Ayr's tries came from AJ Mcfarlane, Grant Anderson, Scott Sutherland and a Jeff Wilson score in the dying minutes of the game.
Frazier Climo got into the action with a penalty and three conversions.
Glasgow's Calum Forrester started in the back row for Ayr.
West Of Scotland - missing two influential players in Gordon Bulloch and Guy Perrett - came unstuck at Myreside going down 38-12 to Watsonians. Peter Horne converted his own try for West and Graham Fisken added a consolation score in injury time.
Glasgow lock Richie Gray and prop Jon Welsh started for West.
Glasgow Hawks suffered another dose of misery as they were swept aside 32-17 by Edinburgh Accies at Old Anniesland. Hawks got off to a good start with a first-minute try by Craig Gossman but Accies took control of play and the scoreboard. Hawks other points came from a double from Jonno Wright and a conversion from Mike Rainey.
Glasgow's Chris Kinloch started at full-back for Accies.
Hydro Electric Division One
Currie 13 - Stirling County 13
Glasgow Hawks 17 - Edinburgh Acads 32
Hawick 32 - Selkirk 15
Heriot's 25 - Ayr 29
Melrose 20 - Boroughmuir 27
Watsonians 38 - West Of Scotland 12
Hydro Electric Division Two
Aberdeen GSFP 23 - Biggar 20
GHA 27 - Kelso 21
Haddington 18 - Gala 23
Hamilton 26 - Dundee HSFP 39
Jed-Forest 34 - Stewart's Melville FP 18
Peebles 41 - Musselburgh 0
Hydro Electric Division Three
Ardrossan Acads 21 - Ellon 29
Dunfermline 24 - Hillhead-Jordanhill 19
Falkirk 47 - Cartha QP 12
Garnock 54 - Livingston 0
Morgan Academy FP 21 - Kirkcaldy 26
Perthshire 50 - Irvine 15