Content uploaded by S. Nitrayová
Author content
All content in this area was uploaded by S. Nitrayová on Jan 29, 2015
Content may be subject to copyright.
Potravinarstvo® Scientific Journal for Food Industry
Volume 8 72 No. 1/2014
INTRODUCTION
Plant products are currently popular to combat various
physiological threats. Scientific evidence has been
provided that dietary phytochemicals can play important
roles in the treatment and prevention of many diseases.
With increasing public health awareness, demand for
functional foods with multiple health benefits has also
increased. It is possible to say that all foods are functional
because they provide varying amounts of nutrients for
growth or support of vital processes. Functional foods are
generally considered as the foods which offer various
benefits that may promote optimal health or reduce the risk
of disease (Hasler et al., 2000).
The seeds of most plants are rich in various nutrients and
can provide a lot of health benefits. Flax seed and chia
seed are renowned as good nutritional sources. These
seeds originate from agricultural crops: Flax (Linum
usitatissimum L.) and Chia (Salvia hispanica L.).
Flax is a member of the family Linaceae. It is a food and
fibre crop (Flax varieties grown for human consumption
are different from flax varieties grown to produce fibre)
that is grown in cooler regions of the world. Flax is an
annual plant growing to about 1.2 m tall, with slender
stems. The flowers are usually blue, with five petals; they
can also be bright red. The fruit is a round and dry capsule
(5-9 mm), contains several glossy, flat, oval seeds with a
pointed tip, 4 - 6 mm in length (Daun, et al., 2003). The
seeds have a chewy texture and a pleasant nutty taste
(Carter, 1996). There are two basic varieties, brown and
yellow or golden. Seed colour is determined by the amount
of pigment in the outer seed coat.
Salvia hispanica, or more commonly known as chia, has
a long history of use as a food in South and Central
America, not only for humans but for animals as well. It
was one of the main foods of the old Aztecs and Mayas.
Chia is a biannually cultivated plant which is a member of
the family Labiatae. It is a low water user plant which is
well adapted to arid and semiarid climates (Ayerza, 1995).
Chia can grow up to 1 m tall, has opposite arranged leaves
and chia flowers are small and usually purple (3-4 mm)
with small corollas. The seed coat colour ranges from
black, grey, and black spotted to white and the shape is
oval with size varying from 1 to 2 mm (Ixtaina et al.,
2008).
Polyunsaturated fatty acids (PUFA): linoleic acid (C18:2
n-6) and α-linolenic (C18:3 n-3) are essential nutrients, i.e.
humans and animals must obtain them by food because the
body requires them for many metabolic processes, but
Potravinarstvo, vol. 8, 2014, no. 1, p. 72-76
doi:10.5219/332
Received: 10 February 2014. Accepted: 20 Februaryl 2014.
Available online: 7 May 2014 at www.potravinarstvo.com
© 2014 Potravinarstvo. All rights reserved.
ISSN 1337-0960 (online)
AMINO ACIDS AND FATTY ACIDS PROFILE OF CHIA (
SALVIA HISPANICA
L.)
AND FLAX (
LINUM USITATISSIMUM
L.) SEED
Soňa Nitrayová, Matej Brestenský, Jaroslav Heger, Peter Patráš,
Ján Rafay, Alexander Sirotkin
ABSTRACT
The seeds of most plants are rich in various nutrients and can provide a lot of useful health benefits. The objective of this
study was to determine and compare differences in fat, fatty acids, crude protein and amino acids concentrations for chia
and flax seeds. Study was carried out using brown and gold seeds of Flax (Linum usitatissimum L.) and Chia (Salvia
hispanica L.). The mean protein content in tested seeds ranged from 211.8 to 252.5 g/kg dry matter and in chia seed was
about 13.10% higher than the average value of crude protein content in brown and gold flax seed (223.25 g/kg dry matter).
Differences in the content of individual amino acids among the seeds were not statistically significant (P <0.05), except that
for glutamic acid. Percentage of the essential to the total amino acids, which is considered as indicator of protein quality,
was 37.87%, 33.76% and 35.18%, for chia, brown and gold flax seed respectively, which demonstrates the high quality of
these proteins. The average fat content of flax seeds was about 71.42 g/kg higher than that in chia seed (321.37 g/kg dry
matter). The fatty acids composition showed the presence of palmitic, stearic, oleic, linoleic, α- linolenic and arachidic fatty
acids in all tested samples. The α-linolenic acid constitutes on average 54.38% of the total fatty acids of flax seeds and
63.79% of chia seed, and for linoleic acid it was 15.30% and 18.89%. All seeds had low n-6 PUFA / n-3 PUFA ratio.
Results of our study confirmed the excellent quality of protein and fat in chia seed, brown and gold flax seed samples. There
was no significant effect of the flax seed coat colour for all measured values. Chia seed is the richest of n-3 PUFA
α-linolenic fatty acid in the vegetable world. Both, flax seed and chia seed are the good choice of healthy food to maintain a
balanced serum lipid profile. It must be pointed that flax seeds must be ground to release their nutrients, but chia seeds do
not.
Keywords: amino acid; α-linolenic fatty acid; chia seed; fatty acid; flax seed
Potravinarstvo® Scientific Journal for Food Industry
Volume 8 73 No. 1/2014
cannot synthesize them (Gorjao et al., 2009). Then highly
unsaturated metabolites can be created from these fatty
acids; arachidonic acid and γ-linolenic acid (n-6 PUFA)
from linoleic acid (LA) and the most important
metabolites: eicosapentaenoic acid and docosahexaenoic
acid (n-3 PUFA) from α-linolenic acid (ALA).
The well-known source of n-3 PUFAs are marine fish
(Gorjao et al., 2009), but flax seeds and chia seeds are
important plant sources as well. These are the two vegetal
species having the highest concentration of ALA (Ayerza,
1995; Coates and Ayerza, 1998; Oomah et al., 1995).
Most of studies have been carried out with fish and fish
oils, which are rich in eicosapentaenoic acid and
docosahexaenoic acid, but also with various plant seeds
and their oils as a source of ALA.
A low ratio of n-6 PUFA / n-3 PUFAs in daily food is
the best way how to help many metabolic processes in the
body. The problem is that for today’s diets the high
content of saturated fatty acids and n-6 PUFA and low
content of n-3 PUFA is typical (Simopoulos, 2004).
Typically modern diets have greater ratio
n-6 PUFA / n-3 PUFA than 15:1. This imbalance increases
the risk of heart disease and support body’s inflammatory
processes. The ideal ratio is from 1:1 to 3:1.
The aim of this study was to determine and compare
differences in nutrient content (fat, fatty acids, crude
protein and amino acids concentrations) for chia and flax
seed.
MATERIAL AND METHODOLOGY
The object of our analyses were six samples of brown
and gold flax seed (Figure 1) and three samples of chia
seed (Figure 2) which were obtained from health food
stores.
Tested seeds were milled and analyzed for content of dry
matter, crude protein and ether extract in accordance with
AOAC (1990) standard procedures.
The amino acid composition of tested samples was
analyzed by ion-exchange chromatography (Llames and
Fontaine, 1994). The content of amino acids after
hydrolysis with 6 M HCl and Met with Cys after oxidative
hydrolysis were determined using an automatic AA
analyzer (AAA 400; Ingos, Prague, Czech Republic).
The content of long chain fatty acids we analysed after
extraction of samples with petroleum ether and subsequent
esterification with esterifying agent such as methyl esters
of fatty acids by gas chromatography using gas
chromatograph GC 6890N (Agilent Technologies).
Experimental data were analysed by ANOVA using
Statgraphic Plus package (version 3.1; Statistical Graphics
Corp.,Rockville, MD). Differences were considered
statistically significant if P <0.05. When a significant value
for treatment means was observed, differences between
means were assessed using Fisher’s LSD procedure.
RESULTS AND DISCUSSION
The main values for studied nutrients: dry matter, fat,
crude protein and amino acids are summarized in Table 1.
The values of dry matter show a close similarity between
the chia seed, brown and gold flax seed.
The concentration of crude protein in all samples ranged
from 211.8 to 252.5 g/kg dry matter. Numerically highest
content of crude protein was determined in chia seed
(252.5g/kg dry matter) and this value was about 13.10%
higher than the average value of crude protein content in
brown and gold flax seed (223.25 g/kg dry matter).
Difference in the content of crude protein between brown
and gold flax seed was also close to ten percent (9.78%).
Our values of crude protein content correspond to those in
the literature. Sammour (1999) reported that the total
proteins in flax seed represent about 20-30% of the seed
meal, which makes it a good source of proteins.
The highest amount of total amino acids was in brown
flax seed (202.0 g/kg dry matter). Crude protein content
was higher in chia seed but total amino acid content was
higher in brown flax seed, due to higher content of
nonessential amino acids especially glutamic acid, glycine
and aspartic acid (Table 1). There was only one
statistically significant difference - for glutamic acid in
chia and brown flax seed. The amount of total essential
amino acids was the lowest in the gold flax seed (64.0 g/kg
dry matter) and almost practically the same in chia and
gold flax seed (68.6 and 68.2 g/kg dry mater). All the
above mentioned differences were not statistically
significant (P <0.05).
Figure 1 Flax ( Linum usitatissimum ) and flax seed
Figure 2: Chia ( Salvia hispanica) and chia seed
Potravinarstvo® Scientific Journal for Food Industry
Volume 8 74 No. 1/2014
When comparing the proportions of amino acids in
brown and gold flax seed, except methionine and
threonine, all other amino acids in gold flax seed were
lower compared with brown flax seed, but differences
were not statistically significant (P <0.05). Proteins of flax
seeds are limited by lysine, threonine and tyrosine
(Thompson and Cunnane, 2003). Our values of lysine
content in both colour varieties of flax seeds were lower
than the content of lysine in chia seed (Table 1). Proteins
of flax seeds are characterized by a high coefficient of
digestibility (89.6%) and biological value (77.4%)
(Martinchik, 2012). Brown flax seed proteins contain
relatively higher levels of aspartic acid, glutamic acid and
arginine (Table 1). These values indicate the high content
of amides (Ayad, 2010). The amino acid pattern of flax
protein is similar to that of soybean protein, which is
viewed as one of the most nutritious of the plant proteins
(Oomah and Mazza, 1993). Flax seed proteins, brown
and gold variety, contain 33.76% and 35.18% as
percentage of the essential to the total amino acids. The
value of this indicator for chia seed was 37.87%. Proteins
with such high values are considered as a high quality
protein. Ayad (2010) reported 36% for flax seed protein in
his study.
The protein quality of chia has been demonstrated to be
higher than that of common cereals and oil seeds (Weber
et al., 1991; Reyes-Caudillo et al., 2008), which is in
accordance with our results. All tested seeds were rich in
fat (Table 1). The average fat content of both varieties of
flax seed was about 71.42 g/kg higher than that in chia
seed, but there were no significant differences in total fat
content. There was close similarity to the results of
Capitany et al. (2013), which present 327 ±8.0 g/kg for
chia seed in his study.
Gas chromatography analysis of the fatty acids
composition showed the presence of palmitic, stearic,
oleic, linoleic, α-linolenic and arachidic fatty acids in all
tested samples. In addition, three more fatty acids were
identified in all analyses: lauric, myristic and palmitooleic.
However, all of them were present just in traces. Only one
significant difference among fatty acids was detected, it
was for oleic acid (Table 2). The fatty acid profile for
Table 1 Content of studied nutrients in analysed seeds, g/kg DM
Chia seed
Brown Flax seed
Gold Flax seed
SEM
Dry matter
930.3
935.0
925.1
0.1
Fat
321.37
383.44
402.13
0.1
CP*
252.5
234.7
211.8
0.1
Arginine
20.0
24.0
20.7
0.1
Phenylalanine
11.6
10.2
9.2
0.1
Histidine
6.1
5.1
4.8
0.0
Isoleucine
7.4
8.6
7.7
0.1
Leucine
14.2
12.9
11.7
0.2
Lysine
9.3
9.1
8.8
0.3
Methionine
6.7
4.9
5.1
0.3
Threonine
5.4
7.1
7.5
0.5
Valine
7.9
10.3
9.2
0.1
Alanine
9.4
9.9
9.1
0.1
Aspartic acid
12.8
14.1
11.3
1.1
Cystine
4.2
3.2
2.8
0.0
Glutamic acid
28.7a
45.1b
39.6b
0.8
Glycine
9.1
13.3
12.0
0.1
Proline
12.8
9.1
8.3
0.2
Serine
9.4
10.2
9.4
0.2
Tyrosine
6.1
4.9
4.7
0.0
Total AA*
181.1
202.0
181.9
1.4
Total EAA*
68.6
68.2
64.0
1.1
Total NEAA*
112.5
133.8
117.9
2.7
abc means in row are significantly different (P ˂0.05)
*CP - crude protein, AA - amino acids, EAA - essential amino acids, NEAA - non-essential amino acids
Potravinarstvo® Scientific Journal for Food Industry
Volume 8 75 No. 1/2014
tested seeds was similar to that reported by another authors
(Ayerza, 1995, 2009, 2010; Coates and Ayerza, 2009;
Martinchik, 2012). ALA constitutes on average 54.38%
of the total fatty acids of flax seeds and 63.79% of chia
seed and for LA it was 15.30% and 18.89%. Our results
are in accordance with Bhatty (1993) who reported the
ratio of LA in chia seed with about 18% and ALA with
about 64% as unique. There was 53.3% of ALA for flax
seed in his study. All these dates are close to ours. Both
chia and flax seeds are rich in ALA, but chia seed is the
highest plant-based source of ALA (Ayerza and Coates,
2011).
All seeds had low n-6 PUFA / n-3 PUFA ratio (Table 2).
This observation has important health implications. The
best way to lower the risk of coronary heart disease is to
keep dietary n-6 PUFA / n-3 PUFA ratios as low as
possible (Jones et al., 2006).
The 2010 Dietary Guidelines for Americans states
reported that an adequate intake of ALA ranges between
1.1 and 1.6 grams/day for adults. Since 12 to 18 grams
(2 to 3 teaspoons) of chia contain between 2.5 and 3.6
grams of ALA, this is more than a sufficient amount to
meet this recommendation.
The EFSA Journal (2009) published labelling reference
value for the n-3 PUFA ALA which is 2 g per day. This
amount is consistent with recommended intakes for
individuals in the general population in European countries
based on considerations of cardiovascular health.
Flax seeds and chia seeds can be also used for feeding to
animals to enrich their eggs and meat with omega 3 fats.
Eggs from hens fed with chia had higher ALA content as
compared to hens fed with flax seed (EFSA Journal,
2009; Coates and Ayerza, 2009).
It is necessary to know that chia seeds can be consumed
directly and do not need to be ground unlike flax, which
must be ground or milled prior to consumption. Since flax
seed content is protected by a thick shell and to obtain
benefits from flax seeds it is necessary to use not whole
seeds. Whole seeds passing through the digestive system
undigested.
CONCLUSION
The quality of protein and fat in chia seed, brown and
gold flax seed samples is excellent. Chia seed is the best
known plant source with the highest content of n-3 PUFA
α-linolenic fatty acid. Both flax seed and chia seed are the
good choice of healthy food to maintain a balanced serum
lipid profile. These seeds can be an appropriate alternative
to n-3 PUFA sources for vegetarians and people allergic to
fish. Flax seeds must be ground to release their nutrients,
but chia seeds do not.
REFERENCES
Association of Official Analytical Chemists (AOAC). 1990.
Official Methods of Analysis. 15th ed. AOAC, Arlington,
VA.
Ayad A. A. 2010. Characterization and properties of
flaxseed protein fractions: dissertation theses. Montreal,
Canada: MC Gill University. p. 180.
Ayerza, R., Coates, W., 2011. Protein content, oil content
and fatty acid profiles as potential criteria to determine the
origin of commercially grown chia (Salvia hispanica L.).
Industrial Crops and Products, vol. 34, no. 2, p. 1366-1371.
http://dx.doi.org/10.1016/j.indcrop.2010.12.007
Ayerza, R. 1995. Oil content and fatty acids composition of
chia (Salvia hispanica L.) from five Northwestern locations in
Argentina. Journal of the American Oil Chemist’s Society,
vol. 72, no. 9, p. 971-1090. [cit. 2014-02-13] Retrieved from
the web:
http://link.springer.com/article/10.1007%2FBF02660727
Ayerza, R. 2009. The seeds protein and oil content, fatty
acids composition, and growing cycle length of a single
genotype of chia (Salvia hispanica L.) as affected by
environmental factors. Journal of Oleo Science, vol. 58, no.7,
p. 347-54. http://dx.doi.org/10.5650/jos.58.347
Ayerza, R. 2010. Effect of seed color and growing locations
on fatty acid content and composizion of two chia (Salvia
hispanica L.) genotypes.as affected by environmental factors.
Table 2 Content of fatty acids, %
Chia seed
Brown Flax seed
Gold Flax seed
SEM
12:0
Lauric acid
0.03
0.03
0.03
0.00
14:0
Myristic acid
0.06
0.06
0.04
0.01
16:0
Palmitic acid
7.04
6.14
5.39
0.04
16:1 n-7
Palmitoleic
acid
0.03
0.05
0.02
0.01
18:0
Stearic acid
2.84
4.23
3.17
0.00
18:1 n-9
Oleic acid
7.30a
22.43b
18.70b
0.22
18:2 n-6
Linoleic acid
18.89
14.47
16.13
0.02
18:3 n-3
α- linolenic acid
63.79
52.38
56.37
0.16
20:0
Arachidic acid
0.02
0.21
0.15
0.00
Ʃ n-6
18.89
14.47
16.30
0.02
Ʃ n-3
63.79
52.38
56.37
0.16
n-6 PUFA / n-3 PUFA
0.30
0.28
0.29
0.04
abc means in row are significantly different (P ˂0.05)
Potravinarstvo® Scientific Journal for Food Industry
Volume 8 76 No. 1/2014
Journal of the American Oil Chemist’s Society, vol. 87,
no. 10, p. 1161-1165. http://dx.doi.org/10.1007/s11746-010-
1597-7
Bhatty, R.S. 1993. Further compositional analyses of flax:
mucilage, trypsin inhibitors and hydrocyanic acid. Journal of
American Oil Chemists´ Society, vol. 70, no. 9, p. 899-904.
http://dx.doi.org/10.1007/BF02545351
Capitani, M. I., Ixtaina, V. Y., Nolasco, S. M., Tomás, M.
C. 2013. Microstructure, chemical composition and mucilage
exudation of chia (Salvia hispanica L.) nutlets from
Argentina. Journal of the Science of Food and Agriculture.
vol. 93, no. 15, p. 3856-3862.
http://dx.doi.org/10.1002/jsfa.6327
Carter, J. F. 1996. Sensory evaluation of flaxseed of
different varieties. Proceedings Flax Institute, vol. 56,
p. 201-203.
Coates, W., Ayerza. R. 1998. Commercial production of
chia in Northwestern Argentina. Journal of the American Oil
Chemist’s Society, vol. 75, no. 10, p. 1417-1420.
http://dx.doi.org/10.1007/s11746-998-0192-7
Coates, W., Ayerza. R. 2009. Chia (Salvia hispanica L.)
seed as an n-3 fatty acids source for finishing pigs: effect on
fatty acids composition and fat stability of the meat and
internal fat, growth performance, and meat sensory
characteristics. Journal of Animal Science, vol. 87, no. 11,
p. 3798-804. http://dx.doi.org/10.2527/jas.2009-1987
Daun, J. K., Barthet, V. J., Chornick, T. L., Duguid, S.
2003. Structure, composition, and variety development of
flaxseed. Flaxseed in Human Nutrition, 2nd ed, Champaign,
IL: AOCS Press, p. 1-40, ISBN: 978-1-893997-38-7
http://dx.doi.org/10.1201/9781439831915.ch1
Gorjao, R., Azevedo-Martins, A. K., Rodrigues, H. G.,
Abdulkader, F., Arcisio-Miranda, M., Procopio, J., Curi, R.
2009. Comparative effect of DHA on cell function.
Pharmacology and Therapeutic, vol. 122, no.1, p. 56-64.
http://dx.doi.org/10.1016/j.pharmthera.2009.01.004
Hasler, C. M., Kundrat, S., Wool, D. 2000. Functional foods
and cardiovascular disease. Journal Current Atherosclerosis,
vol. 2, no. 6, p. 467-75. http://dx.doi.org/10.1007/s11883-000-
0045-9
Ixtaina ,V. Y., Nolasco, S. M., Tomás, M. C. 2008. Physical
properties of chia (Salvia hispanica L.) seeds. Industrial
Crops and Products, vol. 28, no. 3, p. 286-293.
http://dx.doi.org/10.1016/j.indcrop.2008.03.009
Jones, J. R., Lineback, D. M., Levine, M. J. 2006. Dietary
Reference intakes: implications for fiber labeling and
consumption: a summary of the International Life Sciences
Institute North America Fiber Workshop, June 1-2, 2004,
Washington, DC. Nutrition Reviews, vol. 64, no. 1, p. 31-38.
http://dx.doi.org/10.1111/j.1753-4887.2006.tb00170.x
PMid:16491667
Llames, C. R., J. Fontaine. 1994. Determination of amino
acids in feeds: Collaborative study. Journal of AOAC
(Association of Official Analytical Chemists) International,
vol. 77, no. 5, 1362-1402.
Martinchik, A. N., Baturin, A. K., Zubtsov, V. V.,
Molofeev, V.I. 2012. Nutritional value and functional
properties of flaxseed. Voprosy pitaniia, vol. 81, no. 3,
p. 4-10.
Oomah, B. D., Kenaschuk, E. O., Mazza, G. 1995. Phenolic
acids in flaxseed. Journal of Agricultural and Food
Chemistry, vol. 43, no. 8, p. 2016-2019.
http://dx.doi.org/10.1021/jf00056a011
Oomah, B. D., Mazza, G. 1993. Flaxseed proteins - A
review. Food Chemistry, vol. 48, no. 2, p. 109-114.
http://dx.doi.org/10.1016/0308-8146(93)90043-F
Reyes-Caudillo, E., Tecante, A., Valdivia-Lopez, M. A.
2008. Dietary fibre content and antioxidant activity of
phenolic compounds present in Mexican chia (Salvia
hispanica L.) seeds. Food Chemistry, vol. 107, no. 2,
p. 656-663. http://dx.doi.org/10.1016/j.foodchem.2007.08.062
Sammour, R. H. 1999. Proteins of linseed (Linum
usitatissimum L.), extraction and characterization by
electrophoresis. Botanical Bulletin of Academia Sinica,
vol. 40, no. 2, p. 121-126.
Scientific Opinion of the Panel on Dietetic products,
Nutrition and Allergies on a request from European
Commission related to labelling reference intake values for
n-3 and n-6 polyunsaturated fatty acids. The EFSA Journal,
2009, 1176, p. 1-11.
Simopoulos, A. P. 2004. Omega-6/Omega-3 essential fatty
acid ratio and chronic diseases. Food Review International.
vol.1, no. 1, p. 77-90. http://dx.doi.org/10.1081/FRI-120028831
Weber, C. W., Gentry, H. S., Kohlhepp, E. A., McCrohan,
P. R. 1991. The nutritional and chemical evaluation of chia
seeds. Ecology of Food and Nutrition, vol. 26, no. 2,
p. 119-125. http://dx.doi.org/10.1080/03670244.1991.9991195
Acknowledgments:
This article was written during realization of the project
"ZDRAVIE no. 26220220176" supported by the
Operational Programme Research and Development
funded from the European Regional Development Fund.
Contact address:
MVDr. Soňa Nitrayová, PhD., National Agricultural and
Food Center, Reasearch Institute of Animal Production
Nitra, Institue of Nutrition, Hlohovecká 2, 951 41
Lužianky, Slovakia, E-mail: nitrayova@vuzv.sk
Ing. Matej Brestenský, PhD., National Agricultural and
Food Center, Reasearch Institute of Animal Production
Nitra, Institue of Nutrition, Hlohovecká 2, 951 41
Lužianky, Slovakia, E-mail: m_brestensky@vuzv.sk
Doc. Ing. Jaroslav Heger, PhD., National Agricultural
and Food Center, Reasearch Institute of Animal
Production Nitra, Institue of Nutrition, Hlohovecká 2, 951
41 Lužianky, Slovakia, E-mail: jaroslavheger@gmail.com
Ing. Peter Patráš, PhD., National Agricultural and Food
Center, Reasearch Institute of Animal Production Nitra,
Institue of Nutrition, Hlohovecká 2, 951 41 Lužianky,
Slovakia, E-mail: patras@vuzv.sk
Doc. Ing. Ján Rafay, PhD., National Agricultural and
Food Center, Reasearch Institute of Animal Production
Nitra, Institute of Small Farm Animals, Hlohovecká 2, 951
41 Lužianky, Slovakia, E-mail: rafay@vuzv.sk
Prof. Ing. Alexander Sirotkin, DrSc., National
Agricultural and Food Center, Reasearch Institute of
Animal Production Nitra, Institute for Farm Animal
Genetics and Reproduction, Hlohovecká 2, 951 41
Lužianky, Slovakia, E-mail: sirotkin@vuzv.sk
