THE INFLUENCE OF FISH-MINERAL CONCENTRATE ON THE PROFILE OF FATTY ACIDS IN PIG’S LIVER AND BACKFAT

Zygmunt Usydus¹, Zbigniew Dobrzański², Justyna Kanderska¹, Adolf Korniewicz³, Roman Kołacz^4
1 Sea Fisheries Institute in Gdynia, Poland
² Department of Environment Hygiene and Animal Welfare, The Faculty of Biology and Animal Science, Wrocław University of Environmental and Life Sciences, Poland
³ Department of Animal Nutrition and Feed Science, Wrocław University of Environmental and Life Sciences, Poland
⁴ Department of Environmental Hygiene and Animal Welfare, Wrocław University of Environmental and Life Sciences, Poland

ABSTRACT

The study determined the influence of fish-mineral concentrate (KR-M) addition to fodder in the amount of 4 and 8% during the period of pig fattening up to approximately 100 kg of mass, on the profile of fatty acids in pig’s liver and backfat. The influence of KR-M was marked in liver fat by statistically significant (p<0.05) decrease of SFA and MUFA content with the increase of PUFA, including L-PUFA (EPA, DPA and DHA). Almost twofold increase of n-3 family acids occurred, while n-6/n-3 ratio was limited. The influence of KR-M in backfat was demonstrated by statistically significant (p<0.05) decrease of MUFA content, while PUFA increased, including L-PUFA (DPA and DHA). Over twofold increase of n-3 family acids occurred, while n-6/n-3 ratio was limited. The profile of backfat fatty acids was distinctly different than in liver; there were 9 acids more in this organ, and PUFA content was twofold higher. A more advantageous fatty acids’ profile in the experimental groups can be explained by the influence of fish oil and, possibly, the carriers applied (humins, aluminosilicates).

Key words: fish-mineral concentrate, pigs, liver, backfat, fatty acids.

INTRODUCTION

Fodder materials obtained from fish and fish waste play a more and more important role in animal feeding. An incredibly important advantage of fodder fish oils is a result of high content of polyunsaturated fatty acids (PUFA), and particularly polyunsaturated, long-chained and omega-3 family ones, i.e. L- PUFA n-3. As we know, EPA acids (eicosapentaenoic), DPA (docosapentaenoic) and DHA (docosahexaenoic) belong to them. Their content depends on the type of raw material and oil production technology [2, 9], and in mackerel oil it can constitute even 32.08% of the general fatty acid pool [28].

L-PUFA-family acids are absent in vegetable oils and are synthesised, to a limited extent, in animals and humans from alpha-linolenic acid (ALNA). L-PUFA acids from fish oils transit from the digestive tract into the bloodstream and liver during the digestion process, and as a result of complicated metabolic transformations they are deposited in animal tissues (muscle, fat) [4, 13, 18] as well as in milk [1, 11] and poultry eggs [21, 25]. Thus, they enrich animal-origin products with valuable elements fulfilling many biologically important functions in the human organism, among others they have a positive influence on the blood circulation and lipid metabolism, preventing atherosclerosis and hypercholesterolemia [10, 15, 27]. L-PUFA acids inhibit some forms of neoplasms, weaken inflammatory and allergic reactions, play an important role in brain and immune system functioning [5, 16].

In previous studies [3, 6, 8, 13, 30], the authors concentrated on the determination of influence of various vegetable and animal fats on the shaping of fatty acid profile in muscles, more seldom in liver or backfat, which undoubtedly constitute a valuable raw material for processing or direct consumption.

The aim of the study has been to determine the influence of fish-mineral concentrate addition applied in fodder concentrates for fattening pigs on the profile of fatty acids in liver and backfat.

MATERIAL AND METHODS

The experimental material included 30 finishing pigs (line 990) coming from the Experimental Farm of Animal Husbandry Institute in Pawłowice, with approximately 28 kg of initial body mass, and at the age of about 10 weeks. All animals wee kept in individual pens with concrete grill, equipped with auto-feeders (ad libitum feeding) and nipple drinkers. The animals were randomly assigned to 3 feeding groups of 10 animals each (5 sows and 5 hogs):

Group I – control one, fed with standard feed mixture
Group II – fed like group I, with 4% of KR-M
Group III – fed like group I, with 8 % of KR-M

KR-M consists of fish oil with plant oil admixture, put on mineral carriers (humin and aluminosilicate raw materials). It includes 89.03% of dry mass, 40.86% of raw ash, 1.29% of raw protein, 4.38% of raw fibre, 31.55 % of raw fat, 9.55 % of NFE, 15.89 g Ca/kg, 4.23 g Mg/kg, 1.32 g P/kg as well as other macro- and microelements. The concentrate includes 32.7 % SFA, 55.6 % MUFA and 11.7 % PUFA, while its energetic value amounts to 10.7 MJ/kg [28]. The authors registered KR-M to patent protection in the Patent Office of the Republic of Poland in 2004 [29].

Complete feed concentrates were produced according to the established formula in the local fodder laboratory of the Experimental Farm of the Animal Husbandry Institute in Pawłowice. The concentrate included the following ground grains: wheat, triticale, maize, extracted rape and soy meals, wheat bran, fish meal, chalk and fodder salt, dicalcium phosphate, lysine and vitamin-mineral premix. KR-M was used instead of wheat bran in group II and III. The metabolic energy was similar in all three groups and amounted to 1.7 MJ/kg, raw protein content in particular groups (I, II and III) was 17.65, 17.3 and 17.0 % respectively, raw fat: 2.3, 3.4 and 4.5 %, raw fibre: 5.0, 4.75 and 4.5 %, raw ash: 4.55, 6.1 and 7.6 %, lysine 0.96% [28]. Generally, the formulary composition and nutritive value of the applied mixtures correspond to Pig Feeding Standards [24].

The experiment was finished after 14 weeks with the finishing pigs’ slaughter at Meat Plant “SALUS”, where liver samples (from both lobes) and backfat samples were collected (from the back – at the border of thoracic and lumbar vertebrae). The samples were sent to the laboratory of the Department of Animal Products Technology of Agricultural University in Wrocław, where fat was extracted with the application of standard laboratory procedures [14]. The livers included 6.2 – 6.8 % of raw fat, while backfat – 79 – 81 %, which is consistent with other data [7, 12]. After freezing, the samples were sent in this form, in special containers, to the laboratory of the Sea Fisheries Institute, where they were subject to fatty acid content analyses. The assays were conducted by means of a chromatographic method [26], on gas chromatograph coupled with a mass spectrometer (manufactured by Varian, Saturn 2000). The chromatographic analysis of fatty acids was carried out after their prior transformation into methyl esters. After esterification, the samples were purified and neutralized, and subsequently spread over – previously deactivated with methanol – Bakerbond spe columns, filled with silica gel modified with benzenesulphonate groups. The extracts prepared in this way were analysed with the application of GC/MS technique by means of Rtx-5 MS capillary chromatographic column of 30 m length. The above-described method is used in MIR Research Laboratory – according to the elaborated experimental procedure (No PB-13/05).

The collected numerical data were analysed statistically by means of variance analysis, and the differences between groups were estimated with Duncan’s multiple range test, using Statgraphics v. 5.0 software.

RESULTS AND DISCUSSION

The results of fatty acids content determination in fat extracted from liver were listed in table 1. As can be seen, the addition of KR-M caused a statistically significant (p<0.05) decrease of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) pool in this fat. The biggest differences occurred between group I (control group) and III (8% KR-M) in case of C _16:0 and C _18:0 acids as well as C _18:1. A decreased content of these acids in experimental groups (II and III) was accompanied by an advantageous increase of unsaturated acids’ pool (UFA), and in particular polyunsaturated (PUFA), and among them long-chained ones (L-PUFA). This concerns C _20:5 (EPA), C _22:3 (DPA) and C _22:6 (DHA) acids. The concentration of C _18:3 n-3 (ALNA) acid, which is a precursor of n-3 L-PUFA acids, also increased twofold in groups taking KR-M. The content of n-3 family acids increased significantly in experimental groups, while n-6/n-3 relationship was limited.

Table. 1. Profile of fatty acids in finishing pigs’ liver fat

Fatty acid	Group I	Group II	Group III
Myristic C 14:0	0.19	0.17	0.12
Pentadecanoic C 15:0	0.08	0.08	0.06
Palmitic C 16:0	21.22 a	19.27 b	19.18 b
Heptadecanoic C 17:0	1.29	1.31	1.34
Stearic C 18:0	29.67	27.16	26.39
Arachidic C 20:0	0.06	0.08	0.05
Behenic C 22:0	0.12	0.07	0.10
Myristoleic C 14:1	0.00	0.03	0.03
Palmitoleic C 16:1	1.28 a	1.42 a	0.63 b
Heptadecenic C 17:1	0.23	0.19	0.18
Oleic C 18:1 n9c	17.63	15.91	15.77
Eicosenoic C 20:1	0.25	0.24	0.29
Nervonic C 24:1	0.00	0.03	0.03
Linolelaidic C 18:2 n6t	0.01	0.02	0.08
Linoleic C18:2 n6c	13.81	13.58	13.93
α-linolenic C 18:3 n3c	0.67 a	1.35 b	1.66 b
γ-linolenic C 18:3 n6	0.21	0.23	0.12
Eicosadienoic C 20:2 n6	0.61	0.59	0.73
dihomo-γ-linolenic C 20:3 n6	1.14	1.51	1.58
Arachidonic C 20:4 n6	6.00	7.27	7.33
Eicosapentaenoic C 20:5n3	0.55 a	2.29 b	2.22 b
Docosapentaenoic C 22:5 n3	2.08 a	2.70 b,c	3.23 b,d
Docosahexaenoic C 22:6 n3	2.90 a	4.50 b	4.95 b
Σ SFA	52.63 a	48.14 b	47.24 b
Σ UFA	47.37	51.86	52.76
Σ MUFA	19.39	17.82	16.93
Σ PUFA	27.98 a	34.04 b	35.83 b
Σ L-PUFA	5.53 a	9.49 b	10.40 b
Σ n-3	6.20 a	10.84 b	12.06 b
Σ n-6	21.78	23.20	23.77
Σ n-6/ Σ n-3	3.51a	2.14 b	1.97 b

a-,b, c-d – significant differences between groups at p < 0.05

The available literature includes numerous reports on the influence of fodder fat on the profile of fatty acids in pigs’ tissues and organs. D’Arrigo et al. [7] for example, found – in liver fat of pigs fed with a fodder including linseed oil or/and olive oil – a significant increase of oleic acid (C _18:1 n-9) and alpha-linolenic acid (C _18:3 n-3) as well as n-3 family acids with an accompanying decrease of n-6 forms in relation to the control group (sunflower oil). In this experiment, its authors obtained a slight increase of content of L-PUFA family acids in liver fat of the experimental groups. A similar effect was obtained by Enser et al. [13] when feeding the finishing pigs with fodder enriched with alpha-linolenic acid (ALNA), originating from linseed. Other authors [8] found statistically significant differences in the values of content of saturated acids (SFA), monounsaturated ones (MUFA) and, most importantly, polyunsaturated ones (PUFA) in tissues and organs of growing piglets receiving a low-fat diet (3% of fat – group I) and a high-fat diet, including 17% of beef tallow (group II) or fish oil (group III). For example, 2-3 fold decrease of the acids pool of C _18:2 n-6 and C _20:4 n-6 occurred in the liver fat of group III, with 30-fold EPA content increase in comparison to group I and II. The applied fats (tallow and fish oil) did not have a significant influence on the behaviour of transcription of genes responsible for fatty acids metabolism. An important transcription factor for adipocytes, i.e. factor 1 (ADD1), did not differ between the groups [8]. However, genetic factors have some influence on the accumulation of fatty acids in the finishing pigs’ liver, since Migdał et al. [23] found some differences in the formation of these acids, particularly MUFA, in 4 groups of hybrid pigs with various addition of pbz, wbp and pietrain breeds. The profile of fatty acids in liver, found in our experiments, is different than in the muscles of pigs; it includes over two-fold less MUFA, three-fold more PUFA, and even over ten-fold more of long-chained acids (L-PUFA) [4, 28, 30]. It proves easy transformation of L-PUFA family acids into the liver tissue, while using fish oil in finishing pigs’ feeding. In this context, the results of fatty acids content determination in backfat are particularly interesting (table 2).

Table. 2. Profile of fatty acids in finishing pigs’ backfat fat

Fatty acid	Group I	Group II	Group III
Pentadecanoic C 15:0	0.07	0.02	0.01
Palmitic C 16:0	23.71	22.90	22.26
Heptadecanoic C 17:0	0.42	0.35	0.32
Stearic C 18:0	18.43	19.52	19.49
Arachidic C 20:0	0.19 a	0.39 b	0.40 b
Palmitoleic C 16:1	2.66	1.76	2.50
Oleic C 18:1 n9c	40.46 a	37.78 b	36.64 b
Eicosenoic C 20:1	0.62	0.89	1.10
Linoleic C18:2 n6c	10.11	11.29	11.78
α-linolenic C 18:3 n3c	0.55 a	1.00 b	1.17 b
Eicosadienoic C 20:2 n6	0.48	0.53	0.59
Arachidonic C 20:4 n6	2.23 a	3.38 b	3.34 b
Docosapentaenoic C 22:5 n3	0.02 a	0.05	0.18 b
Docosahexaenoic C 22:6 n3	0.05 a	0.14 b	0.22 b
Σ SFA	42.82	43.18	42.48
Σ UFA	57.18	56.82	57.52
Σ MUFA	43.74 a	40.43 b	40.24 b
Σ PUFA	13.44 a	16.39 b	17.28 b
Σ L-PUFA	0.07 a	0.19 b,c	0.40 b,d
Σ n-3	0.62a	1.19 b,c	1.57 b,d
Σ n-6	12.82 a	15.20	15.71 b
Σ n-6/ Σ n-3	20.68 a	12.77 b	10.01 b

a-b, c-d – significant differences between groups at p < 0.05

The addition of KR-M to the mixture for finishing pigs caused a statistically significant (p<0.05) decrease of monounsaturated fatty acids (MUFA) in the fat extracted from backfat. The greatest differences occurred between the control group and experimental ones in case of oleinic acid (C _18:1). The decreased content of these acids in group II and III was accompanied by an advantageous increase of polyunsaturated fatty acids (PUFA) pool, and among them the long-chained ones (L-PUFA). This concerns C _22:3 (DPA) and C _22:6 (DHA) acids. The concentration of ALNA acid (C _18:3 n-3) also increased twofold in the groups receiving the concentrate, which is similar as in case of liver. The content of n-3 family acids increased over two-fold in the experimental groups, with advantageous limitation of n-6/n-3 ratio.

The profile of fatty acids in backfat is different than in liver but similar to the content found in muscles, although no EPA (C _20:5) and GLNA (C _18:3 n-6) at all were found in backfat. The content of n-6 family acids is considerably lower than in liver, but higher than in muscles [28]. It is worth mentioning that Korniewicz et al. [20], when administering fish oil to finishing pigs, based on humus-mineral carriers in the amount of 10% of daily dose, obtained a slightly different profile of fatty acids in backfat, namely SFA amounted to 52.73%, and UFA – 47.27 %, while the greatest differences were related to oleinic acid (C _18:1) as well as DPA and DHA in comparison to the authors’ own experiments. Also other authors [3, 8, 13, 30, 31] report a slightly different profile of backfat fatty acids or adipose tissue fatty acids after the application of various fodder fats. Wiesman et al. [31], on the other hand, found a lower content of stearic (C _18:0) and linolenic (C _18:3) acid, and a higher content of oleinic acid (C _18:1) in the external layer of backfat in comparison to the internal layer. Also Migdał et al. [22] found statistically significant differences in case of these acids in these two backfat layers, which concerned other unsaturated acids, too, while there were no differences for the general pool of PUFA and MUFA. The fatty acid profile for backfat taken from a place above scapula was slightly different. Thus, the different data found in literature, describing the fatty acids’ profile of backfat are clear, considering the multiplicity of factors determining lipid metabolism in these animals.

Summarising, it should be stressed that although the profiles of liver and backfat fatty acids differed significantly, yet they were more advantageous in the experimental groups. This fact can be explained by the influence of fish oil, and – possibly – also the carriers applied (humins, aluminosilicates), though the mechanism of their physiological and biochemical activity is still unknown.

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Study conducted within the scope of realisation of project PBZ-KBN No 060/T09/2001.

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Zygmunt Usydus
Sea Fisheries Institute in Gdynia, Poland
Kołłataja 1, 81-332 Gdynia, Poland
Phone: (+4858) 620-17-28
email: zygmunt@mir.gdynia.pl

Zbigniew Dobrzański
Department of Environment Hygiene and Animal Welfare, The Faculty of Biology and Animal Science, Wrocław University of Environmental and Life Sciences, Poland
J. Chełmońskiego 38 C
51-630 Wrocław
Poland
Phone: +48 71 320 5865
email: zbigniew.dobrzanski@up.wroc.pl

Justyna Kanderska
Sea Fisheries Institute in Gdynia, Poland
Kołłataja 1, 81-332 Gdynia, Poland
Phone: (+4858) 620-17-28

Adolf Korniewicz
Department of Animal Nutrition and Feed Science,
Wrocław University of Environmental and Life Sciences, Poland
Chełmonskiego 38 C, 51-630 Wrocław, Poland
email: Phone: (+4871) 320-58-39

Roman Kołacz
Department of Environmental Hygiene and Animal Welfare,
Wrocław University of Environmental and Life Sciences, Poland
Chełmońskiego 38 C, 51-630 Wrocław, Poland
Phone: (+48 71) 32 05 865

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