_Of draught animals_ XIX. In respect of those instruments of agriculture which are called inarticulate, Saserna says that two yokes of oxen will be enough for two hundred jugera of arable land, while Cato prescribes three yokes for two hundred and forty jugera in olives: thus if Saserna is correct, one yoke of oxen is required for every hundred jugera, but if Cato is correct a yoke is needed for every eighty jugera. My opinion is that neither of these standards is appropriate for all kinds of land, but each for some kind: for some land is easy and some difficult to plough, and oxen are unable to break up some land except by great effort and often they leave the ploughshare in the furrow broken from the beam: wherefore in this respect we should observe a triple rule on every farm, when we are new to it, namely: find out the practice of the last owner; that of the neighbours, and make some experiments of our own. "Cato adds," resumed Scrofa, "that on his olive farm there are required three asses to haul out the manure and one to turn the mill, and on his hundred jugera vineyard a yoke of oxen and a pair of asses for the manure, and an ass for the wine press." In respect of cattle kept for all these purposes, which it is customary to feed in the barn yard, it should be added that you should keep as many and only as many as you need for carrying on the work of the farm, so that more easily you can secure diligent care of them from the servants whose chief care is of themselves. In this connection the keeping of sheep is preferable to hogs not only by those who have pastures but also by those who have none, for you should keep them not merely because you have pasture, but for the sake of the manure. Watch dogs should be kept in any event for the safety of the farm. XX. The most important consideration with respect to barn yard cattle is that the draft oxen should be fit for their work: when bought unbroken they should not be less than three years old nor more than four, strong, but well matched, lest the stronger wear out the weaker: with large horns, black rather than any other color, broad foreheads, flat noses, deep chests and heavy quarters. Old steers which have worked in the plains cannot be trained to service in rough and mountain land; a rule as applicable when reversed. In breaking young steers it is best to begin by fastening a fork shaped yoke on their necks and leaving it there even when they are fed; in a few days they will become used to it and disposed to be docile. Then they should be broken to work gradually until they are accustomed to it, as may be done by yoking a young ox with an old one, so that he may learn what is expected of him by imitation. It is best to work them first on level ground without a plough, then with a light plough, so that their first lessons may be easy and in sand and mellow soil.