In this section:
Parasitism & Dairy Production
Impact of Parasitism on Dairy Production in South Australia
In recent years the Parasitology Group of SARDI Livestock Services has examined the transmission and economic implications of roundworms and liver fluke on dairy production in South Australia.
In the 1994–1995 season 560 adult cattle on 7 properties were included in a drench productivity study. From 60–120 adult milkers on each property were alternately allocated to either a drenched or an undrenched control group in order of expected calving date. Treated animals were drenched once in the dry period with oxfendazole (Systamex-Coopers) for roundworms and triclabendazole (Fasinex-Ciba-Geigy) for liver fluke and twice for roundworms in the first 80 days of lactation. Milk production data (including total milk, protein and fat) for each cow were obtained over a 200 day period from herd testing records. Increased production responses to treatment for fluke and roundworms in 6 of the 7 herds ranged from: [milk], 2.3 - 9.2% (mean 4.9%); [butter fat], 1.3 - 14% (mean 4.9%); and [protein], 3.1 - 9.6% (mean 5.8%), and were consistent at both 100 and 200 days of lactation.
Another productivity study was conducted the following season using 630 cattle from 8 herds. The same drenches were used, but this time animals were only treated in the dry period for liver fluke and roundworms. Consistent, but lower, average production responses of 2% - 4% were again recorded in 7 herds.
Using a modified ELISA test developed in NSW for the detection of antibodies to liver fluke a bulk milk survey of all 753 South Australian commercial dairy herds for antibodies to liver fluke was conducted, followed by field visits to every farm with unusual or unexpected results. The following positive tests were recorded by geographical region: Meningie (Murray) Lakes 39%; Murray Flats 34%; Fleurieu Peninsula 25%; South east 10%; Mid-North 8%; Adelaide Hills 6%. The bulk milk ELISA is not quantitative but can be used to identify herds which merit further attention because they may be heavily infected. It can also provide peace of mind where the geographical distribution of liver fluke is discontinuous and the infection status of herds is uncertain. For these reasons it has been immensely valuable in providing the appropriate directions in the SA studies.
Further information contact:
Dr Ian Carmichael
