First question to answer you question. Are you sure its Solanum nodiflorum? It would be very unusual for that indigenous species to be a weed in a paddock - it is more likely to be S. nigrum or an allied species like S. physalifolium.
Solanum nigrum and S. nodiflorum are not that easy to tell apart though. Solanum nodiflorum has the flowers in a pseudoumbel (i.e. flowers all radiated out like a star from a central 'stalk'), those of S. nigrum are in racemes (a single stalk with flowers running off it one by one along the stalk. The sepals at the base of the fruits in S. nodiflorum are reflexed (and usually pretty narrow), those of S. nigrum are accrescent (so clasp the fruit) and are very broad. Usually S. nodiflorum stems have small hooks on them, S. nigrum almost never.
Irrespective - I'd treat them as potentially poisonous - though stock don't tend tio eat them unless there is nothing else. Its usually best to regard all Solanum as toxic.