Table 1.
Proportions of individual fatty acid species in milk samples collected at three stages of lactation
| Postnatal day 7 (n = 78) | PMA 32 weeks (n = 61) | PMA 40 weeks (n = 24) | ||
|---|---|---|---|---|
| Fatty acid | Median (25th–75th perc.) | Median (25 th –75 th perc.) | Median (25th–75th perc.) | |
| Branched‐chain FA (BCFA) | ||||
| 13‐methyltetradecanoic acid | iso‐15:0 | 0.02 (0.02–0.03) | 0.02 (0.02–0.03) | 0.03 (0.02–0.04) |
| 12‐methyltetradecanoic acid | anteiso‐15:0 | 0.04 (0.03–0.06) | 0.04 (0.03–0.06) | 0.05 (0.03–0.07) |
| 14‐methylhexadecanoic acid | iso‐16:0 | 0.04 (0.03–0.05) | 0.04 (0.03–0.05) | 0.05 (0.03–0.06) |
| 15‐methylheptadecanoic acid | iso‐17:0 | 0.07 (0.06–0.09) | 0.08 (0.06–0.10) | 0.08 (0.05–0.11) |
| 14‐methylheptadecanoic acid | anteiso‐17:0 | 0.07 (0.06–0.09) | 0.08 (0.06–0.09) | 0.09 (0.07–0.11) |
| ΣBCFA | 0.25 (0.19–0.32) | 0.27 (0.21–0.34) | 0.29 (0.16–0.41) | |
| Saturated FA (SFA) | ||||
| Lauric acid | 12:0 | 4.50 (3.19–5.98) | 4.61 (3.13–6.13) | 5.13 (3.36–5.85) |
| Tridecanoic acid | 13:0 | 0.02 (0.02–0.03)a , b | 0.02 (0.01–0.02) | 0.02 (0.01–0.02) |
| Myristic acid | 14:0 | 9.40 (7.54–11.25)a | 8.26 (6.69–9.92) | 9.25 (7.76–10.98) |
| Pentadecanoic acid | 15:0 | 0.28 (0.24–0.33) | 0.29 (0.22–0.34) | 0.29 (0.21–0.36) |
| Palmitic acid (PA) | 16:0 | 24.55 (22.62–26.34)a , b | 23.34 (20.41–25.15) | 24.45 (21.59–26.14) |
| Margaric acid | 17:0 | 0.25 (0.21–0.30) | 0.24 (0.21–0.29) | 0.26 (0.20–0.31) |
| Stearic acid (SA) | 18:0 | 6.04 (5.11–6.72) | 6.08 (5.29–7.07) | 6.34 (5.08–7.64) |
| Nonadecanoic acid | 19:0 | 0.01 (0.01–0.01)a , b | 0.01 (0.01–0.01) | 0.01 (0.01–0.02) |
| Arachidic acid (ArA) | 20:0 | 0.18 (0.15–0.20)b | 0.18 (0.15–0.20) | 0.15 (0.12–0.18) |
| Heneicosanoic acid | 21:0 | 0.00 (0.00–0.00)a | 0.00 (0.00–0.00) | 0.00 (0.00–0.00) |
| Behenic acid (BA) | 22:0 | 0.05 (0.04–0.06)b | 0.05 (0.04–0.07) | 0.04 (0.03–0.05) |
| Tricosanoic acid | 23:0 | 0.01 (0.01–0.01)a , b | 0.00 (0.00–0.01) | 0.00 (0.00–0.01) |
| Lignoceric acid (LigA) | 24:0 | 0.06 (0.05–0.08)a , b | 0.04 (0.03–0.05) | 0.03 (0.02–0.03) |
| ΣMCSFA (C12‐16) | 38.94 (36.22–43.12)a | 36.25 (33.31–38.82) | 38.94 (35.77–41.29) | |
| ΣLCSFA (≥C17) | 6.61 (5.68–7.41) | 6.72 (5.84–7.71) | 6.85 (5.44–8.34) | |
| ΣSFA | 46.14 (42.25–49.77)a | 43.52 (40.04–45.83) | 45.48 (42.77–48.73) | |
| Monounsaturated FA (MUFA) | ||||
| Myristoleic acid | 14:1n‐5 | 0.22 (0.17–0.28) | 0.21 (0.17–0.28) | 0.25 (0.20–0.29) |
| Palmitoleic acid | 16:1n‐7 | 1.73 (1.47–2.28) | 1.75 (1.42–2.21) | 1.64 (1.48–2.01) |
| Oleic acid (OA) | 18:1n‐9 | 36.15 (33.35–38.97)a | 38.47 (35.85–40.71) | 36.33 (33.15–38.11) |
| cis‐Vaccenic acid | 18:1n‐7 | 2.85 (2.57–3.13)a , b | 2.68 (2.39–2.90) | 2.36 (2.13–2.68) |
| Gondoic acid (GA) | 20:1n‐9 | 0.47 (0.39–0.55)a , b | 0.41 (0.36–0.46) | 0.33 (0.30–0.37) |
| Erucic acid (EA) | 22:1n‐9 | 0.09 (0.07–0.10)a , b | 0.06 (0.05–0.07) | 0.04 (0.04–0.05) |
| Nervonic acid (NA) | 24:1n‐9 | 0.09 (0.06–0.12)a , b | 0.03 (0.03–0.04) | 0.02 (0.02–0.03) |
| ΣMUFA | 41.78 (37.96–45.33)a | 43.90 (41.11–45.86) | 41.26 (37.88–43.37) | |
| Polyunsaturated FA n‐9 | ||||
| Mead acid | 20:3n‐9 | 0.01 (0.01–0.01) | 0.01 (0.00–0.01) | 0.01 (0.01–0.01) |
| Polyunsaturated FA n‐6 (PUFA n‐6) | ||||
| Linoleic acid (LA) | 18:2n‐6 | 8.33 (7.43–9.49)a , b | 10.08 (8.32–11.17) | 10.11 (8.27–12.07) |
| γ‐linolenic acid (GLA) | 18:3n‐6 | 0.04 (0.03–0.07)a , b | 0.05 (0.04–0.07) | 0.05 (0.04–0.06) |
| Eicosadienoic acid | 20:2n‐6 | 0.24 (0.21–0.30)a , b | 0.16 (0.13–0.19) | 0.14 (0.12–0.17) |
| Dihomo‐γ‐linolenic acid (DGLA) | 20:3n‐6 | 0.36 (0.27–0.47)a , b | 0.23 (0.18–0.26) | 0.17 (0.15–0.2) |
| Arachidonic acid | 20:4n‐6 | 0.34 (0.27–0.39)a , b | 0.23 (0.20–0.26) | 0.22 (0.19–0.24) |
| Docosadienoic acid | 22:2n‐6 | 0.03 (0.03–0.04)a , b | 0.01 (0.01–0.02) | 0.01 (0.01–0.01) |
| Adrenic acid (AdrA) | 22:4n‐6 | 0.14 (0.09–0.18)a , b | 0.06 (0.05–0.07) | 0.05 (0.05–0.06) |
| Docosapentaenoic acid (DPAn‐6) | 22:5n‐6 | 0.03 (0.02–0.04)a , b | 0.02 (0.01–0.02) | 0.02 (0.01–0.02) |
| ΣPUFAn‐6 | 9.44 (8.63–10.93)a | 10.80 (9.1–12.18) | 10.78 (8.54–12.79) | |
| ΣLCPUFA n‐6 (≥C20) | 1.15 (0.97–1.45)a , b | 0.71 (0.62–0.8) | 0.60 (0.56–0.69) | |
| Polyunsaturated FA n‐3 (PUFA n‐3) | ||||
| α‐linolenic acid (ALA) | 18:3n‐3 | 1.12 (0.85–1.33)a , b | 1.39 (1.12–1.88) | 1.35 (0.97–2.21) |
| Stearidonic acid (SDA) | 18:4n‐3 | 0.02 (0.01–0.02)a , b | 0.02 (0.01–0.03) | 0.02 (0.01–0.02) |
| Eicosatrienoic acid | 20:3n‐3 | 0.06 (0.05–0.08)a , b | 0.04 (0.03–0.05) | 0.03 (0.03–0.05) |
| Juniperonic acid (JA) | 20:4n‐3 | 0.08 (0.06–0.10)a , b | 0.06 (0.04–0.08) | 0.04 (0.04–0.05) |
| Timnodonic acid/eicosapentaenoic acid | 20:5n‐3 | 0.05 (0.03–0.06) | 0.05 (0.04–0.07) | 0.04 (0.04–0.07) |
| Docosapentaenoic acid (DPAn‐3) | 22:5n‐3 | 0.17 (0.13–0.22)a , b | 0.13 (0.10–0.16) | 0.13 (0.10–0.15) |
| Docosahexaenoic acid | 22:6n‐3 | 0.29 (0.24–0.38)a , b | 0.20 (0.15–0.27) | 0.15 (0.13–0.22) |
| ΣPUFA n‐3 | 1.79 (1.58–2.1)a | 1.91 (1.6–2.59) | 1.93 (1.44–2.59) | |
| ΣLCPUFA n‐3 (≥C20) | 0.67 (0.55–0.84)a , b | 0.48 (0.38–0.65) | 0.39 (0.35–0.56) | |
Data are expressed as the molar per cent (mol%) of all analysed fatty acids.
a
Significantly different between postnatal day 7 and PMA 32 weeks.
b
Significantly different between postnatal day 7 and PMA 40 weeks according to the Wilcoxon signed‐rank test (p < 0.05).