OCCURRENCE OF CONJUGATED CIS-9,TRANS-11-OCTADECADIENOIC ACID IN BOVINE-MILK - EFFECTS OF FEED AND DIETARY REGIMEN

Twenty-eight lactating cows were used to study the effects of differen t diets and different dietary regimens on the variation of cis-9,trans -11-octadecadienoic acid in milk. Cows were divided into three groups and assigned to dietary treatments differing in the ratio of forage to concentrate. The control group was fed a diet with an average ratio o f forage to concentrate of 50:50. The two trial groups were fed a tria l diet either in restricted or nonrestricted amounts. Variation of cis -9,trans-11-octadecadienoic acid in milk was substantial (2.5 to 17.7 mg/g of fat). Cows fed restricted amounts of the trial diet, which con tained a lower forage to concentrate ratio than did the control diet, exhibited, on average, the highest concentration (11.28 mg/g of fat). For cows fed for ad libitum consumption, the trial diet did not differ significantly from the control diet (6.6 vs. 5.0 mg/g of fat). The co ncentration of cis-9,trans-11-octadecadienoic acid and trans-11-C-18:1 was positively correlated. Therefore, conjugated linoleic acid in bov ine milk, if considered to be beneficial, could be increased through a suitable dietary regimen.