After the pig is weighed, the ownership of the pig generally belongs to the original owner. After all, the price is not known until it is weighed, and the buyer has not paid, so the ownership of the pig still belongs to the original owner.

If both parties sign a contract, then according to the provisions of the contract, the performance of the contract has priority. If the goods are provided first and then paid, the ownership of the goods belongs to the debtor. If the buyer fails to perform the payment obligation, he may bring a lawsuit to the court and ask the debtor to perform and bear the liability for breach of contract. If, according to the contract, both parties with mutual debts perform at the same time, the ownership of the goods belongs to the supplier on the premise that the buyer does not pay. Or, the party that should perform first (the payer) does not perform the payment obligation first, and the party that performs later may refuse to perform.