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John Dunne November/December 2022

Animal Nutrition

Animal Nutrition

  • Mineral Analysis Results
  • Silage sample results


  • Grazing management of weanlings out in grass
  • Closing farm cover


  • Weighing of stock
  • Animal Housing Protocol

Animal Nutrition

As part of the future beef programme, a mineral analysis was taken from the silage fed to the cows .The report highlighted no copper antagonists and low levels of Magnesium. Therefore, a mineral with high levels of Mg ie.+20% will be given pre-calving.

Macro Minerals

Magnesium (Mg):  Magnesium plays a crucial role in mobilising calcium from bones and increasing gut absorption, to reduce milk fever. Low levels of magnesium can also cause slow calving. Magnesium is not stored in the body, so it is very important it be fed right up to calving.

After calving Mg supplementation is required especially on lush spring or autumn grass to prevent grass tetany.  


Phosphorous (P): Makes up approx. 30% of total minerals in the body. A phosphorous deficiency can severly affect reproduction, causing silent heats, irregular oestrus and low conception rates. Low phosphorous is also associated with pica – i.e. eating stones etc.  


Sodium (Na):  Aids in nutrient transfer, waste removal, involved in muscle and heart contraction, rumen and blood pH. Deficiency signs are urine licking, reduced male fertility, lower milk production and depraved eating behaviour.


Calcium (Ca):   Calcium maintains normal muscle function and a deficiency can cause difficult calving’s and retained placenta. Obviously once a cow is lactating the requirement for calcium increases dramatically, it is a deficiency in calcium that cause milk fever.  A cow is unable to physically consume her calcium requirement, she has to mobilise it from her own bones. In order for her to be able to do this post calving, she has to start pre calving. Magnesium aids in this process and this is why minerals high in magnesium are fed pre calving. If calcium is fed pre calving, it meets her pre-calving requirement and she won’t have started the process of mobilising calcium from her bones and this will lead to a deficiency after calving, therefore - Do not feed calcium pre calving.


Trace elements

Copper (Cu): Deficiency can lead to small weak calves, scours and decreased milk. In weanlings, it can cause poor growth rates.

Selenium (Se): One of the few elements that can pass through the placenta from the cow to the calf. It is important as a deficiency can cause muscular dystrophy (weakening and wasting of muscle). Some areas are high in Se, so you should test your silage to ensure you do not cause a toxicity. A deficiency can also cause an issue with retained placentas. 

Iodine (I): Deficiency can cause small weak calves, dead or hairless calves, or calves that do not want to suck. The animal will have low immunity. It can also lead to poor reproductive performance. It is also not stored in the body and needs to be fed right up to calving.

Cobalt (Co): Involved in the synthesis of B12 by the rumen, deficiencies more often seen in sheep. Can cause a rough coat, poor appetite and anaemia.

Manganese (Mn): A deficiency can affect growth, bone formation and the nervous system leading to poor growth, reproduction and bowing of the joints.

Zinc (Zn): Plays a role in the immune system and repair of damaged tissues. while it is also involved in the synthesis and metabolism of proteins and carbohydrates, teat keratin formation. A deficiency can lead to poor skin, mastitis, slow healing of wounds, bad hoofs and stiff joints. It can also lead to lower conception rates.


Vitamin A: Increases disease resistance and stimulates the immune system. Cows that have a deficiency in vitamin A can also produce dead, weak or blind calves because vitamin A is needed for normal growth and development including growth of the foetus. Again it is passed through the colostrum. Can also cause retained placenta.

Vitamin D3: Essential in calcium and phosphorous metabolism. Promotes growth and mineralisation of healthy bones, therefore plays an important role in the prevention of milk fever

Vitamin E: Required for good health and immune function. If fed pre calving it elevates the level in colostrum and help to keep your calves heathy. It does not pass through the placenta, so calves must get adequate colostrum.

Silage Analysis

The first cut silage yielded good results with a DMD of 74.44%; Crude Protein of 13.9% and with a dry matter of 22 %. This is the pit silage and is fed to all stock through a diet feeder.















There is still 145 weanlings out on grass. The ground conditions in November were quiet good and the weanlings were grazing out the pasture to 4 cm without any damage. The ground been grazed is silage ground that was reseeded this year so the sward is very leafy and the cover needed to be grazed off. The weanlings are given 2 day allocations.

The weather conditions deteriorated in early December making it more difficult to graze out the paddocks. Stock were moved on quicker to avoid poaching . If the wet weather continues some of the stock can be housed or the weanlings will be moved onto the forage rape.

The closing cover is 480kgs DM/ha which is on the low side.



The in calf heifers are housed into 2 pens and there are 3 pens of in calf mature  cows which will start calving in the first week of Febuary. These 5 pens are getting silage plus straw through the diet feeder.

All other stock including the finishing animals are on ad lib silage plus the following ration;

  • 3 ton of rolled barley
  • 8tons of rolled oats
  • 3tons of soya bean
  • 250kgs of molassess and
  • 2 bags of minerals

The weanling grazing outside get 1 kgs/head/day while the finishing animals get 5 kgs/head/day.