You can have either an estate agent/auctioneer value the land and house or an agricultural consultant. An agricultural consultant could value the stock too or the local friendly mart manager might do it- indeed many marts have an inhouse valuer/auctioneer who might do the whole lot. Usually, at least in this neck of the woods, it would be for a flat fee, but of course it really depends on the number of stock and quality involved.. If you're talking about a pedigree herd, and for some reason you want the valuation high ( agricultural relief), then you might need to look to the Breeders society for a valuation, and that would be more expensive. If the nephew is not taking on the stock and is going to sell them, then he would be better off to sell straight away ( depending on cattle prices obviously) and use the sale price as the market value.