The general construction of a brooder house is similar to that of the breeding house, and differs only in interior arrangements. The latter has no interior arrangements whatever, while the former has the system of heating and covers necessary for giving warmth to the young stock. In fig. 17 is shown a design of single-brooder house and ground plan that is generally used by duck raisers. This house should be built upon a good foundation and be entirely proof against rats. A good plan is to sink half-inch wire mesh about 2 feet in the ground and around the entire inside of the building; this will make it perfectly secure against rats and mice. The accepted plan of a brooder house makes it 15 feet wide and as long as desired. The building is 4 feet high in front and 5 feet in rear. GROUND PLAN. [Illustration: Fig. 13.--Plan and ground plan of five-pen breeding house for ducks.] It is divided into pens 12 feet long and 6 feet wide, and has a 3 foot passageway extending the entire length of the building. The ground plan (fig. 17) shows the general arrangement of the interior and location of the brooders. The brooder box is next to the passageway, or walk, and runs the entire length of the building. This box is 30 inches wide and 8 inches high; the sides are 7 inches high and nailed securely; the top of the cover is nailed across with cleats to make it substantial, and the cover has an inch strip nailed underneath in front and back to keep it in position. These strips rest against the 7-inch sides and make the brooder snug and tight when closed. The heating pipes are directly beneath the cover and are 2-inch pipes, flow and return. Some prefer 1-inch pipes, using two flows and two returns. When three pipes are used they should be about 8 inches apart from center to center. These pipes rest on the partition boards of the pens. The front of the brooder, leading into the pens, is cut out in the center about 4 inches deep and 4 feet long (fig. 18, _A_), while the ends and the other side are solid, being 7 inches high. The construction of the brooder is clearly shown in fig. 18, _B_, with cover removed, while fig. 18, _C_, shows cover. The heater is located at the end of building. [Illustration: Fig. 14.--House for breeding ducks.] Another plan of brooder house is that shown in fig. 19. This house is known as a double brooder house, with walk in the center and pens on either side, and with heater at the end. Many prefer this plan to the single brooder house, as the care and attention required for the youngsters is much less and the cost of heating is reduced, one heater being sufficient for both lines of pipes. Then, again, this latter plan shortens the length of the building by one-half and makes the work more concentrated. The arrangement of the interior is the same as that of the single brooder house. [Illustration: Fig. 15.--House for breeding and growing ducks.]