Very impressive beast. How much vegetation is there in this enclosure? Some twenty years ago Port Lympne had a huge male (Amaziga?) in a sizeable enclosure full of hawthorn bushes, ie you couldn't say that the absence of bushes was allowing the mane to grow lavishly.
It is a very large enclosure and very thickly vegetated. During the feeding time he took his meat deep into the bush, which I assume he does at every feeding (which is three days a week). So the thick brush does not seem to have an adverse affect on his mane.