A PASTURE HANDBOOK • 77 



Other stomach and intestinal roiindwoiins, notably trichostrong\'les 

 and nodular worms as well as tapeworms, liver flukes, and lungworms 

 also cause heavy losses. The key to effective control of most of these 

 parasites is the use of pastures that are reasonably free of parasites. 

 Low or swampy areas should be drained, filled, or fenced off. Over- 

 stocking and crowding of animals should be avoided. Pastures should 

 be rotated where practicable; or suitable medication should be pro- 

 vided to minimize pasture contamination and protect the animals from 

 heavy infestations. 



Among the drugs used for removing internal parasites from sheep 

 and goats phenothiazine is preferable for removing roundworms, as 

 it is the only drug that can be administered in salt free-choice for the 

 continuous, effective control of these parasites. Farm flocks may be 

 kept reasonably free from parasites by supplying them with a mixture 

 of loose salt 9 parts, and phenothiazine 1 part. The animals usually 

 will consume sufficient quantities of this mixture to prevent the devel- 

 opment of infective larvae that are deposited on the pastures. The 

 mixture should be sheltered from rain and made available during the 

 entire grazing reason. The animals should be given at least one 

 therapeutic dose of the drug during the winter or early spring and put 

 on uninfested pastures at the beginning of each grazing season. Ani- 

 mals requiring special treatment during the period of free-choice 

 medication can be detected easily. 



ROTATING PASTURES TO CONTROL PARASITES 



The rotation of sheep and lambs and other livestock on temporary 

 pastures and cultivated fields is helpful in controlling parasites. In 

 the case of sheep the best plan is to provide fresh pasture every 2 

 weeks and not allow the flock to go on a field a second time unless the 

 land has been plowed in the interval, or time enough has elapsed to 

 cause the death of the stomach w^orm larvae that were left on the field 

 during the previous grazing. Some permanent pasture is required 

 for emergency use during periods of drought, excessively wet weather, 

 and in cases of failure to obtain stands of temporarj'^ seeding. 



It is advisable to depend almost completeh^ on temporary pastures 

 only when the entire farming system is devoted to the production of 

 feed for sheep. The frequent plowing aids in the control of parasites. 

 Many parasites will die before a new crop is ready for pasturing. 

 Because of the continued chance of infection of lambs from grass along 

 fence rows and in unplowed yards and barn lots, complete freedom 

 from parasites is seldom obtained. Therefore, as rotated pastures are 

 not 100-percent effective in the control of stomach w^orms the dosing of 

 the sheep is necessary also to control these worms. 



This type of sheep production is a modification of the English system 

 of pasturing the lowlands with sheep, which has proved very successful 

 with the mutton breeds. 



SCHEDULE OF TEMPORARY PASTURES 



A schedule of temporary pastures suitable for keeping down infesta- 

 tion of stomach worms in sheep is given in table 11. This schedule 

 is based on experience with such crops at the Beltsville Research 

 Center, Beltsville, Md. 



