Production effects of subclinical liver fluke infection in growing dairy heifers
Oakley, G.A.; Owen, B.; Knapp, N.H.
Veterinary Record 104(22): 503-507
1979
ISSN/ISBN: 0042-4900 PMID: 483540 Document Number: 144213
Groups of 15 three-month-old female British Friesian calves were managed as follows: Group 1 - not infected, fed to gain 680 g/day; group 2 - artificially infected with liver fluke (Fasciola hepatica) and fed to gain 680 g/day; group 3 - artificially infected and fed the same quantity of feed as that consumed by group 1; group 4 - not infected and fed to increase in weight at the same rate as group 3. By the onset of lactation, average burdens of 24 adult flukes (range 0 to 109) were present. F. hepatica infection in growing heifers (0 to 484 days) had a limiting effect on growth rate and impaired efficiency of feed conversion. Infected animals consumed more feed to achieve the same or lower performance than non-infected. The effect was most marked with animals on a moderately high plane of nutrition. A low plane of nutrition masked this effect on growth, but not that on feed conversion. During the "gestation period" (484 to 746 days), following synchronisation of oestrus with cloprostenol, conception rate to double artificial insemination was significantly higher (P<0.05) in group 1 than in other groups. There was a trend for calves born to fluke-free heifers to be heavier than those from infected dams. [AS] 4 groups of 15 British Friesian calves initially aged 3 months were treated as follows: not infected, fed to gain 680 g/day during growth; artificially infected with liver fluke and fed to gain 680 g/day; artificially infected and fed the same quantity of feed as that consumed by 1st group; not infected and fed to increase in wt. at same rate as 3rd group. By the onset of 1st lactation animals from the 2nd and 3rd groups had burdens ranging from 0 to 109 adult fluke, av. burden was 24. At no time was any animal clinically affected by liver fluke disease. Av. 305-day lactation yields of 4% FCM were 3985.6, 4164.6, 3940.8 and 3968.5 kg for the 4 groups resp. There was no significant difference between groups in milk yield or composition.