Calcium: It’s More than Strong Bones

Calcium: It’s More than Strong Bones

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By Jaclyn Krymowski  It’s a basic nutrition fact most of us learn in childhood — calcium (Ca) builds strong bones! As with people, this essential mineral also provides our goats with structural integrity from the time they are playful kids through adulthood. Besides bone composition, it also aids with proper muscle contraction and other systemic functions. 

A much lesser-known fact about calcium is its dependence on other nutrients to do its job. To properly function and be effective, it relies on assistance from phosphorus (P) and vitamin D. When one or both are lacking, as-fed calcium will be ineffective. In other words, it’s all about balanced and proper dietary composition. 

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All About Absorption 

Calcium has direct ties to the body’s endocrine system and nutritional action. In addition to musculoskeletal functions, it involves blood coagulation, enzyme activity, hormone release, and other vital functions. Blood transports the Ca ions throughout the body to fulfill all these needs, making them especially sensitive to absorption by the organism. 

Unlike some nutrients, the amount of this mineral that is actually being absorbed and utilized in the gastrointestinal tract isn’t perfectly reflective of what is fed. Ironically, when calcium is overfed or improperly balanced with other minerals, it can decline overall absorption.  

When adequate vitamin D is in the diet, it mitigates issues with the absorption of calcium and phosphorus. For young kids, colostrum is their first source of vitamin D. After that, the primary mode of intake is exposure to natural sunlight.  

When phosphorus or vitamin D are lacking, as-fed calcium will be ineffective. It’s all about balanced and proper dietary composition.

Owners can artificially supplement vitamin D to animals that don’t receive enough sunlight from pasture time. However, because this vitamin is fat soluble (meaning it can quickly build up to toxic levels), it should only be given when necessary in a very strategic way with veterinary guidance. Too much vitamin D can lead to excessive calcium buildup in the blood, causing several issues. 

The Role of Phosphorus 

Much like vitamin D, phosphorus is essential to supporting calcium. A goat’s diet requires a minimum Ca:P ratio of at least 1.2:1. Skewing this ratio will result in delayed growth in kids or metabolic issues in adults. Commercial complete feeds should already meet this ratio, but homemade rations should be lab-evaluated by accredited nutritionists to meet specifications.  

While goats can reuse phosphorus thanks to recycling it through their saliva, it may still need supplementation if the diet is inadequate.  

According to Dr. Steve Hart, a researcher from Langston University and author of Meat Goat Nutrition, “Phosphorus is the most commonly encountered mineral deficiency and also the most expensive macromineral.” 

One of the most common places we see issues with phosphorus and calcium is in lactating and pregnant does. They need higher levels for milk production and fetal growth, and a lack thereof causes milk fever (hypocalcemia) which can be deadly if left untreated postpartum. But remember, adequate phosphorus levels must also be present in the diet.  

Feeding an appropriate ratio of alfalfa and grain to pregnant and lactating animals can significantly reduce the odds of milk fever. Alfalfa (offered in any form) is high in Ca, and natural phosphorus is found in almost all grains (corn, oats, wheat, barley, etc.), hays, and other grassy forages. 

Toxicity and Deficiency 

On the opposite end of the spectrum, feeding too much of either calcium or phosphorus can cause problems. An imbalance of Ca:P can lead to urinary calculi in bucks and wethers. Fats added to rations can lead to this imbalance since fats are high in phosphorus. 

This is part of the reason it is crucial to re-evaluate diets to ensure that any new ingredients added don’t cause an imbalance down the line. 

“Generally, twice as much calcium as phosphorus should be in the diet of ruminant animals,” writes Hart. “An excess can cause abnormal bone growth. Major common dietary sources of calcium include limestone and dicalcium phosphate.”  

Another scenario of high-calcium feeding is the calcification of soft tissues. This is brought on by tissue damage due to a lack of magnesium, not from high calcium itself. 

Growing animals (young stock) or adults can experience soft or deformed bones due to a lack of calcium, phosphorus, or vitamin D. Similarly, an abundance of phosphorus in the presence of normal or deficient calcium can also cause abnormal bones. 

While they only make up a very tiny portion of the total diet, mineral nutrition is crucial to many bodily functions. This is a classic example of the intricate dietary interplay with various nutrients.  


  • ADK Goat Club. (2013, February 7). Calcium: Phosphorus ratio – why alfalfa is essential. Calcium: Phosphorus Ratio — Why Alfalfa is Essential. Retrieved September 24, 2022, from,and%20the%20feeding%20of%20alfalfa  
  • Kopf, K. (2020, September 13). Finding the Balance Maintaining Health with Goat Minerals. Backyard Goats. Retrieved September 15, 2022, from  
  • Goats. (2019, August 14). Goat nutrition calcium. Goats. Retrieved September 15, 2022, from 
  • MSD Veterinary Manual. Retrieved October 7, 2022, 
  • Pond, W. G., Church, D. C., Pond, K. R., & Schoknecht, P. A. (2005). In Basic Animal Nutrition and Feeding (Fifth, pp. 164–167; 440-441). essay, John Wiley & Sons.  

Originally published in the January/February 2023 issue of Goat Journal and regularly vetted for accuracy.

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