Vitamin D function in sheep

Abstract

The incomplete nutrition of animals, including sheep, can lead to a disruption of homeostasis, reduced production, development of disease, and even animal death. Vitamin D refers to a group of closely related substances that possess antirachitic activity. This is the only vitamin that is not only taken into the organism by way of dietary origin (hay, food of animal origin in carnivores), but is also synthetised in the body (skin) with the help of sunlight. Typically, grazing sheep rarely need vitamin D supplements. This is because sheep can compensate for the lack of vitamin D in their food by synthesizing vitamin D in the skin if they are exposed to UVB radiation or sunlight. However, if sheep exposure to the sun is reduced by prolonged bad weather or indoor animal breeding, and when the vitamin D2 content of the diet is low, then the animal may have insufficient vitamin D consumption. In lambs, vitamin D deficiency is manifested by rickets, and in adult sheep by osteomalacia and hypocalcaemia. In sheep, this usually occurs in late pregnancy but has been observed in animals of all ages. Following the above, the aim of this review is to acquaint veterinarians with new knowledge about the roles and metabolism of vitamin D in sheep and its importance for the health and maintenance of productive abilities of the individual animal or herd.