Recent research on improving the quality of grain legumes for chicken growth

Animal Feed Science and Technology 76 (1999) 185±193

Review

Recent research on improving the quality of grain legumes for chicken growth K.G. Wiryawan1, J.G. Dingle* School of Veterinary Science and Animal Production, The University of Queensland, Gatton, QLD 4343, Australia Received 16 September 1997; accepted 14 July 1998

Abstract Grain legumes are potential sources of energy and amino acids for poultry, but their use is still limited because of uncertainty about the amount and effect of any antinutritional factors (ANF) they may contain. Their ANF can be decreased and their nutritional quality increased through plant breeding, by mechanical treatment (dehulling), by heat treatment or by supplementation with enzyme mixtures. The improvement of the nutritive value is related to increases in the metabolizable energy (ME) values and the digestibility of the proteins of the grain legumes. # 1999 Elsevier Science B.V. Keywords: Grain legumes; Treatments; Enzyme; Energy; Digestibility; Chickens

1. Introduction Soybean meal (SBM), fish meal and meat meal currently occupy a central role in the feeding of poultry in many developed and developing countries. However, an increasing human demand for protein in developing countries and a relatively high cost of imported ingredients has turned the attention of animal nutritionists to the exploitation of nonconventional ingredients and by-products which these regions have in abundance (D'Mello, 1995; Bourne, 1997; Anon, 1998). Grain legumes are potential substitutes for soybean meal because of the similarity of their amino acid profiles. Although the use of grain legumes in poultry production is regarded primarily as supplying a source of protein (Wiseman and Cole, 1988; Wiryawan * Corresponding author. Tel.: +61-754-601-251; fax: +61-754-601-444; e-mail: [email protected] 1 Permanent address: Faculty of Animal Husbandry, University of Mataram, Mataram 83125, NTB, Indonesia. 0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved PII: S 0 3 7 7 - 8 4 0 1 ( 9 8 ) 0 0 2 1 8 - 1

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and Dingle, 1995), they are also potential sources of energy because most contain over 600 g kgÿ1 carbohydrate (mainly starch) (Reddy et al., 1984). For example, ten-grain legumes; black gram (Phaseolus mungo), chickpea cv. Kaniva (Cicer arietinum), chickpea cv. Desi (Cicer arietinum), faba bean (Vicia faba), field pea (Vigna sinensis), green gram (P. aureus), lentil (Lens culinaris), lupin (Lupinus angustifolius), pigeon pea (Cajanus cajan) and solvent-extracted soybean meal (Glycine max) gave a gross energy value of 15.690.6 MJ kgÿ1 (Wiryawan and Dingle, 1995). Despite their good amino acid profile and high energy content, the use of grain legumes in commercial poultry production is still limited because of uncertainty about their effective nutritional quality. Feeding raw legumes to chickens generally results in lower growth rate and reduced feed efficiency compared with feeding processed legumes. However, each legume produces a different response. Miller and Holmes (1992), for example, reported that increasing the level of raw chickpea and mung bean from 100 to 400 g kgÿ1 in the diets of broilers reduced their weight gain by 14%, while feeding the same levels of raw field peas resulted in weight gains similar to that produced by a commercial diet. On the other hand, the feed conversion ratio (FCR) of meat chickens fed diets containing 100 to 300 g kgÿ1 raw pigeon pea was not significantly different from the FCR of chickens fed a control diet. However, FCR was increased by up to 14 and 19% when the level of raw pigeon pea was increased to 400 and 500 g kgÿ1, respectively (Tangtaweewipat and Elliott, 1989). A major constraint on the use of grain legumes in poultry diets is that they may contain antinutritional factors (ANF) that depress poultry performance. The most commonly found ANF in legumes are protease (trypsin and chymotrypsin) inhibitors, tannins, lectins, amylase inhibitors, glycosides, phytate and alkaloids. Other ANF which may play an important role in decreasing the nutritive value of grain legumes are non-starch polysaccharides (Chang and Satterlee, 1981; Semino et al., 1985). The presence, distribution and the negative effects of ingestion of ANF in grain legumes have been reviewed widely; for example, Liener and Kakade (1980), Liener (1989); Huisman and Tolman (1992), Gatel (1994) and D'Mello (1995). It is agreed that most ANF exert their negative effect through interference with normal digestive functions. The distribution and physiological effects of ingestion of ANF are presented in Table 1. A number of techniques is available for eliminating ANF, thus improving the nutritional value of grain legumes. The purpose of this paper is to highlight methods that can be used to reduce ANF. Emphasis is placed on the effectiveness of heat treatment and enzyme supplementation for improving the nutritional value of grain legumes for poultry production. 2. Plant breeding The content of ANF in grain legumes is genetically determined, so that the level of ANF varies between and within legumes (Leterme et al., 1992; Grosjean et al., 1993). This raises the possibility of improving the nutritional value of grain legumes through

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Table 1 Distribution and physiological effects of antinutritional factors (ANF) in grain legumes a ANF

Distribution

Physiological effect

Protease inhibitors

most legumes

Tannins Lectins Amylase inhibitors Glycosides oligosaccharides saponins cyanogen vicine/convicine Phytate Alkaloids Non-starch polysaccharides (NSP) b

most legumes most legumes most legumes

depressed growth, pancreatic hypertrophy/hyperplasia, acinar nodules, interference with protein digestion interference with protein and starch digestion depressed growth, death interference with starch digestion

most legumes most legumes lima bean faba bean most legumes lupins most legumes

flatulence affect intestinal permeability respiratory failure haemolytic anaemia interference with mineral availability reduced palatability, depressed growth depressed digestibility of protein, starch and fat

a b

Adapted from Liener (1989). Smits and Annison (1996).

genetic manipulation (Bond and Duc, 1993), but makes the selection of a single breeding method for eliminating ANF seem unlikely. Some promising results have been shown by plant breeders in their efforts to eliminate ANF (Bond and Duc, 1993). Reduction of tannin content through genetic manipulation of faba beans, for example, has resulted in increased digestibility of dry matter and nitrogen in pigs (Van der Poel et al., 1992). Plant breeding is, however, a long-term process and the results, at least for the removal of trypsin inhibitors in peas (Pisum sativum), have not been consistent. Some cultivars after cross-breeding had higher trypsin inhibitor activities than one of their parents, and cultivars derived from the same cross showed different trypsin inhibitor activities (Leterme et al., 1992). These results suggest that the hereditary transmission of trypsin inhibitor activities was not systematic and that plant breeding does not produce fast or predictable results. 3. Mechanical treatments The most widely used methods for the reduction of the negative effects of ANF are physical treatments. They can be grouped into mechanical treatments and heat treatments. Decortication is an effective method for reducing tannin content of grain legumes since most tannins reside in the testa. Weight gain, FCR, apparent metabolizable energy (AME) and apparent protein digestibility (APD) were improved by 5.7, 7.0, 13.9 and 16.4%, respectively, when growing chickens were fed dehulled-high-tannin peas compared with those fed an untreated pea diet (Brenes et al., 1993a). This improvement may have occurred not only because of the reduction of tannin content but also because of the reduction of fibre content associated with removal of the testa. Longstaff and McNab (1991) reported that digestibilities of amino acids, starch and lipid of a diet with tannin-

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free hulls of faba bean were lower than those of a control diet. Lectins and trypsin inhibitors, however, are concentrated in the cotyledons, so that dehulling will not reduce all ANF. 4. Heat treatments Heat causes denaturation of proteinaceous inhibitors. It is a good method of decreasing the activity of lectins, and also that of trypsin and chymotrypsin inhibitors. Several different heat treatments can be applied to reduce the lectin activity (LA) and `heat-labile' trypsin inhibitor activity (TIA) which generally result in improving the nutritional value of grain legumes. The effect of heat treatment on the nutritive value of soybean meal has been investigated intensively for over half a century. Evans and McGinnis (1946) and Evans et al. (1947), as cited by Allison (1949), demonstrated that moderate heating increased the nutritive value of soybean meal for chickens. The improvement may have been associated with a decrease in urease activity and trypsin inhibitor activity (Araba and Dale, 1990). Results of studies of field peas showed that inclusion of 475 g kgÿ1 autoclaved (1218C for 20 min) high-tannin peas (Pisum sativum) in a corn±soy basal diet increased the apparent metabolizable energy and apparent protein digestibility by 21 and 11%, respectively, compared with inclusion of the same amount of raw peas (Brenes et al., 1993a). Application of the same technique to the low-alkaloid varieties of sweet lupin (Lupinus albus) meal increased weight gain by 11% and reduced FCR by 10%, but the differences failed to reach the 5% level of significance (Brenes et al., 1993b). It is likely that these improvements were due to an increase in breakdown of the cell walls of the cotyledon which increased the accessibility of nutrients to digestive enzymes (Carre et al., 1991). The results of these studies suggest that the effects of autoclaving are specific to each legume, and may depend on the concentration of each of the different heat-labile ANF. Comparative studies in rats (Kadam et al., 1987) showed that autoclaving, infrared radiation and boiling in water were effective means for reducing trypsin inhibitor activity and lectin activity of winged bean (Psophocarpus tetragonolobus). Weight gain, protein digestibility and biological value were dramatically increased when rats were fed autoclaved, infrared-treated or boiled winged bean diets (Table 2). The biological values of diets containing autoclaved, infrared-treated and boiled winged bean were not significantly different. The application of infrared radiation to peas for young chickens also resulted in a significant increase in apparent metabolizable energy, apparent protein digestibility and starch digestibility for young chickens (Igbasan and Guenter, 1996). These treatments are potential methods for improving the nutritional value of grain legumes. In addition to the above, the choice of the treatment will depend on the availability of facilities and on economic considerations. To use heat treatments effectively, the temperature and duration of processing have to be carefully controlled (Araba and Dale, 1990; Kratzer et al., 1990; Van der Poel, 1990). Excessive heat can result in a reduction of protein solubility and may destroy certain amino acids. The protein solubility in potassium hydroxide solution of soybean meal autoclaved at 1218C for longer than 10 min was <70% and the weight gain of chickens

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Table 2 Effect of heat treatments on ANF of wing bean and on weight gain, true protein digestibility (TPD) and biological value (BV) for rats a Treatment

Trypsin inhibitor (mg gÿ1)

Lectin (units mgÿ1)

Tannins (mg gÿ1)

Phytate (mg gÿ1)

Weight gain (g/7 days)

TPD (%)

BV (%)

Untreated Oven heated Microwave Autoclave Infrared Boiling water

17.7 17.4 17.9 0.70 0.66 0.36

200 192 196 nd 10 nd

7.6 7.5 7.4 5.1 6.7 2.5

6.1 6.1 5.9 5.9 5.8 6.1

ÿ12 ÿ12.6 ÿ14 2.6 9.2 10.4

50.5 30.7 37.3 72.2 84.4 84.3

ÿ73.7 ÿ102.1 ÿ69.9 53.2 70.5 70.8

a

Adapted from Kadam et al. (1987).

fed a diet containing that soybean meal was lower than for those autoclaved for 5 and 10 min (Araba and Dale, 1990). Extending steam heating of Phaseolus vulgaris beans from 40 to 80 min resulted in lower weight gain and higher feed conversion ratio in piglets (Van der Poel et al., 1990). Similarly, protein efficiency ratios of autoclaved winged bean offered to four-week-old Japanese quail decreased from 0.40 to 0.22 when heating duration was increase from 45 to 90 min (Mutia et al., 1996). Excessive heating may reduce the availability of some amino acids, especially lysine. Van Barneveld et al. (1993) reported that the availability of lysine from heat-treated peas for pigs was decreased by 21% when the heating temperature was increased from 110 to 1508C for 15 min. Autoclaving at 1258C and 180 kPa for 5 min enhanced the nutritional value of black gram and lupin, but autoclaving for 20 min significantly reduced the net weight gain and net protein ratio of both legumes (Wiryawan and Dingle, 1998) (Fig. 1). With prolonged or elevated heating, basic amino acids, such as lysine, undergo a Maillard reaction making them less available for growth. It is, therefore, important to find the exact conditions of heating which maximize the improvement of the nutritive value of the legumes. 5. Chemical treatments Enzyme supplements that hydrolyze non-starch polysaccharides increase the metabolizable energy and protein values of grain legumes in the same way they do in wheats (Choct and Annison, 1992; Choct et al., 1995; Hew et al., 1995). Several reports on the application of enzymes to improve the nutritional value of lupins have been published. Bryden et al. (1994) found that adding a feed enzyme, `lupinase' (bgalactanase and a-galactosidase), to lupin diets increased the apparent metabolizable energy value by 10.7%. Similarly, the addition of 0.5 to 0.75 g kgÿ1 of an enzyme mixture containing hemicellulase, xylanase, pentosanase and cellulase activities to diets containing dehulled lupins increased the AME value by 14% (Annison et al., 1995). An intensive study in Canada (Marquardt et al., 1996) concluded that the nutritive value of alkaloid-free lupin can be increased by dehulling, by autoclaving and by supplementation

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Fig. 1. Effect of duration of autoclaving on (A) net weight gain and (B) net protein ratio of black gram and lupin measured with growing chickens (Wiryawan and Dingle, 1998).

with an appropriate mixed enzyme preparation. Studies of the effects of enzyme supplementation of ten-grain legumes (black gram, chickpea cv. Kaniva, chickpea cv. Desi, faba bean, field pea, green gram, lentil, lupin, pigeon pea, all raw, solvent-extracted soybean meal) showed that the addition of 1 g kgÿ1 xylanase increased the true metabolizable energy value of most grain legumes for meat chickens (Wiryawan et al., 1995). The lowest TME legumes, lupin and faba bean, had the greatest relative and actual increase in TME value with added enzyme (Fig. 2). The net protein ratio of the above ten-grain legumes increased significantly (p < 0.01) after supplementation of chicken diets with a mixed-enzyme product containing xylanase, a-amylase and protease (Wiryawan et al., 1997). A significant (p < 0.05) positive correlation (r ˆ 0.64) between percent improvement in NPR values following enzyme supplementation and the NDF content of grain legumes was also observed (Table 3). Legumes with a greater cell wall content showed a better response to mixed enzyme supplementation than those with a lower amount of cell wall content. It is likely that the xylanase acts to break the cell wall and the a-amylase and protease then assist the endogenous amylase and protease to digest the exposed starch and protein.

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Fig. 2. Effect of enzyme supplementation on true metabolizable energy (TME) value of grain legumes for growing chickens (Wiryawan et al., 1995). GE, gross energy.

In conclusion, recent research has confirmed that short-time heat treatment is effective in reducing many ANF in grain legumes; however, enzyme supplementation has equal potential and would be the method of choice in the future in the absence of heating facilities. The effectiveness of certain treatments, such as mechanical removal of tannins, depends on the location of the ANF in grain legumes. The improvements of the nutritive value of grain legumes by certain treatments are related to increases in the ME values and in the digestibilities of the legume proteins. Table 3 Effects of enzyme supplementation on the net protein ratio (NPR) value of grain legumes for chickens a Legume

Control

With enzyme

Improvement (%)

Significance

NDF content (g kgÿ1)

Faba bean Chickpea cv. Desi Pigeon pea Lupin cv Gungurru SBM b Chickpea cv. Kaniva Black gram Lentil Field pea Green gram

3.00 3.31 3.29 3.23 3.67 3.65 3.02 3.78 3.77 3.86

3.58 3.76 3.69 3.49 3.94 3.88 3.16 3.95 3.91 3.91

19.33 13.60 12.16 8.05 7.36 6.30 4.64 4.50 3.71 1.30

Ð ** Ð* Ð* ns c ns c ns c ns c ns c ns c ns c

209.6 234.2 195.7 239.4 164.9 108.5 148.4 138.2 177.6 139.9

a

Data from Wiryawan et al. (1997). Solvent extracted soybean meal, NDFˆ Neutral Detergent Fibre. c Not significantly different. *(p<0.05); **(p<0.01). b

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