10 BULLETIN 39, PORTO RICO EXPERIMENT STATION. 
liver fluke breeds in stagnant water and is taken into the body from 
drinking such water. The growth oi young animals is materially 
checked by the parasite, which darkens and congests the hepatic 
lymph glands, weakens the heart action and the jugular pulse by 
disturbing the hepatic circulation, and enlarges the liver. Loss due 
to the parasite may be prevented to considerable extent by avoid- 
ance or drainage of marshy places and stagnant water, and by pro- 
viding the cattle with fresh water protected from contamination. 
AVAILABLE CATTLE FEEDS. 
Cattle readily adapt themselves to countries having a plentiful 
supply of nutritious grasses, and they make thriftier growth in such 
places than they do where the pasturage is scant. An increase in the 
production of grasses suitable for grazing purposes is naturally fol- 
lowed by a development in animal production, and the crops are con- 
verted into beef, milk, and butter with the least expenditure of money 
for labor. Likewise, a decrease in grass production is followed by a 
decline in the stock-breeding industry. To produce hardy cattle, 
therefore, the stockman must grow an abundance of grasses that have 
a high feeding value so that the animals will either put on flesh or 
yield large quantities of milk. 
Porto Rico offers great possibilities for the production of nutri- 
tious grasses. Many of her idle lands could be turned into profitable 
pasture lands, and the lands now in pasture could be made to pro- 
duce a larger quantity of rich grasses. The high lands of the island 
produce many native grasses that are inclined to be wiry and low 
in yield, some of them bearing only little leaf. The station re- 
cently introduced for use on these lands a variety of grass (Poly trios 
prcemorsa) which gives much promise as a pasture grass. Para 
grass (Panicum barbinode) , or malojillo, is the leading grass on the 
lowlands. It is a vigorous grower and is much relished by cattle. 
Guinea grass (P. inaximum) flourishes in the limestone sections of 
the island and produces the highest type of feed. Breeding stock 
is raised to the best advantage in regions where this grass is grown. 
Of the several grasses introduced by the station, elephant or 
Napier grass (Pennisetum purpureum) produces the largest quantity 
of forage (PL III, Fig. 1), yielding in one trial 19 tons per acre 
on high land within seven months after planting. Some of the 
earliest plantings at the station have been ratooned for six years. 
Elephant grass thrives on a variety of soils and is greatly relished 
by cattle, the entire stalk being eaten, provided it is cut before 
becoming woody. Elephant grass has given the greatest impetus to 
dairying in Porto Rico of any crop that has been introduced. It 
has high value as a stock feed. Much of the unproductive land 
should be planted in this excellent grass. 
