|Livestock Research for Rural Development 3 (3) 1991||
Citation of this paper
Relative effects of heat and urea-treated jackbean (Canavalia ensiformis) and swordbean (Canavalia gladiata) on the performance of laying hens
A B I Udedibie
Department of Animal Production, Federal University of Technology, Owerri, Nigeria
Two feeding trials were conducted with laying hens to determine the relative effect of boiling alone and of ensiling with urea followed by boiling of jackbeans and swordbeans, incorporated at levels of up to 20% in the diet. In the first experiment, boiled jackbeans and swordbeans were incorporated in layer's diets at 10% and 20%. In the second experiment, urea-ensiled and boiled jackbeans and swordbeans were incorporated in layer's diets at 10% and 20%. In both experiments, each diet was fed to 5 replicates of 20 layers.
The results of the 12 week experiments showed that the optimal dietary level of boiled jackbeans for layers was about 10%. That of boiled swordbean appeared to be less than 10%. Urea-ensiled and boiled jackbeans could be incorporated in layers' diets at up to 20% with good results while swordbeans treated by this method could be included at 10% of the diet.
KEY WORDS: Poultry, layers, canavalia, jackbean, swordbean, anti-nutritional factors, urea-ensiling, boiling
The scarcity of locally produced protein supplements for inclusion in animal diets in the tropics has created a need to find alternative sources. Fluctuations in availability and cost of agro- industrial byproducts such as oilseed meals and cereal by-products have rendered the livestock industry unstable. There is need, therefore, to turn attention towards the exploitation of novel legumes such as the jackbean (Canavalia ensiformis) and the swordbean (Canavalia gladiata).
The genus, Canavalia, comprises a small group of some 48 species which are distributed throughout the tropics. Two of these species, Canavalia gladiata (swordbean) and Canavalia ensiformis (jackbean) are fairly well known and cultivated, particularly in the Far East, where the young pods and beans are used as vegetables (Pursegrove 1982). The raw ripe seeds are rich in nutrients, particularly protein and carbohydrates (Molina et al 1974; Wyss and Bickel 1988; Udedibie and Nwaiwi 1988; Bressani et al 1987) but are poisonous (Orru and Demel 1941; Borchers and Ackerson 1950). Jackbean and swordbean are similar in vegetative parts and flowers but the seeds of the swordbean are larger, typically claret coloured; those of the jackbean are white. Both species are used in Nigeria as ornamental plants and in some places are believed to be "snake repellents".
Swordbean contains gibberellin A-15, a growth-promoting hormone (Tokoya and Takama 1981) and its leaf meal has been shown to be a good source of pigment for egg yolks (Udedibie 1987) but information on its nutritive value is quite sketchy.
Research on the genus Canavalia seems to be concentrated on the jackbean and it has been found that its nutritive value could be improve to some extent by boiling or autoclaving (Borchers and Ackerson 1950; D'Mello et al 1985; Udedibie and Nwaiwi 1988). Recent studies by Udedibie and Madubuike (1988) have shown that the optimal dietary level of boiled jackbean for layers is 10%, indicating the presence of certain thermostable antinutritional factors. The best known of these substances is Concanavalin A (Con A), a lectin (Hague 1975; Jaffe 1980) which has been reported to interfere with the absorption of nutrients (Liener 1986). Canavaline, a thermostable, poisonous, alkaline aminoacid, which is a structural analogue of arginine, has also been reported to be present in jackbean seed at more than 3% of the dry matter (Rosenthal 1972; Leon et al 1989). Soaking of jackbean in a urea solution and ensiling it prior to boiling has, however, been shown to remarkably improve the nutritive value of jackbean for broilers (Montilla et al 1981; Nkwocha 1988) with dietary inclusion of the bean of up 25%. Udedibie and Nkwocha (1989) have recently reported that swordbean is of inferior nutritive value for broilers than jackbean.
The studies reported here were designed to determine the relative value of heat and urea-ensiled jackbean (JB) for laying hens.
Materials and methods
The jackbeans and swordbeans used for these studies were produced at the Teaching and Research Farm Federal University of Technology, Owerri, Nigeria and at the sub-station of the national Root Crops Research Institute, Otobi, in Benue State of Nigeria. Raw jackbeans and swordbeans were separately boiled for one hour, dried in the oven at 60 °C for 48 hours and then milled. Samples of raw and the boiled jackbeans and swordbeans were analyzed, using standard methods (AOAC 1980) to determine nutrient composition. Based on the results of the analyses, 5 dietary treatments were formulated (Table 1). Two of the diets contained the boiled jackbean at dietary levels of 10% and 20%. Another two diets contained the boiled swordbeans also at 10% and 20% dietary levels. The control diet contained no jackbeans or swordbeans.
One hundred (100) layers at 6 weeks of laying life were divided into 5 groups of 20 and randomly assigned to the treatment diets; each group was further sub-divided into 5 replicates of four birds each, and each replicate housed in a cage. The birds were fed ad libitum; water was also liberally provided. Birds were weighed at the beginning and at the end of the experiment. Feed consumption was recorded every week. At the end of the 12 week trial, 10 birds (2 from each replicate) were randomly selected from each group, sacrificed and their internal organs removed and weighed.
|Table 1: Composition (%) of treatment diets (Experiment 1)|
|Cystine + Meth*||0.50||0.56||0.58||0.52||0.53|
* Calculated from data given by Bressani et al (1987) Values
for Jackbeans and swordbeans.
** Based on D'Mello et al (1985) values for Jackbeans.
*** BJB = Boiled jackbean; BSB = Boiled swordbean.
**** To provide the following per kg of feed: vit A 1000 iu; vit D3 1500 iu; vit E 3 iu; vit K 2 mg; riboflavin 3 mg; path. acid 6 mg; macin 150 mg; choline 3 mg; vit B12 0.08 mg; folic acid 4 mg; Mn 0.8 mg; Zn 0.5 mg; iodine 1.0 mg; Co 1.2 mg; Cu 10 mg; Fe 20 mg.
The data generated (body weight change, feed intake, egg production, egg weights, feed conversion ratio) were subjected to analysis of variance and whenever significance for treatment effects was detected, means were compared using the Least Significant Difference (LSD) (Snedecor and Cochran 1967).
Raw ripe jackbeans and swordbeans were separately ensiled in a 45% solution of urea for 7 days at room temperature in plastic containers, rinsed with fresh water thereafter and then boiled for one hour before drying and milling. They were then analyzed as in experiment 1 and used in formulating four layer diets; 2 diets contained 10% and 20% of the urea-ensiled/boiled jackbeans; the other 2 diets contained 10% and 20% of urea-ensiled/boiled swordbeans. The control diet did not contain jackbean or swordbeans. The diets are shown in Table 2.
|Table 2: Composition (%) of treatment diets (Experiment 2).|
|Cystine + Meth*||0.54||0.59||0.60||0.58||0.61|
* As in table 1
** As in table 1
*** UJB = urea-ensiled/boiled jackbean; USB = urea-ensiled and boiled swordbean.
**** As in table 1
One hundred (100) layers at 10 weeks of laying life were divided into 5 groups of 20 layers and each group assigned randomly to the treatment diets. Each treatment group was also further sub-divided into 5 replicates of 4 birds each and each replicate housed in a cage. Feed and water were liberally provided. Birds were weighed at the beginning and at the end of the 12 week feeding trial. At the end of the trial, 5 birds from each treatment group (one from each replicate) were randomly selected and sacrificed and their internal organs removed and weighed. Data collection and analyses were as in experiment 1 above.
Results and discussion
Data on the nutrient composition of raw and heat-treated jackbeans and swordbeans are shown in Table 3. Raw jackbean and swordbean were about even in their crude protein contents (29.2% vs 28.2%). There was however, about 9% reduction in their protein contents after boiling, and an indication that during boiling some nitrogenous substances in the raw beans were solubilized and lost. The crude fibre content of boiled swordbeans was higher than that of the boiled jackbean, which is probably a reflection of the amount of seed coat in the swordbeans. Their crude protein values agree closely with values of 26%, 30% and 28.4% respectively earlier reported in Nebraska (Borchers and Ackerson 1950), Guatemala (Molina et al 1974) and Zurich (Wyss and Bickel 1988). Ether extract, total ash, nitrogen free extract, calcium, phosphorus and gross energy of the two species were similar and were only slightly affected by cooking.
|Table 3: Proximate composition of raw processed jackbeans and swordbeans*|
* RJB = raw jackbean; BJB = boiled jackbean; UJB =
urea-ensiled/ boiled jackbean; RSB = raw swordbean; BSB = boiled
swordbean; USB = urea-ensiled/boiled swordbean.
** All values expressed on 100% dry matter basis.
Data on performance of the layers are shown in Table 4. At 20% dietary level, both boiled jackbean and swordbean significantly (P<0.05) reduced body weights. Feed intakes at this same dietary level were also significantly (P<0.05) reduced. At the 10% dietary level, the swordbean slightly depressed feed intake although this was statistically non-significant (P>0.05). The mean percent hen- day egg production followed a similar pattern. Hen-day egg production was significantly (P<0.05) depressed at 20% dietary level of boiled jackbean and 10% dietary level of boiled swordbean. The depression was much severe at 20% dietary level of boiled swordbean (P<0.01). Consequently feed conversion ratio was adversely affected by boiled swordbean at the 20% dietary level. Egg weights were not affected by treatments.
The weights of the internal organs, liver, gizzard and heart, expressed as percent of final body weights were also not affected by treatments. There was no reason to believe that the deaths recorded during the trial were due to the inclusion of jackbean or swordbean in the diets.
|Table 4: Effect of boiled jackbean and swordbean on the performance of laying hens.|
|Body weight (kg)|
|Mortality (%)||2||-||1||2||2 -|
|Feed intake (g/d)||112.20a||113.80a||80.02b||96.80ab||84.10b 2.840|
|prod. (%)||62.60a||63.20a||51.00b||56.20b||43.40c 2.240|
|Average egg wt (g)||58.20||57.80||58.00||57.40||57.00 0.020|
|Feed/kg eggs (kg)||3.08a||3.12a||2.91a||3.00a||3.38b 0.011|
ab means within a row with differents subscripts are different
ac means within a row with differents subscripts are different (P<0.01)
These results tend to confirm the earlier observations by Udedibie and Madubuike (1988) on boiled jackbeans and, in addition, show that swordbean appears to be an inferior feed ingredient to jackbean when subjected to the same heat-treatment. The fact that 20% dietary level of boiled jackbean and 10% dietary level of boiled swordbean adversely affected the performance of the layers showed that there were still some anti-nutritional factors in the two beans after boiling for one hour.
Data on the nutrient contents of urea-ensiled/boiled jackbean and swordbean are presented in Table 3. Both boiling alone and ensiling with urea prior to boiling had similar effects on the nutrient composition of the two species of Canavalia. The process reduced the protein contents of the raw seeds to about the same degree as boiling alone in Experiment 1.
Data on performance of the layers on the urea-ensiled/boiled swordbean and jackbean are shown in Table 5. Urea-ensiled/boiled swordbean at the 20% dietary level significantly (P<0.05) reduced the body weights, feed intake and hen-day production of the layers. Egg weights, feed conversion ratio and the visceral organs of the layers were not affected by treatments. It appears, therefore, that the optimal dietary level of urea-ensiled and boiled swordbean for layers is about 10%. The layers on both 10% and 20% dietary level of urea-ensiled and boiled jackbeans compared very favourably with those on the control diet in all the parameters measured. From the data in Table 5, it is apparent that 20% dietary inclusion of urea- ensiled and boiled jackbeans is feasible without affecting performance of layers.
|Table 5: Effect of urea-ensiled/boiled jackbean and swordbean on the performance of laying hens.|
|Average egg wt.(g)||57.90||58.00||58.10||57.90||58.00||0.020|
|Feed/kg eggs (kg)||3.05||3.02||3.02||2.98||3.01||0.010|
ab means within a row with differents subscripts are different (P<0.05).
The reason for the difference in performance of the layers on the jackbean and swordbean diets cannot immediately be adduced. Available literature indicates that both jackbean and swordbean are relatively high in the essential aminoacid lysine (5.73g/16g N and 5.62g/16g N, respectively) although fairly low in methionine (Bressani et al 1987; Leon et al 1989). However, their methionine contents are higher than that of groundnut cake, the main protein supplement in the control diet (1.9g/16g N) (NRC 1971). The process of ensiling in urea prior to boiling seems to remove the thermostable anti-nutritional factors in raw jackbean, thereby rendering available to the layers nutrients contained in the diet. The failure of the swordbean to respond as positively to these treatments as the jackbean, could in part be attributed to the very thick seed coat of the swordbean which Bressani et al (1987) have reported to be about 20.3% of the seed as against 10.8% in the jackbean.
The funds for this study were provided by the International Foundation for Science (IFS), whose assistance is highly appreciated.
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