Professor Dylan Jones is Pro Vice-Chancellor for Biomedical and Life Sciences at Cardiff University.
He told ITV Cymru Wales that the university's animal research procedures are strictly regulated, 'certainly not cruel' and play an important part in establishing ways to alleviate human suffering.
He conceded that the institution would like to reduce the number of animals used, but said it would be 'some time' before scientists could rely solely on other methods of testing, as some remain 'unsophisticated and unreliable'.
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Crowds came to hear him speak this afternoon in Bangor - a seat where fewer than 100 votes could make the difference at the next election.
Scattered showers with the odd heavy burst possible but there will be plenty of sunny spells too.
A rather wet and windy evening, with rain in the north and showers elsewhere.