32 CIECULAE 14 8, U. S. DEPAETMEXT OF AGRICULTURE 



procedure because it disseminates infective eggs and larvae of para- 

 sites which have developed in stables and yards. Owners of 

 Thoroughbred horse farms who have learned of the danger to horses 

 as a result of spreading fresh manure on pastures have discontinued 

 this practice and are discarding manure as fertilizer altogether. 

 Such a procedure is too wasteful for farm practice, as the manure 

 must be utilized and is safe after it has been stored for a time. 

 Conditions of storage should permit the spontaneous heating process, 

 which is destructive to eggs and larvae of parasitic worms, to act 

 throughout the manure for a sufficient time. 



When manure is stored in open piles it heats in the middle but 

 remains cold on the surface. Such manure is dangerous, so far as 

 parasite transmission is concerned, because the eggs and larvae pres- 

 ent on the surface of the manure pile escape destruction. It is, 

 therefore, important that the outer 3 or 4 inches of exposed manure 

 piles be turned over every week or so in order to bury the exposed 

 manure under the inner material of the pile and sterilize it by 

 heating. If this is not done, the manure should not be placed on 

 any field to which horses may have access even months later, as the 

 eggs and larvae of many species of parasites are longlived and very 

 resistant to unfavorable influences. It has been determined that the 

 eggs and larvae of parasites present in manure can be more certainly 

 and easily destroyed if the manure is stored in closed containers 

 or boxes, having double walls and a double floor, with a 4 to 6 inch 

 space between the walls and floor filled with sawdust, and the top 

 of the container covered with a well-fitting lid. (Fig. 23.) It is 

 essential that the containers be tight in order to retain as much heat 

 as possible; the greater the heat developed and retained in manure 

 boxes the sooner the eggs and larvae will be destroyed. 



The sawdust acts as an insulator, but even with this precaution 

 it is desirable to use tongue-and-groove lumber in the construction 

 of manure containers in order to make them tight. Concrete boxes 

 will not serve, as the manure at the sides is chilled and there is not 

 heating enough to destroy parasites. 



For practical purposes manure which has been kept in such con- 

 tainers for at least two weeks may be considered free from living- 

 eggs and larvae of parasites and may be safely spread on pastures. 



In default of such measures, spread horse manure on fields which 

 are to be pastured by animals other than horses, or plow it under. 



SUMMARY OF CONTROL MEASURES 



The most common and most troublesome parasites of horses in 

 the United States live, at least part of their lives, in the digestive 

 tract, either free in the lumen, attached to the walls, or embedded 

 in the lining of the wall. These parasites produce eggs which pass 

 out in the manure on to pastures, the floors of stalls, and other 

 places. All such worm infestations in horses trace back to manure 

 as the original source. 



Manure must be regarded as dangerous, and control measures 

 should be designed to prevent contaminating the feed and water 

 with manure so far as it is possible to do so. The following meas- 

 ures are designed to reduce the possibilities of gross infestations of 

 horses with parasites : 



