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Australian sweet lupin (Lupinus angustifolius)
Narrow-leafed lupin
Extracted from the GRDC Hanbdook 'The Chemical Composition and Nutritive Value of Australian Pulses'
Nutritive Value
Australian sweet lupins (ASL) are now widely accepted as a supplement for ruminants because they are high in available energy and protein and have advantages in handling, storing and feeding. They are particularly used to feed sheep in times of pasture shortage. They are also widely used in pig and poultry nutrition where they are valued for their consistent quality and low content of anti-nutritional factors.
TABLE 1. Nutrient composition of Australian sweet lupins (g/kg as received)
|
Mean |
Minimum |
Maximum |
Number |
|
| Dry Matter |
911 |
896 |
930 |
908 |
| Protein |
320 |
272 |
372 |
3782 |
| Ash |
27 |
23 |
32 |
180 |
| Fat |
59 |
49 |
70 |
1023 |
| Fibre |
154 |
117 |
237 |
180 |
| ADF |
197 |
160 |
236 |
190 |
| NDF |
235 |
195 |
288 |
183 |
| Lignin |
9 |
4 |
19 |
111 |
| Weight (mg) |
144 |
114 |
218 |
1045 |
TABLE 2. Nutritive values of lupins and other major pulses per kilogram of seed
|
Nutrient |
Lupins (ASL) |
Field peas |
Soybean meal |
|
Crude protein (N x 6.25), g |
322 |
230 |
440 |
|
Total lysine, g |
15 |
15.6 |
28 |
|
Available lysine, pigs* |
10.4 |
14.3 |
24.9 |
|
Available lysine, poultry* |
13.5 |
14.2 |
25.5 |
|
Total sulfur amino acids, g |
7.0 |
5.7 |
12.5 |
|
Total tryptophan, g |
4.1 |
2.1 |
5.2 |
|
Crude fat, g |
58 |
11 |
8 |
|
GE (MJ) |
18.1 |
16.8 |
|
|
DE, pigs (MJ) |
14.6 |
14.5 |
14.5 |
|
ME, cattle (MJ) |
12.0 |
11.7 |
13.7 |
|
ME, sheep (MJ) |
12.2 |
12.0 |
13.7 |
|
AME, poultry (MJ) |
10.7 |
11.5 |
10.7 |
|
Total calcium, g |
2.2 |
0.9 |
4.0 |
|
Total phosphorous, g |
3.0 |
3.9 |
6.0 |
|
Total sulphur, g |
2.3 |
1.8 |
|
|
Crude fibre, g |
148.9 |
58.4 |
|
|
ADF, g |
197 |
85.1 |
110 |
|
NDF, g |
227 |
128.7 |
130 |
|
Lignin, g |
7.0 |
10.1 |
7 |
|
Starch, g |
<10 |
420 |
* Reported values vary widely. Conservative values are given here.
Composition
Protein content and quality
The crude protein content of bulk supplies of lupins is generally constant at 30-32 per cent.
The protein is of reasonable quality, it can be used without pre-treatment, and it has a high digestibility in all species. In pigs the availability of lysine seems to be low (Table 2). It may be influenced by the energy source in the diet.
TABLE 3. Essential amino acid content of Australian sweet lupin (g/16 g N)
|
Amino acid |
Mean |
Minimum |
Maximum |
Number |
|
Arginine |
11.62 |
10.60 |
12.90 |
116 |
|
Histidine |
2.57 |
2.12 |
2.86 |
118 |
|
Isoleucine |
3.91 |
3.57 |
4.41 |
118 |
|
Leucine |
6.90 |
5.91 |
7.40 |
118 |
|
Lysine |
4.75 |
4.22 |
5.19 |
118 |
|
Methionine |
0.66 |
0.49 |
0.82 |
113 |
|
Phenylalanine |
3.85 |
3.17 |
4.17 |
113 |
|
Threonine |
3.54 |
3.00 |
3.82 |
118 |
|
Tryptophan |
1.00 |
0.56 |
1.16 |
17 |
|
Valine |
3.78 |
3.17 |
4.23 |
118 |
|
Cys + Met |
2.01 |
1.50 |
2.45 |
113 |
|
Tyr + Phe |
7.55 |
6.33 |
8.07 |
86 |
In ruminant animals the composition of the protein is of less importance although the content of methionine may be limiting for wool production in sheep and milk production in high producing dairy cows. However a high proportion of dietary protein is undegraded in the rumen and can increase the overall nutritive value of the feed. In narrow-leafed lupins up to one-third of the protein is undegraded in the rumen and much of the response to lupin seed supplements in sheep and cattle reproduction has been attributed to this undegraded portion.
For pigs and poultry lupins require supplementation with free lysine and methionine or to be used with a protein source rich in these amino acids.
Mineral content
The variability in samples from throughout Australia is low for most of the major elements. However the content of sodium is variable, depending on soil type, and supplementation with salt may be advisable in situations where the lupins are used for grazing animals over a long period with poor quality roughages. Phosphate levels are acceptable but calcium may be low, although evidence of a response to supplementary calcium is limited.
TABLE 4. Mineral content of Australian sweet lupins (per kg as received)
|
Mineral |
Mean |
Minimum |
Maximum |
Number |
|
g |
||||
|
Calcium |
2.2 |
1.5 |
2.9 |
623 |
|
Magnesium |
1.6 |
1.1 |
2.0 |
524 |
|
Phosphorus |
3.0 |
2.1 |
4.3 |
846 |
|
Potassium |
8.0 |
6.6 |
9.1 |
614 |
|
Sodium |
0.4 |
0.3 |
1.1 |
422 |
|
Sulphur |
2.3 |
1.5 |
2.9 |
611 |
|
mg |
||||
|
Copper |
4.7 |
2.5 |
6.8 |
547 |
|
Iron |
68.5 |
31.0 |
150.0 |
535 |
|
Manganese |
19.0 |
6.7 |
76.0 |
584 |
|
Molybdenum |
1.6 |
0.7 |
2.9 |
41 |
|
Zinc |
34.1 |
24.7 |
45.0 |
551 |
|
g |
||||
|
Cobalt |
78 |
10 |
260 |
56 |
|
Selenium |
89 |
18 |
240 |
138 |
The ratio of nitrogen to sulphur (22 to 1) is higher than the average values for grasses (14 to 1) and pasture legumes (17 to 1) and this may be undesirable for sheep. Some experiments have shown a positive response in wool growth by weaners when a mineral supplement including sulphur was supplied.
Concentrations of cobalt, copper and zinc are often below animal requirements and they should be included in any mineral supplement used in conjunction with lupin feeding. Selenium varies with soil type and rainfall, and supplementation may be advisable in some circumstances.
L. angustifolius is not an accumulator of heavy metals. Of over 300 samples tested from a wide range of growing conditions none exceeded the proposed Codex Alimentarius limit of 0.1 mg/kg for cadmium or 2.0 mg/kg for lead.
Anti-nutritional factors and toxins
There have been very few reports of detrimental effects of feeding lupins to livestock.
Lupins contain low levels of several common anti-nutrients (Table 5) and unlike whole soybeans and most other grain legumes do not require heat treatment to destroy the lectins and protease inhibitors which can reduce protein digestion and availability.
TABLE 5. Anti-nutritional factors in Australian sweet lupins
|
Factor |
Units |
Mean |
Minimum |
Maximum |
Number |
|
Alkaloids |
% |
0.02 |
<0.01 |
0.04 |
1316 |
|
Oligosaccharides* |
% |
4.07 |
2.90 |
5.20 |
202 |
|
Phytate |
% |
0.50 |
0.32 |
0.84 |
254 |
|
Saponins |
mg/kg |
573 |
442 |
740 |
11 |
|
Tannins(total) |
% |
0.29 |
0.19 |
0.51 |
208 |
|
Tannins(cond) |
% |
0.01 |
n.d. |
0.11 |
236 |
|
TIA |
mg/kg |
0.12 |
0.05 |
0.24 |
148 |
|
CTIA |
mg/kg |
0.08 |
n.d. |
0.59 |
8 |
|
Lectins |
dilut |
n.d. |
28 |
- Sum of raffinose, stachyose and verbascose
There is no evidence of other toxic or inhibitory substances which are often found in unprocessed plant protein sources.
Lupinosis, a liver disease caused by ingestions of toxins produced by the fungus Diaporthe toxica, formerly named Phomopsis leptostromiformis, has been prevalent in Western Australian lupin crops for many years but has generally only been associated with ingestion of infected stems (stubble) or leaves.
There are a few documented reports of lupinosis from feeding seed but it has been shown that the phomopsins, the toxins produced by the fungus, are present only in discoloured seeds with heavily discoloured seeds being the most toxic. This discolouration which ranges from pale yellow to dark brown is independent of the characteristic mottling of Gungurru and similar varieties. Most discoloured seeds can be removed by commercial grading.
Sheep are reputed to tolerate consumption of up to 10 per cent discoloured seed in their diet and cattle are more tolerant of the toxins. However it cannot be assumed that such levels will be safe and a very cautious approach to feeding discoloured seed should be taken.
Modern varieties are Diaporthe-resistant but very low levels of toxins can still be produced in their seed.
Lupins for animal feed
Energy content
All components of the ASL seed are readily digested by ruminant animals, whose resident microbial populations produce the enzymes required to degrade both the soluble and insoluble complex carbohydrates that make up the seed coat and cell wall fraction of the cotyledon, as well as the simpler oligosaccharides. A big advantage of lupins is that ruminants do not normally need a period of introduction to avoid acidosis. Furthermore, the content of lignin, the compound which usually limits the digestion of fibre, is very low (< 1 per cent) and so the overall digestibility of lupin seed is high, about 90 per cent. This high digestibility combined with the moderate oil content of lupins, results in an estimated metabolisable energy value (in vivo) of 13 MJ/kg which is higher than for most cereal grains.
Recent studies in Europe have indicated a 'true net energy value of lupins' at 10 MJ/kg for pig
TABLE 6. Energy values of Australian sweet lupins (MJ/kg)
|
Mean |
Maximum |
Minimum |
Number |
|
|
GE |
18.4 |
17.9 |
18.6 |
7 |
|
DE Pigs |
14.6 |
12.0 |
17.0 |
9 |
|
ME Cattle |
12.0 |
2 |
||
|
ME Sheep |
12.2 |
10.0 |
13.0 |
10 |
|
AME Poultry |
10.4 |
10.0 |
10.7 |
2 |
Non-ruminant animals on the other hand lack the enzymes able to digest the complex carbohydrates in the stomach and small intestine. Unless there is fermentation in the lower tract (for example in horses and pigs) the digestibility of energy from lupin seed in these species is much lower.
Even where substantial fermentation in the lower tract does occur, the net energy yield from lupins is lower than for feeds which are largely digested in the upper tract. Furthermore there is evidence in pigs that this value may be influenced by other components of the diet. Results from a recent study gave the DE of whole seed for pigs at 15.8 MJ/kg, and for kernels at 16.9 MJ/kg. These are higher than earlier reports, and the difference could be attributed to finer grinding of the meal. It may be more economical to use a finer grind of whole seed than to dehull.
The oil contains about 35 per cent mono-unsaturated fatty acids (nearly all as oleic acid), 45 per cent polyunsaturated fatty acids (37 per cent linoleic, 6 per cent linolenic, 2 per cent others) and 2 per cent sterols. Tests have shown the oil to be stable for long periods.
Lupins for ruminants
Sheep trained to eat lupin seed will readily fossick for the seed and broadcasting can therefore be used as a valuable tool in grazing management. There is little need for processing, but cracking or milling whole seed is advisable for cattle.
Farmers should ensure a slow introduction of sheep to lupin seed if the sheep are in poor condition to avoid the risk of an acidosis and rumenitis induced by an atypical fermentation of the cell wall material. Well-nourished sheep do not suffer this condition.
While dehulling seed can improve the utilisation by non-ruminants, the hulls and other particles removed during the process can be satisfactorily pelleted to make a complete feed for sheep, or incorporated into formulated feed for ruminants.
Lupins for monogastrics
Commercial pig growers have successfully used up to 30 per cent whole lupin seed in pig rations. It is often not economical to dehull lupins to enhance their feed value. While the digestible energy is comparable to other legumes, commercial feed formulators tend to discount this by 1 to 1.5 MJ because so much of the carboyhydrate is fermented in the hind gut, and the energy is not fully available.
Poultry rations normally contain less than 10 per cent lupins, frequently kernels, because of the problem of 'sticky' or 'wet' droppings. While aesthetically undesirable and a potential health risk to the birds, through respiratory stress from ammonia and coccidiosis, this is not known to affect feed conversion. There is some evidence that the addition of commercial enzymes to poultry feed will improve the energy utilisation and reduce the incidence of 'sticky' droppings. Research has shown that it is not necessary to dehull lupins for use in broiler feeds.
Lupins in aquaculture
Diets for rainbow trout can contain up to 25 per cent whole lupins and it is common practice to feed whole or cracked seed to marron and yabbies in farm dams. Up to 10 per cent lupins are used in commercial diets of tilapia and milkfish. Pink snapper diets can contain up to 40 per cent lupin seed meal with no loss in productivity. Up to 50 per cent of the fishmeal or soybean meal in diets of tiger prawns can be replaced by lupins. Commercial diets for silver perch can contain up to 30 per cent lupins.
Heating, flaking and rolling lupins give only marginal increases in feed quality. Too much heat can cause a marked reduction in amino acid utilisation.
Analytical data for lupin kernels are shown in Table 7. Too few data are available to define relationships between kernel amino acids and kernel, or whole seed, total nitrogen or crude protein values.
TABLE 7. Nutrient composition of kernels from Australian sweet lupins (g/kg as received)
|
Mean |
Minimum |
Maximum |
Number |
|
|
Dry matter |
900 |
895 |
908 |
9 |
|
Protein |
416 |
355 |
489 |
33 |
|
Ash |
27 |
24 |
30 |
7 |
|
Fat |
65 |
52 |
77 |
19 |
|
Fibre |
87 |
21 |
256 |
9 |
|
ADF |
70 |
63 |
84 |
6 |
|
NDF |
71 |
64 |
78 |
6 |
|
Lignin |
7 |
4 |
8 |
6 |
|
Calcium |
1.0 |
0.5 |
1.3 |
19 |
|
Phosphorus |
5.10 |
3.30 |
7.10 |
19 |
|
Potassium |
6.8 |
4.6 |
8.5 |
15 |
|
Sulphur |
2.5 |
2.1 |
3.0 |
15 |
|
GE (MJ/Kg) |
18.9 |
1 |
||
|
DE Pigs (MJ/Kg) |
16.3 |
15.0 |
18.0 |
3 |
See also:
Lupins for human consumption
In nutritive terms lupin seed could be an attractive alternative to dry beans and soya beans which are presently the major legume seed for human consumption. The protein and oil in lupin seeds are more readily digested, there is a lower content of phytate which can reduce the availability of dietary calcium and zinc, fewer protease inhibitors and a negligible content of lectins.
Lupin seed has a high content of the dietary fibre component which is typically associated with cholesterol-lowering activities. Feeding studies with rats have consistently shown a lowering of plasma cholesterol. In human studies the fibre showed characteristics of both soluble and insoluble dietary fibre.
See also:
Lupin sprouts are available commercially in Australia. They are usually thicker and longer than bean sprouts and can be used as a salad vegetable, in stir-fries or for pickling. The content of alkaloids and phytate is further reduced by germination.
Adding 5-20 per cent lupin flour to wheat flours will give products similar to the full wheat product (breads, pastas, biscuits, etc.) but with an improved nutritional value. The lupin flour addition tends to extend the shelf-life and imparts a golden colour.
Lupin seed can be fermented to produce high quality tempe, a traditional Indonesian food, and miso and natto, traditional Japanese foods. Other uses for lupins include as a snack food base, and in the production of dietary fibre, protein concentrates, and fermented sauces.
The green immature seed has a similar taste and texture to those of green peas.
Page reviewed: 5 September 2006
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