PRODUCTION EFFECTS OF LIVER FLUKE (FASCIOLA HEPATICA) INFECTION IN BEEF CATTLE

SUMMARY Young Hereford steers of even body weights were grazed on pasture at 2 levels of stocking rate and artificially infected with 0, 600 or 1,200 metacercariae of Fasciola hepatica. In addition all groups obtained a low grade natural infection. Steers were slaughtered at intervals throughout the 32-week trial period and total fluke counts obtained. Fluke counts were significantly higher in all artificially infected groups when compared to the natural infection alone groups with the exception of the 600 metacercariae group during the 12 to 32-week analysis period. There were no significant differences between counts in steers in the 2 nutritional regimes. Rates of growth were significantly reduced by 14.7% and 14.1% in steers receiving a superimposed artificial infection rate of 1200 metacercariae and grazed at 3.54 beasts/hectare and 4.39 beasts/hectare respectively. Similarly group body weights were depressed 3% and 20% in steers receiving 600 metacercariae and grazed at 3.54 beasts/hectare and 4.39 beasts/hectare respectively. There was a significant interaction between level of nutrition and size of artificial infection on body weight changes in the first 12-week period.