Stomach Worms in Sheep. 9 



before they are taken up by the lambs. There is but very slight 

 danger that young lambs will become affected seriously while running 

 with older sheep in barns or yards free from vegetation. Early lamb- 

 ing, combined with good feeding of the ewes to make them milk well, 

 or of the lambs themselves in a "creep," or with both, brings early 

 lambs to marketable weight and finish before the most dangerous 

 part of the summer. Where lambs must remain for several months 

 on pasture, frequent changing of pasture must be resorted to, to 

 keep infestation below the extent that is injurious. 



A PRACTICABLE METHOD OF PASTURE ROTATION. 



The means of preventing the stomach-worm larvae from getting 

 into the lambs is suggested by what has been said concerning its 

 development and powers of resistance. It was stated that a pasture 

 that had been occupied by wormy sheep would need to be for at 

 least a year without cattle, sheep, or goats in order to become 

 practically free from stomach-worm larvae. 



From 10 to 20 days, according to temperature and moisture, must 

 intervene between the dropping of the feces containing stomach- 

 worm eggs and the development of many of the larvae to a point 

 where they will develop into adult worms after being swallowed. If 

 sheep are moved to a fresh pasture before the eggs in their droppings 

 develop into mature larvae, complete health can be maintained. The 

 practical difficulty lies in always having a fresh pasture available. 

 If only permanent grass pasture were used, adequate control would 

 call for as many separate pastures as would allow the flock to be 

 moved at least every 2 weeks without going on the same ground 

 twice within 12 months. The time of grazing during freezing 

 weather would not be included in such a plan, as few of the eggs or 

 young larvae would survive. It should be observed that it is not 

 simply the changing of pastures that is called for, but changing to 

 clean ground. Putting infested sheep on pasture in May, removing 

 them during June and returning them in July, offers an excellent 

 chance for infestation from the eggs dropped during the first pastur- 

 ing which would have hatched out into young worms waiting to be 

 taken up. 



Some modifications of such a plan are quite practicable on any 

 farm. In the first place, the danger is greatest to the lambs, and after 

 they are sold or separated the ewes may go back to pastures usod 

 earlier in the season with much less danger of injury than would be 

 incurred by the lambs. This change, however, would render that 

 pasture unsafe for young lambs during the following spring. Hay- 

 fields, grain stubble, and cornfields can be utilized in the rotation of 

 fields to furnish fresh grazing. 



