Spines
Pinapple leaves are spiny and contain bromelain (a proteolytic enzyme). They may injure and cause skin problems to the workers who cut the leaves to feed animals. Pineapple leaves should not be used to feed pigs and poultry (Göhl, 1982).
Pesticides residues
In Hawaii in 1982, heptachlor (a carcinogenic pesticide) was found in the milk from cows fed fresh chopped pineapple leaves. The pesticide had been used to control the ants that tend mealybugs (Morton, 1987).