MILK AND MEAT QUALITY DUE TO RAPESEED PRODUCTS APPLICATION IN FARM ANIMALS
F. Schöne1, G. Jahreis2, G. Flachowsky3, U. Kirchheim1
1Agricultural Institution of Thuringia, D-07743 Jena, Naumburger Straße 98, Germany;
e-Mail: b8scfr@rz.uni-jena.de
2Friedrich-Schiller-University, Institute of Nutrition, D-07743 Jena, Dornburger Straße 24,
Germany [1]
3Federal Agricultural Research Centre, Institute of Animal Nutrition, Bundesallee 50,
D-38116 Braunschweig, Germany
ABSTRACT
Rapeseed constituents e. g. the glucosinolates may impair the performance of farm animals, however, the fat of rapeseed and rapeseed press cake affects the composition of fat produced from the animal in a more favourable way. In experiments with a total of 140 growing pigs up to 59 g rapeseed fat/kg diet and with a total of 40 growing bulls up to 84 g rapeseed fat/kg diet were tested via ground rapeseed and high fat rapeseed cake. In a market-monitoring study, 16 samples of a butter produced from milk of cows fed daily 350 - 400 g rapeseed oil equivalents were compared with 16 samples standard butter. In fattening animals no feeding effects on carcass and meat quality parameters, i.e. pH, meat colour, shear force and sensory characteristics could be detected. Meat composition did not vary, also not in intramuscular fat content. Depending on the amount of dietary rapeseed fat, the subcutaneous fat, particularly in pig carcasses, contained more polyunsaturated fatty acids (PUFA); for each 10 g rapeseed fat/kg diet there was an 0.8 % increase of linoleic acid and an 0.3 % increase of linolenic acid (basis 100 % fatty acid methyl esters). Using rapeseed fat in dairy cow rations lowered the palmitic acid content and increased the oleic acid content in fat of bulk milk samples as well as in butter. The softer milkfat and the better spreadability of butter is accompanied by an increased trans-fatty acid (TFA) content. However, conjugated linoleic acid (CLA) represents a part of TFA. CLA has some beneficial effects in contrast with the most TFA. In pigs as well as in ruminants additional rapeseed fat equivalents should be limited to 20 - 30 g/kg feed dry matter. In rape-cake diets for pigs the fat content is at least one third lower because glucosinolates limit this feed component to maximally 50 to 100 g/kg diet depending on the glucosinolate content.
KEYWORDS: Dietary fat, fatty acids, depot fat, butter
In previous experiments, pigs consumed rapeseed feed up to 1.5 ... 2 mmol glucosinolates/kg diet at the same level as the control diets free of glucosinolates (Schöne et al 1997). More than 3 mmol glucosinolates/kg diet caused a significant feed intake and growth depression (Tischendorf 1998). In ruminants no acceptance problems of today´s rapeseed products seem to exist, however, a high oil level via rapeseed and high-fat rapeseed press cake impaired rumen function and lowered digestibility and feed consumption (Flachowsky et al.1994). Despite such disadvantages of too much glucosinolates or rapeseed fat, there are some favourable effects on fatty acid composition, mainly of milkfat of cows receiving rapeseed fat (Jahreis et al. 1996). The objectives of present pig and bull experiments with rapeseed and rapeseed-cake diets were to quantify the fat changes in regard to transfer of rapeseed oil fatty acids to fat of animal body. In milk production the rapeseed oil application reached marketability. A special butter with higher oleic acid content competes with a butter standard. A representative number of these two kinds of butter and the respective bulk milk samples was to investigate.
MATERIAL AND METHODS
Animal experiments: Three experiments with a total of 140 fattening pigs (hybrids - Pietrain x Landrace) and two experiments with a total of 40 bulls (Expt 1 Simmental-Blackpied hybrids, Expt 2 Simmental) were carried out. In pigs as a maximum level 150 g/kg diet rapeseed and rapeseed-press- cake were tested corresponding to additional 59 g rape fat /kg rapeseed diet and 20 g/kg rapeseed-cake diet. Bulls received as maximum levels in Expt 1 214 g rapeseed/kg diet = 104 g ether extract/kg diet (= 84 g additional rapeseed fat) - the further feed ingredients being barley, chopped wheat straw and a mineral premix - in Expt 2 230 g rapeseed-press cake/kg diet - the further feed ingredients being grain, dried beet pulp and a mineral premix = 53 g ether extract/kg diet (= additional 39 g rapeseed fat/kg diet). All diets tested and the results of feed analysis were published (Flachowsky et al. 1994, Schöne et al. 1997). Slaughtering the pigs at the 12th - 14th rib region of left carcass half a chop sample was taken. Backfat of pigs and kidney fat of bulls were extracted with hexane, the freeze-dried meat samples with chloroform/methanol. Fatty acids were determined by capillary chromatography (CP9001, 30 m fused silica capillary column CP-WAX 52 CB, temperature programme 130 - 230 °C, 4°C/min., flame, ionization detector after esterification with sodium methylate.
Milk fat and butter study:Bulk-milk samples were taken from January to March 1998 in 9 cow herds with usual feeding and 4 herds with 350 g rapeseed-oil equivalents application per cow and day. Samples of special butter made from high oleic acid milkfat originated from a dairy, the standard butter represented different dairies. Fatty acid determination of milk and butter fat corresponded to backfat and meat fat analysis. In four butter samples of each segment the content of trans-fatty acids (TFA) was determined (Jahreis et al. in these proceedings). The method of cutting-resistance measurement was published (Schöne et al. 1998).
RESULTS AND DISCUSSION
In slaughtered pigs and bulls no feeding effects on carcass and meat-quality parameters, i.e. pH, meat colour, shear force and sensory characteristics, could be detected (Kirchheim et al. 1998). Meat composition did not vary, also not in intramuscular fat content.
Pig experiments: In the experiment with graded levels of rapeseed the fatty acid composition of dietary fat was varied, the fat content of diet, however, also varied (Table 1). According to low fat content the grain soya-bean meal diet had the lowest content of linoleic acid, 11g/kg, and linolenic acid, 1.3 g/kg. The diet with full-fat soya beans contained the highest linoleic acid content, 29 g/kg diet, and the 15 % rapeseed diet contained the highest linolenic acid content, 6.9 g/kg diet. It was a strong relationship between the linoleic as well as the linolenic acid content of backfat and diets. In the full-fat soya group, a threefold dietary linoleic acid content compared to soya-bean meal control doubled this fatty acid in backfat. The intermediate backfat linoleic acid content of the 15 % rapeseed group corresponded with 21 g/kg diet. One percent dietary rapeseed fat (21 % linoleic acid and 10 % linolenic acid ) = 2.5 % rapeseed increased backfat linoleic acid by 0.80 % and linolenic acid by 0.33 %. A borderline of 15 % polyunsaturated fatty acids (PUFA) (Enser et al. 1983) of total backfat fatty acid methylesters was exceeded with 60 g rapeseed fat/kg diet = 150 g rapeseed/kg diet. In intramuscular fat an additional linoleic acid intake did not change linoleic acid content; linolenic acid, however, was affected in intramuscular fat similarly to backfat. In case of full-fat soya beans, the higher dietary PUFA content decreased mainly the oleic acid content of animal-body fat. Rapeseed fat (60 % oleic acid) lowered the saturated fatty acids (SAFA); backfat monounsaturated fatty acids, mainly represented by oleic acid content, remained constant. With regard to consumers´health, a high-oleic-acid fat would be better, due to atherosclerosis-risk decrease by less LDL cholesterol and more HDL cholesterol in blood (Derr et al. 1993).
In the experiments with rapeseed cake the additional fat consumption was maximal 24 g/kg in 15 % rapeseed-press cake diet (not shown). The changes of linoleic and linolenic acid content of body fat agreed largely with results of the groups with 50 g rapeseed/kg diet (Table 1).
A higher oxidation susceptibility and lower storability of high PUFA fat was counteracted by tocopherols of rapeseed oil and by dietary tocopheryl acetate supplements (Flachowsky et al. 1997).
Table 1: Pig experiment with ground rapeseed - Fatty acid (FA) composition1) (SAFA saturated FA, MUFA = monosaturated FA, C18:2 and C18:3) of fats of diet and animal body, % of detected fatty acid methylesters
|
Rapeseed level g/kg diet |
0 |
0 |
50 |
100 |
150 |
SEM |
|
Ether extract g/kg diet |
24 |
60 |
46 |
64 |
83 |
|
|
Dietary fat |
|
|
|
|
|
|
|
SAFA |
17.6 |
16.0 |
11.9 |
10.0 |
9.1 |
- |
|
MUFA |
22.2 |
22.2 |
43.3 |
50.3 |
53.4 |
- |
|
C18:2 |
53.6 |
53.6 |
36.5 |
30.8 |
28.0 |
- |
|
C18:3 |
6.6 |
8.1 |
8.4 |
9.0 |
9.4 |
- |
|
Back fat |
|
|
|
|
|
|
|
SAFA |
41.1b |
37.9ab |
41.9b |
37.1ab |
34.0a |
0.43 |
|
MUFA |
49.7b |
42.4a |
47.7b |
49.2b |
50.4b |
0.32 |
|
C18:2 |
8.4a |
17.6c |
9.1a |
11.8ab |
12.8b |
0.29 |
|
C18:3 |
0.6a |
1.8b |
1.2b |
1.9b |
2.7c |
0.05 |
|
Intramuscular fat |
|
|
|
|
|
|
|
SAFA |
37.6b |
37.2b |
36.9b |
35.2ab |
34.3a |
0.39 |
|
MUFA |
43.6 |
42.1 |
45.2 |
45.2 |
45.0 |
0.55 |
|
C18:2 |
13.8 |
16.2 |
13.5 |
14.7 |
15.9 |
0.45 |
|
C18:3 |
0.4a |
0.8b |
0.9b |
1.0bc |
1.3c |
0.03 |
1) 0.9 - 1.3 % C14:0, 0.6 - 1.4 % C20:1. Only in intramuscular fat 3.4 - 4.5 % C20:4
Different letters in the same row indicate significant differences (P<0.05).
Bull experiments: As a tendency, the highest rapeseed levels tested decreased feed consumption and body weight gain (Flachowsky et al 1994). In these groups the high dietary fat content (77 and 104 g ether extract/kg) is assumed to have depressed the rumen fermentation - the rumen fluid samples had significantly lowered molar ratios of acetic acid and butyric acid and significantly higher molar ratios of propionic acid (Flachowsky et al. 1994). Regarding one third higher SAFA concentration of cattle fat comparing with pig fat the high rapeseed fat dose applicated diminished the SAFA content. It was a shift from palmitic acid to stearic acid with increasing dietary rapeseed oil content. The stearic and oleic acid increase of depot fat results from rumen hydrogenation of oleic acid, linoleic acid and linolenic acid of rapeseed oil. The linoleic acid content of depot fat not higher because of rapeseed oil application, indicates an almost complete biohydrogenation of plant oil PUFA. The intramuscular fat contained essentially more unsaturated fatty acids and less SAFA than the depot fat. With regard to palmitic and stearic acid the changes induced by rapeseed oil were similar to the depot fat. Contrasting with the higher oleic acid content of the depot fat due to rapeseed oil application this effect was not observed for the intramuscular oleic acid content.
Table 2: Bull experiment with ground rapeseed - Fatty acid (FA) composition1) (SAFA saturated FA, MUFA = monosaturated FA, C18:2 and C18:3) of fats of diet and animal body, % of detected fatty acid methyl esters (Flachowsky et al. 1994)
|
Rapeseed level g/kg diet1) |
0 |
71 |
141 |
214 |
SEM |
|
Ether extract g/kg diet 1) |
25 |
51 |
77 |
104 |
|
|
Dietary fat |
|
|
|
|
|
|
SAFA |
21.1 |
13.9 |
11.7 |
10.5 |
- |
|
MUFA |
23.0 |
43.7 |
50.1 |
53.5 |
- |
|
C18:2 |
47.8 |
33.2 |
28.2 |
26.4 |
- |
|
C18:3 |
5.2 |
7.8 |
8.6 |
9.0 |
- |
|
Kidney fat |
|
|
|
|
|
|
C16:0 |
23.1c |
19.2b |
18.2ab |
16.5a |
0.94 |
|
C18:0 |
30.4 |
33.8 |
34.7 |
34.3 |
1.98 |
|
SAFA |
58.5 |
57.4 |
57.1 |
54.8 |
2.20 |
|
MUFA |
32.8a |
34.9ab |
35.4ab |
36.6b |
1.06 |
|
C18:2 |
2.2 |
1.8 |
1.8 |
2.0 |
0.16 |
|
Intramuscular fat |
|
|
|
|
|
|
C16:0 |
24.2c |
21.5b |
20.8ab |
19.0a |
0.65 |
|
C18:0 |
17.8a |
20.6ab |
22.1b |
23.5b |
0.97 |
|
SAFA |
48.0 |
47.4 |
47.5 |
47.0 |
1.18 |
|
MUFA2) |
40.7 |
40.8 |
41.8 |
40.6 |
0.96 |
|
C18:22) |
6.2 |
5.3 |
4.2 |
5.0 |
0.81 |
|
C18:3 |
0.5 |
0.5 |
0.4 |
0.6 |
0.12 |
1) 286 g chopped wheat straw/kg diet in all groups and ground barley 714 g/kg diet in the control and 643, 573 and 500 g in the rapeseed groups.
2) 0.2 % C18:3
Table 3: Study on milk fat and butter - Fatty acid (FA) composition (%) (SAFA saturated FA, MUFA = monosaturated FA, PUFA = polyunsaturated FA) and butter spreadability without or with rapeseed oil application1) in cows2).
|
|
Without oil |
|
|
|
With oil |
|
|
|
|
|
Mean |
± |
SE |
|
Mean |
± |
SE |
|
|
Bulk milk fat % |
9 samples |
|
10 samples |
|
||||
|
SAFA |
72.7 |
± |
0.40 |
|
65.9 |
± |
0.57 |
*** |
|
MUFA |
23.4 |
± |
0.23 |
|
30.3 |
± |
0.51 |
*** |
|
PUFA |
3.8 |
± |
0.23 |
|
3.8 |
± |
0.06 |
Not significant |
|
Butter fat |
16 samples |
|
16 samples |
|
||||
|
SAFA |
71.1 |
± |
0.40 |
|
62.7 |
± |
0.02 |
*** |
|
MUFA |
26.4 |
± |
0.22 |
|
34.5 |
± |
0.35 |
*** |
|
PUFA |
2.5 |
± |
0.05 |
|
2.8 |
± |
0.05 |
** |
|
Cutting resistance N |
0.74 |
± |
0.03 |
|
0.33 |
± |
0.03 |
*** |
1) as rapeseed-press cake with at least 17 % ether extract Significance *P=0.05; **P=0.01; ***P=0.001
2) The concentration of individual FA and the measurement of cutting resistance were published (Schöne et al. 1998)
Quality parameters of milk fat and butter: The results of fatty acid determination in bulk milk samples and in butter confirmed the more favourable composition combined with the better butter spreadability. The dairy established a quality management with regular control of rapeseed-fat intake and milk-fatty acid composition. First investigations showed a higher TFA content of the special butter (6.7 ± 0.08 %, n =4) compared to standard butter (5.5 ± 0.16 %, n=4). However, the special butter contained more conjugated linoleic acid (CLA), 0.54 ± 0.1 %, than the standard, 0.46 ± 0.05 %. Contrary to most of TFA, CLA is assumed to have positive effects on consumer´s health (Jahreis et al. in these proceedings).
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[1]
This investigation was supported by a grant from the German Federal Ministry
of Nutrition, Agriculture and Forestry, No. 93 HS 025/1997