Ducklings are kept in the cold brooder house until they are six or seven weeks old, when they are transferred to large quarters known as growing houses. It is here that they are pushed for the market until they are 10 weeks old, when they are salable. There is no heat in the growing houses, which are used only as a means of shelter during the early spring months. When the weather is well advanced, the ducks seldom take to the houses at night; they prefer the outside and spend their nights on the ground. The growing houses should be abundantly ventilated, as too close an atmosphere will do more harm in a single night than if they had not been housed at all. [Illustration: Fig. 21.--House for growing Ducks.] [Illustration: Fig. 22.--Two-pen house for growing ducks.] [Illustration: Fig. 23.--Three-pen house for growing ducks.] A Pekin duck at 10 weeks is quite large, weighing close to 4 pounds. It is quite as large as a full-grown duck of some of the other breeds. In the space of two or three weeks from the time the ducklings are placed in the growing houses they will be marketed at the weight of 4 to 5½ pounds each. This weight is easily obtained, and when reached the profitable time to sell has arrived, as they then command the best prices. Often a bird kept after this time loses in weight and becomes unprofitable. The growing houses are built after the plan of the breeding houses, only much smaller. They need not be more than 4 or 5 feet high in rear and 1 or 2 feet high in front. Such a house is shown in fig. 21. This and other houses shown in figs. 22 and 23 may be built singly or in rows, with 12-inch boards separating the runs. SUPPLYING WATER. [Illustration: Fig. 24.--Gutter water trough.] As has been previously stated, water for bathing is not at all necessary for growing ducks, but a liberal supply for drinking is absolutely essential to their growth. The food of the duck is such as to require drink when eating, as it is comparatively dry and can not be eaten hurriedly as grain is. When feeding, always replenish the water troughs or fountains with pure, fresh water. A duck when feeding will eat a small quantity and go to the water troughs, for drink, repeating this performance several times during the meal. Conveniences for supplying drinking water to breeding and growing ducks are varied, and almost any contrivance will answer the purpose. When small numbers of ducks are kept, the simplest method of supplying water is in wooden troughs. These may be built V-shape or with square bottoms. They are shown in figs. 24 and 25. [Illustration: Fig. 25.--Flat water trough.]