Fatty acid composition of bovine teat canal keratin.

Keratin from 507 excised teats was pooled, separated into three samples, and analyzed for fatty acid composition of extracellular and intracellular lipids. Mean weight of keratin collected per teat canal was 8.97 mg. Extracellular lipids were recovered in petroleum ether. Intracellular lipids were extracted in chloroform: methanol (2:1, vol/vol) solution. Average keratin wet weight of extracellular and intracellular lipid fractions were 37.1 and 21.9 mg/g, respectively. Polar and nonpolar lipids were present in both fractions. Predominant fatty acids in extracellular and intracellular lipids were C16, C18:1, and C18. Extracellular lipids contained greater concentrations of C4 to C18:1 fatty acids than did intracellular lipids. Percent of total fatty acid weight comprised by each of C4, C10, C12 and C14 was also significantly greater in extracellular than intracellular fractions. Intracellular lipids contained a greater concentration and percent total fatty acid content comprised by C18:2 than extracellular lipids. Data suggest lipids accessible at the keratin interface are in part of milk fat origin.