Routine mineral and vitamin supplementation is common on sheep farms, but an Irish study suggests many decisions are being made without laboratory evidence, veterinary diagnosis or a clear link to improved financial performance.
The research, published in Translational Animal Science, examined mineral and vitamin supplementation practices on Irish sheep farms.
Researchers used a 22-question survey of 177 sheep enterprises participating in the Teagasc National Farm Survey.
The survey was weighted to represent the national farm population, making it one of the more detailed studies of how sheep farmers use minerals and vitamins in pasture-based lamb production systems.
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The headline finding was that supplementation was found to be widespread.
69% of respondents gave mineral and vitamin supplements in addition to concentrate feed. 17% used concentrates as the only source of mineral and vitamin supplementation, 32% used mineral supplements only, 38% used both concentrates and additional mineral products, and 13% used no supplementary minerals or vitamins at all.
However, only a minority of supplementation decisions were based on testing. Just 22% of farmers who supplemented used laboratory analysis, such as soil, herbage, blood or tissue testing.
13% supplemented on veterinary advice, and only 30% of that veterinary advice was itself based on laboratory results.
The study found that 65% of supplementation decisions were made for other reasons, mainly tradition, previous experience, advice from merchants or because neighbouring farmers supplemented.
The most common stages for ewe supplementation were pregnancy, lactation and pre-mating.
In the main results section, 78 percent of farmers who supplemented gave minerals and vitamins during pregnancy, 61% during lactation and 48% pre-mating.
For lambs, 27% supplemented pre-weaning and 51% post-weaning. Mineral buckets were the most common method for ewes, while drenching was the most common method for lambs.
Generic multi-mineral and vitamin products were most commonly used, followed by cobalt-only products. The study did not find a production or profit response from routine supplementation.
Among lowland lamb producers, there was no statistically significant difference in lambs reared per ewe joined, gross output per ewe or gross margin per ewe between farms that supplemented and those that did not.
Pre-mating supplementation also did not significantly increase lambs reared per ewe joined or gross margin per ewe.
The authors of the report did not conclude that mineral deficiency is unimportant.
They noted that mineral deficiency can reduce animal performance and profitability, and that pasture mineral concentrations vary through the grazing season. But they stressed that supplementation should not be the first response to poor performance.
Grassland management, forage feed value and parasite control should also be examined before assuming a mineral deficiency.
Only 6% of respondents had flock health or performance problems associated with mineral or vitamin deficiency diagnosed by a vet. Of those diagnoses, copper deficiency, including swayback, was the most common.
Farmers most often associated deficiency with poor thrive or poor bodyweight gain, followed by reduced fertility and lameness. For Scottish sheep producers, the study’s main message is not to stop using minerals, but to target them.
The published research supports testing, veterinary input and farm-specific diagnosis over routine use of buckets, drenches or generic products without evidence of need.
