saevit in absentis; collecta fatigat edendi
ex longo rabies et siccae sanguine fauces.
"He rages against the absent/inaccessible lambs (absentis
- masc. acc. pl.); his frenzy for eating (edendi ... rabies
), built up (collecta
- fem. nom. sg. agreeing with rabies
) over a long period of time (ex longo
), torments him (fatigat
), and his jaws, dry of blood (also torment him)."
Also possible: "his built-up frenzy for eating after a long time" (taking ex longo
more closely with edendi
). I think it doesn't matter precisely how you take it, because poets often transfer modifiers from one thing to a closely related thing, but the idea remains the same.