CHANGES IN COMPOSITION OF FATTY-ACIDS OF THE FAT IN GOAT MILK DURING LACTATION

In the milk fat collected of 20 animals, the white short-woolled polle d breed, the representation of fatty acids was studied ten times from day 1 to day 255 of lactation by gas chromatography. 22 fatty acids in total were determined with the number of carbons 8 and more. Majority fatty acids, whose average content exceeded 1 %, are presented in tab les together with basic statistical data. In minority fatty acids mini mum and maximum values are given in brackets as found during the lacta tion. The following fatty acids were identified: C8:0 (Tab. I), C8:1 ( 0.10 -2.70 %), C9:0 (Tab. II), C9:1 (0.00 - 6.60 %), C10:0 (Tab. III), C10:0izo (0.00 - 8.78 %), C11:0 (0.00 - 1.01 %), C12.0 (Tab. IV), C12 .1 (0.00 - 1.02 C13:0 (0.00 - 0.34 %), C14:0 (Tab. V), C14:1 (0.00 - 1 .07 %), C15:0 (0.10 - 1.71 %), C15:1 (0.00 - 1.78 %), C16:0 (Tab. VI), C16:1 (Tab. VII), C17:0 (0.06 - 2.29 %), C17:1 (0.00 - 2.29 %), C18:0 (Tab. VIII), C18:1 (Tab. IX), C18:2 (Tab. X) and C18:3 (0.00 - 0.62 % ). The following basic changes in composition of fatty acids were foun d during lactation: After parturition when deposited fat starts to be mobilized, a high content of fatty acids C18:0 (Tab. VM) and C,8:1 (Ta b. IX) and relatively low content C16:0 (Tab. VI) was recorded in colo stral fat. A high proportion of fatty acids C14:0 (Tab. V) and C16:1 ( Tab. VII) after parturition is probably of the same origin. In further period relative representation of fatty acids with 18 C is falling an d the proportion of the fatty acid C16:0 (Tab. VI) is rising. In the p eriod of green feeding fatty acids with 18 C are synthetized through r uminal microflora and their relative contents am increasing, in partic ular that of C18:0 (Tab. VIII), C18:1 (Tab. IX) and C18:3, but the rep resentation of unsaturated fatty acids C14:1 and C16:1 (Tab. VII) is i ncreasing too. The representation of fatty acids with 8, 9 and 10 carb ons is fluctuating relatively little during lactation and without depe ndence on the stage of lactation arid nutrition. The variability of ma jority fatty acid content during lactation is lower compared with the literary data. Relatively higher representation of C9:0 acid (Tab. II) was found in goat milk fat. These differences were probably caused by different nutrition. Goats are usually on the pasture during summer a nd the feeding ration is composed practically exclusively of green for age. In our studies goats were reared in the stall and the summer, eve ntually autumn feeding rations contained except green forage and hay a s well, ground barley and oat, and mineral and vitamin additions. In t he first days after parturition the total fat content (Tab. XI) is hig hest and is falling to day 110 of lactation, to the end of studies it exhibits permanent increase. In dependence on the total fat content in goat milk, contents of some fatty acids are significantly changing du ring lactation. There were positive relationships to the total fat con tents for C16:1 (r = +0.197), C18:0 (r = +0.202) and C18?1 (r = +0.305 ), negative relationships to the total fat content were found for C8:1 (r -0.209, C10:0 (r = -0.208) and for C16:0 (r = -0.262).