"A sausage and pork"
Translation:Une saucisse et du porc
It is because du = some.
If the article du is used, as it is partitive - it is referring to meat.
If it had used the article un, it would have meant a whole animal. When un is used - as it refers to a whole animal - it usually means it is a living animal, as opposed to meat.
Check out The great pig debate