Volume 98, Issue 5, May 2015, Pages 3143–3151
Abstract
The
objective of this study was to describe the prevalence and practices
used to manage internal helminth parasites and external arthropod
parasites on organic and conventional dairy herds in Minnesota. All
organic (ORG) dairy herds in Minnesota (n = 114) and a convenience
sample of conventional herds were invited to participate in the study.
Thirty-five ORG herds and 28 conventional herds were visited once in
summer and fall of 2012. Conventional dairy herds were split into small
conventional (SC, < 200 cows) and medium-sized conventional herds
(MC, ≥200 cows) so that SC herds were comparable in size to the ORG
herds. Dairy managers were surveyed to assess their farm management
practices and perceptions about parasites, hygiene scores were recorded
for adult stock, and fecal samples were collected from a nominal 20
breeding-age heifers to characterize abundance of internal parasites.
Nonparametric tests were used to compare fecal egg counts per gram (FEC)
among farms grouped by management systems and practices. Organic farms
had more designated pasture and were more likely to use rotational
grazing compared with conventional farms, but the stocking densities of
animals on pasture were similar among farm types. The overall FEC were
very low, and only a few individual ORG heifers had FEC >500
eggs/gram. Samples from heifers on ORG farms had significantly more
strongyle-type eggs than those on SC and MC farms (ORG: 6.6 ± 2.1; SC:
0.5 ± 0.3; MC: 0.8 ± 0.7), but egg counts of other types of
gastrointestinal parasites did not differ significantly among the 3 herd
groups. Fly control measures were applied mainly to milking cows and
preweaned calves and were used on 88.6% of ORG herds, 60.0% of SC herds,
and 91.7% of MC herds. Approximately half of the producers reported
having seen skin conditions suggestive of lice or tail mange in their
cattle during the previous winter (ORG: 48.6%, SC: 57.1%, MC: 53.9%).
Although most conventional producers reported treating these skin
conditions, most organic producers stated they had not treated them. In
conclusion, gastrointestinal parasite egg counts were low overall at the
time of the survey, and most surveyed producers did not perceive
gastrointestinal parasites to be a problem for their animals’ health.
Independent of the herd type, fly control was mostly targeted at the
lactating herd and preweaned calves.
Key words
- dairy cattle;
- gastrointestinal parasite;
- flies;
- ectoparasite;
- organic
Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
