Calcium is an essential supplementary mineral for horses, required at 20 – 40 grams per day for a mature horse in light to intense work.  Growing horses also require adequate calcium for bone density and strength which can reduce the risk of limb breakdown as they mature and during their competition lifetime. 

Many horses require supplementary bone minerals on diets which are high in phosphorus, phytates (eg bran) and grains.  Pasture and grass hays are lower in natural sources of calcium compared to the high calcium content in lucerne hay.  Horses on high grain diets also benefit from the calcium and other nutrients supplied by Cal-XTRA to help bone strength and soundness during moderate to intense training.

Cal-XTRA does not swab.  Cal-XTRA does not contain any banned substances and does not contravene the Rules of Racing and Equestrian competition, making it legal to use during training, competition and racing.  However, for use in racehorses, we recommend that you follow local guidelines on use of any supplements prior to race day.

Cal-Xtra does not swab or contain banned substances and does not contravene the Rules of Racing or FEI Competition.  This product is a nutritional supplement to support the health and well-being of a horse. It does not artificially enhance the performance of racing or competition horses. Rules prohibiting the use of any pre-race supplements within 24 hours of racing should be followed if applicable in the local jurisdiction.

If horses have suffered bone weakness from grazing oxalate containing grasses, it is important to optimise Cal-XTRA supplementation to reduce the rate of bone demineralisation and help restore bone calcium content. 

Our studies have shown that reducing grazing for approximately 1 hour before providing Cal-XTRA, and for 1 hour after the supplement is consumed, will further optimise calcium absorption to correct deficiencies that have resulted in bone weakness.  Remove the horse from the C4 grass to minimise oxalate intake and provide a small hard feed containing Cal-XTRA in a yard or stable.  This can help to reduce pre- and post-feed grazing and ensure optimal calcium absorption from Cal-XTRA supplementation. 

In severe cases of osteoporosis involving the limb bones and joints of working and growing horses, X-rays of the bones to determine their relative density should be taken before the horse is put back into training. It can take up to 12 months for calcium stores to be replenished and re-mineralisation is completed. During this time, it is unwise to ride affected horses as bone fracture may occur.

Once the symptoms of ‘Big Head’ are established, further bone demineralisation can be halted by supplementing with calcium, phosphorus, magnesium, Vitamin A and Vitamin D, which are contained in Cal-XTRA. However, severe facial distortion cannot be reversed in adult or aged horses.

Cal-XTRA can be used as a concentrated bone supplement in combination with Kohnke’s Own Cell-Vital to help ensure longer limb growth in young horses from 24 month of age up to 36 months of age when inadequate height could negatively affect future sporting success.  Often these horses have had growth setbacks that impact the formation of long upper limbs, limiting robust movement and good paces.  Contact Kohnke’s Own for an informative factsheet which explains how to use these supplements to help the development of adequate wither height and strong limbs in young performance horses.

A concentrated calcium supplement is particularly important for horses grazing in regions of Australia where the pasture contains high levels of oxalates. Oxalates consumed by horses from the grass bind to calcium released in the small intestine and make it impossible for the horse to absorb calcium properly from their diet.

Reduced calcium uptake can result in it being taken from bone stores to maintain the important level of calcium in blood. This reduces bone density, causing osteoporosis or weakened bones, leading to shifting lameness, teeth and jaw problems, joint issues, altered movement and in severe cases, the condition known as ‘Big Head’. 

Oxalate intake from grass cause both natural calcium in feed and added calcium in normal ration balancing supplements to be less available.  Supplying a high purity, highly concentrated calcium supplement makes more calcium available from the diet and reduces the deficiency associated with poor calcium uptake from oxalate poisoning. 

Even grazing high oxalate containing grasses for 6 weeks can cause calcium demineralisation of the bones in horses.  Often horses will not show symptoms of bone weakness but this may have already occurred.  If you suspect that consuming oxalates has affected calcium absorption in your horse, we recommend feeding Cal-XTRA at the higher supplementation rate  for 2-3 months to correct calcium deficiency and replenish calcium stores in affected horses. 

When horses are showing symptoms of osteoporosis, bone weakness or Big Head, supplementation with the higher rate recommended on the Cal-XTRA label may need to be continued for 4-6 months to reduce the rate of bone demineralisation and help restore bone calcium content. In these cases, it is important to optimise Cal-XTRA supplementation to help replenish calcium stores in the bones for adequate strength and density. 

Even grazing high oxalate containing grasses for 6 weeks can cause calcium demineralisation of the bones in horses.  Often horses will not show symptoms of bone weakness but this may have already occurred.  If you suspect that consuming oxalates has affected calcium absorption in your horse, we recommend feeding Cal-XTRA at the higher supplementation rate (for rapid growth periods) for 2-3 months to correct calcium deficiency and replenish calcium stores in affected horses. 

When horses are showing symptoms of osteoporosis, bone weakness or Big Head, supplementation with the higher rate recommended on the Cal-XTRA label may need to be continued for 4-6 months to reduce the rate of bone demineralisation and help restore bone calcium content. In these cases, it is important to optimise Cal-XTRA supplementation to help replenish calcium stores in the bones for adequate strength and density. 

If you find C4 oxalate containing species of grass in your pastures, it is important to reduce the risk of osteoporosis, Big Head or bone demineralisation in your grazing horses by feeding Cal-XTRA daily.  We recommend feeding Cal-XTRA in Spring and Summer at the higher supplementation rate given on the label (120 g daily for a 500 kg horse at rest or in light work).  In slow grass growth periods, the supplementation rate can be reduced to half (ie 60 grams for a 500 kg horse at rest or in light work).   

Our studies have shown that reducing grazing for approximately 1 hour before providing Cal-XTRA, and for 1 hour after the supplement is consumed, will optimise calcium absorption to correct deficiencies that have resulted in bone weakness.  Remove the horse from the C4 grass to minimise oxalate intake and provide a small hard feed containing Cal-XTRA in a yard or stable.  This can help to reduce pre- and post-feed grazing and ensure optimal calcium absorption from Cal-XTRA supplementation. 

It is not true that ‘Big Head’, or oxalate-linked bone weakness, is only a problem for horses in Queensland or Northern Territory.  Kikuyu and other oxalate-containing grasses have now spread south to costal parts of NSW and Victoria, and many horse owners have reported horses suffering from osteoporosis and Big Head in these regions.  Kikuyu is a common lawn turf grass and is resilient to hot weather and semi-drought climate conditions.  Some horse owners like the hardy nature of kikuyu for grazing horses, but under warm, moist conditions in Spring and Summer, it can contain a higher, more dangerous concentration of oxalate chemicals. 

If you suspect kikuyu is invading your pasture, we recommend supplementing with Cal-XTRA once this grass has been identified, particularly during Spring and Summer high growth periods.  This is especially important if your horse is not consuming lucerne hay which will naturally supply some of the bone minerals needed to offset oxalate consumption. 

Yes, Cal-XTRA is highly palatable with the tasty vanilla flavour that horses love! This flavour does not contain sugar so Cal-XTRA is safe for sugar sensitive horses and ponies.  Cal-XTRA is a dense, heavy and low dust powder which mixes well into wet or dry feeds. 

Cal-XTRA is very easy to feed, with the new larger scoop making it easier at feed prep time.  The Cal-XTRA label features a handy reference table for all different types of dose rates needed, depending on the pasture type, the season, workload and size of the horse.

Lucerne as a legume crop contains higher levels of calcium and magnesium compared to other common hay varieties.  Each kilogram of lucerne as hay or chaff provides approximately 12 grams of calcium, thereby reducing the necessary supplementation rate of Cal-XTRA. 

For horses on high oxalate pastures fed 2 kg of lucerne per day (1 biscuit hay plus lucerne chaff in feed), provide 40 grams of Cal-XTRA per day for horses at rest and 60 grams daily for working horses (400-600 kg body weight).  For more specific dose rates combining various rations with Cal-XTRA, contact our Nutritional Advisors at www.kohnkesown.com.

Most good quality, scientifically designed ration balancing supplements contain calcium.  For example, Kohnke’s Own Cell-Provide, Cell-Vital and Kohnke’s Own Cell-Perform all contain amounts of calcium relative to the needs of resting or working horses. 

Cal-XTRA can provide additional calcium in cases where extra is needed, for example, during bone regeneration, or when tropical grasses are the dominant pasture type available to the horse.  In these cases, you can continue to use a normal ration balancing supplement, and simply add in Cal-XTRA as an economical boost of calcium and other bone minerals relative to the horse’s daily needs. 

Early symptoms of bone demineralisation in horses from consuming high oxalate C4 grass species include intermittent or shifting lameness, failure of young horses to grow adequately to their expected height, clicking joints or weakness in the stifle and pelvis causing altered movement. Some horses may also exhibit poor hoof growth or quality.  Horses will often have loose teeth and inability to chew food, or ‘slobber’ when eating. 

More advanced signs include fracture of pelvic bones, ribs and splint bones, spinal column collapse and hind-limb in-coordination. 

‘Big Head’ (Nutritional Secondary Hyperparathyroidism, NSH) is identified by the classic swollen forehead, nasal and jaw bones.  Big Head is caused by bone weakness that allows the contents of the head to distort the softer and less dense facial bones. 

Distortion of the nose from Big Head may cause noisy breathing due to restricted nasal passages, often with a nasal discharge from altered nasal drainage. 

If you suspect that your horse may have osteoporosis, bone demineralisation or ‘Big Head’ from consuming oxalate-containing grasses, it is important to consult your veterinarian. 

One of the causes of poor bone development in young horses and decalcification or bone weakness in adult grazing horses and ponies is the increasing growth of C4-type tropical grasses in many warmer and coastal regions of Australia.  Tropical grasses, especially kikuyu, are spreading down the East Coast as the climate warms to sub-tropical conditions.

Oxalate chemicals are contained in the leaves of tropical and sub-tropical C4-type grasses and hays.  Oxalates are compounds that reduce the absorption of calcium during digestion and can lead to a deficiency in calcium uptake from the diet.

Even short periods of between four and six weeks of poor calcium intake can lead to skeletal weakness, and in the longer term, potential health issues including osteoporosis, shifting lameness, teeth and jaw problems, joint issues, altered movement, and in severe cases, ‘Big Head’.

Cal-XTRA is a specialised calcium supplement containing bone minerals including calcium, phosphorus and magnesium.  These minerals at supplied in a concentrated level, with high purity calcium making up 30% of the supplement and included as multiple, micro-refined forms.  The calcium in Cal-XTRA is highly absorbable to ensure efficient uptake and utilisation in horses grazing tropical and sub-tropical grasses.

Cal-XTRA is formulated to optimise the calcium to phosphorus ratio in horses, so it can also provide balanced bone minerals for all working and resting horses in a flexible and cost-effective supplement. 

One of the major technological innovations of Cal-XTRA is that it is scientifically formulated to protect calcium absorption in the presence of oxalates through a stable oil coating technology which shields calcium from oxalate binding.  This specialised micro-coating process helps calcium uptake to ensure bone strength and soundness, even when horses are grazing tropical grass pastures.  It also makes Cal-XTRA a dense and low dust powder!

Cal-XTRA also includes the important vitamins A and D3.  Hays and dry tropical pastures are low in the Vitamin A precursor ‘carotene’, especially once the green colour is lost, or bleached by rain or long-term storage. Vitamin A is necessary for calcium utilisation in the growth and maintenance of bone. 

Vitamin D3 is involved in the regulation of calcium absorption and its relationship with phosphorus in bone development and maintenance. Although grazing horses obtain adequate Vitamin D from sunlight synthesis in their skin, including an additional source of Vitamin D in Cal-XTRA helps ensure adequate availability in the small intestine to assist calcium uptake and regulation.

Finally, Cal-XTRA does not contain trace-minerals, such as zinc, iron, copper and selenium, which are included in some calcium supplements. This is because uptake of these trace-minerals is reduced in the presence of high calcium in a calcium supplement.  Cal-XTRA does not contain any fillers which would reduce the potency of the supplement.  All we add extra is a tasty vanilla flavour that horses love!  This flavour does not contain sugar so Cal-XTRA is safe for sugar sensitive horses and ponies. 

Rapid grass growth periods, for example in Spring and Summer, or when paddocks are irrigated or fertilised (especially with nitrogen and phosphate fertilisers), further increase oxalate production.  It is especially important to provide Cal-XTRA to horses grazing pastures with C4-type species under these conditions. 

Cal-XTRA has been formulated to provide different supplementation rates depending on the season, the workload and the pasture the horse is grazing.  For example, a full sized horse at rest in a grassy paddock needs 30 grams daily for general bone mineral maintenance, 60 grams when grazing tropical grasses during ‘slow’ growth periods, and 120 grams per day when grazing tropical pastures during ‘fast’ growth periods. 

Oxalate chemicals are contained in the leaves of tropical and sub-tropical C4-type grasses and hays.  Oxalates reduce the absorption of calcium during digestion and can lead to a deficiency in calcium uptake from the diet.

Grasses or hay that are high in oxalates include setaria, kikuyu, para, buffel, teff, pangola, couch grass and green panic.  They’re common in grazing areas of Queensland, the Northern Territory and increasingly in coastal regions of NSW and Victoria. Horses consuming predominately Teff hay or pangola hay are also at risk of ingesting high levels of oxalates. If you’ve identified high oxalate grass in your pasture, supplementation with Cal-XTRA is recommended to add calcium and bone minerals back into the diet, helping reduce the risk of bone problems.

Although calcium blocks and ‘loose licks’ are promoted as a source of calcium to offset oxalate binding, these forms of supplementation are a ‘hit or miss’ way of providing calcium.  Some horses acquire a taste for the block or lick, usually because it contains molasses as a sweetener, whilst other horses will not be interested and will not consume an adequate amount to correct the action of oxalates in reducing calcium absorption. 

Some ‘Big Head’ or bone supplements use chelated calcium bound to the amino acid methionine, but this compound releases in the small intestine before absorption (European Food Safety Authority (EFSA), 2009).  It may also oversupply sulfur-rich methionine to the diet, causing smelly or ‘acidic’ manure.  Kohnke’s Own has extensive experience with chelated minerals and we’ve found that there is no benefit to calcium chelation, it simply makes the supplement more expensive. 

Cal-XTRA is a higher potency and more palatable form of calcium which equine veterinarian and authority in horse nutrition, Dr. John Kohnke, has field trialled and researched extensively in cases of calcium deficiency and Big Head. 

Southern temperate C3 grasses and native grasses contain an inadequate amount of calcium to meet the needs of heavily pregnant mares in the last 3 months of pregnancy and growing foals up to 2 years of age.  Where a young horse is grazing Springtime lush pasture, the high water content of the grass will further reduce its already inadequate contribution of bone minerals to the diet. 

We recommend supplementing with Kohnke’s Own Cell-Grow, which has concentrated bone minerals balanced with trace-minerals and vitamins for optimum growth and development.  The nutrients in Cell-Grow have been linked to reducing the risk of developmental problems such as OCD, physitis and other limb defects.  

However, in a rapidly growing foal, an additional supplement of Cal-XTRA is useful if the diet is based on cereal grass hay or is low in high calcium legume hay such as lucerne or clover hay.  Cal-XTRA is an important additional and economical bone mineral supplement for rapidly growing horses under these conditions, but is especially recommended when breeding or growing horses are grazing tropical grass pastures which may lead to consumption of oxalate chemicals. 

Many studs and horse farms located in Queensland have regular problems with bone demineralisation as mares, stallions and young horses graze the oxalate containing grass species.  The Cal-XTRA label contains information and supplementation rates for all stages of breeding and growing horses.

Horse owners sometimes ask if Cal-XTRA can be made as a pellet, but due to the highly concentrated formulation, we cannot pellet it.  If you prefer a pelleted calcium supplement, Kohnke’s Own Cell-Osteo is suitable, although we recommend you contact our experienced Nutritional Advisors by email to info@kohnkesown.com or Freecall 1800 112 227 to find the correct dosage of Cell-Osteo for the respective tropical grass season.