THE DISEASES OF SHEEP 335 



and thus greatly reduce the amount of infection to 

 which the lambs will be exposed. 



Two other methods may be suggested by which 

 lambs can be kept free from infection with stomach 

 worms. 



1. It is assumed that a large pasture is available 

 which has had no sheep, goats, or cattle upon it for 

 a year, if a permanent pasture, or since cultivation, 

 if a seeded pasture. This pasture is subdivided into 

 two by a double line of fence, and a drainage ditch 

 is run along the alley between the two fences. At 

 one end of the alley between the two subdivisions a 

 small yard is constructed, communicating with 

 each of the subdivisions by means of a gate. When 

 the lambs are born they are placed in one of the 

 subdivisions and the ewes are placed in the other. 

 The small yard should be kept free of vegetation 

 and must not drain into the lamb pasture. As 

 often as necessary the lambs are allowed in the 

 small yard with the ewes for sucking. The rest of 

 the time the lambs and the ewes are kept separate 

 in their respective pastures. By this arrangement 

 the lambs are exposed to infection only while they 

 are in the small yard, where they may become in- 

 fected either by embryos of the stomach worm pres- 

 ent on the manure-soiled skin of the infested ewe, 

 or by embryos picked up from the ground which 

 has been contaminated by the droppings of the 

 ewes. The chances of infection from the skin of 

 the ewe are so slight that in practice this source 

 of infection need not be considered. The danger 



