Shed trusses and snow load capacity

I'm working on a 3 sided run in for livestock, and had previously been using traditional 2x8 rafter construction for the roof. I came across these designs, and am very intrigued at using this 2x4 truss system instead. One thing I don't see mentioned though is roof load capacity. I live in Michigan, and have to account for snow load in addition to just the weight of the roof. Are 2x4's with this construction able to withstand additional snow load? Ground snow load for my areas is 25psf. Roof pitch will be 3/12, span of roof is 12'.

I looked at the 3D model of your 16x12 shed as well, with this style roof. In the model it looks like you added collar ties on all the trusses. Is that for additional load capacity or another reason? At what point does the need for collars become necessary? I'm planning on doing a 24'x12' structure, and thought about buying and adapting those plans to my needs, but wanted to ask about the snow first.