Farm Ireland
Independent.ie

Tuesday 26 September 2017

Match minerals to the forage analysis

Siobhan Kavanagh

Feeding a good quality dry cow mineral is a key component of successful dry cow management. Getting mineral nutrition right at this stage is important for cow and calf health.

Mineral supplementation of the dry cow will be dictated by the mineral profile of the base forage, which, in most cases, will be grass silage.

Farmers should analyse their dry cow forage annually to assess its nutritive value.

Every three to four years, the forage should be analysed to its mineral profile and formulate appropriate supplementation.

In 2009, Teagasc, in conjunction with Trouw Nutrition, conducted a survey of farms across the country to establish the mineral status of grass silage.

The results showed a decrease in the concentration of many of the major elements in grass silage, compared to a similar survey conducted in the early 1990s.

This highlights the importance of carrying out mineral analysis of silage regularly for individual farms.

The key parameters to follow in forage analysis are:

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* Phosphorus: If phosphorus level is below 0.25pc, then phosphorus supplementation in the pre-calver miner is important.

* Potassium: If potassium level is above 2pc, the risk of milk fever (clinical and sub-clinical) increases. In the medium term, it's important to check the quantity of slurry going on silage ground.

In the short term, if potash levels are high and milk fever is a problem, the silage may need to be diluted down with an alternative forage source.

* Sulphur: Optimum sulphur for grass growth and animal requirement is 0.2pc. If below this, it can indicate lack of sulphur on the land, while high levels can tie on trace elements.

* Trace elements: Trace elements levels tend to be low in all forages.

Most pre-calver supplements carry enough trace elements to meet requirements.

* Molybdenum: Target less than 1.5pc as higher levels can tie up copper

How to calculate what's in a mineral supplement.

Mineral labels have become difficult to interpret. With so many different feeding rates, it is important to check that the mineral mix is supplying what is needed by the cow on a daily basis.

1.To calculate the quantity of major elements (calcium, phosphorus, magnesium and sodium) supplied to the cow daily, look at the following example:

Feeding rate = 120g

Phosphorus inclusion rate = 4pc

Quantity of phosphorus the cow gets daily = 120 x (4/100) = 4.8 g

2.To calculate the quantity of trace elements and vitamins in the mineral:

Feeding rate = 120 g

Copper inclusion rate = 3,300mg

Quantity of copper the cow gets daily = 3,300 x (120/1000) = 396 mg

Table 3 shows the breakdown of a sample pre-calver mineral.

Irish Independent



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