Alpacas are grazing animals and their main food is grass. An alpaca can just live on grass but pregnant and nursing females and working males do need supplements to ensure they get the right mix of minerals. They also appreciate a supply of hay durng the winter when the grass is less nutricious and may even be frozen or covered in snow.
Alpacas like a varied diet and we feed ours on a variety of items in addition to grass - mainly vegetables and fruit such as chopped carrots, apples, celery and even pineapple, lettuce, cabbage, parsley and brussels sprouts. We never throw away any veg or fruit now - anything we have left over goes over the fence to the alpacas! In winter we also give them some aflafa and they love lamb and ewe pencils, both of which we buy from the local feedstock merchants.
From October to April we also give them a monthly supplement of Vitamin D as the short days compared with their original South American home means they don't always make enough themselves. This comes in tubes with a plunger which you put in the side of their mouths. They soon get used to the routine.
We have also discovered that sugar beet is very good for nursing mothers as it helps them lactate and ensures they don't get too thin. However, it's important not to over feed an alpaca as this can also bring health problems.
Some plants are poisonous to alpacas. A full list can be downloaded from the BAS web site, but avoid fox gloves, box, yew and deadly nightshade. Like other pasture animals they will avoid ragwort if it's growing but make sure they never get any in hay.