Feed selection and growth performance of local chickens offered different carbohydrate sources in fresh and dried form supplemented with protein-rich forages

Kong Saroeun, Brian Ogle*, T R Preston** and Khieu Borin

Center for Livestock and Agriculture Development,
PO. Box 2423, Phnom Penh 3, Cambodia
saroeunkb@celagrid.org
* Department of Animal Nutrition and Management,
Swedish University of Agricultural Sciences, Box 7024, 750 07 Uppsala, Sweden
** UTA - TOSOLY - Finca Ecológica, Morario - Guapota -
AA # 48, Socorro, Santander, Colombia

Abstract

A series of experiments were conducted at the farm of CelAgrid in Kandal Province, Cambodia.

Experiment 1 consisted of two related cafeteria trials which were conducted to determine the feed preferences of local chickens when fed different feeds separately. The first trial was conducted for 4 weeks with 40 chickens allocated to 4 pens, with 10 birds per pen. They were given free access to three types of chopped green forages (taro leaf, duckweed and water spinach) and broken rice as source of energy. The daily dry matter (DM) intake of duckweed (3.9 g) was higher than that of water spinach (2.1 g), while the intake of taro leaf was relatively low (0.02 g). The daily crude protein (CP) intakes were 1.1 g, 0.5 g and 0.02 g for duckweed, water spinach and taro leaf, respectively. The second trial was conducted with the same duration and the same number of birds per pen. They were given free access to 3 types of fresh chopped carbohydrate feeds (cassava root, sweet potato tuber and banana fruit) and duckweed as the only source of protein The daily DM and CP intakes of sweet potato and cassava root were 16 g and 0.5 g, respectively, while the banana fruit intake was low.

Experiment 2 was carried out for 2 weeks with 240 local chickens at the age of 60 days (144 females and 96 males). The chicks were housed 10 per pen (4 males and 6 females). The experiment was a 4*2 factorial arrangement in a completely randomized design (CRD) with 3 replications. The chickens had free access to each of the carbohydrates (broken rice, cassava root, sweet potato tuber, and banana fruit) and each of two proteins feeds (soybean meal and duckweed). The total daily DM intake of the broken rice diets was 32.0 g, and was  26.6 g, 24.0 g and 22.5 g of fresh cassava root, sweet potato tuber and banana fruit, respectively. The CP intake of chickens on duckweed was 19.2 g, which was lower than of those fed on soybean meal (34 g). The CP intake of chickens fed different carbohydrates was similar (5-7 g) but the CP intake of the chickens fed on soybean meal was higher (10.4 g) than on duckweed (2 g). The chicks did not gain weight on duckweed, except on the broken rice diets, and had normal growth on soybean meal (4-6 g). Through linear regression analysis, the DM intake was shown to have high relationship with the average daily gain (R²=0.70).

Experiment 3 was carried out for 2 weeks with 210 local chickens (144 females and 96 males) at the age of 60 days. The chicks were housed 10 per pen (4 males and 6 females) and were allotted randomly to treatment. The experiment was 3*2 factorial arrangement in a completely randomized design (CRD) with 3 replications. Chickens had free access to each of three kinds of carbohydrate (cassava root, sweet potato tuber, and banana fruit) in the fresh form or as meal. The total daily DM intakes of the cassava root, sweet potato tuber and banana fruit diets were 21.0 g, 19.6 g and 29.0 g, respectively. The total intake of chickens fed the different forms of carbohydrate feed was not different and was around 20 g/day. The total daily CP intake was similar between the chickens fed on different types or forms of carbohydrate feed, and was around 1.5 g. Linear regression analysis showed that the weight change of chickens had a close relationship with the CP intake (p=0.011, r²=0.75).

Key words: Cafeteria, green forage, duckweed, water spinach, taro leaves, carbohydrate feeds, cassava root, sweet potato tuber, banana fruit

Introduction

Raising local chickens by smallholder farmers in developing countries is based on scavenging and providing some extra feed. Available low cost feeds that farmers can use to supplement their chickens could be by-products and surplus products that can provide energy or protein. Some locally available feeds, such as cassava root, sweet potato tuber and banana fruit, are good sources of energy but they are not used widely by farmers even though they are abundant at harvesting time or the price is low. However, these feeds contain low protein, vitamins, and minerals (Silvestre and Arraudeau 1983; Cerning Beroard and Le Dividich 1976; Le Dividich et al 1976). Therefore, if farmers use them to provide energy to chickens to support activities during scavenging, some protein feeds should be also supplemented and these should be cheap and high in nutrients, such as green forages, including duckweed, water spinach, sweet potato leaf and taro leaf. The CP contents of duckweed, water spinach and taro leaf are 39.3 % (Bui Xuan Men et al 1996), 35.9 % (Nguyen Thi Thuy and Ogle 2005) and 25.0 % (FAO 1993), respectively. These indicate a good potential for smallholder farmers to improve the performance of their scavenging chickens. However, there is a concern in using green forages for chickens because they contain high levels of fiber, which has been associated with reduced nutrient digestibility (Just 1982; Graham 1988).

Therefore, these studies were conducted to evaluate potential carbohydrate feeds to determine whether they could be used fresh or should be processed before they are fed to provide energy to local chickens, and also how they could be used with green protein-rich forages. 

Experiment 1. Preference of local chickens for different green forages and carbohydrate feeds

Material and methods

Duration and location

The experiment consisted of two related trials which were conducted for four weeks each in the farm of the Center for Livestock and Agriculture Development (CelAgrid), which is about 19 km south of Phnom Penh City.

Experimental design

 Green forages selection trial

Three types of green forage (taro leaf, duckweed and water spinach) were fed (Table 1) with broken rice as the main source of energy. There were 10 chicks per each of the 4 pens. The breeds of chicken were Sampov (a local breed) and Kandong (a slow feathering breed) and were 60 days old. Each forage and broken rice were offered separately. All the green forages were offered in the same amount (DM basis) during 10 days of the adaptation period. Subsequently, the amounts were changed according to the preference of the chickens. The green forages were offered 4-5 times each day.

Cassava root, sweet potato tuber and banana fruit selection trial

Carbohydrate feeds (cassava root, sweet potato tuber and banana fruit) were randomly allocated to each of the 4 pens and with 10 chicks per pen, and were offered separately in each pen. The green forage (duckweed) most preferred by the chicken in the first trial was selected and offered as protein feed. All carbohydrate feeds were offered in the same amount of DM during 10 days of the adaptation period and then the amounts were changed according to the observed intakes. The fresh carbohydrates were offered 4-5 times per day.

Data collection and feed analysis

Feed offer and refusals were weighed once per day in the morning to estimate the intake. Samples of feeds were taken for analysis of DM and CP. The chickens were weighed every week.

Statistical analysis

Feed intake was analyzed using the GLM option of the ANOVA program in Minitab 14 (2004) software. Sources of variation were: green forages and error (for the green forage selection trial) and carbohydrate feeds and error (for carbohydrate selection trial).

Results

Chemical composition of the experimental feeds

Both water spinach and taro leaves had higher DM content compared with duckweed, while duckweed had higher protein content in DM basis (Table 2). Crude protein (CP) levels were similar for water spinach and taro leaf, with a higher level for the duckweed.

Protein-rich forages intake (PRF)

The DM intake of duckweed, water spinach and taro leaves was 3.9 g, 2.0 g and 0.02 g per day, respectively (Table 3). The total intake of forages accounted for 18% of the total DM intake and 43% of the CP intake (Figure 1).

Roots/tubers/fruits intake (RTF)

The carbohydrate components accounted for 81% of the total DM intake and 29% of the duckweed intake (Figure 2). Among the carbohydrates, the fresh sweet potato tubers and cassava roots were consumed in similar quantities (together accounting for almost all the intake of the carbohydrate component) with fresh banana fruit being eaten in insignificant amounts (Table 4).  

When the birds were fed cassava root, sweet potato tuber and banana fruit with duckweed, they were less able to satisfy their nutrient requirements than when they were offered the green forage with broken rice. The total CP intake from the duckweed in the RTF (2.4 g/day) was greater than from the forages in PRF (1.7 g/day). However, in the PRF trial the broken rice supplied more crude protein (2.2 g/day) than the roots-tubers-fruit in RTF (0.96 g/day).

Discussion

Among the green forages (duckweed, water spinach and taro leaf) that were fed to the local chickens in the cafeteria system, duckweed was the most preferred, followed by water spinach, while taro leaf was the least preferred. It was observed that when some chickens ate taro leaf, they consumed a little and walked away, while some chickens did not consume it at all. Every feeding time, chickens ran to the trough with duckweed first, and then to the trough with the other feeds. The fresh intake of duckweed in this study (61-116 g/day) was higher than that reported by Hong Samnang (1999) which was 30-40 g/day as a supplement to broken rice, and by Rodriguez and Preston (1999)  (30 to 36 g/day) with rice bran as the supplement. Nguyen Thi Kim Khang and Ogle (2004) found out that Tau Vang chickens confined on-station consumed 40 g/day fresh duckweed as a supplement with concentrate. Nguyen Thi Thuy and Ogle (2005) compared three kinds of green forage as protein feed and found that the daily DM intakes of duckweed, water spinach and sweet potato leaves were 3.3, 1.8 and 2.8 g respectively, which for duckweed and water spinach were similar to the intakes in the present study (3.9 and 2.1 g/day, respectively). However, if compared to the preferences of indigenous chickens in scavenging conditions, they are diverse; Okitoi et al (1999) and Tuitoek et al (2000) reported that chickens prefer grain (49-54%), kitchen waste (13.5-14.5%) insects and worms (6-8%) and green forages (5-15%).

It has been observed that chickens in the free range system pick at carbohydrate feeds such as cassava root, sweet potato tuber and banana fruit, but it is not known whether they really appreciate them. In the present experiment, when offered the three kinds of carbohydrate feed, the chickens spent most time at the trough with cassava root and sweet potato tuber, and ate banana fruit only in small amounts. The DM intake of banana fruit was 16 times smaller than of cassava roots and sweet potato tuber.  Comparing the foraging behavior of scavenging chickens, Okitoi et al (2009) reported that the highest frequency of dietary components retrieved from crops contents of scavenging indigenous chickens in Western Kenya in two seasons was grass, followed by cassava root and maize.

Conclusion

• Among the green forages, duckweed and water spinach were preferred, and among the carbohydrate feeds cassava roots and sweet potato tuber were preferred by local chickens.

Experiment 2. Comparison of different sources of fresh carbohydrate with soybean meal or green forage as protein sources for local chickens

Materials and methods

Location and duration

The experiment was conducted for two weeks in the farm of the Center for Livestock and Agriculture Development (CelAgrid).    

Materials

The chicks were hatched by electric incubator at CelAgrid and raised until they were 60 days old. The carbohydrate feeds were cassava roots, sweet potato tubers, banana fruit and broken rice, and soybean meal and duckweed were the sources of protein. Duckweed was the most preferred green forage as shown in the results from Experiment 1. Duckweed was cultivated in the canals at the CelAgrid farm that are fertilized with effluent from pig manure.

Experimental design

The experiment was designed as a 4*2 factorial arrangement in a completely randomized design (CRD) with 3 replications. There were 10 chickens per replication (pen) (4 males and 6 females per pen). The factors were:

Carbohydrate feeds

• Broken rice (BR)
• Cassava root (CR)
• Sweet potato tuber (SP)
• Banana fruit (BF)

Protein feeds

• Soybean meal (SB)
• Duckweed (DW)

Individual treatments were:

• BRSB: Broken rice + Soybean meal (control treatment)
• CRSB: Cassava root + Soybean meal
• SPSB: Sweet potato tuber + Soybean meal
• BFSB: Green banana fruit + Soybean meal
• BRDW: Broken rice + Duckweed
• CRDW: Cassava root + Duckweed
• SPDW: Sweet potato tuber + Duckweed
• BFDW: Green banana fruit + Duckweed

Housing system

The experimental pens were 24 compartments (each with an area of 7 x 1.5 m) built using wooden and bamboo frames and metal wire mesh. Two feeders (one for the energy feed and one for the protein feed) and one water trough were put in each pen.

Experimental feeds and feeding

Chickens had free access to the carbohydrate and protein feeds. The whole carbohydrate feeds were chopped into small pieces and fed fresh. Duckweed was collected and pressed by hand to reduce the water content before feeding. The chemical composition of the experimental feeds is shown in Table 8.

6.6. Animals and management   

Two hundred and forty local chickens of the same breed were used in the experiment. They were kept 10 per pen (4 males and 6 females) where they had free access to the feed and water. Before starting the experiment, the chickens were vaccinated against Newcastle Disease  and Fowl Pox. Fresh feed was provided 3-4 times per day.

6.7. Data collection

The chickens were adapted to the experimental feeds for 10 days before starting the collection of data. Feed offer and refusals were weighed and recorded daily before and after each of the meals. The weights of the chickens were taken every 7 days. Samples of feed were taken for analysis every 7 days.

6.8. Chemical analysis

The feeds offered and refusals were analyzed to determine DM using microwave radiation (Undersander et al 1993) and N and ash following the methods of AOAC (1990).

6.9. Statistical Analysis

Dry matter feed intake, crude protein intake and live weight gain were analyzed using the General Linear Model (GLM) option of the ANOVA software of Minitab 14 (2004). The sources of variation were: carbohydrate feeds, protein feeds, interaction of carbohydrate feeds*protein feeds and error.

7. Results

Growth rate and feed intake

There were significant interactions for all measurements of feed intake and live weight change (Table 9), which showed contrasting results according to whether the protein source was soybean meal or duckweed.  On soybean meal the chickens gained live weight on all the carbohydrate sources, with the best result on broken rice, followed by sweet potato root and with the poorest growth on cassava root and banana fruit (Table 9). In contrast, with duckweed as the protein source, the chickens lost weight on all the carbohydrate feeds other than broken rice for which the growth rate was the same as with soybean. The differences in live weight change appear to have been caused by differences in feed intake, as live weight gain was linearly related (R² = 0.7; P=0.001) with DM intake.

Discussion

In this study, the live weight gain of chickens fed the control diet (broken rice with soybean meal and broken rice with duckweed) was around 6 g/day, which was similar to those fed on broken rice and green forages in Experiment 1, in which they had similar CP intake (12 % of diet DM). Kingori et al (2003) reported that when indigenous chickens were fed a diet containing 12% CP, they gained 5.8 g/day but they can gain more weight (up to 11.5 g/day) if the diet contains the required protein (16 %) in a balanced diet. However Hong Samnang (1999) reported that the live weight gain of experimental indigenous chickens was 12.5 g/day on broken rice plus duckweed, up to 14.5 g/day on broken rice plus soybean meal and 10 g/day on broken rice alone. One of the reasons is that initial weight of his experimental chickens was higher than that in the present study and the chickens were scavenging, and thus the additional nutrient requirement could be compensated for by the scavenging feed resources. If compared to the results of Nguyen Thi Thuy and Ogle (2005), the live weight gain was higher than that in the present study, and was 20.4 g/day using balanced mixed feed with duckweed and with Loung Phoung chickens. Also, the CP in diet DM was 16.8%, which was higher than that in the present study.

In this study, if the broken rice was replaced by fresh carbohydrate feeds, such as cassava root, sweet potato tuber and banana fruit, there were negative effects on feed intake and live weight gain. The chickens consumed lower amounts of these fresh feeds compared to broken rice and consumed more protein feed if soybean meal was used. They consumed the same amount of duckweed if it was used as protein feed. On the diet of duckweed as protein feed, chickens lost 2 g/day of live weight when they were fed fresh cassava root, sweet potato and banana fruit. Although the protein intake was below the requirement of growing chickens of 14-21 weeks, the other important limitation which prevents the optimal utilization of nutrients is the anti-nutritional factors in the feed.

Fresh whole cassava root can contain 0.44 mg HCN/g (Panigrahi et al 1992). Feeding of fresh cassava roots may cause cyanide toxicity, depending on the cyanide content in the tubers (Mathur et al 1969). Panigrahi (1996) reported that an excess of cyanide content of 100 mg/kg diet appears to adversely affect broiler performance, and laying hens may be affected by levels as low as 25 mg total cyanide/kg diet. Fresh banana fruit also contains tannin (3.40 mg/g), oxalate (4.50 mg/g) and phytate (2.88 mg/g) but the quantity of these anti-nutrients is not excessive (Onibon et al 2007). Fresh sweet potatoes contain trypsin inhibitors, ranging from 90 % inhibition in some varieties to 20 % in others (Lin and Chen 1985), which cause low dry matter digestibility and low metabolizable protein and energy values, even when the rations contained adequate and high quality proteins (Gerpacio et al 1978).

Conclusions

• Among the energy feeds, cassava roots seem to be more promising, as chickens consumed higher amounts. However, processing techniques need be studied, such boiling whole roots, boiling chops or making into chips.

Experiment 3. Effect of fresh or dried cassava roots, sweeet potato tubers and banana fruit, as energy feeds, with fresh duckweed as the protein source on the growth of local chickens

Objective

From the results of Experiment 2 it was hypothesized that the low intakes of the cassava roots, sweet potato tubers and banana fruit may have been caused by their high moisture content when they were offered fresh. Therefore the aim of this experiment was to evaluate the effect of sun-drying and grinding of energy feeds on the growth rate of chickens.

Materials and methods

Materials

The chicks were hatched by incubator in CelAgrid and raised until they were 90 days old. The carbohydrate feeds (cassava roots, sweet potato tubers, banana fruit and broken rice) were bought from a local market every 2-3 days. Some of them were dried under sunlight and ground into the meal form. The same duckweed was selected for use as protein source.

Experimental design

The experiment was designed as 3*2 factorial arrangement plus one control treatment in a completely randomized design (CRD) with 3 replications. There were 10 chickens per replication (pen) (4 males and 6 females). The factors were:

Carbohydrate feeds 

• Cassava root (CR)
• Sweet potato tuber (SP)
• Banana fruit (BF)

Processing

• Fresh
• Sun-dried and ground

Individual treatments were:

• FRCR: Fresh cassava root
• FRSP: Fresh sweet potato tuber
• FRBF: Fresh banana fruit
• SDCR: Sundried cassava root
• SDSP: Sundried sweet potato tuber
• SDBF: Sundried banana fruit
• BR: Broken rice as control diet

Experimental feeds and feeding

Chickens had free access to the carbohydrate feeds and duckweed. The whole fresh carbohydrate feeds were chopped into small pieces before feeding, while the meals were fed directly. Duckweed was collected and presses by hand to reduce the water content before feeding. The chemical composition of the diets is shown in table 14.

Animals and management

In total 210 local chickens were used in the experiment. They were kept 10 per pen (4 males and 6 females) where they had free access to the feeds and water. Before starting the experiment, the chickens were vaccinated against Newcastle and Fowl Pox diseases. The chickens were offered feed 3-4 times per day.

Data collection

The chickens were adapted to the experimental feeds for 10 days before the start of data collection. Feeds offered and refused were weighed and recorded daily before and after each of the meals was provided. The weights of chickens were recorded every 7 days. Samples of feed were taken for analysis every 7 days.

Chemical analysis

The feeds offered and refused were analyzed to determine DM using microwave radiation (Undersander et al 1993) and N and ash following the methods of AOAC (1990).

Statistical Analysis

Dry matter feed intake, crude protein intake and live weight gain were analyzed by using the General Linear Model (GLM) option of the ANOVA software of Minitab 14 (2004). The sources of variation were: energy, feed type, processing type and interaction of energy feed type*processing type and error.

Results

Growth rate and feed intake

When given fresh or dried cassava root, sweet potato and banana fruits, the chickens lost weight, while those fed broken rice gained weight. When cassava roots were given in fresh form there was a slight gain in live weight, but on the dried root the weight change was negative (Tables 15 and 16; Figures 5 and 6). When the treatments in dry form were compared, only broken rice supported positive growth, with cassava root just maintaing the live weight, and there was an increasingly severe loss of weight on the sweet potato and banana fruit.

There were differences in DM intake on the different treatments (Tables 15 and 16; Figure 10) but these showed no relationship with the growth rate (Figure 5). In contrast, there was a close relationship (R²=0.75) between the CP content of the diet DM and the growth rate (Figure 7).

Discussion

The chickens on all the combinations of fresh and dried cassava root, sweet potato tubers and banana fruit, with duckweed as protein feed, lost 2 to 5 g/day of weight, while those on the broken rice control treatment gained in live weight. This result is similar to that of Experiment 2 when using the same feeds in the fresh form, and the same chicken breed, when the chickens also lost around 2 g/day. The reason could be the presence of anti-nutritional factors in the fresh form of feed, which was discussed in Experiment 2.

One of the objectives of this study was to reduce the level of anti-nutritional factors in the fresh cassava root, sweet potato tubers and banana fruit by sun-drying and grinding into a meal. However, grinding makes it difficult for chickens to pick up feed if it almost becomes a powder. The results of other studies also show negative effects of using these processed carbohydrate feeds in high percentage in the formulated diets. Gomez et al (1984) reported that on sun-drying more than 86% of the HCN present in cassava was lost, probably due to the evaporation of free cyanide at about 28°C. However, using cassava root meal in poultry feed has a limitation because of its low protein content and deficiency of essential amino acids. Banday and Gowdh (1992) reported that broilers fed boiled cassava meal showed higher body weight gains than with raw cassava root, but the level of inclusion of this feed in the diet was not known. Eshiett and Ademosun (1980) reported that sun-dried cassava root meal could be included in broiler diets up 450 g/kg with no significant changes in growth performance, while Gomez et al (1983) reported that the performance of chickens on a control diet was similar to that of chickens fed up to 200 g/kg cassava root meal of cultivars low or high in cyanide content. Waldroup et al (1984) found out that replacement of one-third of the maize with cassava root meal had no adverse effects on body weight gains of broilers, but there was a reduction in weight gain at higher levels. Ravindran et al (1986) recommended that up to 15% cassava meal could substitute for coconut meal in broiler diets without affecting the growth performance.

Turner et al (1976) examined various diets containing cooked sweet potato as an energy supplement for poultry. Chicks fed on a starter feed reached slaughter weight sooner than when fed on sweet potato diets. Gerpacio et al (1978) studied the performance of two-week old birds fed rations containing sweet potato root meal replacing 0, 50, 75 and 100% of corn in the rations up to 6 weeks of age, and they reported that the performance of birds fed the sweet potato and especially at the higher levels, was less satisfactory compared with corn, suggesting that the replacement of corn only up to 50% is advisable. This result is similar to Maphosa et al (2003), who reported that the inclusion of sweet potato had a negative effect on performance of birds. There was a significant decline in weight gain of birds with increase in inclusion rate of sweet potato meal during the starter phase. There was a numerical decline in feed intake, although there was no significant difference up to 75% maize replacement rate. There was no difference in feed conversion of birds up to 50% maize replacement, but it continued to deteriorate with increase in inclusion of sweet potato meal. Tewe (1994) reported that when sun-dried and oven-dried sweet potato replaced maize at 0, 50, and 100% in broiler rations, the performance was better with the oven-dried rations, and it could replace maize up to 50% in broiler rations, but performance was optimal at 30% replacement. However, Ayuk (2004) reported that sweet potato root meal could replace maize meal in the diet of broilers at up to 40 % with no effect on chicken weight gain.

The meal from whole banana fruit contains less anti-nutritional factors (Onibon et al 2007) and it would appear that a much higher level might be included in the diet of chickens. However, there was a negative effect on growth of feeding the diet of banana fruit meal with duckweed in the present study. Göhl (1981) stated that high levels of banana fruit meal tended to depress growth rate and reduce feed efficiency, and so it is recommended that not more than 10% of the grain portion of the poultry diet should be replaced by banana fruit meal. Sharrock (1996) also reported that banana fruit meal has been used in poultry diets, but high levels in the diet also tend to depress growth and reduce feed efficiency.

Conclusion

• The results of the present study are not conclusive with respect to the effect of processing, and therefore further studies are required, focusing on, in addition to processing techniques, on the effects of mineral supplementation or production system of the chickens.

Acknowledgements

We wish to thank and express our appreciation of the MEKARN project, financed by Sida/SAREC, for supporting this research. The senior author also thank  Sam Tatanakitya, Pech Sopheak and Sok Chanthoeun, for their technical help.

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Received 11 November 2010; Accepted 24 November 2010; Published 9 December 2010

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