Agriculture Reference
In-Depth Information
but still, 45% of Danish organic dairy farms had to fall back on anthelmintic treatments during
the 2002 grazing season (Weinreich
et
al
. 2005).
On Swedish smallholder farms, the most important health problems in organic sheep pro-
duction seem to be associated with feeding, endoparasites, haemonchosis, diarrhoea, high
lamb mortality (3-36%) and lean ewes. These problems were registered as the most common
health problems in 37 organic sheep f flocks, although this is not markedly different from
problems in conventional f locks (Lindqvist 2001). A survey of organic farmers in the UK iden-
tified lameness, mastitis, f ly strike, fasciolosis and other helminthoses as the most prevalent
health problems (Roderick and Hovi 1999). The restrictions or prohibition of chemotherapy
and chemoprophylaxis mean reliance on management practices such as lower stocking densi-
ties and closed f flocks. Internal parasites, particularly gastrointestinal nematodes, are poten-
tially a serious threat to organic sheep and goat production (Keatinge 1996). Most organic
sheep farmers have to rely on grazing management such as repeated moves to clean pastures
and supplementary feeding (Thamsborg
et
al
. 1999), and regular (or pre-emptive) use of
anthelmintics is still part of the control strategy in several countries. For example, Lindqvist
et
al
. (2001) in Sweden estimated that roughly 20% of organic farmers drench ewes around
lambing to control
Haemonchus
contortus
.
The use of vaccination remains an option for organic producers. Clostridial vaccination of
sheep is common on many conventional sheep farms in the UK, and 44% of surveyed organic
farmers were also reported to vaccinate on a routine basis (Roderick
et
al
. 1996), with 10% of
f flocks also being vaccinated against pasteurellosis.
Organic pig production varies significantly within Europe. Hermansen
et
al
. (2004) argued
that it is far more difficult for farmers to change existing conventional production systems to
organic systems for pigs and poultry compared to ruminant systems. Depending on the system,
farrowing and suckling or even fattening take place outdoors while housing with small outside
exercise areas are provided in other systems in colder climate countries such as Germany,
Denmark and the Netherlands. The latter systems have greater space allowance per pig than
conventional production. Available data on animal disease patterns in pigs are limited, but
health and welfare problems appear to differ between organic and conventional production.
External parasites were seen as the biggest problem, followed by infertility, whereas diarrhoea
and respiratory diseases were considered minor problems in a UK study in late 1990s (Hovi
and Roderick 1999). Small Nordic case studies have shown a low incidence of diarrhoea and
respiratory disorders but an increased incidence of joint diseases compared with indoor herds
(Lindsjö 1996, Olsson
et
al
. 1996, Vaarst
et
al
. 1998a, Kugelberg and Johansson 2001), as well as
outdoors where a case study (four herds) showed that among outdoor sows, traumatic lameness,
injuries and sunburn were the most common clinical finding. In several studies, endoparasites
and ectoparasites have been found to be highly prevalent, probably related to outdoor access, a
high level of insoluble fibre (roughage), low level of hygiene and use of permanent pastures.
Some organic herds have experienced massive problems with milk spots in the liver following
recent
Ascaris
infection, resulting in rejections at slaughter. The use of antibiotics was very low
in the organic herds. It is evident from several Danish studies that piglet mortality is high in
organic systems (Lauritsen
et
al
. 2000), although not different from conventional outdoor
systems.
In general, the disease problems in intensive organic egg layer f flocks seem to be the same as
in conventional f flocks, but at times at a higher level. The Danish Poultry Council (2002) found
a higher mortality during the laying period in organic f flocks than in any other egg-producing
f flocks. Without doubt, some specific disease problems are associated with free-range produc-
tion. Coccidiosis, helminth parasites, histomoniasis and ectoparasites occur more frequently in
free-range f flocks, and diseases carried by wild birds (e.g. pasteurellosis, salmonellosis, avian
