Nguyen Thi Hong Nhan, T R Preston1 and Frands Dolberg2
Department of Animal Husbandry, Faculty of Agriculture, Cantho University, Vietnam
Studies were done to determine the optimum inclusion rates in poultry diets of meals made from sun dried leaves of Trichantera gigantea meals, and of the fresh leaves in diets for ducks, as locally available sources of carotene and plant protein. Three trials were made in collaboration with smallholder farmers in Cantho City.
In trial l a randomized block design was used with three levels (0,2 and 6% air dry basis) of Trichantera leaf meal with 180 laying hens. The second trial lasted 10 weeks and evaluated 0 or 6% Trichantera leaf meal in the diet of 300 laying quails. The results for mean egg production and egg quality of laying hens and quails were similar for the control and experimental diets. The cost of production tended to be lower for diets with Trichantera leaf meal.
In the third trial, 200 ducks were fed from 21 to 60 days of age to evaluate fresh leaves of Trichantera and water spinach in fattening diets. There were no significant differences between treatments for daily weight gain and feed conversion ratio. Carcass parameters were not affected by treatments, except that breast muscle percent increased with increasing intake of Trichantera. Key words: Trichantera gigantea, water spinach, laying hen, laying quail, ducks.
1 Finca Ecologica, University of Agriculture and Forestry, Thu Duc, Ho Chi Minh City, Vietnam
2 Department of Political Science, University of Arhus, Denmark
Village surveys in the Mekong delta (Nguyen Thi Kim Dong, personal communication) have shown that protein is likely to be the first limiting factor in poultry diets at the level of small scale farmers. Research is needed to explore the possibility of utilizing locally available protein resources, especially the leaves from multipurpose trees and water plants, to replace the conventional protein-rich concentrate meals. It is common practice by farmers in tropical countries to use small amounts of green feed to protect against possible vitamin deficiencies and to provide unidentified growth factors.
The multi-purpose tree Trichantera gigantea (Preston and Murgueitio 1994), introduced into Vietnam from Colombia in 1991 has adapted readily to a wide range of ecosystems throughout Vietnam (Nguyen Ngoc Ha and Phan Thi Phan 1995; Nguyen Thi Hong Nhan et al 1996). The crude protein content of the foliage (leaves and the thin stems, which are also consumed by the animals) varies from 18 to 20 % in dry matter and apparently most of that is true protein and has a good amino acid balance (Rosales 1997). According to some early work there are few secondary plant compounds and the calcium content has been found to be particularly high compared to other fodder trees (Galindo et al 1989). Water spinach is another potential source of leaf protein and carotene (Naren Toung et al 1994) and is widely used by farmers in the Mekong Delta as a supplementary feed for their animals.
Three on-farm trials were conducted with the following objectives:
Table 1: Composition of diets for laying hens in Trial 1.
|Soya bean meal||10||10||10|
|Trichantera leaf meal||-||2||6|
|N*6.25, % in DM||18.5||18.5||18.8|
|Feed cost (VND/kg)||2400||2275||2150|
Table 2: Effect of diets on production and composition of eggs in laying hens
|Egg production %||74.5||75.4||75.1||0.5/0.9|
|Feed conversion g/egg||138||138||121||3.2/0.6|
|Egg yolk (%)||26.9||26.8||26.4||0.3/0.57|
* On scale of 1 to 10
Materials and methods
A total of 180 laying hens housed in cages made from bamboo were allocated to three diets; the control (C) containing 54% yellow maize and two test diets with broken rice instead of maize and either 2 or 6% of meal from sun dried leaves of Trichantera gigantea. The diet composition is in Table 1.
Table 3: Composition of diets for laying quails (Trial 2)
|Cassava root meal||-||15||35|
|Lys + Met||0.2||0.2||0.2|
|Trichantera leaf meal||-||6||6|
|N*6.25 in DM||24.8||24.2||24.1|
Three diets were fed to 300 laying quail during a period of ten weeks. The control diet contained yellow maize which in the experimental diets was replaced by Trichantera gigantea leaf meal (6% of diet) and cassava root meal as partial (TGP) or total (TGT) replacement of the maize meal. Details of the diets are in Table 2.
Table 4: Effect of diets on production and quality of eggs
|Egg production %||84.8||91.2||89.7||2.7/0.26|
|Feed conversion g/egg||23.9||23.4||22.8||1.3/0.8|
|Egg weight, g||9.9||10.4||10.1||0.2/0.28|
|Egg yolk, %||28.9||28.9||28.4||0.7/0.9|
* On scale 1–10
In the third trial, 200 Snow White ducks were fattened from 21 to 60 days of age with diets based on broken rice and rice bran and with fresh leaves of Trichantera gigantea or water spinach (Ipomoea aquatica) offered on free choice basis. The basal diet was modified by reducing the levels of soya bean meal and fish meal by 10%. The treatments were: Control (basal diet), SBTG (Trichantera ad libitum and 10% reduction of soya bean meal in the basal diet); SBWS (same as SBTG but with water spinach instead of trichantera); FMTG (same as SBTG but with replacement of fish meal); and FMWS (same as FMTG but with water spinach). There were 4 replicates of the five dietary treatments (ten ducks per treatment/replicate). The composition of the control diet is in Table 5. The leaves were fed freshly harvested on ad libitum basis. At the beginning, and at the end of the experimental period and every 10 days in between, all ducks were individually weighed. Daily feed consumption was recorded on a pen basis.
Result and discussion
Trial 1: Laying hens
Substitution of maize by broken rice and Trichantera leaf meal lowered the cost of the diet from 2,400 to 2150 VND/kg (1 USD=VND 11,000) with no change in the protein content.
The effects of the diets on production and on egg composition of egg are shown in Table 2.
There were no differences in egg production between the three treatments; feed conversion was similar on the control and 2% Trichantera leaf meal diets (138g/egg) but a little lower with 6% Trichantera leaf meal (121g/egg). Feed cost (VND/egg) decreased gradually from 329 in the control to 313 and to 260 in the TG2 and TG6 treatments.
Table 5: Composition of the control diet for growing ducks
|Crude protein in DM||18.8|
Trial 2: Laying quails
Mean values for egg production, feed conversion and egg quality are given in Table 4.
There was an indication (P=0.26) for egg production to be higher on the diets containing Trichantera leaf meal. Feed conversion was similar on all diets. Yolk color tended to be better (P=0.09) on the diets containing the Trichantera leaf meal.
Trial 3: Fattening ducks
It was not possible to collect precise data on the intake of the trichantera leaves and the water spinach but spot observations taken on weighing days indicated that the average intake (fresh basis) was in the range of 70–80 g/duck/day. This is equivalent on a dry matter basis to some 10% of the total daily intake. Sarria (1994) reported slightly higher levels of intake of Trichantera leaves, as a proportion of diet dry matter, in pigs. Growth performance data (Table 6) showed no differences between treatments.
Table 6: Effect of trial diets on growth performance of ducks
|Live weight, kg|
|Feed intake (g/d)|
At the end of the trial, four ducks per treatment (two females and two males) were slaughtered. Table 7 shows the results of the carcass analysis. The only significant effect of treatment was for breast muscle which increased from 8.05% on the control to 10.5% for the FMTG treatment (P=0.004). The skin color was observed to take on a bright yellow appearance in the ducks having access to the Trichantera.
A vitamin/mineral premix was not included in the diets and no deficiency symptoms were observed. This is an important advantage in rural areas where premixes may not be available or are expensive.
Conclusions and recommendations
Table 7: Effect of diets on carcass composition and intestine of ducks
|Carcass, % LW||73.8||71.2||76.4||73.3||75.9||2.2/0.49|
|Leg muscle, %||6.75||6.73||6.56||6.85||6.1||0.28/0.4|
This research was supported financially by the International Foundation for Science through a grant (B/2231-1) to the senior author.
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