3 Maataloustieteellinen Aikakauskirja Vol. 56: 33—38, 1984 The effect of feed grains of the fatty acid composition of milk fat VEIKKO KANKARE and VEIJO ANTILA State Institute for Dairy Research SF-31600 JOKIOINEN, Finland Abstract. Finnish milk fat is relatively hard, particularly during the indoor feeding pe- riod. For reasons of both dairy technology and nutrition, however, it would be advantageous to obtain a softer fat. On the basis of the initial experiments, it would appear that the feed concentrates used, particularly their grain component, have a effect on the composition of milk fat. For this reasons, a comparative study of the effect of oats and barley on the fatty acid composition of milk fat was being carried out in the winter of 1983. In a comparison of barley and oats, it was observed that the iodine value of the milk in the experimental group which was fed barley was 5.1 units lower than that of the group fed oats. By itself, the feeding of barley alone was also responsible for a sharp decrease in iodine values when compared to the results obtained during the pre-experimental phase during which the cows were fed barley and oats in a ratio of 1:1. The softening effect of oats on milk fat appeared to be slight when the results from the experimental phase were compared to those of the pre-experimental phase. In a comparison of the fatty acid composition of milk fat in samples from the barley and oats groups, it was found that the greatest differences were in the amounts of palmitic acid (C, 6) and oleic acid (C 18;l) present. The amount of palmitic acid in the milk fat of the barley group was 36.6 %, and in that of the oats group 30.2 %. The corresponding amounts of oleic acid were 14.7 % and 22.1 %. On the basis of this study, it is recommended that oats should be preferred in making up feed concentrate mixtures for milk cows. introduction Finnish milk fat is relatively hard, par- ticularly during the indoor feeding period. Despite the increased use of silage, the iodine values of milk fat have remained at precisely the same levels as prevailed in the 1960 s and 1970 s during the indoor feeding period. For reasons of both dairy technology and nutri- tion, however, it would be advantageous to obtain a softer fat. The initial experiments carried out to achieve this end have shown that a few farms are already capable of pro- ducing fat during the winter that has iodine Index words: feed grain, milk fat, fatty acid composition, iodine value 33 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=22RAa2E0E7p5v0Dn.dGmUzWpjFAzKPALM4VTNaA.5hoUdUei4HOBpkrDZBtVtIC_YdqibyDBaeS25Kcn9DWnzlmJcwMmwEifngrGlTRdJpkCw5k0xMKTaoYJQ5wsyvBoXa7z_YE2f0rhnzexgjhr2kQE5nKc9_oz8aduFW8trDIQMCNCYMFjJiNxd1Lw2CM847QgLwy5BkGs6Z5O7MuqqKXIDuOUZbRiiNet values on a par with those obtained during the summer. On the basis of these experi- ments, it would appear that the feed con- centrates used, particularly their grain com- ponent, have a great effect on the composi- tion of milk fat. For this reason, a study car- ried out in the late winter of 1983 to deter- mine the effect of barley and oats on the composition of milk fat. Methods Experimental Feeding Scheme A comparative study of silage and feed concentrates was being carried out at the In- stitute of Animal Husbandry of the Agricul- tural Research Centre in the late winter of 1983, from which milk samples were obtain- ed for the present study of the effect of oats and barley on milk fat composition. Con- centrates were fed to the cows at a rate of 0.3 kg/kg 4 % milk. During the pre-experimental phase, oats and barley were given to the cows in the same amounts, i.e. in a ration of 1:1. The amounts fed the different groups during the experimental phase are shown in Table 1. The post-experimental phase connected to the present study was of necessity carried out during the period of outdoor grazing. The experimental phase lasted c. 10 weeks. For the fat analyses, the relative milk sam- ples were taken once a week the combined milk of four consecutive milkings. lodine values were determined each week, and the fatty acid composition determined once during the pre-experimental phase and three times during the experimental phase. Analyses Fat was separated from milk by centrifug- ing and churning. The iodine values were determined using the Hanus medod (see Kaufmann 1958). Methyl esters were prepared from the fat being studied, using the method described by Christopherson and Glass (1969), Glass (1971), Christie (1973), and modified by Antila and Kankare (1983). The composition of the fatty acids was determined in a Perkin-Elmer SIGMA 3 gas chromatograph, using an FFAP vitreous sili- ca capillary column with a length of 25 m and a 0 of 0.20 mm. The initial temperature of the column was 70°C, and the final tem- perature 220°C. The rate of temperature rise was 7°C/min. The temperature of the in- jector was 250°C and that of the detector 280°C. The detector was a flame ionisation detector, and hydrogen was the carrying gas. Table I. Scheme of Feeding Experiments Group No. of Cows Silage Concentrates Hay ad libitum controlled weekly kg/day 1 6 Silo 1 barley 0.3 kg/kg 4 % milk 1 12 2 6 » oats 0.3 kg/kg 4 % milk 1 3 6 Silo 2 barley 0.3 kg/kg 4 % milk 1 12 4 6 » oats 0.3 kg/kg 4 % milk 1 5 6 Silo 3 barley 0.3 kg/kg 4 % milk 1 12 6 6 » oats 0.3 kg/kg 4 % milk 1 7 6 Silo 4 barley 0.3 kg/kg 4 % milk 1 12 8 6 » oats 0.3 kg/kg 4 % milk 1 34 The integrator was a Japanese Shimadzu Ltd. data processor, model C-RIB. The fatty acids were identified utilizing standard samples (Nu-Chek-Prep 17 A, 19 A, GLC-73 and U-72-M, as well as Supelco PUFA 2), hydrated milk fat (iodine value < 0.1), and the literature (Renner & Melcher 1976, 1978 a and b, Anon. 1981). The numbering of the fatty acids in the tables uses the same system as that based on the so-called »model chromatogram», which Kankare (1983) and Antila & Kankare (1983) have used earlier. Results and discussion lodine values Figure 1. shows the iodine values obtained and the changes which occurred in these values at different stages of the experiment. Feeding of barley alone caused an im- mediate, sharp drop in the iodine value. Feeding of pats caused a rise in the iodine value in three out of four cases. This rise was, however, not great when compared to the values obtained during feeding Of the barley-oats mixture. Because of changes in the lactation period, all the iodine values dropped during the experimental phase. The average iodine value for the oats groups during the experimental phase was 31.8, and that for the barley groups was 26.7. On this basis, it may be stated that feeding oats has a very strong hardening effect on milk fat. In the post-experimental phase, during which the cows were moved to pasture graz- ing, an exceptionally sharp rise in the iodine values occurred. Fatty acid composition The fatty acid composition of the milk samples from the experimental groups during the pre-experimental and the experimental phases are given as average values in Tables 2 and 3. The feeding of barley clearly increased the FIGURE 1. lODINE VALUES OF MILK FAT 35 Table 2. Saturated fatty acids present in milk fat from samples taken during pre-experimental and experimental phases, % Fatty Carbon Chain Pre-experimental Phase Experimental Phase cl Groups Groups Barley Groups Oats Groups No - 1,3,5*7 2,4, 6&8 1,3, 5&7 2,4, 6 & 7 1 C„ 4.35 4.13 3.63 3.80 2 C, 0.02 0.02 0.03 0.02 3 C 6 2.84 2.75 2.70 2.56 4 C 7 0.01 0.02 0.03 0.03 5 C 8 1.70 1.63 1.72 1.53 6 C 9 0.02 0.02 0.04 0.02 7 C,„ 3.53 3.43 4.16 3.34 9 C M 0.03 0.03 0.07 0.04 10 C, 2 3.58 3.44 4.62 3.46 12 C, 3 iso 0.11 0.10 0.14 0.20 13 Cl 3 0.07 0.06 0.10 0.07 14 C, 4 iso 0.09 0.08 0.09 0.07 15 Cl 4 11.95 11.79 13.36 11.89 17 C ls iso 0.22 0.22 0.23 0.21 18 C,5 anteiso 0.35 0.33 0.33 0.32 19 C,5 0.69 0.68 0.97 0.77 22 C,6 iso 0.23 0.25 0.20 0.20 23 C l 6 anteiso 0.05 0.05 0.04 0.05 24 C,6 30.06 29.84 36.58 30.21 29 C„ iso 0.38 0.37 0.39 0.34 30 C„ anteiso 0.33 0.34 0.29 0.29 31 C„ 0.67 0.68 0.65 0.59 34 C„ iso 0.05 0.05 0.04 0.04 36 C„ 10.83 11.08 7.49 10.99 44 C„ 0.06 0.06 0.06 0.05 49 C 2O 0.14 0.15 0.15 0.15 72.36 71.6 78.11 71.24 amout of saturated fatty acids. The greatest differences between the feeding of barley and oats were observed, on the one hand, in the amounts of palmitic acid (C l6) present, 36.6 °Jo in the barley group and 30.2 % in the oats group; and on the other hand in the amounts of oleic acid (C 18:1 , No. 37), 14.7 % in the barley and 22.1 °7o in the oats group. 36 Table 3. Unsaturated fatty acids present in milk fat from samples taken during the pre-experimental and experi- mental phases, % Fatty Carbon Chain Pre-experimental Phase Experimental Phase Groups Groups Barley Groups Oats Groups No - 1,3, 5&7 2,4, 6&8 1,3, 5 & 7 2,4, 6 & 8 8 C,*, 0.35 0.35 0.41 0.35 11 C|,., 0.08 0.08 0.11 0.08 16 C, 4:1 0.91 0.89 1.12 0.% 20 Cls: , 0.03 0.03 0.04 0.03 21 C|J;, 0.03 0.03 0.03 0.03 21 a C,j., 0.02 0.02 0.03 0.02 25 C,6:l 0.11 0.09 0.11 0.09 26 C,„i 1.30 1.30 1.47 1.30 27 C lfc| 0.05 0.04 0.04 0.02 28 C,6:l 0.02 0.02 0.03 0.02 32 C,T:| 0.23 0.25 0.24 0.25 37 C„:i 20.93 21.38 14.66 22.1 38 e», 0.16 0.16 0.26 0.25 39 C,fc, 0.14 0.14 0.17 0.18 40 Clli:l 0.30 0.31 0.29 0.35 41 Cl8:2 1.18 1.27 1.27 1.19 42 C„.2 0.30 0.29 0.23 0.22 43 C 18:2 0.03 0.03 0.01 47 C,,., 0.46 0.45 0.39 0.44 45 C„ :J 0.07 0.07 0.08 0.08 46 C„ :3 0.54 0.55 0.56 0.47 48 Clg:4 0.04 0.06 0.08 0.09 50 C», 0.17 0.13 0.11 0.15 51 Cx.2 0.02 0.05 0.03 0.04 52 e»:, 0.02 0.03 0.03 53 C M:4 0.03 0.03 0.04 0.03 55 C20;5 0.04 0.04 0.04 0.04 27.54 28.04 21.87 28.7 References Anon. 1981. Identifikation of minor fedtsyrer i maelke- fedt. Statens Forsogsmejcri. Journ. nr. 2300. 34 p. Antila, V. & Kankare, V. 1983. The fatty acid composi- tion of milk lipids. Milchwissenschaft 38: 478—481. Christopherson, S.W. & Glass, R.L. 1969. Preparation of milk fat methyl esters byalcoholysis in an essential- ly nonalcoholic solution. J. Dairy Sci 52: 1289—1290. Christie, W.W. 1973. Lipid analysis. Pergamon Press, p. 92. Oxford. Glass, R.L. 1971. Alcoholysis saponification and the preparation of fatty acid methyl esters. Lipids 6: 919—925. Kankare, V. 1983. Uusia havaintoja maidon lipidikoos- tumuksesta. Meijeritietedlinen Aikakauskirja XLI (n:o 1) 58-T-65. Kaufmann, H.P. 1958. Analyse der Fette und Fettpro- dukte. I. 1104 p. Berlin, Göttingen, Heidelberg. Renner, E. & Melcher, F. 1976. Untersuchunge iiber Minorfettsäuren des Milchfettes. 2. Minorfettsäuren in Humanmilch. Milchwissenschaft 31: 193—199. Renner,E. & Melcher.F. 1978 a. Untersuchungen iiber Minorfettsäuren des Milchfettes. 3. Gesättigte Minor- fettsäuren. Milchwissenschaft 33: 281—285. Renner, E. & Melcher.F. 1978 b. Untersuchungen iiber Minorfettsäuren des Milchfettes. 4. Ungesättigte Minor- fettsäuren Milchwissenschaft 33: 489—492. Ms received January 27, 1984 37 SELOSTUS Rehuviljan vaikutus maitorasvan rasvahappokoostumukseen Veikko Kankare ja Veijo Antila Valtion maitotalouden tutkimuslaitos Suomalainen maitorasva on erityisesti sisäruokinta- kaudella varsin kovaa. Huolimatta lisääntyneestä säilö- rehun käytöstä rasvan kovuutta kuvaavat jodiluvut ovat pysyneet sisäruokintakaudella täysin samalla tasolla kuin 1960- ja 1970-luvuilla. Meijeriteknologisista ja myös ravitsemuksellisista syistä olisi kuitenkin edullista saada muutetuksi rasvaa pehmeämpään suuntaan. Alustavat kokeet osoittivat, että syötetyllä rehuviljal- la onvaikutusta maitorasvan koostumukseen. Siksi Val- tion maitotalouden tutkimuslaitos selvitti Maatalouden tutkimuskeskuksen kotieläinhoidon tutkimusosaston järjestämänsäilö- ja väkirehuja vertailevan tutkimuksen yhteydessä ohran ja kauran vaikutuksia maitorasvan rasvahappokoostumukseen. Koekauden aikana puolet 48 koelehmästä sai rehuviljana pelkästään ohraa ja puo- let pelkästään kauraa. Selvityksessä todettiin rehuviljan vaikuttavan voi- makkaasti maitorasvan koostumukseen. Ohra kovetti selvästi tuotettuarasvaa. Ohraa syöneiden ryhmien mai- don rasvan jodiluku oli 5,1 yksikköäalempi kuin kauraa syöneiden ryhmien. Pelkän ohran syöttö alensi myös jo- dilukuja voimakkaasti verrattuna esikauden tuloksiin, jolloin lehmille syötettiin ohraa ja kauraa suhteessa 1:1. Kauran maitorasvaa pehmentävä vaikutus jää vähäisek- si, kun koekauden tuloksia verrattiin esikauden tulok- siin. Verrattaessa ohra- ja kauraryhmien rasvahappokoos- tumuksia toisiinsa, todettiin suurimmat erot palmitiini- hapon, C| 6 , ja öljyhapon, C lg:l määrissä. Palmitiini- happoa ohraryhmän maitorasvassa oli 36,6 % jakaura- ryhmän maitorasvassa 30,2 %. Vastaavat öljyhapon määrät olivat 14,7 % ja 22,1 °/o. Selvityksen mukaan kauraa tulisi suosia lypsylehmien väkirehuseoksissa. 38