NUTRITIONAL EVALUATON OF RAPESEED CAKE FROM DEHULLED RAPESEED FED FOR PIGLETS AND GROWING-FINISHING PIGS

 

W. Kracht*, H. Jeroch*, S. Daenicke*, W. Matzke, U. Hennig**, W. Schumann***

 

Institute of Animal Nutrition and Planned Crop Storage, Agricultural Faculty of Martin-Luther-University Halle-Wittenberg, Emil-Abderhalden-Str.26, D-06108 Halle/Saale, Germany

** Research Institute for Biology of Farm Animals, Dummerstorf, Section Physiology of Nutrition „Oskar Kellner“, Justus-von-Liebig-Weg 2, D-18509 Rostock, Germany

*** Research Insitute of Agriculture and Fishery of Mecklenburg-Vorpommern, Dorfplatz 1, D18276 Gülzow, Germany

 

ABSTRACT

 

Incomplete defatted by-products of the oil production from not dehulled and dehulled rapeseed were evaluated analytic and in digestibility- and energy balance experiments with piglets (15-20 kg live weight) and pigs (80-85 kg live weight). The dehulling was conducted before oil withdrawal applying a procedure, which was developed by the Cimbria-Sket GmbH Magdeburg and the University Essen. The oil was removed by pressing till to an ether extract content of around 12 %. The rapeseed cakes (Rc) of not dehulled (nd) and dehulled (d) seed contained per kg dry matter (dm) g: crude protein nd 321, d 363; sugar nd 112, d 135; ether extract nd 120, d 128; crude fibre nd 102, d 61; NDF nd 253, d 151; ADF nd 197, d 120; lysine nd 18.5, d 20,4; methionine+cystine nd 15.0, d 17.1; threonine nd 14,9, d 16.1; tryptophane nd 4.4, d 5.0; total glucosinolates nd 15.5 µ mol/g, d 18.0 µmol/g dm; sinapine nd 11.75, 15.43; phytates nd 32.13, d 40.49; phytate-P from total P % nd 81, d 81. The apparent metabolizable energy (ME) contents in MJ/kg dm determined with piglets were: nd 10.95, d 13.62 and with pigs nd13.51, d 15.53. With minipigs (50 kg), which were equiped with ileorectal anastomoses, the precaecal digestibilities (pcd) of amino acids were determined. The pcd of lysine amounted to nd 75 %, d 86 %; of methionine +cystine nd 75 %, d 81 %; of threonine nd 69 %, d 77 % and of tryptophane nd 77 %, d 80 %.

 

KEYWORDS: Digestibility, metabolizable energy, precaecal digestibility, amino acids,                                              glucosinolates           

 

INTRODUCTION

 

In Germany rapeseed cake (Rc) or synonymous expeller is called a rapeseed by-product which contains more than 4 % ether extract. The oil is usually removed only by pressing. From the total quantity of rapeseed residues, which are used for feeding farm animals, the share of cakes amounted to around 10 to 15 %. But the tendency of cake production is increasing, because in the last decades

some small oil plants began to work on account of the rising rapeseed cultivation. The metabolizable

energy (ME) contents of rapeseed cakes exceeds the ME values of rapeseed meal considerably because of its higher fat content. Therefore it should be tested if the effect of removing the hulls, which has been found in the experiments with rapeseed meals, also appears at the higher energy levels of cakes.      

 

 

MATERIAL AND METHODS

 

A black-seeded rapeseed, variety Express, was dehulled before the withdrawal of oil. The applied dehulling procedure was developed by CIMBRIA-SKET GmbH, Magdeburg (Germany), in cooperation with the University Essen (Germany). The procedure will be described by Rasehorn (1999) on the occasion of this congress. The oil was removed by pressing till to a level of around 12 % ether extract. The rapeseed and the Rc from not dehulled (nd) and dehulled (d) rapeseed were subjected to chemical analyses using standard analytical techniques, which were described by Kracht et al. (1998).

The digestibility of crude nutrients and the ME contents of the Rc from nd and d seed were examined in balance experiments with piglets (15-20 kg live weight) and pigs (80-85 kg live weight).  The animals of the group 1 received a basal diet. In the diets of the groups 2 and 3 Rc from nd and d seed were substituted in the basal diet at a proportion of 40 %. In the experiment with piglets as basal diet was used a commercial starter feed, whereas in the experiment with pigs barley was fed, (supplemented with 0.3 % L-lysine of a mineral-vitamin premix). In both trials two successive collection periods were conducted, each of which comprised 5 days with piglets and 7 days with pigs. Per feeding variant were assigned 5 piglets respectively 4 pigs. The digestible energy (DE) content of the diets was measured as difference between the gross energy input with feed and the energy output with feces. The ME contents of the total diets were calculated from the estimated digestible nutrients, using an equation, which was published in the German feed-value table (DLG-Futterwerttabelle-Schweine, 1991). The DE and ME contents of Rc were calculated according to the difference method by substracting the ME content of the basal diet, determined with the animals of group 1, from the ME contents of the total diets, considering the Rc proportion of the diet.

The measurement of the precaecal digestibilities (pcd) of nutrients and amino acids were conducted with 8 minipigs (52-54 kg live weight), which were fitted with an end to end ileorectal anastomosis,with a preserved-caeco-colic valve according to Hennig et al. (1990). Animals were fed each diet 7 days in total, 3 days for adaption and 4 days for quantitative digesta collection. Further details were reported by Kracht et al. (1998). 

 

RESULTS AND DISCUSSION

 

Analytical results

 

The crude fibre content as well as the NDF and ADF levels of the Rc were decreased by dehulling the rapeseed by around 40 %, while the contents of crude protein and sugar rose by 13 and 21 % (Table 1). The ether extract remained nearly on the same level. The lignin content was only decreased about 9 %.

The sums of the 18 amino acids (AA) and of the 10 essential AA of the cake rose by removing the hulls about 12 %, while the lysine content and the sum of methionine + cystine were increased each about 2 g (Table 2).

The content of the different fatty acid groups of the cake was not influenced by dehulling (Table 3).

 

 

 

 

 

Table 1. Contents of crude nutrients, fibres, lignin and sugar of rapeseed and rapeseed

   cake (Rc) from not dehulled and dehulled rapeseed (g/kg dry matter)

 

 

 

Crude protein  

Ether extract 

Crude fibre  

NDF                                  

ADF   

Lignin (ADL)

Sugar        

rapeseed

   40

  181

  495

   66

  157

  145

   90

   52

Rc not dehulled

   68

  321

  120

  102

  253

  197

   80

  112

Rc dehulled

   73

  363

  128

    61

  151

  120

   73

  135

Rc not dehulled=100

  107

  113

  107

    60

    60

    61

   91

  121

            

Table 2. Contents of some essential amino acids in rapeseed and rapeseed

    cakes (Rc) from not dehulled and dehulled rapeseed (g/kg dry matter)

 

 

Dry matter g/kg

Crude protein

Lysine

Methionine +Cystine

Threonine

Tryptophane

å 10 essent. amino acids

å18 amino acids

rapeseed

  938

  181

  10.7

   8.6

   8.6

   2.3

   75.1

 168.9

Rc  not dehulled

  914

  321

  18.5

  15.0

  14.9

   4.4

  129.9

 292.6

Rc  dehulled

  926

  363

  20.4

  17.1

  16.1

   5.0

   145.7

 327.3

 

 

Table 3.  Contents of fatty acid groups in rapeseed and rapeseed cakes (Rc) from not dehulled                         (nd) and dehulled (d) rapeseed (g/kg dry matter)

       

 

Ether extract

Saturated     fatty acids

Unsaturated fatty acids

Mono- unsaturated fatty acids

Poly-unsaturated

fatty acids

rapeseed

      495

      33

     413

     280

     133

Rc nd

      120

        9

     101

       65

       34

Rc d

      127

        9

     104

       71

       35

 

The levels of antinutritional substances were increased in cakes in comparison to seed as consequence of incomplete fat removal (Table 4). By dehulling a further rise of antinutritional substances takes place, because the hulls contain only marginal amounts of these substances. During the withdrawal of oil by pressing with or without steam no intensive hydrothermal treatment procedure is performed as it is the case in the course of the toast procedure, which is conducted in connection with oil extraction. Therefore rapeseed cakes contain higher glucosinolate levels than rapeseed meals. In contrary to meals the cakes from dehulled seed don’t contain lower glucosinolate levels than cakes from not dehulled seed, because the reduction of steam penetration by the hull constituents of the by-products does not become effective during the press procedure. 

 

 

 

Table 4. Antinutritional substances in rapeseed and rapeseed cakes (Rc) from not de-                                      hulled and dehulled rapeseed in dry matter

                        

 

Total Glucosinolates           (µ mol/g)

Sinapine SCN    (g/kg)

Phytic acid               (g/kg)

Phytate- P (g/kg)

Phytate-P from total P (%)

rapeseed

   10.71

  6.65

   19.76

   5.57

   83

Rc  not dehulled 

   15.5

11.75

   32.13

   9.06 

   81

Rc dehulled

   18.0

15.43  

   40.49

  11.42

   81

 

Results of balance experiments with piglets and pigs

 

Digestibility experiments

The piglets consumed daily around 320 g of the diets and the finishing pigs nearly 2400 g.

The digestibility of organic matter of Rc was increased by dehulling the seed in the trial with piglets about 15 units and in trial with pigs by 10 units (Table 5). The digestibility of crude protein rose at piglets and pigs by 14 and 9 units. The digestibility of ether extract was increased at piglets and pigs by 4 units, whereas the digestibility of N-free extract rose about 11 respectively 7 units.

 

Table 5. Digestibilities of crude nutrients of rapeseed cakes (Rc) from not                                                          dehulled and dehulled rapeseed, determined with piglets and pigs (%)

 

Variant

Organic matter

Crude protein

Ether extract

 Crude fibre

N-free extract

Rc not dehulled

 

 

 

 

 

piglets (15-20 kg)

 59 ± 1.3

  65 ± 3.1

  63 ± 5.4

  1.4 ± 3.3

   68 ± 1.4

pigs    (80-85 kg)

 74 ± 2.0

  79 ± 1.9

  74 ± 6.2 

  39  ± 5.3

   80 ± 2.7

Rc not dehulled

 

 

 

 

 

piglets (15-20 kg)

 74 ± 2.1

  79 ± 3.9

  67 ± 5.0

  29  ±  5.1

   79 ± 1.2

pigs    (80 -85 kg)

 84 ± 1.8

  88 ± 1.4

  78 ± 2.5

  58  ±  8.4

   87 ± 1.3

 

Table 6. Energy content of rapeseed cake (Rc) from not dehulled and dehulled rapeseed,                     determined with piglets and pigs /kg dry matter

 

 

Gross energy (GE)       MJ

Digestible- energy (DE)       MJ

Digestibili- ty of  (GE)                             %         

Metaboli-zable  energy (ME) MJ

Metaboliza bility  of DE %

Rm not dehulled

 

 

 

 

 

piglets

 20.97

 11.44 a

  55

  10.95  a

 96

pigs

 20.97

 15.76 b

  75

  13.51  b

 86

Rm dehulled

 

 

 

 

 

piglets

 21.37

 15.25 b

  71

  13.62  b

  89

pigs

 21.37

 17.99 c

  84

  15.53  c

  86

P< 0.05 values in one column with unequal superscripts are significantly different

 

Energy balance experiments

The contents of digestible energ of Rc rose by dehulling per kg dry matter at piglets by 3.81 MJ that are around 33 %, whereas at pigs there was an increase about 2.23 MJ, that are around 14 % (Table 6). The ME contents of Rc rose at piglets by 2.67 MJ (=24 %) and at pigs about 2.02 MJ (= 14 %). The improvement of feed value by dehulling results by an increase of digestibility, the metabolizability of the digestible energy was not changed.

 

Precaecal digestibilities

The precaecal digestibility (pcd) of the organic matter rose by dehulling about 10 units. This rise

was caused nearly to a half by the improved crude protein and the NFE pcd (Table 7). The pcd of the sum of essential amino acids (AA) rose by dehulling about 7 units. The increase achieved at lysine 11, at methionine+cystine. 6, and at threonine 8 units. It is meaningful that the pcd of lysine (= 86 %) agrees with the lysine pcd of soybean oil meal, which amounts to 84 % (Veevoedertabel 1995).   

 

Table 7.  Precaecal digestibilities of organic matter, and of some nutrients and amino                                         acids (AA) of rapeseed cake from not dehulled and dehulld seed % 

 

 

Organic matter

Crude protein

N- free extract

Lysine

Met. +Cys.   

Threonine

Tryptophan

å ess. AA

Rm not dehulled

  57 a

   68 a

   66 a

 75.0 a

 75.0 a

 69.0 a

 77.0

 74.0 a

Rm dehulled

  67 b

   74 b

   71 b

 86.0 b

 81.0 b

 77.0 b

 80.0

  81.0 b

P<0.05, values in one column with unequal superscripts are significantly different

 

CONCLUSION

 

The feed value of rapeseed cake is significantly improved by dehulling the seed. In balance experiments with piglets and pigs was stated that the digestibilities of the crude nutrients and the metabolizable energy content were increased.

 

ACKNOWLEDGEMENTS

The authors are grateful to the UNION ZUR FÖRDERUNG VON OEL-UND ROTEINPFLANZEN, BONN, for the financial support of these researches.

 

REFERENCES

DLG-Futterwerttabellen- Schweine- ,1991: 6. Aufl. DLG-Verlag Frankfurt am Main

HENNIG, U.,  WÜNSCHE,J., SOUFFRANT, W. B., and HERRMANN, U., 1990: Untersuchungen zur präzäkalen Rohproteinverdauung und Aminosäurenresorption unter Anwendung der Ileorektostomie und Fisteltechnik bei Schweinen. Arch. exp. Vet. med. Leipzig, 44, 1, 35-44

KRACHT, W., JEROCH, H. et al. 1998: Gesteigerter Futterwert durch Schälung von Rapssaat, UFOP- Schriften, Heft 10, Union zur Förderung von Oel-und Proteinpflanzen e V.  Godesberger Allee 142-148, D- 53175 Bonn

VEEVOEDERTABEL, 1994: CVB central veevoederbureau runderweg 6, 8219 pk Lelystad, the Netherland