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| Photo 1. Pseudo-stem of the banana plant | Photo 2. Taro (Colocasia esculenta) | Photo 3. Duckwwed raised in ponds fertilized with waste water from a fish pond |
| Livestock Research for Rural Development 26 (11) 2014 | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
This experiment was carried out to evaluate ensiled mixtures of banana pseudo-stem and taro foliage as supplements to a basal diet of restricted rice bran and ad libitum fresh duckweed for growing common ducks. Ninety six common ducks at 21 days old were used in a completely randomized design with four treatments and three replications in a growth trial lasting 70 days. The treatments were silages made from ratios of banana pseudo-stem and taro foliage (leaves +petioles) of 0:100, 20:80, 40:60 and 60:40 (DM basis) which were offered ad libitum.
Feed intake, growth rates and feed conversion were improved when banana pseudo-stem replaced 60% of the taro foliage in the mixed silage, the overall conntribution of the silage to the diet DM being 31%.
Key words: forages, growth, local feed resources, oxalate, water plants
Bananas (Photo 1) are traditionally grown for the production of fruit as food for people, the rest of the plant (trunk and leaves) usually being returned to the soil as a source of organic matter. Contrary to the situation in most plants, the dry matter (DM) in the trunk (more correctly called the pseudo-stem) is more digestible (75%) than in the leaves (65%) (Ffoulkes and Preston 1978), although the former has much less protein (5% in DM of pseudostem vs 10% in DM of leaves ) (Feedipedia 2012). Taro (Colocasia esculenta) is an aquatic plant that grows wild in the nature, near river banks and ponds (Photo 2). The leaves are rich in protein and are easy to ensile when combined with the petioles (Rodriguez and Preston 2009). Nguyen Tuyet Giang et al 2010) showed that when ensiled taro foliage was fed to ducks, as a supplement to rice bran, growth rates were improved and there was a positive effect on carcass quality.
Ensiled mixtures of banana pseudo-stem and taro foliage were fed to common ducks by Dao Thi My Tien et al (2012). Growth rates were best with from 40 to 50% (DM basis ) of taro foliage in the ensiled mixture. At this level of taro foliage in the mixture the protein content was relatively low (<12% in DM) and it was hypothesized that supplementation with protein would probably improve the growth rate of the ducks. In rural areas duckweed (Lemna minor) grows wild on water surfaces especially when there are sources of nutrients from household waste waters. When fertilized with biodigester effluent the protein content can reach over 30% in DM (My Tu et al 2013). It was successfully used to replace soybean meal in rice bran-based diets for fattening ducks with no reduction in growth rate and with better carcass quality (Bui Xuan Men et al 1995).
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| Photo 1. Pseudo-stem of the banana plant | Photo 2. Taro (Colocasia esculenta) | Photo 3. Duckwwed raised in ponds fertilized with waste water from a fish pond |
It was hypothesized that higher proportions of banana pseudo-stem could be included in the ensiled mixtures with Taro foliage if duckweed was also offered ad libitum
The experiment was carried out in the experimental farm of Angiang University, Long Xuyen city, Angiang province, Vietnam from October to December 2011.
The experiment was a Completely Randomized Design with four treatments and three replications (one pen with 8 ducks per treatment/replicate, balanced for sex). The treatments consisted of 4 ensiled mixtures of banana pseudo-stem and taro foliage which were fed as supplements to a basal diet of rice bran and fresh duckweed offered ad libitum.
The individual treatments were:
BS0: Silage with 0% banana stem + 100% taro foliage (in DM)
BS20: Silage with 20% banana stem + 80% taro foliage (in DM)
BS40: Silage with 40% banana stem + 60% taro foliage (in DM)
BS60: Silage with 60% banana stem + 40% taro foliage (in DM)
Ninety six common ducks at 1 day old were collected from brooding houses in Angiang province. After one week of feeding a commercial feed, they were adapted to the experimental diets until they reached 21 days of age. The experiment was ended when the ducks reached 70 days of age. The ducks were housed in cages (5 ducks/m2) made from wood and plastic net.
Pseudo-stems were collected from banana plants on farms near the University at the time of fruit harvest. Taro petioles and leaves were harvested from plants growing on roadsides and other unused areas. These materials were chopped finely (1-2 cm) with a knife (Photo 4), sun-dried for 6-8 h to reduce the moisture to 75-80%, and packed tightly into plastic bags (2 liters capacity) which were placed inside rigid plastic containers. The bags were covered with plastic sheet and stored at room temperature (Photo 5).
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Photo 4. Chopped banana stem and Taro foliage |
Photo 5. The ensiled mixtures |
The rice bran was fed at a fixed level of 30g/day (air dry basis) in week 1, 40 g/day in week 2, 50 g/day in weeks 3 to 5 and 60 g/day for the rest of the experimental period. The silages and the duckweed were offered ad libitum.
Feeds offered and refused were measured separately every day in the morning. Daily feed intakes were calculated according to the total feed consumption of the eight ducks in each pen. The ducks in each experimental unit were weighed individually at the beginning of the experiment and then weekly until the end of the experiment.
The DM, crude protein and ash contents of the feeds were determined according to the procedures outlined in AOAC (1990).
Statistical analysis
Average growth rates of each pen of ducks were calculated from the linear regression of the average live weight (Y) and days on experiment (X). All the recorded data were processed with MS Excel software and subsequently analyzed using the general linear model in the Minitab Software Release version 15 (2007). Sources of variation in the model were treatments and error.
The duckweed and the ensiled mixtures of banana pseudo-stem and taro foliage were rich in minerals (Table 1). A brix value of 4.4-6.3 in the soluble fraction is indicative of a concentration of soluble sugars in DM of the order of 50%, which implies that the ensiled mixtures of banana pseudo-stem and taro foliage are good sources of digestible carbohydrate. The rapid fall in pH after ensiling the foliages separately or together (Dao Thi My Tien et al 2013; Duyet and Preston 2013) confirms the presence of a high concentration of soluble sugar in the banan psuedo-stem and taro foliages. The decreases in the brix value as the proportion of banana pseudo stem in the ensiled mixture was increased indicates a higher content of sugars in the taro foliage than in the banana pseudo-stem.
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Table 1. Chemical composition of experimental feeds |
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Banana pseudo-stem as % of silage DM |
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Rice bran |
Duck weed |
0 |
20 |
40 |
60 |
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DM, % |
88.3 |
6.5 |
11.1 |
13.0 |
13.6 |
13.7 |
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CP, % in DM |
12.8 |
22.8 |
12.8 |
11.9 |
10.7 |
7 |
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Ash, % in DM |
13.7 |
27.3 |
23.4 |
23.1 |
22.0 |
21.2 |
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pH |
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3.9 |
3.8 |
3.9 |
4.1 |
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Brix# |
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6.3 |
5.5 |
4.9 |
4.4 |
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# Indicative of percentage of soluble sugars in the aqueous fraction |
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Growth performance, feed intake and feed conversion
Increasing the proportion of banana stem in the silage resulted in increasing intakes of duckweed, of the mixed silage, and of total DM (Table 2; Figures 1-3). Growth rates and DM feed conversion were also improved as the proportion of banana stem in the silage was increased (Figures 4 and 5). As the proportion of banana pseudo-stem in the silage was increased, the concentration of crude protein in the mixed silage decreased, resulting in a slight decrease in the crude protein concentration of the diet DM (from 14.3 to 13.2% in the diet DM).
There is no obvious reason for the higher feed intake and better growth performance of the ducks that resulted from banana pseudo-stem replacing taro foliage in the mixed silage. The presence of oxalate salts in the taro foliage could be one explanation as there are reports that this may reduce its acceptance by livestock (Masters et al 2001, 2005). On the other hand, ensiling taro foliage has been shown to reduce the content of oxalate salts (Hang and Preston 2010). The highest intake of the mixed banana pseudo-stem/taro foliage was with 31% of the silage in the diet DM. Further studies should be done with this feed as the major component of the diet in order to estimate its true potential as a component of the diet of growing ducks.
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Table 2. Mean values for feed intake, live weight gain and feed conversion of common ducks for diets in which ensiled mixtures of varying proportions of banana pseudo-stem and taro foliage (leaf + stem) were fed as a supplement to rice bran and duckweed |
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Banana pseudo-stem replacing taro foliage (% DM basis) |
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0 |
20 |
40 |
60 |
SEM |
p |
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DM intake, g/d |
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Rice bran |
42.5 |
42.5 |
42.5 |
42.5 |
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BS-TF silage |
8.11 |
12.6 |
13.6 |
13.8 |
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Duckweed |
9.04 |
9.13 |
9.25 |
9.44 |
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Total |
59.7 |
64.3 |
65.4 |
65.7 |
0.50 |
<0.001 |
| CP in diet DM, % |
14.3 |
14.0 |
13.8 |
13.2 |
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Live weight, g |
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Initial |
375 |
398 |
392 |
373 |
8.46 |
0.176 |
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Final |
667 |
735 |
757 |
738 |
19.4 |
0.049 |
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Daily gain |
6.1 |
7.1 |
7.5 |
7.7 |
0.41 |
0.090 |
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DM FCR |
12.3 |
11.4 |
10.9 |
10.7 |
0.51 |
0.40 |
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| Figure 1. Trends in silage DM intake with
increasing proportions of banana pseudo-stem replacing taro foliage |
Figure 2. Trends in duckweed DM intake with
increasing proportions of banana pseudo-stem replacing taro foliage |
Figure 3. Trends in total DM intake with increasing
proportions of banana pseudo-stem replacing taro foliage |
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Figure 4.
Trends in live weight gain of ducks fed silage with increasing proportions of banana pseudo-stem replacing taro foliage |
Figure 5. Trends in DM feed conversion of ducks fed silage with increasing proportions of banana pseudo-stem replacing taro foliage |
The authors are grateful for the support from the MEKARN project, financed by Sida, Sweden.
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Received 18 August 2014; Accepted 21 October 2014; Published 3 November 2014