Minerals are important – for animals and humans
Minerals, including trace elements, are essential for the health of dairy cows – organic and low-input as well as conventional – and also to the nutritional quality of the milk supplied to the consumer.
How to secure better mineral supply
- Take a whole-farm system approach
- Regularly monitor cows to ensure that they are neither over or undersupplied with minerals
- Appoint only one person as responsible for the mineral nutrition from all source.
Milk analyses from cow herds in the UK show that in many cases both organic and conventional cows are undersupplied with minerals while others are being oversupplied. There are serious implications for cow and human health, apart from unnecessary costs.
Mineral management requires an understanding of the supply of minerals from soil and forage, possible antagonists in water, supply from purchased feeds and how to monitor cows and milk mineral levels.
Levels can be managed by the use of alternative forage species and soil management, then if necessary cows can be supplemented through feed, free access minerals, water or bolus. Annual monitoring of cow mineral levels is important for maintaining health and milk quality.
SOLID technical note: Minerals and trace element management in organic and low-input dairy cows.
Macro-minerals Key role
- Sodium Rumen
- Potassium Production.Reproduction.Immune system
- Calcium Skeletal growth. Fertility
- Magnesium Grass staggers
- Phosphorus Skeletal growth. Fertility
Trace elements Key role
- Copper Immunity. Mastitis. Growth. Reproduction. Hormones. Feet. Scours and pale hair
- Cobalt Growth. Feed efficiency
- Zink Mastitis. Growth. Reproduction. Hormones. Feet
- Iron Immunity. Hormones. Excess residues copper availability
- Manganese Immunity. Mastistis. Growth. Reproduction
- Selenium Mastitis. Feet. Reproduction.
- Iodine Thyroid hormones. Calf vigor.
- Molybdenum Excess reduces copper availability
The importance of the soil
The soil has a crucial role to play when it comes to the livestock´s mineral supply. Certain types of soil are well known for causing trace element deficiency. This is often due to inherently low levels of e.g. Selenium, Cobalt, Iodine or Copper in the soil or as a result of the antagonistic effect of high Iron or Molybdenum on the availability of copper to the animal.
To ensure the best possible absorption of minerals by the plants farmers should:
- Ensure good soil structure which allows plant roots to develop
- Keep pH between 6 and 7 to optimize the availability of minerals
Legumes are high in minerals
Organic and low-input farmers typically include a high proportion of legumes in their sown forage crops as the legumes are an important source of N-supply. White clover is in general higher than grass except for Sodium, Potassium, Phosphorus, Iron, Cobalt and Molybdenum.
The levels of most trace elements including Cobalt, Copper, Iron and Zink are higher in legumes than in grasses, whereas the content of Magnesium and Molybdenum are the same.
Herbs in leys
An increasing number of dairy farmers are also include herbs in the leys. Chicory is one of the more wide-spread examples. There are indications that the herbs can make a significant contribution to the total cow needs. However, some farms experience difficulties in maintaining the herbs in a diverse ley, and if that is the case, herb strips in the grass fields may be a solution.
Crops with lower mineral levels
There is a potential to increase the mineral intake by growing different species but it should be noted that some species such as Timothy and kale have lower levels of minerals. This is also the case for whole crop silage, which is commonly fed in organic herds.
Mineral composition of forage species(per kg DM)
Data pooled from N Van Eeckeren, Lois Bolke Institute and I & W Govaerts