It seems nothing but logical that an enormous amount of plantations is needed to provide these large masses of feed for livestock animals. Nearly everyone has seen the endless row of fields when looking down from a plane. More than half of these fields are used to produce plants for fattening animals.
As mostly soy beans are used as feed, tropical countries with a favourable climate have come to be the main exporters, e.g. Brazil and Argentina. These are the very countries that are known for their rainforest.
As more space is needed for plantations, rainforest is cleared to provide new plantations and pasture for cattle.
The consequence of this continued clearing is the extinction of species. The American zoologist Edward Wilson estimates a rate of 70 species per day. http://www.gue.com/ecology-conservation-and-extinction
Besides, our planet’s green lung, which has an enormous capacity of storing oxygen, is being destroyed.
Another problem is created by the immense monoculture which is substituted on the cleared spaces of rainforest. An example of Germany shows a 40% decrease in the number of bird species that has been observed due to the monoculture of maize since 1990.