Alicia Silverstone threw a vegan bash at a farm for her son Bear's third birthday.

The 'Clueless' star, who is married to Christopher Jarecki, invited friends and family to Farm Sanctuary's Southern California Shelter for the event, where her little boy was thrilled when staff named a lamb in his honour.

The 37-year-old beauty opened up about the special event on her blog, writing: ''We had the sweetest time celebrating Bear's birthday at Farm Sanctuary. From loving up the animals to a raging drum circle with the most delicious vegan food and sunshine -- it was a fun-filled and happy day.''

She added: ''At the end of the day, the Farm Sanctuary staff surprised Bear with an incredible birthday gift. They had just rescued a baby lamb (eight days old!!) that was found abandoned in a barn in LA country and decided to name her Bear! She was still in a fragile state so she couldn't be exposed to large groups of people but once the majority of guests took off she was brought out. She was so gentle and adorable. Bear was thrilled. It was beautiful.''

Alicia has previously attracted criticism for some of her parenting decisions, including her son's vegan diet, chewing his food before giving it to him, and ingesting her placenta through a pill.

But she recently said: ''As far as critics, I'm very secure in the choices I make because I'm really informed and I trust my instincts and when I need help, I go to the people I see parent or birth or be pregnant in a way that was really inspiring me. And the rest is just noise.''