Organic wines are made from grapes grown without chemical fertilizers, pesticides, fungicides or herbicides. Vineyards use organic farming practices like breeding grazing animals to replace insecticides, crop rotation and composting. Biodynamic wines follow additional agricultural and post-harvest handling methods. Organic wines have higher levels of resveratrol and promote biodiversity compared to conventional wines which may use genetically modified yeast. Several Argentine wineries profiled practice organic and biodynamic viticulture methods.