The economics of biotin supplementation in swine diets is often given much attention as regards vitamin supplementation formulations (i.e., vitamin premixes). The reason for this most likely is that biotin is thought to be the most expensive vitamin in swine diets. However, based on the requirements and recommended industry levels for biotin supplementation, biotin in swine diets costs less than other vitamins, such as choline and vitamin E. To this point, the nutritionist must consider the extreme variation of biotin content and bioavailability of feedstuffs used in swine diets, which makes them unreliable as a consistent source of biotin in the diet. Therefore, under practical commercial production conditions, criteria such as growth rate, feed conversion, reproductive efficiency and other parameters associated with biotin-responsive conditions should be considered when formulating swine diets.
Although swine and poultry showed clinical signs of deficiency under experimental conditions in the 1940s, for many years it was believed that supplemental biotin was not needed in swine and poultry diets because of the wide distribution of biotin in feedstuffs and the potential synthesis by the animals' intestinal microflora. In the late 1960s and early 1970s, interest in swine and poultry was rekindled when more field cases occurred than in the past. Also, since then well-controlled research has more clearly defined the occurrence of biotin deficiency and the values of supplementation in the practical swine ration. Interferences with the biosynthesis of biotin by intestinal bacteria can individually or collectively lead to a biotin deficiency. These interferences can be in the form of therapeutic administration of antibacterial agents and modern housing systems limiting animals' access to feces. Additionally, biotin deficiencies are now more prevalent because of restricted use of biotin-rich feedstuffs and limited bioavailability of biotin in some grains (e.g., wheat, barley, sorghum) and in some animal protein sources (e.g., meat meal, poultry by-product meal). Biotin antagonists (e.g., molds and feed rancidity) and improved plant genetic characteristics for greater crop production have also contributed to limiting biotin utilization by swine. Cunha (1984) has summarized the possible reasons for more frequent occurrence of biotin deficiencies in swine (Table 1).