Parasites In Sheep And Some Very Heavy Losses

Poverty Bay Herald, Volume LXIV, Issue 19248, 13 February 1937, Page 13

Parasites In Sheep And Some Very Heavy Losses

m,.M....ii.r By " The Gleaner." "■'"'"""

THERE should be no need to stress the point that the infernal parasites of sheep cause inestimable loss to sheep-owners. The important fact is that the disease is becoming more serious in New Zealand, because as lime goes ou we are carrying more sheep per acre. This means more droppings per aero, which means more eggs per acre, and more worm eggs per acre mean more and regular worm infestation.

In England, where the grazing is \ory intensive and therefore the worm infestation heavy, losses are enormous. According to Mr. 10. S. Taylor, writing in the Journal of the Ministry of Agriculture, in October, J 935, data collected from 43 farmers in the South of England in 1933 showed that 5131 lambs were lost out of 33,873, allowing 5 per cent for other diseases. The total loss was £10,341, or £240 per farmer.

In Xew Zealand the trouble is fortunately not so severe, yet according to Mr.*A. Leslie, lately Veterinarian at Lincoln College, "the disease is the most, common in New Zealand and frequently may take an enzootic form and upwards of 50 per cent deaths may be experienced." Unfortunately, this is not the only loss. A serious reduction in growth ' and development, loss of condition, lowered resistance to other diseases, as well as reduction in growth of wool, are some of the conditions following worm infestation.

Insidious Work. The work of internal parasites is insidious as a rule. The usually slow development and unthriftiness may lead the owner to blame the pasture or the season, or condemn the- sheep as poor doers.

The damage done by internal parasites may be produced in several •ways: —By producing toxins which are absorbed by the blood, destroying the red blood cells and causing an anaemic condition; by causing wounds which allow secondary bacterial infection; by causing injury to the blood vessels and various organs of the body; by robbing the host of food required for its own nourishment, particularly by sucking blood, and it is thought by causing a vitamin deficiency. Leading authorities agree that as the margin between normal nnd pathological infestation is a wide one, and as it is seldom if ever possible to eradicate all the worms on the farm the object of any control method should' be to keep the number of parasites within bounds. In order to do this it: is necessary to know a little about the various types of internal parasites and methods of infestation.

Flukes. —Liver fluke is as far as it is known found only in Hawke's Bay. It is a serious pest, as the flukes travel from the small intestine up the bile duct, to the liver where they eauso great damage, and in fluke-in-fested country mortality is often high. Fortunately, stomach flukes are either very uncommon or entirely lacking in Now Zealand.

Tape Worms.—These worms are Hot, serious in comparison wilh other parasites in sheep. Whore sheep livers are badly affected with hydatid cyst* they are' dangerous if eaten by dogs, which pass the disease on to humans, but the sheep suffers little. A Serious Menace.

Lung Worms.—These are a serious menace, not only because they make their seal of operations the lungs, where they cannot be, reached by any drench, but also because in order to reach the lungs they must be swallowed into the stomach. Here they rupture the stomach wall, and enter the blood stream to travel to tho lungs. In rupturing the- membranes and by causing aneurisms (swellings) and clots in small blood vessels they do immeasurable harm. In order to complete their life cycle they break through the lungs, are coughed up and swallowed again to the. stomach, where they lay their eggs. Stomach Worms.—There are several species of these, the majority of which have simple life cycles and for the most part are blood sucking worms. They are found mostly in the abomasum, or fourth stomach, and where they occur in numbers are serious.

Intestinal Worms.—According to Mr Tetley, of Massey College, who has done some considerable work in this, line, "Worms of the small intestine continue to be tin important component of worm infestation in sheep in this country." Myself, I would say they are the most important, because they are more toxic than most others, because generally their life cycles are more complicated, and because it is much harder to control them.