Vitamin D for Beef Cattle
It can be assumed that beef cattle receive sufficient vitamin D from exposure to direct sunlight or from sun-cured feedstuffs.
In exposure to sunlight, the ultra violet rays of sunlight convert 7-dehydrocholestrol contained in the skin to active vitamin D.
In the case of animals covered with hair or fur, oil from the skin – and that which gets onto the hair or fur - is radiated by the sunlight, and as such animals lick themselves or each day they obtain vitamin D.
Since vitamin D plays a role in the metabolism of calcium and phosphorus, one must postulate that the principal function of vitamin D is involved intimately in the utilization of calcium and phosphorus.
Vitamin D is critical for normal adsorption of calcium and phosphorus from the gut.
The body has some vitamin D storage capacity, mainly in the liver an to a limited extent, in the lungs and kidneys.
Deficiency of vitamin D in growing animals results ultimately in external symptoms characterized by deformed bones and excess deposit of cartilage in the usual areas of bone growth.
The blood level of calcium and /phosphorus is lowered but the level of phosphate is increased.
There is widening of the epiphyseal junction in severe or prolonged vitamin D deficiency and the tension of the muscles will cause a bending and twisting of the long bones to give the characteristic deformity of the bone.
There is enlargements at the ends of the bones due to the deposit of excess cartilage, giving the characteristic “beading” effect along the sternum at the pint of attachment o f the rib bones.
Rickets is fairly common in calves and is characterized by decreased growth, stiffness, enlarged joints, and arching of the back.
Vitamin D for Beef Cattle
