Development of a system for clinical evaluation of the biotin status of sows.

Sixteen test gilts were fed an egg white-fortified practical diet and four control gilts an egg white-free diet over a two-parity period in order to monitor changes in the serum biotin levels as induced biotin deficiency progressed. Gilts were individually housed in metal crates with slatted floors. Serum biotin (ng/L) of test animals declined from 1490 (initially) to 610 (month 3), remained stable (months 4-8) and thereafter approached 400, 135 and 30 after months 9, 13 and 15, respectively. Early clinical symptoms, i.e. lesions (on the feet, legs and skin), hoof cracks, hair loss and dry skin, were first observed after six months and became progressively more pronounced with time. After nine months, the induced symptoms resembled those characteristic of biotin deficiency. In contrast, serum biotin remained high in the control animals which did not develop symptoms. The data are interpreted to mean that serum biotin might be used as a sensitive index of biotin deficiency development in sows. On the basis of these observations, a system is proposed for evaluation of the sow's biotin status. Adequate biotin may be indicated by serum biotin level (ng/L) > 700; marginal, > 600 < 700; inadequate, > 400 < 600; and deficient, < 400. Alternatively, several concurrent clinical symptoms (i.e. alopecia, hoof cracks and lesions on the feet, legs and skin) may aid in the diagnosis of inadequate biotin status of sow herds reared under field conditions.