Agriculture Reference
In-Depth Information
The animals' basic nutritional requirements must be met, with regard to the levels of minerals
and vitamins, to ensure their health and welfare. In some countries, supplementation with
vitamins, trace elements and minerals is not a routine practice, whether certified organic or
not. Another aspect of the interaction between animal health and nutrition regarding worm
control is feeding with bioactive forages, which, for example Hoste
et
al
. (2004) and Thamsborg
et
al
(2005) describe, based on an EU-funded project WORMCOPS.
Feeding with home-grown feed
A basic principle of organic agriculture is that the animal herd forms a part of the entire
farming system, which means that the nutrient supply in organic herds should be based prima-
rily on home-grown feed, limiting the amount of bought-in feed material. In many organic
farms, the genetic potential for production is used to maintain a high production, similar to
the level of conventional herds. This puts some very high demands on the quality of feed as
well as the amount of food intake. The aim of giving organic animals only home-grown feeds
must be met in a manner that allows the animals' requirements to be met and still maintain
ecological and economical sustainability. The way of fulfilling such an aim will depend on
local and regional conditions and how the harmony between the animal herd and the land
area can be supported. In the case of organic dairy farming, grassland feeding will be dominant
(e.g. in Switzerland); hay feeding during winter can cover more than 90% of the nutrient
requirement of the dairy cows (Früh 2004). An example from Australia with beef cattle is
given, based on pure grassland feeding (see Box 7.4).
Use of roughage
In organic farming much emphasis is put on roughage feeding, which may have great impact
on health and disease patterns. In cattle, a high proportion of roughage will often be favoura-
ble to the rumen environment and will result in less metabolic disease (e.g. Danish Cattle
Advisory Board 1998). Recent observations on ruminal acidosis suggest that problems may
arise and need further investigation. In organic pig production, the use of roughage such as
pH-lowering silage, may reduce the incidence of gastrointestinal bacterial infections like sal-
monella, dysentery and lawsonia, but increase the prevalence of nematodes (Petkevicius
et
al
.
1999). The extensive use of roughage can be problematic due to its low energy density compared
to most concentrates, as it may dilute ration energy density to a level too low for a high level of
production, referring to the potential conf lict described above with breeding for high produc-
tion. This may present a higher risk associated with unbalanced diets, especially a shortage of
energy combined with an excess of crude protein (Sundrum 2001). In Norway, this caused
lower reproductive efficiency in cattle in the mid 1990s (Reksen
et
al
. 1999), because commer-
cial organic concentrates were not available and the farmers had to rely on home-grown forage.
In most European countries, organic milk production varied between 80% and 95% of the
level found in conventional herds, probably due to a lower energy level in the rations. In a
Danish study, the level of subclinical ketosis in organic dairy herds was found to be at the same
level as conventional, but occurring at a later stage of lactation than in conventional herds,
despite the larger negative energy balance between production and feed-intake in organic
herds (Vaarst 1995). This was explained by the accessibility to feed 24 hours per day, daily
exercise and the feeding of offspring with roughage.
Challenges in tropical areas: feeding from 'organic by default' to 'organic as a
goal'
Much of the existing organic livestock production takes place in relatively intensive produc-
tion systems in Europe and North America, but we should also consider the potential develop-
