent animals from escaping;
Section 1.4 also specifies ramp angles
1.4. (a) Ramps shall not be steeper than an angle of 20 degrees, that is 36,4 % to the horizontal for pigs. Where the slope is steeper than 10 degrees, that is 17,6 % to the horizontal, ramps shall be fitted with a system, such as provided by foot battens, which ensure that the animals climb or go down without risks or difficulties;