Preliminary report on osteochondrosis in cattle in the north-western parts of South Africa

The pathology of vitamin D deficiency in domesticated animals: An evolutionary and comparative overview

Although vitamin D is critical to calcium/phosphorus homeostasis, bone formation and remodeling, there is evolution-based variation between species in vitamin D metabolism and susceptibility to rickets and osteomalacia. Most herbivores produce vitamin D₃ in response to sunlight, but dogs and cats have generally lost the ability as carnivore diets are rich in vitamin D. Nutritional deficiencies and/or poor exposure to sunlight can induce rickets in birds, swine, cattle and sheep, but horses are less susceptible as they have evolved a calcium homeostasis that is quite different than other animals. Adaptations to specific environments also affect disease incidence: llamas/alpacas out of their natural high altitude intense solar radiation environments are highly susceptible to vitamin D deficiency. The pathology of rickets/osteomalacia is similar across species, however fibrous osteodystrophy is more common and may also be present. Rickets/osteomalacia were likely more common in animals before the advent of commercial diets, but can be difficult to definitively diagnose especially in single archeological specimens. Consideration of species susceptibility, location - especially in terms of latitude, and any available information on diet, season of occurrence, husbandry practices or descriptions of affected animals can support the diagnosis of metabolic bone disease in animals.

Response of cattle with clinical osteochondrosis to mineral supplementation

Since 1982, farmers in the North West province and other parts of South Africa have noticed an increase in the incidence of lameness in cattle. Macro- and microscopical lesions of joints resembled osteochondrosis. Pre-trial data indicated that cattle with osteochondrotic lesions recovered almost completely when fed a supplement containing bio-available micro- and macrominerals of high quality. In the present trial, 43 clinically affected cattle of varying ages (1-5 years) and sexes were randomly divided into three groups. Each group was fed the same commercial supplement base with differing micro- and macromineral concentrations to determine the effect of mineral concentrations on the recovery from osteochondrosis. Both supplements 1 and 2 contained 25% of the recommended National Research Council (NRC) mineral values. Additional phosphate was added to supplement 2. Supplement 3, containing 80% of the NRC mineral values, was used as the control. Results from all three groups indicated no recovery from osteochondrosis. Urine pH of a small sample of the test cattle showed aciduria (pH < 6). Supplement analysis revealed addition of ammonium sulphate that contributed sulphate and nitrogen to the supplement. Supplementary dietary cation anion difference (DCAD) values were negative at -411 mEq/kg, -466 mEq/kg and -467 mEq/kg for supplements 1, 2 and 3, respectively, whereas the pre-trial supplement was calculated at +19.87 mEq/kg. It was hypothesised that feeding a low (negative) DCAD diet will predispose growing cattle to the development of osteochondrosis or exacerbate subclinical or clinical osteochondrosis in cattle.