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The True Metabolizable Energy Values for Poultry of Rapeseed and of the Meal and Oil Derived Therefrom1
The True Metabolizable Energy Values for Poultry of Rapeseed and of the Meal and Oil Derived Therefrom1 I. R. SIBBALD
Animal Research Institute, Agriculture Canada, Central Experimental Farm, Ottawa, Ontario K1A 0C6 (Received for publication February 24, 1977)
Poultry Science 56:1652-1656, 1977 INTRODUCTION There is a lack of information describing the true metabolizable energy (T.M.E.) values of rapeseed and of the products derived therefrom. Sibbald and Price (1977) measured the T.M.E. values of the ground, full-fat seeds of nine varieties of Brassica campestris (3.91—5.35 kcal./g. D.M.), four varieties of B. hirta (4.55—5.06 kcal./g. D.M.) and ten varieties of B. napus (4.59-5.71 kcal./g. D.M.); neither meals nor oils derived from these seeds were available for assay. In an earlier report Sibbald (1977a) found the T.M.E. values of four samples of rapeseed meal to range from 2.15 to 2.52, with a mean of 2.31, kcal./g. of dry matter. The meals were obtained from feed manufacturers and were not identified with respect to the type of seed from which they were derived or to the manufacturing process. The work described in this report was designed to measure the T.M.E. values for poultry of full-fat rapeseed and of the meal and oil derived therefrom. The rapeseed was processed commercially by two different methods. MATERIALS AND METHODS Experiment 1. Two lots of rapeseed, identified as Tower and LEAR (low erucic acid
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Contribution number 684, Animal Research Insti-
rapeseed), were processed in a commercial, solvent extraction plant. Samples of the seeds, crude oils, degummed oils and meals were taken for analysis. A basal diet (Table 1) and eight diets prepared therefrom were assayed for T.M.E. by the method of Sibbald (1976); there were six replications. The first four experimental diets consisted of 85% of basal + 15% of rapeseed oil. Two diets consisted of 50% of basal + 50% of finely ground, full-fat rapeseed and there were two diets consisting of 50% of basal + 50% of rapeseed meal. In addition the two rapeseed meals were assayed as received, that is they were not combined with any other feedingstuffs. The T.M.E. values of the rapeseed products were calculated by difference. The ground rapeseed and rapeseed meal were assayed for nitrogen, ether extract, crude fibre, ash and dry matter by the methods of the A.O.A.C. (1975). The oils were assayed for fatty acid composition by gas liquid chromatography using the stationary phases butanediol succinate (5%) and SP-222-PS (10%). Experiment 2. The experiment was of the same design and followed the same procedures as the first experiment. The two lots of rapeseed, identified as Tower and HEAR (high erucic acid rapeseed), were processed in a commercial, prepress solvent extraction plant. The Tower seed used in this experiment was not drawn from the same lot as that used in the first experiment.
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ABSTRACT Two experiments were made to measure the true metabolizable energy (T.M.E.) values of rapeseed and rapeseed products. In the first experiment full-fat Tower and LEAR seeds were assayed as were the crude oils, degummed oils and meals prepared therefrom in a commercial solvent extraction plant. In the second experiment Tower and HEAR seeds were assayed together with oils and meals prepared in a prepress solvent extraction plant. Within experiments there were no differences between the T.M.E. values of the full-fat seeds. In Exp. 1 Tower Oil contained more (P<0.01) T.M.E. than LEAR Oil but in Exp. 2 there was no difference between Tower and HEAR oils (P>0.05). Removal of gums had no effect on oil T.M.E. values. Tower meal contained more T.M.E. than either LEAR or HEAR meals. Processing appeared to affect the availability of the energy of Tower seed; the full-fat seed had a T.M.E. value of 4.96 kcal./g. while the yield in terms of oil and meal was calculated to be 5.45 kcal./g.
T.M.E. OF RAPESEED PRODUCTS TABLE 1.—Composition of the basal diet Ingredient Wheat, ground Soybean meal (49% protein) Ground limestone Dicalcium phosphate Vitamin premix1 Trace mineral premix2
76 20 1.5 1.5 0.5 0.5
RESULTS Experiment 1. The T.M.E. values of the rapeseed products are displayed as means in Table 2; the gross energy values are included in the table for purposes of comparison. The LEAR and Tower full-fat seeds had similar T.M.E. values of 5.10 and 4.96 kcal./g. of dry matter, respectively. A t-test showed that the difference was not significant (P>0.05). The gross energy values were also similar. The
Tower seed contained more ether extract and less crude fibre than the LEAR seed (Table 3) but apparently the differences were too small to cause differences in the T.M.E. values. The T.M.E. data describing the rapeseed oils revealed a varietal difference but removal of the gums had little effect; this was confirmed by an analysis of variance. The Tower oil contained more T.M.E. than did the LEAR oil (9.49 vs. 8.95 kcal./g.; P<0.01); however, removal of the gums from the oils caused no significant (P>0.05) change in the T.M.E. values (9.26 vs. 9.18 kcal./g.). The interaction between oil varieties and the presence or absence of gums was not significant (P>0.05). The data of Table 4 show that the Tower oils contained slightly more dienes and trienes and slightly less monoenes than did the LEAR oils. The removal of gums had little effect on the fatty acid composition. The Tower meal contained more T.M.E. than did the LEAR meal. The assay procedure, that is assaying the meal alone as opposed to assaying a mixture of meal and basal diet, appeared to have a variable effect. Analysis of variance confirmed that the Tower meal contained more (P<0.01) T.M.E. than did the LEAR meal (2.52 vs. 2.21 kcal./g. of dry matter). A simple comparison of the two assay
TABLE 2.—The T.M.E. and gross energy values of rapeseed products Experiment 2
Experiment 1 Rapeseed product
T.M.E.1
G.E.2
LEAR seed Tower seed HEAR seed
5.10 ± 0.05 4.96 ± 0.04
6.84 6.93
LEAR oil crude LEAR oil degummed Tower oil crude Tower oil degummed HEAR oil crude HEAR oil degummed
8.95 8.95 9.58 9.41
± 0.24 ± 0.16 ±0.10 ± 0.29
9.44 9.47 9.45 9.46
+ ± ± ±
4.80 4.80 4.81 4.81
LEAR LEAR Tower Tower HEAR HEAR 1
meal 3 meal 4 meal 3 meal4 meal 3 meal4
... 2.17 2.26 2.60 2.45
0.06 0.05 0.03 0.06
T.M.E.1
G.E. 2
4.87 ± 0.05 4.99 ± 0.10
6.43 6.46
... 9.12 8.92 9.40 9.04
± ± ± ±
0.13 0.14 0.20 0.24
9.43 9.44 9.54 9.56
2.58 2.62 2.25 2.39
± + ± ±
0.14 0.04 0.06 0.06
4.74 4.74 4.77 4.77
Data are means and standard errors of 6 replicate determinations expressed as kcal./g. of dry matter. Data are means of duplicate determinations expressed as kcal./g. of dry matter. 3 Fed in conjunction with the basal diet. 4 Fed alone. 2
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'Supplied (per kg. of premix): vitamin A, 1,577,000 I.U.; vitamin D 3 , 315,000 I.C.U.; vitamin E, 945 I.U.; menadione sodium bisulphite, 0.31 g.; riboflavin, 1.25 g.; niacin, 6.3 g.; calcium pantothenate, 1.57 g.; folic acid, 0.31 g.; choline chloride, 31.5 g.; vitamin B, 2 1.6 mg. 'Supplied (per kg. of premix): Mn, 16 g.; Cu, 1.26 g.; Zn, 1.6 g.; Fe, 0.32 g.
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I. R. SIBBALD TABLE 3.—Proximate composition of the rapeseeds and rapeseed meals*
Nitrogen
Ether extract
Crude fibre
Ash
Experiment 1 LEAR seed Tower seed LEAR meal Tower meal
3.73 3.67 6.55 6.69
42.3 45.4 2.6 2.9
9.50 8.98 12.18 12.27
3.84 4.06 6.91 7.39
Experiment 2 Tower seed HEAR seed Tower meal HEAR meal
4.24 3.83 7.10 7.26
41.3 42.7 2.0 2.3
9.62 9.05 10.48 12.53
4.05 3.98 7.41 7.20
1
Data expressed on the basis of dry matter.
procedures revealed n o significant ( P > 0 . 0 5 ) difference; however, there was a significant ( P < 0 . 0 5 ) interaction which indicated t h a t feeding meal in c o m b i n a t i o n with t h e basal diet decreased t h e T.M.E. of L E A R while increasing t h a t of Tower. T h e t w o meals were very similar in p r o x i m a t e c o m p o s i t i o n which suggests t h a t s o m e o t h e r variable was responsible for t h e difference in t h e T.M.E. values. Experiment 2. T h e T.M.E. a n d gross energy
values of t h e rapeseed p r o d u c t s are displayed as m e a n s in Table 2. T h e T o w e r and H E A R full-fat seeds had mean T.M.E. values of 4 . 8 7 a n d 4 . 9 9 kcal./g. of d r y m a t t e r , respectively. A t-test s h o w e d t h a t t h e m e a n s were n o t different ( P > 0 . 0 5 ) . T h e Tower seed contained m o r e nitrogen, less e t h e r e x t r a c t and m o r e crude fibre t h a n t h e H E A R seed (Table 3) b u t these differences did n o t cause variation b e t w e e n t h e T.M.E. values.
TABLE 4.-Fatty acid compositions of the rapeseed oils (%) Experiment 2
Experiment 1 Fatty acid 1
Tower crude
Tower degummed
LEAR crude
LEAR degummed
Tower crude
Tower degummed
HEAR crude
HEAR degummed
14:0 16:0 16:1 18:0 18:1 18:2 18:3
0.1 4.6 0.3 1.8 61.1 20.4 8.2
0.1 4.7 0.3 1.6 57.7 21.5 9.4
0.1 4.2 0.3 1.8 62.1 19.7 7.6
0.1 4.2 0.3 1.8 61.6 19.6 7.9
0.1 4.8 0.4 1.9 61.1 20.8 7.8
0.1 4.6 0.4 2.0 55.3 19.6 7.4
0.1 3.8 0.3 1.3 21.5 13.9 6.1
0.1 3.6 0.2 1.3 21.8 12.9 5.2
20:1 20:2 22:0 22:1 24:0 24:1
1.7 0.1 0.4 1.2 0.2 0.3
2.2 0.1 0.3 2.1 0.2 0.3
2.0 0.1 0.3 1.8 0.2 0.3
2.0 0.1 0.3 1.6 0.2 0.3
1.7 0.1 0.5 0.8 0.2 0.3
3.3 0.1 0.3 6.1 0.3 0.2
12.2 0.5 0.1 38.3 0.3 1.2
12.6 0.6 0.1 39.8 0.2 1.0
7.3 64.6 20.5 8.2
7.0 62.6 21.6 9.4
6.7 66.4 19.8 7.6
6.8 65.8 19.7 7.9
7.6 64.3 20.9 7.8
7.5 65.3 19.7 7.4
5.7 73.5 14.4 6.1
5.6 75.4 13.5 5.2
Saturates Monoenes Dienes Trienes
'Number of carbon atoms: number of double bonds. Minor fatty acids (15:0, 17:0, 20:4) are not included in the table.
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Rapeseed product
T.M.E. OF RAPESEED PRODUCTS
DISCUSSION The T.M.E. values of the full-fat rapeseeds are similar to those observed by Sibbald and Price (1977). In the present work the ground seeds were blended with a basal diet prior to assay whereas in the earlier work the ground seeds were assayed alone. In the first experiment the Tower and LEAR seeds had T.M.E. values which were not different (P>0.05) but the Tower oil and meal contained more T.M.E. (FKO.01) than did the LEAR oil and meal. The solvent extraction process removed 42% of oil from the Tower seed and 40% from the LEAR seed. Assuming that the residue was meal it is possible to calculate the T.M.E. yields of the two seed varieties following extraction. For example 1 g. of Tower seed yielded 0.42 g. of crude oil (9.58 kcal./g.) and 0.58 g. of meal (2.52 kcal./g.) giving a total T.M.E. yield of 5.45 kcal./g.; this is substantially greater than the T.M.E. value of
the unextracted seed (4.96 kcal./g.). For LEAR seed the calculated T.M.E. yield is 4.91 kcal./g. which is slightly lower than the observed value for the unextracted seed (5.10 kcal./g.). These differences suggest that the processing effectively increased the availability of the energy in Tower seed but had a slight negative effect on the availability of the LEAR energy. In the second experiment the Tower and HEAR seeds and oils exhibited no varietal differences (P>0.05) but the Tower meal contained more T.M.E. (P<0.01) than did the HEAR meal. These seeds were processed in a prepress solvent extraction plant. Unfortunately the extraction rates are not available but it seems probable that the processes enhanced the utilization of the energy of Tower seed. The Tower oil assayed in the first experiment appeared to contain more T.M.E. than did the samples assayed in the second experiment. However, the differences may not be real when viewed in light of the variation associated with the mean values. The fatty acid compositions of the crude oils are remarkably similar (Table 4) but, as mentioned earlier, the degummed oil of the second experiment appears to have been contaminated. The two lots of Tower meal had similar T.M.E. values (2.52 and 2.60 kcal./g. of dry matter) suggesting that the differences in processing had no major effects upon the availability of the energy in the meal; however, this is not conclusive because the two lots of Tower seeds were not drawn from the same source. In the first experiment the method of assay had a small (P<0.05) effect on the T.M.E. values of the two meals. This suggests that the T.M.E. value of rapeseed meal is not additive; however, in the second experiment there were no differences (P>0.05) associated with the method of assay. Sibbald (1977b) found that the T.M.E. values of six feedingstuffs, not including rapeseed meal, were additive. It may be possible for feedingstuffs to interact to make the T.M.E. value of a mixture different from the mean of the T.M.E. values of its component parts but it seems probable that the differences in experiment one were due to experimental variation. Support for this interpretation is provided by the data of the second experiment.
ACKNOWLEDG EMENTS
The author is indebted to J. R. Reynolds and CSP Foods, Saskatoon for the rapeseed
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The crude HEAR oil contained more T.M.E. than did the crude Tower oil (9.40 vs. 9.12 kcal./g.) but the degummed oils had similar values (9.04 vs. 8.92 kcal./g.). Analysis of variance of the data showed that none of the differences was significant (P>0.05). The HEAR oil contained relatively high levels of erucic and eicosenoic acids and substantially less linoleic acid when compared to the Tower oil (Table 4). While the removal of gums had little effect on the composition of the HEAR oil there were differences between the crude and degummed Tower oils; the differences were confirmed by repeating the fatty acid analyses. It seems probable that the degummed Tower oil was contaminated with HEAR oil during the manufacturing process. The Tower meal contained more T.M.E. than did the HEAR meal (2.60 vs. 2.32 kcal./g. of dry matter) but the assay procedure appeared to be without effect (2.41 vs. 2.50 kcal./g. of dry matter). Analysis of variance confirmed the varietal difference (P<0.01) and showed that the difference between assay procedures was not significant (P>0.05). The interaction between varieties and assay procedures was not significant (P>0.05). The HEAR meal contained more nitrogen, ether extract and crude fibre than did the Tower meal (Table 4) but the differences were less than would be expected to cause the observed difference in T.M.E. values.
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I. R. SIBBALD
p r o d u c t s , t o Dr. J. K. G. Kramer of t h e Animal Research Institute w h o provided t h e fatty acid analyses, a n d t o t h e Chemical a n d Biological Research Institute of Agriculture Canada for t h e p r o x i m a t e analyses of t h e seeds and meals. T h e efficient technical s u p p o r t of Mrs. S. T o b i n is gratefully acknowledged.
REFERENCES Association of Official Agricultural Chemists, 1975.
Official Methods of Analysis, 12th ed. Washington, D.C. Sibbald, I. R., 1976. A bioassay for true metabolizable energy in feedingstuffs. Poultry Sci. 55:303—308. Sibbald, I. R. 1977a. The true metabolizable energy values of some feedingstuffs. Poultry Sci. 56:380— 382. Sibbald, I. R., 1977b. A test of the additivity of true metabolizable energy values of feedingstuffs. Poultry Sci. 56:363-366. Sibbald, I. R., and K. Price, 1977. The true metabolizable energy values of the seeds of Brassica campestris, B. hirta and B. napus. Poultry Sci. 56:000— 000. Downloaded from http://ps.oxfordjournals.org/ at Universitaetsbibliothek Osnabrueck on May 27, 2015
Animal Research Institute, Agriculture Canada, Central Experimental Farm, Ottawa, Ontario K1A 0C6 (Received for publication February 24, 1977)
Poultry Science 56:1652-1656, 1977 INTRODUCTION There is a lack of information describing the true metabolizable energy (T.M.E.) values of rapeseed and of the products derived therefrom. Sibbald and Price (1977) measured the T.M.E. values of the ground, full-fat seeds of nine varieties of Brassica campestris (3.91—5.35 kcal./g. D.M.), four varieties of B. hirta (4.55—5.06 kcal./g. D.M.) and ten varieties of B. napus (4.59-5.71 kcal./g. D.M.); neither meals nor oils derived from these seeds were available for assay. In an earlier report Sibbald (1977a) found the T.M.E. values of four samples of rapeseed meal to range from 2.15 to 2.52, with a mean of 2.31, kcal./g. of dry matter. The meals were obtained from feed manufacturers and were not identified with respect to the type of seed from which they were derived or to the manufacturing process. The work described in this report was designed to measure the T.M.E. values for poultry of full-fat rapeseed and of the meal and oil derived therefrom. The rapeseed was processed commercially by two different methods. MATERIALS AND METHODS Experiment 1. Two lots of rapeseed, identified as Tower and LEAR (low erucic acid
1
tute.
Contribution number 684, Animal Research Insti-
rapeseed), were processed in a commercial, solvent extraction plant. Samples of the seeds, crude oils, degummed oils and meals were taken for analysis. A basal diet (Table 1) and eight diets prepared therefrom were assayed for T.M.E. by the method of Sibbald (1976); there were six replications. The first four experimental diets consisted of 85% of basal + 15% of rapeseed oil. Two diets consisted of 50% of basal + 50% of finely ground, full-fat rapeseed and there were two diets consisting of 50% of basal + 50% of rapeseed meal. In addition the two rapeseed meals were assayed as received, that is they were not combined with any other feedingstuffs. The T.M.E. values of the rapeseed products were calculated by difference. The ground rapeseed and rapeseed meal were assayed for nitrogen, ether extract, crude fibre, ash and dry matter by the methods of the A.O.A.C. (1975). The oils were assayed for fatty acid composition by gas liquid chromatography using the stationary phases butanediol succinate (5%) and SP-222-PS (10%). Experiment 2. The experiment was of the same design and followed the same procedures as the first experiment. The two lots of rapeseed, identified as Tower and HEAR (high erucic acid rapeseed), were processed in a commercial, prepress solvent extraction plant. The Tower seed used in this experiment was not drawn from the same lot as that used in the first experiment.
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ABSTRACT Two experiments were made to measure the true metabolizable energy (T.M.E.) values of rapeseed and rapeseed products. In the first experiment full-fat Tower and LEAR seeds were assayed as were the crude oils, degummed oils and meals prepared therefrom in a commercial solvent extraction plant. In the second experiment Tower and HEAR seeds were assayed together with oils and meals prepared in a prepress solvent extraction plant. Within experiments there were no differences between the T.M.E. values of the full-fat seeds. In Exp. 1 Tower Oil contained more (P<0.01) T.M.E. than LEAR Oil but in Exp. 2 there was no difference between Tower and HEAR oils (P>0.05). Removal of gums had no effect on oil T.M.E. values. Tower meal contained more T.M.E. than either LEAR or HEAR meals. Processing appeared to affect the availability of the energy of Tower seed; the full-fat seed had a T.M.E. value of 4.96 kcal./g. while the yield in terms of oil and meal was calculated to be 5.45 kcal./g.
T.M.E. OF RAPESEED PRODUCTS TABLE 1.—Composition of the basal diet Ingredient Wheat, ground Soybean meal (49% protein) Ground limestone Dicalcium phosphate Vitamin premix1 Trace mineral premix2
76 20 1.5 1.5 0.5 0.5
RESULTS Experiment 1. The T.M.E. values of the rapeseed products are displayed as means in Table 2; the gross energy values are included in the table for purposes of comparison. The LEAR and Tower full-fat seeds had similar T.M.E. values of 5.10 and 4.96 kcal./g. of dry matter, respectively. A t-test showed that the difference was not significant (P>0.05). The gross energy values were also similar. The
Tower seed contained more ether extract and less crude fibre than the LEAR seed (Table 3) but apparently the differences were too small to cause differences in the T.M.E. values. The T.M.E. data describing the rapeseed oils revealed a varietal difference but removal of the gums had little effect; this was confirmed by an analysis of variance. The Tower oil contained more T.M.E. than did the LEAR oil (9.49 vs. 8.95 kcal./g.; P<0.01); however, removal of the gums from the oils caused no significant (P>0.05) change in the T.M.E. values (9.26 vs. 9.18 kcal./g.). The interaction between oil varieties and the presence or absence of gums was not significant (P>0.05). The data of Table 4 show that the Tower oils contained slightly more dienes and trienes and slightly less monoenes than did the LEAR oils. The removal of gums had little effect on the fatty acid composition. The Tower meal contained more T.M.E. than did the LEAR meal. The assay procedure, that is assaying the meal alone as opposed to assaying a mixture of meal and basal diet, appeared to have a variable effect. Analysis of variance confirmed that the Tower meal contained more (P<0.01) T.M.E. than did the LEAR meal (2.52 vs. 2.21 kcal./g. of dry matter). A simple comparison of the two assay
TABLE 2.—The T.M.E. and gross energy values of rapeseed products Experiment 2
Experiment 1 Rapeseed product
T.M.E.1
G.E.2
LEAR seed Tower seed HEAR seed
5.10 ± 0.05 4.96 ± 0.04
6.84 6.93
LEAR oil crude LEAR oil degummed Tower oil crude Tower oil degummed HEAR oil crude HEAR oil degummed
8.95 8.95 9.58 9.41
± 0.24 ± 0.16 ±0.10 ± 0.29
9.44 9.47 9.45 9.46
+ ± ± ±
4.80 4.80 4.81 4.81
LEAR LEAR Tower Tower HEAR HEAR 1
meal 3 meal 4 meal 3 meal4 meal 3 meal4
... 2.17 2.26 2.60 2.45
0.06 0.05 0.03 0.06
T.M.E.1
G.E. 2
4.87 ± 0.05 4.99 ± 0.10
6.43 6.46
... 9.12 8.92 9.40 9.04
± ± ± ±
0.13 0.14 0.20 0.24
9.43 9.44 9.54 9.56
2.58 2.62 2.25 2.39
± + ± ±
0.14 0.04 0.06 0.06
4.74 4.74 4.77 4.77
Data are means and standard errors of 6 replicate determinations expressed as kcal./g. of dry matter. Data are means of duplicate determinations expressed as kcal./g. of dry matter. 3 Fed in conjunction with the basal diet. 4 Fed alone. 2
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'Supplied (per kg. of premix): vitamin A, 1,577,000 I.U.; vitamin D 3 , 315,000 I.C.U.; vitamin E, 945 I.U.; menadione sodium bisulphite, 0.31 g.; riboflavin, 1.25 g.; niacin, 6.3 g.; calcium pantothenate, 1.57 g.; folic acid, 0.31 g.; choline chloride, 31.5 g.; vitamin B, 2 1.6 mg. 'Supplied (per kg. of premix): Mn, 16 g.; Cu, 1.26 g.; Zn, 1.6 g.; Fe, 0.32 g.
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I. R. SIBBALD TABLE 3.—Proximate composition of the rapeseeds and rapeseed meals*
Nitrogen
Ether extract
Crude fibre
Ash
Experiment 1 LEAR seed Tower seed LEAR meal Tower meal
3.73 3.67 6.55 6.69
42.3 45.4 2.6 2.9
9.50 8.98 12.18 12.27
3.84 4.06 6.91 7.39
Experiment 2 Tower seed HEAR seed Tower meal HEAR meal
4.24 3.83 7.10 7.26
41.3 42.7 2.0 2.3
9.62 9.05 10.48 12.53
4.05 3.98 7.41 7.20
1
Data expressed on the basis of dry matter.
procedures revealed n o significant ( P > 0 . 0 5 ) difference; however, there was a significant ( P < 0 . 0 5 ) interaction which indicated t h a t feeding meal in c o m b i n a t i o n with t h e basal diet decreased t h e T.M.E. of L E A R while increasing t h a t of Tower. T h e t w o meals were very similar in p r o x i m a t e c o m p o s i t i o n which suggests t h a t s o m e o t h e r variable was responsible for t h e difference in t h e T.M.E. values. Experiment 2. T h e T.M.E. a n d gross energy
values of t h e rapeseed p r o d u c t s are displayed as m e a n s in Table 2. T h e T o w e r and H E A R full-fat seeds had mean T.M.E. values of 4 . 8 7 a n d 4 . 9 9 kcal./g. of d r y m a t t e r , respectively. A t-test s h o w e d t h a t t h e m e a n s were n o t different ( P > 0 . 0 5 ) . T h e Tower seed contained m o r e nitrogen, less e t h e r e x t r a c t and m o r e crude fibre t h a n t h e H E A R seed (Table 3) b u t these differences did n o t cause variation b e t w e e n t h e T.M.E. values.
TABLE 4.-Fatty acid compositions of the rapeseed oils (%) Experiment 2
Experiment 1 Fatty acid 1
Tower crude
Tower degummed
LEAR crude
LEAR degummed
Tower crude
Tower degummed
HEAR crude
HEAR degummed
14:0 16:0 16:1 18:0 18:1 18:2 18:3
0.1 4.6 0.3 1.8 61.1 20.4 8.2
0.1 4.7 0.3 1.6 57.7 21.5 9.4
0.1 4.2 0.3 1.8 62.1 19.7 7.6
0.1 4.2 0.3 1.8 61.6 19.6 7.9
0.1 4.8 0.4 1.9 61.1 20.8 7.8
0.1 4.6 0.4 2.0 55.3 19.6 7.4
0.1 3.8 0.3 1.3 21.5 13.9 6.1
0.1 3.6 0.2 1.3 21.8 12.9 5.2
20:1 20:2 22:0 22:1 24:0 24:1
1.7 0.1 0.4 1.2 0.2 0.3
2.2 0.1 0.3 2.1 0.2 0.3
2.0 0.1 0.3 1.8 0.2 0.3
2.0 0.1 0.3 1.6 0.2 0.3
1.7 0.1 0.5 0.8 0.2 0.3
3.3 0.1 0.3 6.1 0.3 0.2
12.2 0.5 0.1 38.3 0.3 1.2
12.6 0.6 0.1 39.8 0.2 1.0
7.3 64.6 20.5 8.2
7.0 62.6 21.6 9.4
6.7 66.4 19.8 7.6
6.8 65.8 19.7 7.9
7.6 64.3 20.9 7.8
7.5 65.3 19.7 7.4
5.7 73.5 14.4 6.1
5.6 75.4 13.5 5.2
Saturates Monoenes Dienes Trienes
'Number of carbon atoms: number of double bonds. Minor fatty acids (15:0, 17:0, 20:4) are not included in the table.
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Rapeseed product
T.M.E. OF RAPESEED PRODUCTS
DISCUSSION The T.M.E. values of the full-fat rapeseeds are similar to those observed by Sibbald and Price (1977). In the present work the ground seeds were blended with a basal diet prior to assay whereas in the earlier work the ground seeds were assayed alone. In the first experiment the Tower and LEAR seeds had T.M.E. values which were not different (P>0.05) but the Tower oil and meal contained more T.M.E. (FKO.01) than did the LEAR oil and meal. The solvent extraction process removed 42% of oil from the Tower seed and 40% from the LEAR seed. Assuming that the residue was meal it is possible to calculate the T.M.E. yields of the two seed varieties following extraction. For example 1 g. of Tower seed yielded 0.42 g. of crude oil (9.58 kcal./g.) and 0.58 g. of meal (2.52 kcal./g.) giving a total T.M.E. yield of 5.45 kcal./g.; this is substantially greater than the T.M.E. value of
the unextracted seed (4.96 kcal./g.). For LEAR seed the calculated T.M.E. yield is 4.91 kcal./g. which is slightly lower than the observed value for the unextracted seed (5.10 kcal./g.). These differences suggest that the processing effectively increased the availability of the energy in Tower seed but had a slight negative effect on the availability of the LEAR energy. In the second experiment the Tower and HEAR seeds and oils exhibited no varietal differences (P>0.05) but the Tower meal contained more T.M.E. (P<0.01) than did the HEAR meal. These seeds were processed in a prepress solvent extraction plant. Unfortunately the extraction rates are not available but it seems probable that the processes enhanced the utilization of the energy of Tower seed. The Tower oil assayed in the first experiment appeared to contain more T.M.E. than did the samples assayed in the second experiment. However, the differences may not be real when viewed in light of the variation associated with the mean values. The fatty acid compositions of the crude oils are remarkably similar (Table 4) but, as mentioned earlier, the degummed oil of the second experiment appears to have been contaminated. The two lots of Tower meal had similar T.M.E. values (2.52 and 2.60 kcal./g. of dry matter) suggesting that the differences in processing had no major effects upon the availability of the energy in the meal; however, this is not conclusive because the two lots of Tower seeds were not drawn from the same source. In the first experiment the method of assay had a small (P<0.05) effect on the T.M.E. values of the two meals. This suggests that the T.M.E. value of rapeseed meal is not additive; however, in the second experiment there were no differences (P>0.05) associated with the method of assay. Sibbald (1977b) found that the T.M.E. values of six feedingstuffs, not including rapeseed meal, were additive. It may be possible for feedingstuffs to interact to make the T.M.E. value of a mixture different from the mean of the T.M.E. values of its component parts but it seems probable that the differences in experiment one were due to experimental variation. Support for this interpretation is provided by the data of the second experiment.
ACKNOWLEDG EMENTS
The author is indebted to J. R. Reynolds and CSP Foods, Saskatoon for the rapeseed
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The crude HEAR oil contained more T.M.E. than did the crude Tower oil (9.40 vs. 9.12 kcal./g.) but the degummed oils had similar values (9.04 vs. 8.92 kcal./g.). Analysis of variance of the data showed that none of the differences was significant (P>0.05). The HEAR oil contained relatively high levels of erucic and eicosenoic acids and substantially less linoleic acid when compared to the Tower oil (Table 4). While the removal of gums had little effect on the composition of the HEAR oil there were differences between the crude and degummed Tower oils; the differences were confirmed by repeating the fatty acid analyses. It seems probable that the degummed Tower oil was contaminated with HEAR oil during the manufacturing process. The Tower meal contained more T.M.E. than did the HEAR meal (2.60 vs. 2.32 kcal./g. of dry matter) but the assay procedure appeared to be without effect (2.41 vs. 2.50 kcal./g. of dry matter). Analysis of variance confirmed the varietal difference (P<0.01) and showed that the difference between assay procedures was not significant (P>0.05). The interaction between varieties and assay procedures was not significant (P>0.05). The HEAR meal contained more nitrogen, ether extract and crude fibre than did the Tower meal (Table 4) but the differences were less than would be expected to cause the observed difference in T.M.E. values.
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I. R. SIBBALD
p r o d u c t s , t o Dr. J. K. G. Kramer of t h e Animal Research Institute w h o provided t h e fatty acid analyses, a n d t o t h e Chemical a n d Biological Research Institute of Agriculture Canada for t h e p r o x i m a t e analyses of t h e seeds and meals. T h e efficient technical s u p p o r t of Mrs. S. T o b i n is gratefully acknowledged.
REFERENCES Association of Official Agricultural Chemists, 1975.
Official Methods of Analysis, 12th ed. Washington, D.C. Sibbald, I. R., 1976. A bioassay for true metabolizable energy in feedingstuffs. Poultry Sci. 55:303—308. Sibbald, I. R. 1977a. The true metabolizable energy values of some feedingstuffs. Poultry Sci. 56:380— 382. Sibbald, I. R., 1977b. A test of the additivity of true metabolizable energy values of feedingstuffs. Poultry Sci. 56:363-366. Sibbald, I. R., and K. Price, 1977. The true metabolizable energy values of the seeds of Brassica campestris, B. hirta and B. napus. Poultry Sci. 56:000— 000. Downloaded from http://ps.oxfordjournals.org/ at Universitaetsbibliothek Osnabrueck on May 27, 2015