Selection characteristics of local and exotic chickens

Sopha Xaypha

Livestock Research Center, NAFRI, Laos
sopha@mekarn.org; flspvte@laotel.com

Abstract

The characteristics of local and exotic chickens when they have access to duckweed as protein source was investigated. A randomized completely block design with two treatments and two replication consisting of a local, Vietnamese genotype, and an exotic, Tam Hoang, were used to compare the capacity of the breed to select three kinds of feed: fresh duckweed, soya bean meal and broken rice. Feeds were offered  in separate feeders and provided twice a day. Feed offered and residues were recorded every morning. Fresh duckweed offered was analyzed every day for dry matter and every five days for nitrogen. The weight of each bird was recorded every 5 days. At the end of the experiment (20 days), four chickens were slaughtered to observe the crop contents.

There was a significant effect of genotype (P<0.01) on proportions of the total diet consumed. Compared with the local breed, the Tam Hoang breed consumed more of the total diet DM as soya bean meal  (27.4 vs 9.48%), less duckweed (3.7 vs 7.62%)  and less broken rice as (68.9 vs 82.9 %).

Key words: Exotic chickens,  local, duckweed, broken rice, soybean, feed selection.

Introduction

Nowadays, the population growth in the region is so fast that protein becomes a limiting resource. In this connection, poultry production plays a very important role to solve this problem. To reduce the high cost of animal feed, however, it is necessary to develop appropriate technologies for monogastric feeding.

Duckweed (Lemna spp.) has received research attention because of its high nutritive value, especially the high protein content. Duckweed species are small floating aquatic plants found worldwide. In trials with sewage water in Australia, the protein content of the duckweed increased from 20-25 to 35-40% in dry matter when N in the water increased from <5 to 15 mg/litre (Leng et al 1995). Yields of duckweed dry matter were in the range of 10 to 30 tonnes/ha per year, equivalent to protein yields of duckweed of as high as 10 tonnes/ha per year. Duckweed has a great potential of utilization for feeding animals including chickens.

Poultry have a well-developed capacity to select a balanced diet from individual resources made available to them (Mastika and Cumming 1985). Local chickens in a semi-scavenging system in Cambodia were fed broken rice alone (control treatment) or broken rice and either fresh duckweed or ground whole soya beans, offered in separate feeders (Hong Samnang 1998). Supplementation with either duckweed or ground soya beans increased growth rate compared with control birds but the economics strongly favored the duckweed treatment. Observations in Vietnam (Rodriguez and Preston 1999) with local and exotic (Tam Hoang breed from China) hens, in a semi-scavenging system with free night-time access to either fresh duckweed or broken rice offered separately, or mixed together, indicated that the local chickens ate much more fresh duckweed than the exotics, which preferred the mixture. These indications of ecotype, breed per nutrition interaction, were strengthened by another report from Cambodia in which the same exotic breed laid significantly less eggs than local birds, especially when no supplement was given (Khieu Borin, 2003; personal communication).

Ground whole soya beans have been used as the protein supplement for scavenging chickens (Hong Samnang 1998). Soya beans are grown in a very few areas and the soya beans are mainly used for human consumption which makes the price too high for poor farmers. It is considered that a better strategy is to reserve the soya beans for human consumption and to search for other protein sources that are higher yielding in tropical ecosystems (Preston 1995).There are many plants in the tropics have high protein which could replace soya bean meal in poultry feeds in Asia (Ravindran and Blair 1993). Shortage of protein-rich feed resources is the major factor limiting growth of animals in the tropics. In this connection, the use of some locally available feeds is indicated

Broken rice is a palatable, energy-rich and easily used feed. It is used for all classes of livestock, but its high energy value and low fiber content make it especially valuable in rations for growing chickens. Polished rice is seldom used as animal feed because of its high price, but it can be fed in the same way as broken rice (Speedy and Waltham 1998) .

Hypothesis

Local chickens will eat  duckweed in greater quantities than the exotic chickens. Exotic chickens will prefer to eat soybean meal rather than the duckweed.

Objectives

• To compare the local and exotic chicken capacity to select a local feed (duckweed, Lemna minor).
• To study the proportion of broken rice, soybean and duckweed consumed by local and exotic chickens when they had free access to these feeds.

Materials and methods

Location, climate and duration

The experiment was carried out in An Giang University, located in the Long Xuyen district, An Giang province Vietnam, about 200 km North-West of Hochiminh City. The climate of this area is a tropical monsoon, average of rainfall : 1132 mm/year, wet season from May to October, and dry season from November to April. The average temperature range is from 25.5 to 28.3 ^oC . The experiment was conducted from 03 August 2003 to 23 August 2003.

Experimental animals and design

The chickens were selected and bought from a small-holder farmer. A total of 16 chickens, 8 local, of Vietnamese origin, and 8 exotic (Tam Hoang) ab out 8 weeks of age were confined in pens. The average initial weight of the birds was 337g (local) and 916g (exotic). The birds were allocated at random in the pens constructed by plastic netting and each pen was 2 m long and 2 m wide. There were four pens with 4 birds per pen. Feeders and drinkers were made from plastic material. Both drinkers and feeders were cleaned daily in the morning before feeding. All animals were vaccinated against Newcastle disease. The birds were adapted to the condition of the experiment for four days before being allocated into the experimental groups.The type of experiment design was a CRBD (Completed Randomize Block design)

The layout of experiment

Experimental feeds

Three kinds of feed were offered in separate feeders: broken rice, soybean meal and fresh duckweed. Feed was provided twice a day in the morning (7:00 am) and afternoon (17:00) and fed ad libitum. The fresh duckweed was collected every morning from a pond outside of An Giang University by farmers; broken rice and soybean meal were bought from the local market.  Water was available all the time.

 

 

 

Photo 1: Exotic and local birds eating the duckweed

Measurements

The weight of each bird was recorded every 5 days. Feed offered and residues were recorded every morning before feeding. Fresh duckweed offered was analyzed every day for dry matter and every five days for nitrogen. Dry matter was carried out following Undersander et al (1993) whereas nitrogen was determining according to AOAC (1990). Water extractable dry matter solubility was carried out according to Ly et al (1997).

At the end of the experiment (20 days), four chickens were slaughtered to observe the contents of the crop content, which was classified according to the nature of feed found in the organ.

Statistical analysis

The data were subjected to analysis of variance (ANOVA) by using the General Linear Model (GLM) and regression analysis of MINITAB (version 13.31).

Results and discussion

During the experiment, the chickens were healthy and gained in body weight. However, one chicken died caused by fighting with the others. The water extractable dry matter was high for duckweed  (Table 2) suggesting a high digestibility for this aquatic plant, but the protein content was low probably because the pond where it was growing contained few nutrients.

Feed intake

Regarding to fresh feed intake, there was a significant effect of breed (exotic and local) on broken rice and soybean consumed. The exotic ate more than the locals because they were heavier.  However, there were significant differences in the proportions of the total DM consumed. The local breed ate less of the total diet in the form of soya bean meal and more as duckweed and as broken rice (Table 3; Figure 1).

 

Figure 1: Percentage of total DM consumed by local and exotic chickens
with free access to broken rice, soya bean meal and duckweed

Feed proportions in crop

Examination of the crop content of the chickens that were slaughtered (Table 4) appears to support the diet selection data, in that there was more duckweed in the crops of the local chickens and no soya bean meal. However, numbers were too small to permit precise comparisons.

 

Discussion

The opportunity to select from three sources of feed is a test of the capacity of the chickens to balance their nutritional requirements. The exotic chickens preferred to eat the high protein soya bean than the duckweed. The result was that the actual protein content of the diet consumed by the chickens was higher for the exotics (19.5% crude protein in DM) than for the locals (13.1%).   Rodriguez and  Preston (1999) also observed that in a scavenging system, when Tam Hoang and the local chickens had free access to duckweed and a mixed feed, the local chickens ate more of the duckweed than the Tam Hoang.  Similar findings were recorded by Nguyen Thi Khang (2002), comparing local and exotic breeds in a scavenging system.  

It could be argued that that the exotic birds selected a diet of higher protein content in view of their greater growth potential.  This was not the case in the experiment reported by Nguyen Thi Thuy  and  Ogle (2003), in which Tam Hoang chickens selected a diet with 12.9% protein whereas local "Tau Vang" birds selected a diet with 14.9% protein, the former having much higher growth rates (21 g/day versus 11 g/day).

The duckweed used in this experiment was lower in protein (22.5% CP in DM) compared with that used by Hong Samnang (1999) which had 27% CP. It is not known if the protein content of the duckweed may be a factor influencing the intake.
 

Conclusion

The result from this experiment clearly showed that local chickens have different feed preferences than exotic chicken, and more readily eat a vegetative protein source such as duckweed.

Acknowledgements

The present mini-project experiment is part of a study on the" selection characteristics of local and exotic chickens" supported by the MEKARN project financed by the SIDA-SAREC Agency. The author expresses his gratitude to all the personal of the experimental farm of the An Giang University , for help with the experiment, especially Dr T.R. Preston who organized and advised me all the time. Thanks are also expressed to Dr Ly, MSc Chhay Ty and MSc San Ty for analytical assistance in the laboratory.

References

Leng R A 1999 Duckweed: A tiny aquatic plant with high potential for agriculture and environment. Animal Production and Health Series. FAO, Rome No: 143.

Hong Samnang 1999 Duckweed versus ground soya beans as supplement for scavenging native chickens in an integrated farming system. Livestock Research for Rural Development,(11)1: http://www.cipav.org.co/lrrd/lrrd11/1/sam111.htm

Gohl B 1998 Tropical Feeds (Version 8). FAO, Rome

Bui Xuan Men, Ogle B and Preston T R 1995 Duckweed (Lemna spp) as replacement for roasted soya beans in diets of broken rice for fattening ducks on a small scale farm in the mekong delta. Livestock Research for Rural Development (8)3: http://www.cipav.org.co/lrrd/lrrd8/3/men83.htm

Nguyen Thi Kim khang 2001 Scavenging behaviour and feed selection by local and exotic chickens. http://www.mekarn.org/minipro/khang.htm

Nguyen Thi Thuy  and Brian Ogle  2003 Evaluation of feed selection, nutrient intake, growth rate and egg performance of confined Tau Vang and Tam Hoang chickens.  MSc Thesis Mekarn: SUAS

Rodriguez Lylian  and  Preston T R 1999 Observations on scavenging Local (indigenous) and Tam Hoang (exotic) chickens given free access (when confined ) to duckweed (Lemnacease) offered alone or mixed with rice bran. Livestock Research for Rural Development. (11)1: http://www.cipav.org.co/lrrd/lrrd11/1/lyl111.htm

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