Calcium deficiency (hypocalcicosis)
Calcium deficiency or hypocalciosis is a sporadic condition occurring in a particular group of animals causing osteodystrophy.
Aetiology: Calcium deficiency may be primary or secondary. Primary deficiency due to lack of calcium in diet is not common. Secondary deficiency is associated with marginal calcium intake and some conditioned factors mainly the excess intake of phosphorous. Artificial diets containing cereal or grass hays, which contain little calcium and grains with high phosphorous content, may be associated with secondary calcium deficiency. Young growing animals and adult pregnant or lactating animals are on high calcium demand and are likely to suffer from hypocalcicosis if they do not get adequate calcium and balanced calcium: phosphorus ratio in the diet.
Clinical findings: Poor growth and defective teeth development are the prominent signs in young animals. Maldevelopment of teeth is characterized by gum deformity, poor development of incisors, delayed eruption and abnormal wear of permanent teeth due to defective development of dentine and enamel. Lactating ewes and lambs show profound hypocalcaemia. Fasting and exercise precipitate tetany in lactating ewes. Inappetence, stiffness, lameness, tendency of fracture of long bones, poor milk yield and difficult parturition are other sings of calcium deficiency. Secondary calcium deficiency is one of the causative factors for specific disease syndromes such as rickets, osteomalacia, osteodystrophia fibrosa of horse and pigs, and degenerative arthropathy of cattle.
Diagnosis: Specific clinical signs supported with data on serum and dietary levels of calcium and phosphorous and radiographic examination of bones are useful diagnostic tools of calcium deficiency. Dental lesions in calcium deficiency and fluorosis in sheep resemble closely and estimation of fluoride in teeth or bones or in urine is required for differential diagnosis. Bone histology, analysis of bone ash and response to dietary supplementation with calcium are also useful in confirming diagnosis of calcium deficiency.
Treatment and Prevention: Parenteral administration of calcium salts is advised for treatment of animals showing tetany. Dietary correction of calcium and phosphorous levels is necessary to overcome calcium deficiency.Adequate calcium and vitamin D in the diet, and reduction of excessive intake of phosphorous are vital for prevention of calcium deficiency. Depending on their body weight daily requirement of growing dairy cattle (heifer) is 9-26 g calcium, 7-20 g phosphorous and 300 IU vitamin D per kg dry matter. Mature lactating cows need 17-34 g calcium, 13-26 g phosphorous and 300 IU vitamin D per kg dry matter in their diet for maintenance. For each kg of milk produced, 2-3 g calcium, and 1.7-2.4 g phosphorous are added to the daily maintenance requirement. The optimum calcium:phosphorous ratio ranges within 2:1 to 1:1. Better absorption of calcium in cattle occurs at 2:1 ratio. Calcium: phosphorous ratio of 2-2.5:1 is recommended to reduce chances of hypocalcaemia without risk of urolithiasis in sheep.