We do spray their bellies, especially the woollier types. All we have left of those now are Shetlands. Before we spray the backs, we tip the sheep, spray under the crutch (a common place for strike) and around the pizzle/sheath/penis/winkle, whatever you call it. We don't use the wide sprayer at all, as our primitives are fairly narrow so the spray readily runs off, and being accurate on the underside is easier with the kind of sprayer we use. It's worth tipping them any way just to keep an eye on udders and male bits.