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Variation in fatty acid composition of ewes' colostrum and mature milk fat
International Dairy Journal 20 (2010) 637e641
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International Dairy Journal journal homepage: www.elsevier.com/locate/idairyj
Short communication
Variation in fatty acid composition of ewes' colostrum and mature milk fat Eva Pavlíková a, Jaroslav Blasko a, Renáta Górová a, Gabriela Addová a, Róbert Kubinec a, *, Milan Margetín b, Ladislav Soják a a b
Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovak Republic Animal Production Research Centre Nitra, Hlohovecká 2, SK-949 92 Luzianky, Slovak Republic
a r t i c l e i n f o
a b s t r a c t
Article history: Received 15 January 2010 Received in revised form 15 February 2010 Accepted 17 February 2010
Temporal content variations of approximately 70 C4eC24 fatty acids (FA) in colostrum and milk of ewes consuming winter diet were determined by gas chromatography. The content of monounsaturated, polyunsaturated and straight-chain saturated FA 14:0e16:0 in colostrum was higher whereas the content of 4:0e12:0, 18:0 and branched-chain saturated FA 15:0e17:0 was lower than that in mature milk. The effect of ewe breed on the FA profiles was not significant. The composition of FA changed most significantly 1e2 days after lambing in agreement with the time schedule of colostrum formation. Nevertheless, the content of FA further successively changed up to approximately the 6th day of lactation, whereas further changes up to the 60th day of lactation were smaller. This is consistent with the recommendation that ewes' milk is suitable for human consumption after six-to-eight days of lactation. The higher contents of palmitic and myristic acids in colostrum compared with mature milk suggest that FA composition in colostrum matches the changing needs of the growing lambs. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction Colostrum is a secretion from the mammary gland formed just before parturition and in the first 24e48 h after lambing, and it changes to mature milk subsequently. The production and composition of colostrum depends on nutrition in late gestation and genetic and physiological status of ewes. The colostrum contents of fats, proteins, lactose, and minerals vary with time after the birth most significantly within 24 h after parturition. The milk fat in colostrum is very important means to deliver some of its beneficial biologically active substances. Previous studies were focused on time-dependent changes in the contents of organic and inorganic components in ewes' colostrum. In the study of changes in colostrum and ewes' (Würtemberg breed) milk composition, Antunovi c, Steiner, Sen ci c, Mandi c, and Klapec (2001) found the highest milk fat content on the 2nd day of lactation followed by a decrease on the 10th and 30th day of lactation, and an increase on the 60th day of lactation in the winter as well as in the summer feeding season. To determine the exact colostrum producing period in Awassi ewes, Keskin, Güler, Gül, and Biçer (2007) studied the daily changes in milk fat contents for ten days after parturition. The authors found the highest fat content (w10%) on the first day postpartum, while that on the 10th day
* Corresponding author. Tel.: þ421 2 60296 330; fax: þ421 2 60296 690. E-mail address: [email protected] (R. Kubinec). 0958-6946/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.idairyj.2010.02.008
decreased to w7%. No information is available on the variation of detailed fatty acid (FA) composition in ewes' colostrum during the first days after parturition. This study was aimed at determining changes in fatty acid composition in milk during the transition from colostrum to mature milk of ewes receiving a winter diet during lamb suckling period using gas chromatographic analysis. The differences in the content of individual straight-chain saturated (SSFA), branch-chain saturated (BSFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in colostrum and mature ewes' milk were evaluated.
2. Materials and methods 2.1. Ewe breeds and feeding regimes Investigations were carried out at the experimental ewes' farm of Animal Production Research Centre in Tren cianska Teplá, Slovak Republic. The FA contents of milk fat of three dairy ewes' breeds (5 Tsigai, 5 improved Valachian and 5 Lacaune) were analysed as bulk samples daily for ten days after lambing and further at days 30 and 60. Investigated Slovak herds Tsigai and improved Valachian ewes have a higher content of dry matter and basic milk components fats and proteins in their milk (Table 1) than ewes' breeds with higher milk production, i.e., East-Frisian, Awassi and Lacaune.
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Table 1 Average content of basic components of Tsigai and improved Valachian ewes' milk (g 100 g1). Breed
Number of analysed milk samples
Dry matter
Fat
Protein
Lactose
Tsigai Improved Valachian
47 206 90 001
19.9 19.3
8.1 7.7
6.0 5.8
4.9 4.9
2.2. Fatty acid and statistical analyses The FA content of ewes' milk fat samples was gas chromatographically analysed under conditions published before (Ostrovský et al., 2009). Statistical data analysis was performed from three parallel determinations of each milk sample. A one-way ANOVA was used to evaluate the differences between the FA composition during lactation period being a dependent variable and lactation day as an independent variable. Significant differences were considered at the level P < 0.05.
3. Results and discussion Gas chromatographic analyses of FA samples from milk of individual ewes of Tsigai, improved Valachian and Lacaune breeds showed that the differences in the average individual fatty acids content of ewes' milk fat of three breeds were not statistically significant. Therefore, colostrum samples as well as milk samples were analysed in this study as bulk samples of the 15 ewes. The FA profiles in milk sampled from ewes during the colostrum period and the mature milk period are presented in Table 2.
3.1. Straight-chain saturated fatty acids SSFA 4:0 to 12:0, most of the 14:0 (95%) and about half of the 16:0 are synthesized in the mammary gland, whereas 18:0 is the product of ruminal microbial biohydrogenation of dietary unsaturated FA. Human studies have shown that SSFA 4:0e10:0 have positive, 12:0e16:0 negative and 18:0 neutral health effects (Shingfield, Chilliard, Toivonen, Kairenins, & Givens, 2008). The time-dependent changes in SSFA content of milk fat during the first 10 days and up to the 60th day after lambing are presented in Fig. 1. Significant differences in SSFA profile variations between the group 4:0e10:0, 12:0e16:0, and 18:0 were observed. The content of FA 4:0e10:0 increased (P < 0.001), that of 14:0 and 16:0 decreased (P < 0.001), and that of 12:0 and 18:0 increased (P < 0.001) up to approximately the 6th day of lactation. In the period between the first and sixth lactation day, the content of 6:0e10:0 and 18:0 increased approximately by 100%, and that of 14:0 and 16:0 SSFA decreased by 30 g 100 g1 of fatty acid methyl esters (FAME) on average. The content of SSFA between the 10th and the 60th lactation day decreased particularly for 18:0 (P < 0.001), whereas it increased for 16:0 and 14:0 (P < 0.001). The changes for other SSFA were less significant. The 16:0 was the most abundant SSFA in milk samples analysed (up to 29 g 100 g1 FAME). Unexpectedly, the content of 16:0 and 14:0 in the colostrum was higher than that in the mature milk fat (P < 0.001). SSFA 14:0e16:0 are considered potentially dangerous in human subjects in regard of cardiovascular risk secondary to increased serum concentrations of both LDL- and HDL-cholesterol (Shingfield et al., 2008). However, higher HDL-cholesterol in plasma may protect against infections and microbial toxins (Canturk, Canturk, Okay, Yirmibesoglu, & Eraldemir, 2002).
3.2. Branch-chain saturated fatty acids The BSFA are derived especially by the activity of the bacteria in the rumen, and they can serve as a potential diagnostic tool for rumen bacterial function (Vlaeminck, Fievez, Cabrita, Fonseca, & Dewhurst, 2006). In vitro studies showed anticarcinogenic effects of both, iso and anteiso BSFA, and their cytotoxicity is comparable with that of cis-9,trans-11 octadecadienoic acid (CLA) (Lock & Bauman, 2004). The higher anticarcinogenic activity was observed with 16:0 iso, while inhibitory effects were less pronounced with increasing or decreasing lengths of carbon chain (Wongtangtintharn, Oku, Iwasaki, & Toda, 2004). Nine BSFA 13:0e18:0 were found in ewes' colostrum and mature milk samples. Significant time-variations in BSFA fat content were observed during lactation. The sum content of BSFA was 1.6 g 100 g1 FAME on the first colostrum day, 1.9 g 100 g1 FAME on the 6th day of lactation (P < 0.05), and it increased up to 2.4 g 100 g1 FAME on the 60th day of lactation period (P < 0.01). The time-variations of most abundant BSFA 15:0e17:0 through the 60-day lactation period are presented in Fig. 2. Of note, the content of 15:0e17:0 BSFA rose more during the first six days of lactation (P < 0.01) and decreased for the next four days (P < 0.05) and up to the 60th day of lactation. Only the content of 17:0 iso remained unchanged. Lower BSFA content in colostrum compared with mature milk seems to be associated with a bacterial response to rumen stress stimuli (Vlaeminck et al., 2006) associated with lambing. 3.3. Monounsaturated fatty acids Monounsaturated cis-9 10:1e18:1 and trans-11 (trans vaccenic acid, TVA) and trans-10 isomers of 18:1 FA are characteristic in milk fat. Mammary gland epithelial cells contain the D-9 desaturase complex which converts SSFA 10:0e18:0 to corresponding cis-9 10:1e18:1 MUFA as well as the positional isomers of trans 18:1 to cis-9,trans 18:2 isomers. Trans FA are a product of rumen bacterial biohydrogenation of consumed PUFA. Temporal variations in cis-9 10:1, 14:1, 16:1 and 18:1 fat contents on days 1e10, 30 and 60 are presented in Fig. 3. In the first six days after lambing, the content of individual cis-9 MUFA decreased most significantly for cis-9 16:1 (from 1.8 to 0.8 g 100 g1 FAME) (P < 0.001) and cis-9 14:1 (from 0.5 to 0.1 g 100 g1 FAME) (P < 0.001). With progressive lactation, the content of cis-9 MUFA decreased between the 6th and the 30th day of lactation for cis-9 18:1 (P < 0.001) and cis-9 16:1 (P < 0.05), and subsequently it increased up to the 60th lactation day (P < 0.01). The most abundant unsaturated FA in milk fat cis-9 18:1 (up to 26 g 100 g1 FAME) lowers plasma cholesterol levels. In contrast to cis-9 MUFA, the fat content of TVA and trans-10 18:1 increased over the first 5e6 lactation days (P < 0.001) in association with different formation mechanism of cis-9 and trans MUFA. On day 10 we unexpectedly found a lower content of trans10 18:1 (by 0.5%), and to smaller extent, of TVA (by 0.25%). Lower contents of both isomers were probably associated with lowered ruminal bacterial biohydrogenation of consumed PUFA. A similar trend in content variation was found for both isomers between days 30 and 60. On 10th, 30th and 60th lactation days, in the winter as well as in the summer season, Antunovi c et al. (2001) observed variations in ewes' milk fat sum content. 3.4. Polyunsaturated fatty acids In vitro studies, animal model studies, and also human studies showed beneficial health effects of milk PUFA (CLA; linoleic acid, LA; a-linolenic acid, ALA; arachidonic acid, AA; and
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Table 2 Fatty acid composition of milk fat of ewes fed with a winter diet on the 1st, 2nd, 6th, 10th, 30th and 60th day of lactation (g 100 g1 FAME).a FAME
1st day
2nd day
6th day
10th day
30th day
60th day
S
SEM
4:0 6:0 8:0 9:0 10:0 10:1 11:0 12:0 12:1 13:0 iso 13:0 anteiso 13:0 14:0 iso 14:0 14:1 15:0 iso 15:0 anteiso 15:0 15:1 16:0 iso 16:0 6-9t-16:1 10-13t-16:1 9c-16:1 10-12c-16:1 17:0 iso 17:0 anteiso 17:0 þ phytanic acid 9c-17:1 18:0 iso 18:0 6-8t-18:1 9t-18:1 10t-18:1 11t-18:1 TVA 12t þ 6-8c-18:1 9c þ 10c-18:1 11c þ 15t-18:1 12c-18:1 13c-18:1 16t-18:1 15c-18:1 16c-18:1 8t13c-18:2 9c12t-18:2 9t12c-18:2 18:2 n-6 LA 11t15c-18:2 9c15c-18:2 19:0 18:3 n-6 GLA 18:2 þ 19:1 18:3 n-3 ALA 9c11t-18:2 CLA 20:0 tt CLA 9c-20:1 20:2 21:0 20:3 n-6 20:4 n-6 AA 22:0 20:5 n-3 EPA 23:0 24:0 22:5 n-3 DPA 22:6 n-3 DHA
1.90 0.94 0.75 0.01 2.37 0.15a 0.02 2.58 0.04a 0.05ab 0.01a 0.05a 0.05a 12.51 0.54 0.15a 0.19a 0.52 ND 0.19a 29.46 0.16a 0.32 1.77 0.08 0.44 0.41a 0.67a 0.38a 0.10 6.41 0.25ab 0.27ab 0.62a 1.08a 0.14a 26.16 0.64 0.30ab 0.07ab 0.24 0.41a 0.06 0.17a 0.16a 0.04 2.88a 0.12a 0.04a 0.07 0.03 0.03a 0.54a 1.14a 0.20a 0.08a 0.01a 0.01 0.05 0.04 0.30a 0.07a 0.04a 0.02a 0.01 0.15a 0.07a
2.41a 1.44 1.17 0.03a 3.56 0.19 0.04a 2.79 0.03ab 0.05ab 0.01a 0.05a 0.06ab 10.68a 0.35 0.17ab 0.21a 0.61a ND 0.21a 28.07 0.16a 0.32 1.46 0.10 0.46 0.41a 0.71a 0.36a 0.10 7.78 0.26ab 0.25a 0.59a 1.28b 0.16ab 25.08a 0.63 0.31b 0.09a 0.31a 0.40a 0.07 0.16a 0.15a 0.04 2.94a 0.11a 0.04a 0.10a 0.03 0.03a 0.57a 1.05a 0.20a 0.06b 0.02a 0.02 0.05 0.04 0.35ab 0.05a 0.07b 0.02a 0.02a 0.16a 0.09a
2.68ab 1.89a 1.75a 0.04a 5.04 0.14a 0.05a 3.24a 0.02b 0.04a ND 0.06a 0.08bc 8.06b 0.11a 0.19b 0.27b 0.62a ND 0.25b 22.15a 0.16a 0.33 0.78a 0.06a 0.49 0.46b 0.87b 0.30b 0.12 12.79 0.32c 0.29b 1.19 1.76 0.19b 24.57a 0.71 0.30ab 0.08ab 0.36b 0.34b 0.06 0.12b 0.13ab 0.04 3.19 0.12a 0.06ab 0.12a 0.03 0.02a 0.60ab 0.90 0.21a 0.07ab 0.02a 0.02 0.05 0.04 0.33ab 0.07a 0.07b 0.03a 0.03ab 0.16a 0.08a
2.74b 2.01ab 1.80a 0.04a 5.37 0.14a 0.05a 3.15a 0.01 0.04a 0.01a 0.06a 0.09c 8.09b 0.10a 0.22 0.30b 0.68a ND 0.28b 22.71a 0.14ab 0.34 0.77a 0.06a 0.49 0.45b 0.83b 0.32b 0.12 13.34 0.28b 0.27ab 0.58a 1.57 0.24c 24.15a 0.70 0.32b 0.06b 0.37b 0.3b 0.06 0.14ab 0.11b 0.03 2.89a 0.14ab 0.06ab 0.13a 0.04 0.02a 0.57a 0.78 0.24b 0.06b 0.02a 0.02 0.06 0.03 0.32ab 0.07a 0.07b 0.02a 0.02a 0.15a 0.08a
2.80 b 2.16b 2.05 0.04a 6.61 0.15a 0.06a 3.97 0.02b 0.05ab 0.01a 0.08 0.12d 10.20ac 0.13a 0.29c 0.42 0.88 0.01 0.33c 24.78b 0.14ab 0.31 0.73 0.04b 0.49 0.47b 0.69a 0.23 0.09 11.43 0.31c 0.28b 0.97 1.34b 0.34 19.34 0.68 0.33b 0.09a 0.36b 0.26c 0.07 0.12a 0.13ab 0.03 2.61b 0.16b 0.07b 0.10a 0.03 0.06b 0.43 0.67b 0.28b 0.05b 0.04b 0.01 0.09 0.04 0.23c 0.11 0.04b 0.06 0.04b 0.11b 0.05b
2.65ab 1.97ab 1.81a 0.03a 6.02 0.14a 0.05a 3.49 0.02b 0.06b 0.01a 0.08 0.14d 9.80c 0.13a 0.29c 0.47 0.99 0.01 0.33c 25.73b 0.13b 0.35 0.84 0.05ab 0.50 0.53 0.85b 0.29b 0.10 10.63 0.23a 0.23a 0.47 1.13a 0.26c 21.19 0.65 0.27a 0.07ab 0.31a 0.26c 0.06 0.12a 0.12b 0.03 2.68b 0.14ab 0.07b 0.12a 0.04 0.07b 0.68b 0.66b 0.35 0.05b 0.05b 0.01 0.12 0.03 0.26c 0.16 0.05a 0.08 0.06 0.11b 0.05b
*** *** *** *** *** * *** *** *** ** NS ** *** *** *** *** *** *** e *** *** * NS *** *** NS ** *** *** NS *** *** ** *** *** *** *** NS * ** *** *** NS ** ** NS *** ** ** *** NS *** *** *** *** ** *** * *** NS *** *** *** *** *** *** **
0.177 0.253 0.258 0.005 0.841 0.032 0.006 0.239 0.006 0.001 0.002 0.006 0.018 0.891 0.095 0.029 0.057 0.086 e 0.028 1.387 0.003 e 0.204 0.010 e 0.019 0.039 0.025 e 1.340 0.016 0.036 0.135 0.136 0.043 1.245 e 0.013 0.005 0.025 0.034 e 0.010 0.031 e 0.092 0.008 0.006 0.009 e 0.010 0.041 0.104 0.027 0.005 0.010 0.003 0.008 e 0.023 0.019 0.007 0.012 0.009 0.012 0.028
Summary Total SSFA 4:0e24:0 Total SSFA 4:0e10:0 Total SSFA 12:0e16:0 Total BSFA Total MUFA Total PUFA
58.57a 5.97 45.12 1.60a 33.72a 5.80a
59.72a 8.61 42.20 1.68ab 32.41ab 5.89a
59.69a 11.39a 34.13a 1.90bc 32.11b 5.96a
61.34a 11.95ab 34.69a 2.00cd 30.85b 5.49
66.35b 13.67 39.91b 2.25de 26.17c 4.82b
64.87b 12.49b 40.09b 2.43e 27.14c 5.14b
*** *** *** *** *** ***
1.299 1.377 2.045 0.146 1.605 0.174
a Abbreviations: FAME, fatty acid methyl esters; TVA, trans vaccenic acid; LA, linoleic acid; GLA, g-linolenic acid; ALA, a-linolenic acid; CLA, conjugated linoleic acid; AA, arachidonic acid; EPA, eicosapentaenoic acid; DPA, docosapentaenoic acid; DHA, docosahexaenoic acid; c, cis; t, trans; SSFA, straight-chain saturated fatty acids; BSFA, branched-chain saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; 9c11t-18:2 CLA content, the sum content of cis-9,trans11 þ trans-7,cis-9 þ trans-8,cis-10 CLA isomers; SEM, standard error of mean; S, significance; *, P < 0.05; **, P < 0.01; ***, P < 0.001; NS, not significant (P > 0.05); ND, not detected; Variation among means marked with the same superscript is not significant (P > 0.05).
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Fig. 1. Time-dependent changes in milk fat contents of individual SSFA during the first 10 days and up to the 60th day of lactation: -, 4:0; 6, 6:0; +, 8:0; ;, 10.0; B, 12:0; ,, 14:0; :, 16:0; C, 18:0.
eicosapentaenoic acid, EPA) (Shingfield et al., 2008). However, their content in milk fat is relatively low. LA showed the highest content up to 2.9 g and 2.7 g 100 g1 FAME (P < 0.05) in colostrum and mature milk, respectively. The presence of CLA in milk fat is linked to the isomerization and biohydrogenation of dietary LA and ALA by rumen bacteria and D-9 desaturase activity in the mammary gland. Time-dependent changes in milk fat contents of individual PUFA during the 60-day lactation period are presented in Fig. 4. Unlike SSFA and MUFA, the content of PUFA changed less significantly on the first colostrum day. Remarkable variations in PUFA content during lactation were noted for CLA and LA (P < 0.001). Over the first six lactation days, the CLA content decreased (P < 0.01) and LA content increased (P < 0.01), whereas those of ALA, AA and EPA remained almost unchanged. Over the lactation period up to days 30 and 60, the PUFA content decreased to values below those in colostrum (except for ALA on the 60th lactation day). Fig. 4 shows interesting mirroring time-dependent changes for CLA and LA (precursor of CLA), similar to CLA and ALA in the case of ewes fed with pasture (Ostrovský et al., 2009). The high activity of mammary gland D-9 desaturase for CLA and modified ruminal microbial activity affecting biohydrogenation in
Fig. 3. Time-dependent changes in milk fat contents of individual cis-9 10:1e18:1, trans-10 and trans-11 18:1 during the first 10 days and up to the 60th day of lactation: ,, cis-9 10:1; :, cis-9 14:1; C, cis-9 16:1; ;, cis-9 18:1; q, trans-11 18:1; 8, trans-10 18:1.
Fig. 4. Time-dependent changes in milk fat contents of individual PUFA during the first 10 days and up to the 60th day of lactation: -, linoleic acid; :, a-linolenic acid; B, cis-9,trans-11 18:2; q, arachidonic acid; ;, eicosapentaenoic acid.
the rumen for formation of TVA during colostrum induced wide variations in the TVA/CLA content ratio, i.e., 0.95 on the first colostrum day versus 2.0, 2.0 and 1.7 on the 6th, 30th and 60th day of lactation, respectively. 4. Conclusions
Fig. 2. Time-dependent changes in milk fat contents of individual BSFA during the first 10 days and up to the 60th day of lactation: C, i 15:0; B, ai 15:0; -, i 17:0; ,, ai 17:0; :, i 16:0.
The content of MUFA, PUFA and SSFA 14:0e16:0 in colostrum was higher while the content of SSFA 4:0e12:0, 18:0 and BSFA iso and anteiso 15:0e17:0 was lower than that in mature milk. The composition of FA changed most significantly during the first two days of lactation. This is in agreement with the time schedule of colostrum formation during 1e2 days after lambing. Nevertheless, the content of FA successively changed up to approximately 6th day of lactation, and further time-changes of FA content were smaller. This is consistent with the recommendation that the ewes' milk should be consumed after six-to-eight days of lactation. An unexpected higher content of 16:0 and 14:0 in colostrum compared with mature milk may be related to more important protective effect against infections and toxins than cardiovascular risk in terms of lamb protection.
E. Pavlíková et al. / International Dairy Journal 20 (2010) 637e641
Acknowledgments This work was supported by the Slovak Research and Development Agency under contract No. APVV-0163-06, LPP0198-06, LPP-0089-06, and Grant Agency VEGA No. 1/0297/08 and 1/0298/08. References Antunovi c, Z., Steiner, Z., Sen ci c, D., Mandi c, M., & Klapec, T. (2001). Changes in ewe milk composition depending on lactation stage and feeding season. Czech Journal of Animal Sciences, 46, 75e82. Canturk, N. Z., Canturk, Z., Okay, E., Yirmibesoglu, O., & Eraldemir, B. (2002). Risk of nosocomial infections and effects of total cholesterol, HDL cholesterol in surgical patients. Clinical Nutrition, 21, 431e436.
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Keskin, M., Güler, Z., Gül, S., & Biçer, O. (2007). Changes in gross chemical compositions of ewe and goat colostrum during ten days postpartum. Journal of Applied Animal Research, 32, 25e28. Lock, A. L., & Bauman, D. E. (2004). Modifying milk fat composition of dairy cows to enhance fatty acids beneficial to human health. Lipids, 39, 1197e1206. Ostrovský, I., Pavlíková, E., Blasko, J., Górová, R., Kubinec, R., Margetín, M., et al. (2009). Variation in fatty acid composition of ewes' milk during continuous transition from dry winter to natural pasture diet. International Dairy Journal, 19, 545e549. Shingfield, K. J., Chilliard, Y., Toivonen, V., Kairenins, P., & Givens, D. I. (2008). Trans fatty acids and bioactive lipids in ruminant milk. In Z. Bösze (Ed.), Bioactive components of milk. Advances in experimental medicine and biology, Vol. 606 (pp. 3e65). New York, NY, USA: Springer Science and Business Media, LLC. Vlaeminck, B., Fievez, V., Cabrita, A. R. J., Fonseca, A. J. M., & Dewhurst, R. J. (2006). Factors affecting odd- and branched-chain fatty acids in milk: a review. Animal Feed Science and Technology, 131, 389e417. Wongtangtintharn, S., Oku, H., Iwasaki, H., & Toda, T. (2004). Effect of branchedchain fatty acids on fatty acid biosynthesis of human breast cancer cells. Journal of Nutritional Science and Vitaminology, 50, 137e143.
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International Dairy Journal journal homepage: www.elsevier.com/locate/idairyj
Short communication
Variation in fatty acid composition of ewes' colostrum and mature milk fat Eva Pavlíková a, Jaroslav Blasko a, Renáta Górová a, Gabriela Addová a, Róbert Kubinec a, *, Milan Margetín b, Ladislav Soják a a b
Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, SK-842 15 Bratislava, Slovak Republic Animal Production Research Centre Nitra, Hlohovecká 2, SK-949 92 Luzianky, Slovak Republic
a r t i c l e i n f o
a b s t r a c t
Article history: Received 15 January 2010 Received in revised form 15 February 2010 Accepted 17 February 2010
Temporal content variations of approximately 70 C4eC24 fatty acids (FA) in colostrum and milk of ewes consuming winter diet were determined by gas chromatography. The content of monounsaturated, polyunsaturated and straight-chain saturated FA 14:0e16:0 in colostrum was higher whereas the content of 4:0e12:0, 18:0 and branched-chain saturated FA 15:0e17:0 was lower than that in mature milk. The effect of ewe breed on the FA profiles was not significant. The composition of FA changed most significantly 1e2 days after lambing in agreement with the time schedule of colostrum formation. Nevertheless, the content of FA further successively changed up to approximately the 6th day of lactation, whereas further changes up to the 60th day of lactation were smaller. This is consistent with the recommendation that ewes' milk is suitable for human consumption after six-to-eight days of lactation. The higher contents of palmitic and myristic acids in colostrum compared with mature milk suggest that FA composition in colostrum matches the changing needs of the growing lambs. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction Colostrum is a secretion from the mammary gland formed just before parturition and in the first 24e48 h after lambing, and it changes to mature milk subsequently. The production and composition of colostrum depends on nutrition in late gestation and genetic and physiological status of ewes. The colostrum contents of fats, proteins, lactose, and minerals vary with time after the birth most significantly within 24 h after parturition. The milk fat in colostrum is very important means to deliver some of its beneficial biologically active substances. Previous studies were focused on time-dependent changes in the contents of organic and inorganic components in ewes' colostrum. In the study of changes in colostrum and ewes' (Würtemberg breed) milk composition, Antunovi c, Steiner, Sen ci c, Mandi c, and Klapec (2001) found the highest milk fat content on the 2nd day of lactation followed by a decrease on the 10th and 30th day of lactation, and an increase on the 60th day of lactation in the winter as well as in the summer feeding season. To determine the exact colostrum producing period in Awassi ewes, Keskin, Güler, Gül, and Biçer (2007) studied the daily changes in milk fat contents for ten days after parturition. The authors found the highest fat content (w10%) on the first day postpartum, while that on the 10th day
* Corresponding author. Tel.: þ421 2 60296 330; fax: þ421 2 60296 690. E-mail address: [email protected] (R. Kubinec). 0958-6946/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.idairyj.2010.02.008
decreased to w7%. No information is available on the variation of detailed fatty acid (FA) composition in ewes' colostrum during the first days after parturition. This study was aimed at determining changes in fatty acid composition in milk during the transition from colostrum to mature milk of ewes receiving a winter diet during lamb suckling period using gas chromatographic analysis. The differences in the content of individual straight-chain saturated (SSFA), branch-chain saturated (BSFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in colostrum and mature ewes' milk were evaluated.
2. Materials and methods 2.1. Ewe breeds and feeding regimes Investigations were carried out at the experimental ewes' farm of Animal Production Research Centre in Tren cianska Teplá, Slovak Republic. The FA contents of milk fat of three dairy ewes' breeds (5 Tsigai, 5 improved Valachian and 5 Lacaune) were analysed as bulk samples daily for ten days after lambing and further at days 30 and 60. Investigated Slovak herds Tsigai and improved Valachian ewes have a higher content of dry matter and basic milk components fats and proteins in their milk (Table 1) than ewes' breeds with higher milk production, i.e., East-Frisian, Awassi and Lacaune.
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Table 1 Average content of basic components of Tsigai and improved Valachian ewes' milk (g 100 g1). Breed
Number of analysed milk samples
Dry matter
Fat
Protein
Lactose
Tsigai Improved Valachian
47 206 90 001
19.9 19.3
8.1 7.7
6.0 5.8
4.9 4.9
2.2. Fatty acid and statistical analyses The FA content of ewes' milk fat samples was gas chromatographically analysed under conditions published before (Ostrovský et al., 2009). Statistical data analysis was performed from three parallel determinations of each milk sample. A one-way ANOVA was used to evaluate the differences between the FA composition during lactation period being a dependent variable and lactation day as an independent variable. Significant differences were considered at the level P < 0.05.
3. Results and discussion Gas chromatographic analyses of FA samples from milk of individual ewes of Tsigai, improved Valachian and Lacaune breeds showed that the differences in the average individual fatty acids content of ewes' milk fat of three breeds were not statistically significant. Therefore, colostrum samples as well as milk samples were analysed in this study as bulk samples of the 15 ewes. The FA profiles in milk sampled from ewes during the colostrum period and the mature milk period are presented in Table 2.
3.1. Straight-chain saturated fatty acids SSFA 4:0 to 12:0, most of the 14:0 (95%) and about half of the 16:0 are synthesized in the mammary gland, whereas 18:0 is the product of ruminal microbial biohydrogenation of dietary unsaturated FA. Human studies have shown that SSFA 4:0e10:0 have positive, 12:0e16:0 negative and 18:0 neutral health effects (Shingfield, Chilliard, Toivonen, Kairenins, & Givens, 2008). The time-dependent changes in SSFA content of milk fat during the first 10 days and up to the 60th day after lambing are presented in Fig. 1. Significant differences in SSFA profile variations between the group 4:0e10:0, 12:0e16:0, and 18:0 were observed. The content of FA 4:0e10:0 increased (P < 0.001), that of 14:0 and 16:0 decreased (P < 0.001), and that of 12:0 and 18:0 increased (P < 0.001) up to approximately the 6th day of lactation. In the period between the first and sixth lactation day, the content of 6:0e10:0 and 18:0 increased approximately by 100%, and that of 14:0 and 16:0 SSFA decreased by 30 g 100 g1 of fatty acid methyl esters (FAME) on average. The content of SSFA between the 10th and the 60th lactation day decreased particularly for 18:0 (P < 0.001), whereas it increased for 16:0 and 14:0 (P < 0.001). The changes for other SSFA were less significant. The 16:0 was the most abundant SSFA in milk samples analysed (up to 29 g 100 g1 FAME). Unexpectedly, the content of 16:0 and 14:0 in the colostrum was higher than that in the mature milk fat (P < 0.001). SSFA 14:0e16:0 are considered potentially dangerous in human subjects in regard of cardiovascular risk secondary to increased serum concentrations of both LDL- and HDL-cholesterol (Shingfield et al., 2008). However, higher HDL-cholesterol in plasma may protect against infections and microbial toxins (Canturk, Canturk, Okay, Yirmibesoglu, & Eraldemir, 2002).
3.2. Branch-chain saturated fatty acids The BSFA are derived especially by the activity of the bacteria in the rumen, and they can serve as a potential diagnostic tool for rumen bacterial function (Vlaeminck, Fievez, Cabrita, Fonseca, & Dewhurst, 2006). In vitro studies showed anticarcinogenic effects of both, iso and anteiso BSFA, and their cytotoxicity is comparable with that of cis-9,trans-11 octadecadienoic acid (CLA) (Lock & Bauman, 2004). The higher anticarcinogenic activity was observed with 16:0 iso, while inhibitory effects were less pronounced with increasing or decreasing lengths of carbon chain (Wongtangtintharn, Oku, Iwasaki, & Toda, 2004). Nine BSFA 13:0e18:0 were found in ewes' colostrum and mature milk samples. Significant time-variations in BSFA fat content were observed during lactation. The sum content of BSFA was 1.6 g 100 g1 FAME on the first colostrum day, 1.9 g 100 g1 FAME on the 6th day of lactation (P < 0.05), and it increased up to 2.4 g 100 g1 FAME on the 60th day of lactation period (P < 0.01). The time-variations of most abundant BSFA 15:0e17:0 through the 60-day lactation period are presented in Fig. 2. Of note, the content of 15:0e17:0 BSFA rose more during the first six days of lactation (P < 0.01) and decreased for the next four days (P < 0.05) and up to the 60th day of lactation. Only the content of 17:0 iso remained unchanged. Lower BSFA content in colostrum compared with mature milk seems to be associated with a bacterial response to rumen stress stimuli (Vlaeminck et al., 2006) associated with lambing. 3.3. Monounsaturated fatty acids Monounsaturated cis-9 10:1e18:1 and trans-11 (trans vaccenic acid, TVA) and trans-10 isomers of 18:1 FA are characteristic in milk fat. Mammary gland epithelial cells contain the D-9 desaturase complex which converts SSFA 10:0e18:0 to corresponding cis-9 10:1e18:1 MUFA as well as the positional isomers of trans 18:1 to cis-9,trans 18:2 isomers. Trans FA are a product of rumen bacterial biohydrogenation of consumed PUFA. Temporal variations in cis-9 10:1, 14:1, 16:1 and 18:1 fat contents on days 1e10, 30 and 60 are presented in Fig. 3. In the first six days after lambing, the content of individual cis-9 MUFA decreased most significantly for cis-9 16:1 (from 1.8 to 0.8 g 100 g1 FAME) (P < 0.001) and cis-9 14:1 (from 0.5 to 0.1 g 100 g1 FAME) (P < 0.001). With progressive lactation, the content of cis-9 MUFA decreased between the 6th and the 30th day of lactation for cis-9 18:1 (P < 0.001) and cis-9 16:1 (P < 0.05), and subsequently it increased up to the 60th lactation day (P < 0.01). The most abundant unsaturated FA in milk fat cis-9 18:1 (up to 26 g 100 g1 FAME) lowers plasma cholesterol levels. In contrast to cis-9 MUFA, the fat content of TVA and trans-10 18:1 increased over the first 5e6 lactation days (P < 0.001) in association with different formation mechanism of cis-9 and trans MUFA. On day 10 we unexpectedly found a lower content of trans10 18:1 (by 0.5%), and to smaller extent, of TVA (by 0.25%). Lower contents of both isomers were probably associated with lowered ruminal bacterial biohydrogenation of consumed PUFA. A similar trend in content variation was found for both isomers between days 30 and 60. On 10th, 30th and 60th lactation days, in the winter as well as in the summer season, Antunovi c et al. (2001) observed variations in ewes' milk fat sum content. 3.4. Polyunsaturated fatty acids In vitro studies, animal model studies, and also human studies showed beneficial health effects of milk PUFA (CLA; linoleic acid, LA; a-linolenic acid, ALA; arachidonic acid, AA; and
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Table 2 Fatty acid composition of milk fat of ewes fed with a winter diet on the 1st, 2nd, 6th, 10th, 30th and 60th day of lactation (g 100 g1 FAME).a FAME
1st day
2nd day
6th day
10th day
30th day
60th day
S
SEM
4:0 6:0 8:0 9:0 10:0 10:1 11:0 12:0 12:1 13:0 iso 13:0 anteiso 13:0 14:0 iso 14:0 14:1 15:0 iso 15:0 anteiso 15:0 15:1 16:0 iso 16:0 6-9t-16:1 10-13t-16:1 9c-16:1 10-12c-16:1 17:0 iso 17:0 anteiso 17:0 þ phytanic acid 9c-17:1 18:0 iso 18:0 6-8t-18:1 9t-18:1 10t-18:1 11t-18:1 TVA 12t þ 6-8c-18:1 9c þ 10c-18:1 11c þ 15t-18:1 12c-18:1 13c-18:1 16t-18:1 15c-18:1 16c-18:1 8t13c-18:2 9c12t-18:2 9t12c-18:2 18:2 n-6 LA 11t15c-18:2 9c15c-18:2 19:0 18:3 n-6 GLA 18:2 þ 19:1 18:3 n-3 ALA 9c11t-18:2 CLA 20:0 tt CLA 9c-20:1 20:2 21:0 20:3 n-6 20:4 n-6 AA 22:0 20:5 n-3 EPA 23:0 24:0 22:5 n-3 DPA 22:6 n-3 DHA
1.90 0.94 0.75 0.01 2.37 0.15a 0.02 2.58 0.04a 0.05ab 0.01a 0.05a 0.05a 12.51 0.54 0.15a 0.19a 0.52 ND 0.19a 29.46 0.16a 0.32 1.77 0.08 0.44 0.41a 0.67a 0.38a 0.10 6.41 0.25ab 0.27ab 0.62a 1.08a 0.14a 26.16 0.64 0.30ab 0.07ab 0.24 0.41a 0.06 0.17a 0.16a 0.04 2.88a 0.12a 0.04a 0.07 0.03 0.03a 0.54a 1.14a 0.20a 0.08a 0.01a 0.01 0.05 0.04 0.30a 0.07a 0.04a 0.02a 0.01 0.15a 0.07a
2.41a 1.44 1.17 0.03a 3.56 0.19 0.04a 2.79 0.03ab 0.05ab 0.01a 0.05a 0.06ab 10.68a 0.35 0.17ab 0.21a 0.61a ND 0.21a 28.07 0.16a 0.32 1.46 0.10 0.46 0.41a 0.71a 0.36a 0.10 7.78 0.26ab 0.25a 0.59a 1.28b 0.16ab 25.08a 0.63 0.31b 0.09a 0.31a 0.40a 0.07 0.16a 0.15a 0.04 2.94a 0.11a 0.04a 0.10a 0.03 0.03a 0.57a 1.05a 0.20a 0.06b 0.02a 0.02 0.05 0.04 0.35ab 0.05a 0.07b 0.02a 0.02a 0.16a 0.09a
2.68ab 1.89a 1.75a 0.04a 5.04 0.14a 0.05a 3.24a 0.02b 0.04a ND 0.06a 0.08bc 8.06b 0.11a 0.19b 0.27b 0.62a ND 0.25b 22.15a 0.16a 0.33 0.78a 0.06a 0.49 0.46b 0.87b 0.30b 0.12 12.79 0.32c 0.29b 1.19 1.76 0.19b 24.57a 0.71 0.30ab 0.08ab 0.36b 0.34b 0.06 0.12b 0.13ab 0.04 3.19 0.12a 0.06ab 0.12a 0.03 0.02a 0.60ab 0.90 0.21a 0.07ab 0.02a 0.02 0.05 0.04 0.33ab 0.07a 0.07b 0.03a 0.03ab 0.16a 0.08a
2.74b 2.01ab 1.80a 0.04a 5.37 0.14a 0.05a 3.15a 0.01 0.04a 0.01a 0.06a 0.09c 8.09b 0.10a 0.22 0.30b 0.68a ND 0.28b 22.71a 0.14ab 0.34 0.77a 0.06a 0.49 0.45b 0.83b 0.32b 0.12 13.34 0.28b 0.27ab 0.58a 1.57 0.24c 24.15a 0.70 0.32b 0.06b 0.37b 0.3b 0.06 0.14ab 0.11b 0.03 2.89a 0.14ab 0.06ab 0.13a 0.04 0.02a 0.57a 0.78 0.24b 0.06b 0.02a 0.02 0.06 0.03 0.32ab 0.07a 0.07b 0.02a 0.02a 0.15a 0.08a
2.80 b 2.16b 2.05 0.04a 6.61 0.15a 0.06a 3.97 0.02b 0.05ab 0.01a 0.08 0.12d 10.20ac 0.13a 0.29c 0.42 0.88 0.01 0.33c 24.78b 0.14ab 0.31 0.73 0.04b 0.49 0.47b 0.69a 0.23 0.09 11.43 0.31c 0.28b 0.97 1.34b 0.34 19.34 0.68 0.33b 0.09a 0.36b 0.26c 0.07 0.12a 0.13ab 0.03 2.61b 0.16b 0.07b 0.10a 0.03 0.06b 0.43 0.67b 0.28b 0.05b 0.04b 0.01 0.09 0.04 0.23c 0.11 0.04b 0.06 0.04b 0.11b 0.05b
2.65ab 1.97ab 1.81a 0.03a 6.02 0.14a 0.05a 3.49 0.02b 0.06b 0.01a 0.08 0.14d 9.80c 0.13a 0.29c 0.47 0.99 0.01 0.33c 25.73b 0.13b 0.35 0.84 0.05ab 0.50 0.53 0.85b 0.29b 0.10 10.63 0.23a 0.23a 0.47 1.13a 0.26c 21.19 0.65 0.27a 0.07ab 0.31a 0.26c 0.06 0.12a 0.12b 0.03 2.68b 0.14ab 0.07b 0.12a 0.04 0.07b 0.68b 0.66b 0.35 0.05b 0.05b 0.01 0.12 0.03 0.26c 0.16 0.05a 0.08 0.06 0.11b 0.05b
*** *** *** *** *** * *** *** *** ** NS ** *** *** *** *** *** *** e *** *** * NS *** *** NS ** *** *** NS *** *** ** *** *** *** *** NS * ** *** *** NS ** ** NS *** ** ** *** NS *** *** *** *** ** *** * *** NS *** *** *** *** *** *** **
0.177 0.253 0.258 0.005 0.841 0.032 0.006 0.239 0.006 0.001 0.002 0.006 0.018 0.891 0.095 0.029 0.057 0.086 e 0.028 1.387 0.003 e 0.204 0.010 e 0.019 0.039 0.025 e 1.340 0.016 0.036 0.135 0.136 0.043 1.245 e 0.013 0.005 0.025 0.034 e 0.010 0.031 e 0.092 0.008 0.006 0.009 e 0.010 0.041 0.104 0.027 0.005 0.010 0.003 0.008 e 0.023 0.019 0.007 0.012 0.009 0.012 0.028
Summary Total SSFA 4:0e24:0 Total SSFA 4:0e10:0 Total SSFA 12:0e16:0 Total BSFA Total MUFA Total PUFA
58.57a 5.97 45.12 1.60a 33.72a 5.80a
59.72a 8.61 42.20 1.68ab 32.41ab 5.89a
59.69a 11.39a 34.13a 1.90bc 32.11b 5.96a
61.34a 11.95ab 34.69a 2.00cd 30.85b 5.49
66.35b 13.67 39.91b 2.25de 26.17c 4.82b
64.87b 12.49b 40.09b 2.43e 27.14c 5.14b
*** *** *** *** *** ***
1.299 1.377 2.045 0.146 1.605 0.174
a Abbreviations: FAME, fatty acid methyl esters; TVA, trans vaccenic acid; LA, linoleic acid; GLA, g-linolenic acid; ALA, a-linolenic acid; CLA, conjugated linoleic acid; AA, arachidonic acid; EPA, eicosapentaenoic acid; DPA, docosapentaenoic acid; DHA, docosahexaenoic acid; c, cis; t, trans; SSFA, straight-chain saturated fatty acids; BSFA, branched-chain saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; 9c11t-18:2 CLA content, the sum content of cis-9,trans11 þ trans-7,cis-9 þ trans-8,cis-10 CLA isomers; SEM, standard error of mean; S, significance; *, P < 0.05; **, P < 0.01; ***, P < 0.001; NS, not significant (P > 0.05); ND, not detected; Variation among means marked with the same superscript is not significant (P > 0.05).
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Fig. 1. Time-dependent changes in milk fat contents of individual SSFA during the first 10 days and up to the 60th day of lactation: -, 4:0; 6, 6:0; +, 8:0; ;, 10.0; B, 12:0; ,, 14:0; :, 16:0; C, 18:0.
eicosapentaenoic acid, EPA) (Shingfield et al., 2008). However, their content in milk fat is relatively low. LA showed the highest content up to 2.9 g and 2.7 g 100 g1 FAME (P < 0.05) in colostrum and mature milk, respectively. The presence of CLA in milk fat is linked to the isomerization and biohydrogenation of dietary LA and ALA by rumen bacteria and D-9 desaturase activity in the mammary gland. Time-dependent changes in milk fat contents of individual PUFA during the 60-day lactation period are presented in Fig. 4. Unlike SSFA and MUFA, the content of PUFA changed less significantly on the first colostrum day. Remarkable variations in PUFA content during lactation were noted for CLA and LA (P < 0.001). Over the first six lactation days, the CLA content decreased (P < 0.01) and LA content increased (P < 0.01), whereas those of ALA, AA and EPA remained almost unchanged. Over the lactation period up to days 30 and 60, the PUFA content decreased to values below those in colostrum (except for ALA on the 60th lactation day). Fig. 4 shows interesting mirroring time-dependent changes for CLA and LA (precursor of CLA), similar to CLA and ALA in the case of ewes fed with pasture (Ostrovský et al., 2009). The high activity of mammary gland D-9 desaturase for CLA and modified ruminal microbial activity affecting biohydrogenation in
Fig. 3. Time-dependent changes in milk fat contents of individual cis-9 10:1e18:1, trans-10 and trans-11 18:1 during the first 10 days and up to the 60th day of lactation: ,, cis-9 10:1; :, cis-9 14:1; C, cis-9 16:1; ;, cis-9 18:1; q, trans-11 18:1; 8, trans-10 18:1.
Fig. 4. Time-dependent changes in milk fat contents of individual PUFA during the first 10 days and up to the 60th day of lactation: -, linoleic acid; :, a-linolenic acid; B, cis-9,trans-11 18:2; q, arachidonic acid; ;, eicosapentaenoic acid.
the rumen for formation of TVA during colostrum induced wide variations in the TVA/CLA content ratio, i.e., 0.95 on the first colostrum day versus 2.0, 2.0 and 1.7 on the 6th, 30th and 60th day of lactation, respectively. 4. Conclusions
Fig. 2. Time-dependent changes in milk fat contents of individual BSFA during the first 10 days and up to the 60th day of lactation: C, i 15:0; B, ai 15:0; -, i 17:0; ,, ai 17:0; :, i 16:0.
The content of MUFA, PUFA and SSFA 14:0e16:0 in colostrum was higher while the content of SSFA 4:0e12:0, 18:0 and BSFA iso and anteiso 15:0e17:0 was lower than that in mature milk. The composition of FA changed most significantly during the first two days of lactation. This is in agreement with the time schedule of colostrum formation during 1e2 days after lambing. Nevertheless, the content of FA successively changed up to approximately 6th day of lactation, and further time-changes of FA content were smaller. This is consistent with the recommendation that the ewes' milk should be consumed after six-to-eight days of lactation. An unexpected higher content of 16:0 and 14:0 in colostrum compared with mature milk may be related to more important protective effect against infections and toxins than cardiovascular risk in terms of lamb protection.
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Acknowledgments This work was supported by the Slovak Research and Development Agency under contract No. APVV-0163-06, LPP0198-06, LPP-0089-06, and Grant Agency VEGA No. 1/0297/08 and 1/0298/08. References Antunovi c, Z., Steiner, Z., Sen ci c, D., Mandi c, M., & Klapec, T. (2001). Changes in ewe milk composition depending on lactation stage and feeding season. Czech Journal of Animal Sciences, 46, 75e82. Canturk, N. Z., Canturk, Z., Okay, E., Yirmibesoglu, O., & Eraldemir, B. (2002). Risk of nosocomial infections and effects of total cholesterol, HDL cholesterol in surgical patients. Clinical Nutrition, 21, 431e436.
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