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Case of vitamin deficiency in calves cracked

High mortality isn’t normally associated with vitamin deficiencies, but for one Alberta producer, stressful winter weather may have been the tipping point. The family lost 22 of the 70 calves born to heifers during the 2013 calving season.

Getting the Viking Veterinary Clinic involved from the outset, when unexplained deaths started happening early in the calving season, led to corrective measures that prevented further losses.

Dr. Lacey Fowler says it was initially disheartening when heart, lung, liver and intestine samples taken from dead calves still left them empty-handed. The colour of the heart muscle was paler than normal with some noticeable white streaks, but the findings weren’t consistent with white muscle disease. No reason could be found for the deaths that kept happening day after day.

The only common denominator was that all of the dead calves had been born to first-calf heifers, while everything appeared to be fine among the 200 mature cows.

Some calves were stillborn. Others lived only two or three hours regardless of whether they were weak and couldn’t stand or quite alert and able to nurse with assistance.

After the fifth death, the carcasses were taken to Prairie Diagnostic Services at the University of Saskatchewan for complete post mortems with requests for full mineral panel screening on the livers and cultures for neospora and bovine viral diarrhea. The results were negative for both diseases, but the mineral tests gave them their first real clue — low vitamin E levels.

Subsequently, blood samples were drawn from 24 heifers selected at random to test for magnesium, manganese, iron, cobalt, copper, zinc, selenium, molybdenum and vitamin E levels.

Fourteen happened to be home-raised heifers; eight were from a group of 40 purchased in late December, and the origin of two wasn’t confirmed. Some had calves at foot and others had lost their calves.

Fowler says nothing in the results was unexpected or unusual for an Alberta winter except, once again, low vitamin E levels were suspicious. Twelve heifers were deficient in vitamin E, three were marginal and nine were normal.

The test results weren’t conclusive because some of the deficient heifers had live calves and some of the heifers with normal vitamin E levels had lost their calves.

“We hypothesized that because the heifers were still growing, their vitamin E needs would be higher,” Fowler says.

It’s possible that the calves were deficient in vitamin E at birth and that alone compromised their ability to survive. The mechanism by which this could cause death isn’t well described in scientific literature.

If their dams were deficient in vitamin E, then calves able to suck would have received vitamin E-deficient colostrum. This would further compromise their viability because colostrum and milk are the main sources of vitamin E for newborn calves.

“Our presumptive diagnosis was hypovitaminosis E,” Fowler says. “This is unique because vitamin deficiencies are normally associated with low-level subclinical disease — you don’t expect to walk out and find dead calves every day. Also, we didn’t see the selenium deficiency in conjunction with vitamin E deficiency that characterizes typical white muscle disease, or a vitamin A deficiency often seen in conjunction with a vitamin E deficiency.”

Treatment results show they hit the nail on the head because the death toll rapidly decreased after they started supplementing vitamins in the ration with injections.

Treatment

Vitamins A, D, E and K are fat soluble, but the risk of toxicity is relatively low.

Selenium is a different matter. A little is crucial, but a little too much can be deadly. Be careful when feeding supplements that contain selenium because it’s quite easy to reach a toxic level of selenium before meeting the vitamin requirements, Fowler cautions.

All calves on the ground received vitaminE/selenium with vitamin A/D injections as did subsequent newborns immediately after birth.

The newborns were also tube-fed a commercial colostrum product to ensure adequate intake of colostrum for effective passive immunity and essential vitamins.

Given that vitamin E is necessary for proper immune system function, it was highly probable that the calves had compromised immune systems, therefore all newborns were treated with an antimicrobial as a preventative measure.

The farm was running an excellent vaccination program and the herd appeared to have sufficient amounts of feed and bedding.

Both the heifer ration and cow ration were based on greenfeed bales. The cows received 10 pounds of alfalfa-grass hay as a supplement and loose trace mineral fed free-choice. The heifers received 10 pounds of hammered oats with a 32 per cent protein supplement and a trace mineral salt block with selenium. A 2:1 (calcium:phosphorus) mineral/vitamin mix was fed for the first half of the winter feeding period.

Feed supplies weren’t tested, so it can only be assumed that the heifer ration was short on vitamin E.

A general observation overall was that the condition seemed to be affecting the home-raised heifers more than the purchased heifers. Fowler says this may have been because the home-raised heifers received a vitamin-E deficient diet for a longer span of time than the purchased heifers, which probably had a more balanced diet before arrival.

Take-home messages

Injections of vitamins A, D and E meet requirements for about two weeks, which means that giving injections at preg-check time in fall isn’t enough to carry animals through winter. In fact, cattle coming off pasture could already have depleted stores of fat-soluble vitamins if they have been grazing mature forages. Pregnant and growing heifers would deplete vitamin stores more rapidly than mature cattle because of their higher requirements.

Vitamins A, D and E are plentiful in green forage, but don’t overwinter well in stored forages, Fowler says.

Feed testing is a good start, but be aware of dwindling vitamin levels in hay as the winter progresses.

The best way to ensure adequate vitamin and mineral intake is to top-dress grain or in a total-mixed ration. If feeding free choice, know what the intake per head per day should be and monitor the number of bags, blocks or tubs the herd is consuming.

Herd investigations are a collaborative effort between producers, veterinarians and nutritionists, often involving experts at veterinary schools, she says. Having good management records, including feed labels and freezing liver samples from suspicious deaths, can help get to the bottom of a disease outbreak.

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