Ok, for 5 years my Shetlands bred and no issues with fertility. FF last year, only seemed 2 older males were breeding and the 2 younger I figured were still too young, 18 months to 2 yrs. old. So this year I have 3 males 2 years old. One older male, he is breeding and picks on another male occasionally...5 females almost 2yr old to 5 yr old. Only seem breeding twice by same male on same female . Out in pasture in daytime with pools, have a night pen that has 3 nesting areas, and a pool... and only gotten a few fertile eggs and a bunch of infertile eggs ... they get grass in daytime and grains and layer at night (geese aren't fond of the layer)... What can or should I do? Separate them into smaller groups? age? feed? Move the older pair out? night pen is about 12 x 30...and the females are laying all in one nest...