The lack of a connective is called "asyndeton", and it's not uncommon in Lucretius. Michael Gilleland collected some examples, if you're interested in seeing it taken to the extreme.
Bailey, at this line, calls it without elaboration "Lucretian asyndeton".
Is a distinction drawn between "wild" and "maddened by desire"?
Yes. The former can mean "not domesticated", rather than indicate any sort of mental state. Juvenal (11.104), for examples, calls the lupa that suckled Romulus and Remus a Romulea fera.
Taken together, ferae pecudes indicate common barnyard animals that are still wild (in the undomesticated sense), as it does in Varro:
Etiam nunc in locis multis genere pecudum ferarum sunt aliquot, ab ovibus, ut in Phrygia, ubi greges videntur complures, in Samothrace caprarum, quas Latine rotas appellant. Sunt enim in Italia circum Fiscellum et Tetricam montes multae. De subus nemini ignotum, nisi qui apros non putat sues vocari. Boves perferi etiam nunc sunt multi in Dardanica et Maedica et Thracia, asini feri in Phrygia et Lycaonia, equi feri in Hispania citeriore regionibus aliquot.
Even now there are several species of wild animals in various places: as of sheep in Phrygia, where numerous flocks are seen, and in Samothrace those goats which are called in Latin rotae; for there are many wild goats in Italy in the vicinity of Mount Fiscellum and Mount Tetrica. As to swine, everybody knows — except those who think that wild boars ought not to be called swine. There are even now many quite wild cattle in Dardania, Maedica, and Thrace; wild asses in Phrygia and Lycaonia, and wild horses at several points in Hither Spain.
Looking only at the passage at hand, reading ferae pecudae as adj. + noun makes total sense. Lucretius is painting a picture of the natural world that delights in Venus. Honestly, I'd say this is my preferred reading.
The issue comes into play that, as Bailey notes, "[Lucretius] frequently couples the wild and domestic animals." He provides two parallels, 1.163 (armenta atque aliae pecudes, genus omne ferarum [N.B. I don't think this is a good parallel - cmw]) and 2.343 (laeta armenta feraeque [which is a much clearer and cleaner parallel]), for reading it thus. He further says there's no reason that Venus is limited specifically to wild animals, but I don't think that's a proper reading. It's not that Venus is limited, but rather Lucretius is painting an idyllic portrait of the wild countryside untouched by human intervention. He's showing examples, not providing an exhaustive list.
There's not much more I can say about it at this point without writing a proper article examining Lucretius' portrayal of the wild and the domestic and human influences on it.