Effects of duodenal infusions of palmitic, stearic, or oleic acids on milkcomposition and physical properties of butter

Four dairy cows fitted with a duodenal cannula were used in a 4 x 4 Latin s quare design to investigate the effects of daily duodenal infusion of 500 g of fatty acids (containing mainly C-16:0, C-18:0, or cis-C-18:1) on fecal concentrations of fatty acids, fatty acid profiles of milk fat, and solid f at content of butter. Fecal concentrations of C16:0 and especially of C-18: 0 were increased by duodenal infusion. Infusion with C-16:0 increased the p roportion of C-16:0 in milk fat and delayed softening of butter when the te mperature rose. infusion with C-18:0 resulted only in a slight increase of C-18:0 proportion in milk fat and did not significantly affect solid fat in butter between -10 and 30 degrees C. With the infusion of cis-C-18:1, the proportion of cis-C-18:1 in milk fat was more than twice that of control, t o the detriment of C-16:0. Butter contained low proportion of solid fat, ev en at low temperatures. Increasing C-16:0 or Cis-C-18:1 in milk fatty acid via duodenal infusion can be used to study their specific effects on butter characteristics, but, because of a low transfer from infusion to milk, thi s method is less efficient with C-18:9.