According to Marriage Certificate here:
"South Africa, Free State Dutch Reformed Church Records, 1848-1956," database with images, FamilySearch (https://familysearch.org/ark:/61903/3:1:3QS7-L9QG-YPNG?cc=1910846&a... : 4 November 2016), Free State > Rouxville > image 164 of 461; Dutch Reformed Church Synod Centre, Bloemfontein.
Susara Johanna Labuschagne (Smith) was 21 when she married, with permission from her father Gert Smith, to much older though previously unmarried (jonkman) Hendrik Labuschagne. This would indicate that the D.O.B. listed on this profile, as of 09/04/2017, is incorrect.
The correct D.O.B. would therefore be c. 1856. What is the source for the 1825 D.O.B.?