Based on the total ratings provided, the top five contenders for the 4.00 at Ayr are:

1. Mountbatten (IRE) – 395.1
2. Flylikeaneagle (IRE) – 340.0
3. Yaaser (IRE) – 335.9
4. Wadacre Grace – 329.3
5. Star Shield – 327.9

Let’s delve deeper into each horse’s prospects for this race:

1. Mountbatten (IRE) tops the total ratings at 395.1. This low-mileage 4yo scored at Doncaster last time, taking his turf record to 2-4. His wins have come on both soft and fast ground, indicating versatility with regards to track conditions. This is his second attempt at 1m, and he could be a big player if he is as effective at this distance. Considering his recent form and the potential for further improvement, he’s a strong contender.
2. Flylikeaneagle (IRE) comes in second with a total rating of 340.0. He recently scored a clearcut victory at Musselburgh when switched back to Flat from hurdling. However, he disappointed over this course and distance on his most recent outing. Despite this, he has a generally respectable record at Ayr. If he can bounce back from his latest performance, he could still pose a threat.
3. Yaaser (IRE) holds the third-highest total rating at 335.9. He proved productive last spring/summer, winning four times on good/firmer ground, including twice at Ayr. Despite yet to finding ideal conditions this term, he hinted at a return to form at Hamilton ten days ago, suggesting potential for a strong performance here.
4. Wadacre Grace stands fourth in the ratings with a score of 329.3. Primarily campaigned on AW, she has won three times. Her form dipped markedly on her return to turf at Musselburgh last month, though she may do better on this forecast faster surface. Given her track record, she’s not to be dismissed lightly.
5. Star Shield is the fifth on the list, with a total rating of 327.9. He justified favouritism in a four-runner contest over this course and distance three weeks ago. Returning to a deeper field, he’s only 2lb higher and could well remain competitive.

An additional consideration is Hortzadar who, although ranking seventh in total ratings (305.3), demonstrated a strong performance with a close second at Ripon on his reappearance. He may have found his following run coming too soon when only eighth at Beverley. However, he is still well treated and has potential if bouncing back to the Ripon form.

In conclusion, Mountbatten (IRE) appears to be the frontrunner based on his current form and total rating. However, the race’s outcome could change based on varying factors, including the day’s conditions and individual horse performance. Hortzadar’s potential for a strong comeback should not be overlooked, despite his lower total rating.