Why Testing Matters: Improving Mineral Nutrition in Sheep Flocks
Minerals are essential for sheep health, reproduction, and productivity. They support immune function, bone development, muscle activity, and reproductive performance. Most sheep producers recognize their importance and provide some form of mineral supplementation. However, recent research conducted at Penn State suggests that many flocks may still be receiving mineral supplementation that is not precisely matched to their needs.
To better understand how sheep producers manage mineral nutrition, Penn State researchers conducted a survey of sheep producers in Pennsylvania. The goal was to characterize current mineral supplementation practices and assess how producers make decisions about mineral nutrition in their flocks. Overall, producers demonstrated strong awareness of the importance of minerals for flock health and reproductive performance. Survey responses indicated strong awareness of the importance of mineral nutrition. Specifically, 77.8% of respondents rated minerals as "very important" for sheep health and 78% rated them as "very important" for ewe reproduction. In addition, 91% of producers reported providing mineral supplements to their flocks at certain or all stages of production.
However, the survey also revealed that mineral supplementation is rarely guided by diagnostic testing. While over 90% of producers reported providing mineral supplements, only 30.7% had tested their soil or forage for mineral content, and just 9% had tested animals for mineral deficiencies. Instead, mineral supplementation decisions were most often based on previous experience, advice from extension educators, or recommendations from other producers rather than laboratory analysis.
These findings suggest that while producers recognize the importance of mineral nutrition and routinely supplement their flocks, mineral programs may not always be tailored to the specific conditions of each farm. Increasing the use of soil, forage, and animal testing could help producers develop more targeted mineral programs that improve flock health while avoiding unnecessary supplementation costs.
Scan QR code above to access Penn State research article (Helbus AM, Clemens MS, Yankocy SR and Stenhouse C (2025) Producer knowledge and application of mineral supplementation in sheep farming systems. Front. Vet. Sci. 12:1694107. doi: 10.3389/fvets.2025.1694107.Â
 Link to research article: Producer knowledge and application of mineral supplementation in sheep farming systems
Why Mineral Testing Is Important
Mineral availability in forage can vary widely depending on soil type, fertilizer use, plant species, maturity, and weather conditions. As many sheep production systems rely heavily on grazing, animals obtain most of their nutrients directly from pasture or stored forage such as hay.
Without testing, it can be difficult to know whether your flock is receiving the correct mineral balance. Both deficiencies and excesses can negatively affect animal health and productivity and can contribute to issues such as weak or stillborn lambs, poor reproductive performance, reduced growth rates, metabolic disorders such as milk fever or grass tetany, and impaired immune function.
Importantly, many mineral deficiencies are subclinical, meaning that animals may not show obvious signs until productivity has already been affected. Diagnostic testing allows producers to move from general mineral supplementation to targeted supplementation practices, which can improve flock health while reducing unnecessary costs.
Mineral Requirements Change During the Production Cycle
Another important consideration is that mineral requirements are not constant throughout the year. The nutritional demands of ewes increase significantly during certain stages of production, particularly late pregnancy and lactation. During late gestation, rapid fetal growth places greater demands on the ewe for minerals such as calcium, phosphorus, and trace minerals to support the growth of the fetus.
During lactation, mineral requirements increase further because ewes must supply minerals in milk while maintaining their own health and body reserves. Inadequate mineral intake during this time can affect milk production, lamb growth, and ewe recovery after lambing.
As forage quality and mineral content can fluctuate seasonally, testing forage and feed sources can help producers ensure that mineral supplementation programs adequately support these higher-demand periods.
Key Mineral Ratios to Pay Attention To
In addition to ensuring adequate mineral intake, the balance between minerals is critical. Certain minerals interact with each other and must be provided in appropriate ratios.
Some of the most important ratios in sheep diets include:
Calcium:Phosphorus
The calcium-to-phosphorus ratio in sheep diets should typically be maintained between 1.5:1 and 2:1, with ratios closer to 2:1 often recommended for growing lambs or animals receiving high-grain diets to help reduce the risk of urinary calculi. Imbalances in this ratio can lead to problems such as urinary calculi (particularly in ram lambs), poor bone development, and reduced growth performance. Moreover, during times of high calcium use such as late gestation and lactation ewes could benefit from CA:P ratios of 3:1, as they are utilizing more calcium developing milk and bone formation of the fetus. Testing forage and feed can help producers confirm that mineral levels are balanced and ensure the diet supports proper animal health and performance.
Copper:Molybdenum
Sheep are particularly sensitive to copper, and interactions with molybdenum and sulfur strongly influence copper availability in the body. Copper levels must be carefully controlled in sheep diets as excess copper can lead to toxicity, which may be fatal. Classic signs of significant copper toxicosis includes jaundice and lethargy clinical signs associated with chronic copper poisoning are sudden in onset and affected animals become increasingly weak. Some sheep may spend time wandering aimlessly or head-pressing. As the disease progresses, jaundice develops and breathing becomes shallow and rapid due in part to the development of anaemia. Copper to Molybdenum should be approximately 6:1 ratio.
Signs in sheep with extreme copper toxicosis:
Additionally, high molybdenum levels can interfere with copper absorption and create secondary copper deficiency.Â
Selenium and Vitamin E Balance
Selenium deficiencies are common in some regions and can lead to white muscle disease in lambs. Selenium deficiency occurs in soils of certain geographic areas world-wide leading to pasture/crop deficiency. Most soils in Pennsylvania are selenium deficient. Vitamin E concentrations are high in green grass, but fall rapidly under drought conditions. Excessive Selenium supplementation can also be toxic. The safe range between deficiency and toxicity is relatively narrow, which makes diagnostic testing particularly valuable.
Diagnostic Testing: The Missing Step
Testing is one of the most effective ways to optimize a flock’s mineral program.
 Useful diagnostic tests include:
- Soil testing: Helps determine mineral availability in pastures.
- Forage testing: Measures the mineral content of hay, pasture, and other feeds that animals actually consume.
- Animal testing: Blood or liver testing can identify mineral deficiencies or imbalances within the flock.
Together, these tests provide a complete picture of mineral availability and animal status, allowing producers to design supplementation programs that are both effective and economical. If collecting blood for mineral analysis it is recommended to use a royal blue top vacutainer tube as the materials, including the stopper and tube plastic, are certified to have extremely low levels of metal contamination. This ensures the results reflects the patient's status, not tube materials.
When getting an animal processed at your local butcher even if you do not eat the liver; this is an excellent time for sample collection and request if you can have the liver to send to the diagnostic lab for mineral analysis. Liver samples are the gold standard for analyzing mineral deficiencies and toxicities in the herd/flock.
If you are interested in testing soil, forage, feed, or animal samples, Penn State Extension maintains a list of laboratories that provide these services.
You can find the full guide here:
Where to Test Agricultural Commodities – Penn State Extension
Scan QR code above to go to article with testing resources
Take-Home Messages
- Many Pennsylvania sheep producers recognize the importance of minerals and already supplement their flocks.
- However, diagnostic testing is rarely used, meaning that mineral supplementation may not always match flock requirements.
- Testing soil, forage, and animals allows producers to fine-tune mineral supplementation programs.
- Properly balanced mineral programs, including key ratios such as calcium:phosphorus and copper:molybdenum, are critical for flock health and reproduction.
- Targeted mineral programs can improve productivity while reducing unnecessary feed costs.
If you are interested in learning more about mineral testing or developing a mineral program for your flock, contact Penn State Extension or visit the diagnostic testing resources listed above.
 Link to research article: Producer knowledge and application of mineral supplementation in sheep farming systems
