Art sculpture 29h59'59'' : humans feeding off cow's suffering

This art installation by Liu Qiang shows humans' overexploitation and reliance of other animals - in this case our desire for milk puts great strain on the cow. She is not even able to feed her own young with the milk, but instead have to feed all the humans madly scrambling after her udders. It also shows something very unnatural - why would a big bunch of humans run and scramble after an animal for her milk? Is there not other food availble to us?