STRATEGIC LIVER FLUKE CONTROL

For beef or dairy producers in fluke affected areas, the failure to implement an adequate control program can be costly. Reduced growth rates and poor milk production are some of the potential consequences of persistent infections of Liver Fluke in cattle.

In beef cattle and replacement dairy heifers, fluke infections can reduce daily weight gain by 0.5kg/head/day, or add 80 days to the time required to reach 300kg body weight. The dairy producer is also penalised by a reduction in milk production that can exceed 0.6L/day.

LIVER FLUKE – THE ECONOMIC PENALTY IS SOMETIMES HARD TO SEE

As recognised and described by specialists the chronic form of fluke disease, caused by adult liver fluke living in the bile ducts, is the economically important form of this disease. Cattle rarely show signs of disease; most of the effects of liver fluke are on production. Infected cattle convert grass to energy less efficiently. They grow more slowly, and are more susceptible to secondary infections. This translates into animal performance below genetic potential.

LIFECYCLE OF LIVER FLUKE

1. Adult fluke lay thousands of eggs which are passed in the dung.
2. The fluke larvae that hatch from these eggs find a host snail of the Lymnaea species (mud snail). The larvae develop, multiply, then leave the snail. Up to 4000 larvae leave the snail for every one entering.
3. The larvae attach to grass, and encyst. These cysts can survive for months in this state until swallowed by grazing cattle or sheep.
4. Inside the cattle, the young fluke migrate to the liver and enter the bile ducts where they mature and produce more eggs.

DIAGNOSIS OF LUKE DISEASE

Several options are available for diagnosis of fluke infestation; however, each option has significant limitations.

FAECAL SAMPLES

A positive faecal egg count indicates female adult fluke are present and producing eggs. Herds with a positive fluke egg count should be treated. However, a single negative faecal egg count must be interpreted with caution. False negative results do occur as adult fluke are erratic egg layers, and egg counting gives no indication about the possible presence of immature stages soon to mature to adult parasites.

BLOOD TESTS

Identify presence of fluke in the body but do not give an indication of severity. It is recommended to treat following any positive result.

MILK TESTS

Identify presence of fluke in the body but do not give an indication of severity. It is recommended to treat following any positive result.

BREAKING THE LIFECYCLE

The ideal strategy for controlling fluke is to treat infected cattle to kill all mature fluke and halt on-going pasture contamination. Targeting on-farm contamination of snails by fencing off infective areas is also a strategy to attack the fluke lifecycle at its weakest point.

IMPORTANCE OF FLUKE IN BEEF CATTLE

Liver fluke is a chronic disease in growing cattle. Affected cattle convert grass to body tissue less efficiently, grow more slowly and are more susceptible to secondary infections. This translates to reduced weight gain, lower weaning weight, condemned livers and reduced feed efficiency: all factors leading to a reduction in overall animal performance. These are losses that can be prevented.

IMPORTANCE OF FLUKE IN DAIRY CATTLE

Replacement dairy heifers must achieve critical mating weights by 14-15 months of age to ensure entry into the milking hers at 2 years of age. Liver fluke threatens the ability of heifers to achieve mating weight targets on time. Liver tissue damage and bile duct scarring will impair subsequent lactation performance. In fluke endemic areas, the dry-off treatment must control both nematode and fluke parasite burdens to maximise body condition score at calving and subsequent milk production.

TREATMENT STRATEGIES WITH IVOMEC PLUS

Successful fluke control strategies combine the timing of treatments to minimise pasture contamination, while optimising animal performance.

CONTROL STRATEGY FOR BEEF CATTLE AND REPLACEMENT DAIRY HEIFERS

1. IVOMEC® PLUS IN AUTUMN: removes all existing adult liver fluke, plus intestinal parasites including Ostertagia, Cooperia and sucking lice. In winter minimal fluke pick up occurs as snail activity declines.
2. IVOMEC® PLUS IN SPRING: any fluke remaining in the cattle from the previous autumn will now be adults and must be killed to prevent contamination of the host snails as they re-emerge at the end of winter. In addition, the removal of all intestinal worms means cattle take full advantage of spring feed.

CONTROL STRATEGY FOR LACTATING DAIRY CATTLE

A treatment with IVOMEC® Plus at drying off for dairy cattle removes all adult liver fluke in the bile ducts, which cause production loss and ongoing pasture contamination. In addition, IVOMEC Plus removes all intestinal parasites that can have an equally detrimental effect on milk production.

IMMATURE FLUKE DEVELOPING RESISTANCE TO FASINEX®

An important principle in the fight against parasites developing resistance to an anthelmintic is to always use only a fully effective compound to control the target parasite. IVOMEC® Plus, being a different chemical family to Fasinexâ (Triclabendazole 120gm/L), is a suitable alternative to maintain control of adult liver fluke. There are no reports of resistance to IVOMEC® Plus.

Combined into a strategic control program, IVOMEC® Plus can help delay the onset of resistance to other chemical groups.

© Steve Cselka 2002 - 2011