The French wine growers who apply biodynamic cultivation face a different and interesting problem. Part of the biodynamic doctrine is that some preparations must be prepared before being spread in the vineyard. There are two preparations, numbers 500 and 501, where cow manure respectively silicon are to be prepared in cow horns and then buried during the fall. However, there is now a shortage of cow horns in France, largely caused by a breeding of breeds without horns!
Source: La Revue du Vin de France