Hi there.
After several years of breeding fluffy bottom chickens including Orpington, Silkies and others... I have NEVER yet had to trim bottom for fertility issues.
But that is MY experience. And I have a little more to share...
Weather (season), age (too young OR old), stock density, extended inbreeding, broodiness, and many other things can effect fertility.
Wyandottes specifically... it is known that breeding several generations of nothing but rose comb can slow the motility of sperm in future generations (not your original stock unless it is already at that point). Some breeders (mostly hatchery contracted) sneak a straight comb into their stock to help prevent this.
Also just because a hen lays an egg doesn't mean it's viable.
Personally NO, I wouldn't trim bottoms... I feel as though pokey pin feathers sticking out while they rub vent won't help either bird.
Nutrition is always a factor to me... that effects overall health and hatchability. Fat under nourished birds will have a harder time with the act of breeding and laying.
Hope this is helpful.
