Copper critical for pre-calving cows

It doesn’t take much to correct a deficiency so watch for symptoms

Recently, I gave a dinner presentation to a group of beef producers outlining the importance of feeding a good mineral program to pre-calving cows. Afterward, I was surprised by the number of questions about the possibility of a copper deficiency in their beef cattle. With calving season underway or soon to start, we all agreed that cattle mineral-feeding programs should assure pregnant cows receive all copper they need.

With much of this discussion centered on feeding copper to beef cows, it is interesting to note the mineral is only required in very small amounts.

A daily total of 125-140 mg copper should be consumed by beef cattle in order to satisfy all their vital and performance functions. After it is consumed, absorbed, and retained; copper does not become part of any final structural component in the body (a.k.a. 99 per cent of calcium is found in bones). Rather, it sits in many enzyme systems as an invisible activator (re: on/off switch) involved in many body chemical reactions.

For example, copper plays an indirect role in making red blood cells. It activates special enzymes used to regulate iron absorption (another metal involved in the manufacture of oxygen-carrying hemoglobin). Other copper enzymatic functions include immune function, cell health and integrity, maintenance of bone and connective tissue, normal reproductive activities and hoof formation.

In most copper-deficiency cases, either cattle do not consume enough copper in their feed (primary deficiency) or excess antagonistic nutrients such as molybdenum and/or sulphates in the feed or from water tie up biologically usable copper (secondary deficiency). As a result the deficiency symptoms are subtle and often similar to other nutrient deficiencies or even are associated with non-feed related issues.

Checklist for copper deficiency

Here is a practical checklist broken into three categories that I use to investigate the possibility of a marginal primary or secondary copper deficiency in a cow herd:

  • General — Lethargic cows and calves, poor milking cows (slow-growing calves), unexplained sickness or deaths, higher incidence of injury, poor growth on replacement heifers, failure to maintain overwinter BCS, poor hoof condition.
  • Health — Higher rates of scours, respiratory (pneumonia) and other common cattle diseases, greater susceptibility to bacterial, viral and other disease, poor response and recovery from disease, higher rates of treating cattle, higher rates of sudden death, poor vaccination takes (including measured titres).
  • Reproduction — Silent heats in cows and heifers, high percentage of open cows, high incidence of early embryonic deaths, difficult calving season, poor calving percentage, post-calving problems, delayed or failure to recycle after calving and getting rebred and spread-out calving/breeding seasons.

From this checklist, if a producer suspects an underlying marginal copper deficiency in a cow herd, before calling a veterinarian to take blood samples for testing, I suggest that forage samples (and pasture — when available) are tested first. Test for copper as well as sulphur, molybdenum, calcium, and zinc.

This is good first-step advice. A few years ago, I worked with a feed mill that supplied a typical loose cattle mineral to a cow-calf operator whose cows had suffered from poor pregnancy rates and other ailments for years. We suspected some type of trace mineral deficiency (not necessarily copper at the time) in several of the owner’s pastures, because his trouble seem to originate from a specific area of the farm.

Forage tests came back and showed that their molybdenum level was 5.0 ppm (dm. basis), which could significantly tie up dietary copper in the total cattle diet. As a result, the feed mill fortified copper to the mineral in a more biologically available form (re: chelated organic copper) and adjusted the total dietary copper fed; to a ratio of at least 2:1 copper to molybdenum in the diet. By blocking the inference by molybdenum, these cows responded with higher conception rates in the following pasture season.

In this particular case, we didn’t take any blood samples for copper testing, but this practice is common among veterinarians when determining copper status in a cow herd. Blood collection is simple to do and copper analysis is relatively inexpensive.

Keep in mind, since blood pulls copper from the liver (re: liver stores most of the copper in the body), testing blood/serum copper levels is only a good screening tool in the most advanced cases of copper deficiency. Although, liver copper levels are the most reliable test for verifying poor copper status in cattle, the downside of taking liver biopsies is high degree of stress to the animal, time-consuming, expensive and the results taken from animals dying from disease are questionable.

Regardless, the general recommendation for correcting a verified marginal copper deficiency in many cow herds can be a straightforward matter of feeding cattle a well-balanced commercial mineral containing supplemental copper. The NRC copper requirement for young and mature cattle is no more than 15 mg/kg of diet (dm. basis), which takes care of the beef animals’ basic copper requirement and also takes into account the antagonistic effects on dietary copper by moderate molybdenum or sulphur levels in forages, other feedstuffs or water.

A purchased mineral containing 1,500-3,000 mg/kg of dietary copper and fed at 50-100 grams per head per day should prevent or solve most copper deficiency problems.

About the author

Columnist

Peter Vitti is an independent livestock nutritionist and consultant based in Winnipeg. To reach him call 204-254-7497 or by email at [email protected]

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