Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS

1 st WorkshopXIII International Feed Technology SymposiumPOSSIBILITY TO MODIFY THE CONTENT OF CONJUGATEDLINOLEIC ACID IN MILK FAT FROM COWS' MILK BYNUTRITIONFrida Bauman 1 , Nurgin Memiši 2 , Goran Grubić 3 , Nenad Đorđević 31 INPAK – Gospodara Vucića 145 – Beograd, Serbia2 AD Mlekara – Subotica, Tolminska 10, Serbia3 Institute of Animal Husbandry, Agricultural Faculty Zemun, SerbiaABSTRACTModification of milk fat content by changing the regime of nutrition is not a completelynew concept. The intensive development of the dairy industry, as well as the markettrend increasingly targeted at using "health foods" are moving in the direction of findingways to lower high contents of saturated fatty acids and cholesterol in milk, and increasethe level of nutritionally valuable substances. Since variations milk quantity andcomposition are dominantly conditioned by hereditary factors (55%), the remainingvariation (45%) is conditioned by paragenetic factors, among which nutrition is by allmeans the most important. Fat predominantly consists of triglycerides containing over200 different fatty acids. Fatty acids can have short (C 4 – C 10 ), medium (C 12 – C 16 ) andlong chain fatty acids (C 18 ) on the carbon atom. Short and medium chain fatty acidsaccount for 30% of milk fat. Long chain fatty acids originate from meals and dependingon the type of meal, account for 40 to 60% of milk fat. Milk fat contains numerousanticancerogenic substances among which conjugated linoleic acid is the mostimportant, and its content in milk can significantly be changed via nutrition, i.e. byutilizing certain feeds. In addition, the content of conjugated linoleic acid in milk fatdepends to a large extent on seasonal variations, as well as on existing individualvariations in animals fed the same rations, and the manner and system of cow nutrition,i.e. the share of individual feeds in the ration.Key words: nutrition, food supplements, milk fat, conjugated linoleic acid, fatty acidsINTRODUCTIONIn addition to a significant influence on quantity, nutrition can also influence milkquality, even though to a limited extent. Cows can not achieve their highest productionor its stability during lactation, without daily adequate and balanced nutrition (29, 28,24). Milk fat is the richest source of conjugated linoleic acid. Conjugated linoleic acid(CLA) is a common name for position and geometric isomers of octadecadienoic acidresulting as intermediary products in the process of hydrogenation of linoleic acid in therumen of ruminants, and to date 9 different compounds were identified in commercialproducts (30,36). During the last 15 years, two CLA isomers, cis9, trans11 – isomer andtrans 10, cis12 – isomer, attract considerable attention of scientists (30). There is dataindicating that these isomeric fatty acids have numerous physiological effects, ananticancerogenic action, antiaterogenic, and immunomodulatory action on experimental244