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Responsible Mineral Nutrition for Youngstock

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Responsible Mineral Nutrition for Youngstock
By Anna Roberts 13 days ago

Whether our aim is to improve growth from our youngstock, improve feed conversion rates of our beef animals, or to just simply produce more milk from dairy cows, one sure way to enhance this is by increasing nutrient utilisation. This is a free tool - we just need to learn how to use it to our advantage.

Copper is one of the essential trace elements required by cattle and has several functions as it’s an important component of enzymes. Enzymes are specialist proteins that perform specific functions within the body to assist or improve chemical reactions. They break down compounds into substances that the microbes can utilise as nutrient sources, ultimately allowing the animal to perform to its full potential. If this requirement is not met, then deficiency occurs. A lack of available copper can lead to poor growth, scouring, bone fractures, lack of pigmentation and anaemia. A deficiency can also impact on fertility.

Copper toxicity is becoming an increasing problem in cattle so careful formulation of diets is paramount.

One sign could be a delay or depression of first oestrus in a heifer. This has an important economic effect. If a heifer hasn’t calved by 24 months, each additional day costs an extra £2.87 per day in rearing costs alone.

During my seven years with Wynnstay one discussion that will always remain with me was a farmer wanting to supplement his dry cows (dairy) with a trace element bolus containing copper. After asking a few more questions, I learnt that he bought his cow cake from one company, his minerals from another and wanted boluses from me. I then asked him if he had a nutritionist who formulated his diets. He replied he didn’t, he did them himself.

After scrutinising the product labels and adding up the additional copper provided in the cake, minerals and boluses, we concluded that supplementing ex Copper toxicity is becoming an increasing problem in cattle so careful formulation of diets is paramount, with extra consideration given to more susceptible breeds such as Jerseys and Blues and milk-fed calves. Supplementing copper from several sources, which on their own may not be excessive, can build up if combined and could potentially cause copper toxicity.

Copper toxicity is caused by a build-up of copper within the liver over a long period of time. Sudden deaths seem to be triggered by stressful events such as transport or a sudden dietary change. The sudden release of stored copper causes anaemia, weakness and depression, and in the latter stages of copper toxicity their urine turns a dark red colour. Dry cows in late pregnancy seem particularly susceptible. Monitoring copper levels to determine your farm’s copper status can be achieved by post mortem of barren cows and liver biopsies of milking cows, this will give a more sensitive and accurate result than blood testing.

I came across an article by N.R. Kendall et al 2015, which really drove home how severe the implications of copper toxicity can be. Liver samples were collected from one abattoir over a three-day period. Information such as age, breed and geographical location were compared. The trial showed that dairy breeds had higher liver copper concentrations than beef breeds. Holstein-Friesian and ‘other’ dairy breeds had 38.3% and 40% of cattle above the Animal Health and Veterinary Laboratories agency (AHVLA) reference range (8000 μmol/kg dry matter), whereas only 16.9% of animals in the combined beef breeds exceeded this value. Could this be because dairy cows are being fed a ‘higher plane’ of nutrition with additional copper supplemented via other sources, whereas beef breeds are fed a more simple and basic diet of silage. Over 50% of the liver samples that were tested had “greater than normal “ concentrations of copper with almost 40% of the female dairy cattle having liver copper concentrations above the AHVLA reference range, which clearly demonstrates that a high proportion of the UK herds are at risk of chronic copper toxicity! The trial also demonstrated that age of the animal was not a contributing factor to copper toxicity.


Requirements
Maximum Permitted Levels (MPL’s)


Calves (Pre ruminants)
10mg/kg DMI 17mg/kg DMI
Adult cows
20mg/kg DMI* 34mg/kg DMI
*under normal conditions and in the absence of significant antagonists (NRC 2001, ACAF-2011, Regulation (EU) 2018/1039


Supplementing additional copper

All sources of copper need to be accurately estimated before extra supplementation is considered. This includes sources from injections, grass, mineral buckets, forages, boluses compounds, straights, minerals, mineral blocks and not forgetting water, to ensure diets are not in excess. Copper supplementation should be regularly assessed by you, your nutritional adviser and your vet. However, should extra copper need to be supplemented over the NRC guidelines, a full risk assessment should only be carried out by your vet in the first instance.

One question we need to ask ourselves: “Who is nutritionally responsible for our cattle?”

For further help and support of your growing youngstock, please contact your regional Calf & Youngstock Specialist.

Sandy Wilson

Sandy Wilson

Animal Health Specialist

07879 841672