The design requirements to achieve a good environment for healthy animals are described. Mechanically ventilated livestock buildings are usually insulated, with a constant maintained temperature of about 40 °F or above, extra heat being applied as necessary; naturally ventilated buildings depend on air movements, have no insulation, and inside temperatures approximate to outside temperatures. The fresh air inlet and exhaust systems are discussed in detail for mechanical ventilation; types of fans are described and rating tables illustrate their performance. Rules for the location of fans and the design of the fresh air intake system are emphasized and the influence of seasonal factors is discussed. The location of naturally ventilated buildings should be at least 50 ft away from other structures; ridge and wall openings are discussed in terms of dimensions; the roof underside should be steep and smooth and of proper construction.
There is no single best manure handling system. Odor and appropriate time of disposal are two of the most difficult waste problems facing dairymen. Systems may range from a gutter cleaner and daily hauling with a manure spreader to extended storage in concrete tanks whose contents are pumped and spread periodically. Daily hauling requires the lowest investment in equipment but has the disadvantage of possible higher labor costs and the hazard of encountering unfavorable weather, soil, or crop conditions. Slat floors in warm free-stall barns, or gutters with grated bottoms in conventional stall barn, both with under-the-building manure storage, offer suitable systems for manure handling with a minimum of labor. Carefully planned ventilation systems of high capacity must be provided for all confined units. Research shows that manure containing little bedding deposited in the end of a 30 × 90 × 8 ft external flat-bottom tank will distribute itself under its own weight. Waste heat from the dairy barn ventilation system is used to prevent freezing.
Health and productivity in animals are planned, not accidents. Microorganisms cause disease. When susceptible animals are exposed to concentrated aerosols of pathogenic organisms, they get sick. The most important step in preventing pneumonia in weaned calves is to correct environmental and managerial deficiencies which allow transmission of large numbers of organisms with sufficient virulence to cause disease. Buildings that house animals should be designed with regard to disease prevention. Virulence of an organism increases by serial passages through susceptible individuals, so young non-immune animals should not be exposed to recovered carrier animals. Potential exposure of calves to older animals carrying disease is often disregarded in the interests of economical construction. Environments and management procedures should be designed so a novice animal caretaker can perform assigned duties without contributing to disease.
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