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2003 - 2004 CUIPM Grants -
Final Reports
Alternative Anthelmintics for Organic Dairy Cattle
Project Leader: Dr. Jean Bertrand
Professor, Animal and Veterinary Science
117 Poole Ag. Center, Clemson University, Clemson, SC 29634-0311
Statement of Problem
Internal parasites are a major concern for cattle and dairy farmers because parasite
infestations inhibit weight gain, decrease milk production, and reduce overall health. Internal
parasite control has shown to increase economic returns $25 to $200 per head.
The life cycle of parasites begin when cattle ingest them while grazing. The worms stay
in the abomasum or small intestine of the host. These adult parasites lay numerous eggs that are
eliminated in the feces, starting the cycle over. Chemical dewormers, or anthelmintics, result in
increased milk production and economic gains for farmers. There is a need, however, for nonchemical
alternative anthelmintics because of increased parasite resistance to these drugs,
concerns over chemical residues left in the animal products and increased numbers of organic
beef and dairy farms. The objective of this study was to evaluate condensed tannins and a
product containing diatomaceous earth as alternatives to chemical anthelmintics.
Methods and Materials
Twenty-seven Jersey, Holstein, and Guernsey dairy heifers were used in this study and all
were under eleven months of age. They were divided into three groups of nine heifers based on
age, breed, and original pasture location to ensure these factors were consistent throughout the
groups. Treatments were (1) control, (2) diatomaceous earth (DE) (Natural Wormer Bolus, The
Fertrell company, Bainbridge, PA), and Quebracho condensed tannin (CT) extract (Tannin
Corporation, Peabody, MA). Heifers had ad libitum access to water and bermudagrass pasture.
Treatments began the week of 21 June 2004 and lasted for six weeks. The heifers were
group fed daily at 0800 h. Feed was distributed in troughs and the heifers were allowed to eat
until the feed was consumed. All heifers were fed approximately 3.18 kg of the same basal diet.
Heifers in the control group did not receive anthelmintic. Heifers on DE were given two boluses
weekly for three weeks, as per the instructions of the manufacturer. This product also contained
garlic and cayenne pepper. Heifers on CT were daily fed an additional 0.71 kg per head of the
Quebracho CT extract.
Body weights were recorded. Fecal grab samples were obtained weekly and fecal egg
counts (FEC) were determined on the day of collection using the modified Wisconsin sugar
flotation method. Each slide was scanned under a light microscope (American Optical, Buffalo,
NY) at 10x and the fecal egg counts (FEC) recorded. The three groups of eggs counted were
Nematodirus, Strongyloids, and Trichuris.
Results
Heifers on the control and DE treatments consumed their feed in about 45 minutes.
Heifers on CT, however, took approximately three hours to consume their feed, probably
because of the astringent taste of the CT. There were no significant differences for body weight
or body weight gain among treatments (Table 1). Because of changes in weekly body weights,
there was a significant week effect, but there was not a significant treatment by week effect.
Heifers gained an average of 20.2, 16,4, and 20.4 kg for control, DE, and CT, respectively,
during the six-weeks study. There was not an overall significant treatment effect for FEC or for
counts of individual types of eggs. However, as illustrated in Figure 1, there was a significant
treatment effect in week six. FEC for heifers on both CT and DE were significantly lower than
for heifers on control.
Impact
The results of this project illustrate that the use of DE and CT have potential as
alternatives to chemical anthelmintics. This could lead to increased productivity and profits for
dairy and beef farmers looking for alternatives. Future work should evaluate different levels of
DE and CT in an attempt to gain a response earlier than six weeks after administration.
Additionally, longer studies should be conducted to evaluate the long-term effects of these
compounds and to measure their effectiveness throughout an entire year of grazing.
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