6 BULLETIN 36, PUERTO BICO EXPERIMENT STATION 
Molasses or Yaragua grass [MeUma mintU Is another grass 
that may assist in parasite control. The fine hairs with which this 
is covered and it- sticky exudation hinder seed ticks from 
climbing upon the plant and so act as a deterrent to the spread of the 
attle tick. 
PASTURE MANAGEMENT 
Statements in regard to pastures apply principally to the dry 
area- and mountain sections. Foung calves cannot be pastured 
successfully in the wet coastal areas because of the greater abundance 
of parasites. Older cattle may be pastured in these wet areas with 
considerable safety, if proper measures are used in controlling the 
liver fluke. 
( Overstocking of pasture, a common practice in Puerto Rico, favors 
the infection of animals by parasites. Heavy stocking means more 
manure and this in turn results in heavier concentration of parasite 
and larvae. Animal- grazing on such pastures have 
opportunity for picking up parasite eggs and larvae. How 
overstocking is sometimes a relative term. During the drv season a 
pasture may l>e overstocked, hut during the wet season with a much 
heavier growth of grass the same pasture may have a much higher 
carrying capacity. The overstocking in the dry season may not 
cause the same amount of infestation as a similar overstocking in the 
rainy season, owing to the presence of fewer parasib 
Pasture rotation is an excellent method of parasite control. 
prevent setting up dangerous infestations, it i> advisable that calves 
he moved every '2 week- to clean pastures, during the wet season, and 
should not he returned to the same pasture for at Least v months. 
Such a system of management requires considerable fencing and 
more land than i- usually available. Consequently a modification 
of this program or other control measures are necessary. However, 
any rotation is valuable, especially with heavy stocking. The more 
often calves can he moved into (dean pastures, the more effectively 
infestation will be kept down. 
Stock rotation is another mean- of helping to control paras 
Horses ami cattle are maintained in separate pastures and alternated 
twice a year. Theoretically the changes should l>e made about the 
middle of both the dry and wet seasons. The saying, u Permanent 
pastures perpetuate parasites ", applies here as elsewhere, especially 
as pastures in this climate are used throughout the year, and there 
are no crops or land available for temporary pastures. 
Location of the pasture is important in controlling parasites. 
Pastures, especially for calves, should be confined to the hillside-. 
because bottom land-, being less thoroughly drained and receiving 
the wash from the hillsides, are likely to he more highly infested with 
eggs and larvae of parasites than the hill land-. Calves should 
l»e kept away from low -pot- in the pasture by fencing and should 
be watered in troughs from which there i- no overflow. A .-mall 
surrounding a watering trough or spring may provide sufficient 
moisture for the propagation of parasites and thus serve m- a con- 
stant source of infestation. The bottom land- may he used for held 
crops or if necessary for pasturing mature cattle. 
