BARNS FOR WISCONSIN DAIRY FARMS 15 



AMOUNT OF AIR REQUIRED FOR BARN VENTILATION 



Horses 71 cubic feet an animal a minute 



Cows 59 cubic feet an animal a minute 



Swine 23.2 cubic feet an animal a minute 



Sheep 15.3 cubic feet an animal a minute 



Hens 52 cubic feet an animal a minute 



Assuming that air travels through a flue from a stable at 

 the rate of 290 to 300 feet a minute, the size of outlets and 

 inlets may be determined as follows : 



Total no. of cu. ft. 

 of air required 



x 144 sq. in. = Total cross-sectional area 

 300 in 1 sq. ft. sq. in. of inlets or outlets. 



Total cross sectional 

 areas of outlets 



= Cross-sectional area of each outlet. 

 No. of outlets 



Total cross-sectional 

 area of inlets 



= Cross-sectional area of each inlet. 



No. of inlets 



To estimate the amount of air required for a herd of 27 

 head of cattle and for five horses we would multiply 27, the 

 number of cattle by 59, the number of cubic feet of air 

 required for a cow, which is 1,593. To provide fresh air for 

 the horses multiply 71, which is the number of cubic feet of 

 air required for one horse by 5, the number of horses to be 

 kept. This equals 355 cubic feet. The total requirement then 

 would be 1,593 cubic feet for the cattle and 355 for the 

 horses or a total of 1,948 cubic feet. 



In order to get the total cross-sectional area of either out- 

 lets or inlets divide 1,948 by 300 (the rate at which air travels 

 a minute in the flues of a stable) and you would have 6.49. 

 Multiplying 6.49 by 144 (the number of square inches in a 

 square foot) would give 934.5, the total cross-sectional area 

 in square inches of inlets or outlets for this barn. Now the 

 total required area 934.5 will be divided by the number of 

 flues to be provided. A sufficient number of inlet flues should 

 be provided so that the fresh air will enter the barn every 

 10 to 12 feet. This barn being 36x86 feet, the inlet flues 

 spaced at 12 feet intervals would require 18 flues. 



To get the area of each inlet divide the total cross-sectional 

 area of inlets by 18 (1,948-7-18=52) and each flue should 



