I´m quite surprised that Marwell are using horizontal bars with such a long-horned species.I wouldn´t advise that and vertical bars would be a little better, but still a risk.Too many stabling solutions in zoos are being taken straight from equine husbandry without being suitably adapted.The stabling carpentry people are sometimes prepared to do the job with the materials they use regularly for their bloodstock customers, unless the curator demands otherwise.For long-horned species, a panel of strong grid-mesh is the best solution.If it becomes knocked out of shape every few years, no harm done & it can be replaced for very little cost.Far better to have that happen than an injured animal.The above are general observations - I am unaware of the set of circumstances that led to the horizontal bars at Marwell which is of course an outstanding institution.