Effect of snail (Achatina fulica) meal on broiler production and meat sensorial quality

M Diomandé, M Koussemon*, K V Allou** and A Kamenan

Laboratory of Biochemistry Food Sciences and Technology, University of Abobo-Adjame,
09 P.O.Box 2312 Abidjan 09, Côte d'Ivoire
diomassey@yahoo.fr
*Laboratory of Microbiology, University of Abobo-Adjame,
P.O.Box 801 Abidjan 02, Côte d'Ivoire
koussemonmarina@yahoo.fr
**Laboratory of Animal Nutrition, Ministry of Animal Production and Sea Ressources,
PO Box 989 Abidjan 06, Côte d'Ivoire

Abstract

Snail meal (Achatina fulica) was assessed for its nutritive value in diets of broilers. The study was based upon 330 chicks of a day old which were fed on diets containing 1 to 10 % of snail (Achatina fulica) meal, in substitution of fish meal. The levels of protein (62.4 vs. 58.2%), ash (22.7 vs. 20.0%), and calcium (7.7 vs. 7.0%) were higher in snail meal than in fish meal. Eleven diets whose snail meal content varied from 0 to 10% were fed over a period of eight weeks  to the broilers. For the sensorial analysis, the thighs of 4 slaughtered chickens per cage were cooked in oil for 20 minutes. The tasting staff was composed of people chosen randomly in the commune of Adjame (Abidjan) with 10 men and 10 women.

Growth rates in the starter phase showed a negative curvilinear response (R² = 0.90) to increasing proportions of snail meal . Growth rates were maintained as snail meal replaced up to 30% of the fish meal followed by a steady decline up to 100% replacement of the fish meal. In the grower stage there was an indication (R² = 0.44) of  a slight decrease in growth rate as the snail meal was raised from 0 to 30% replacement of fish meal followed by an increase as snail meal replacement increased from 30 to 100% of fish meal.  The sensorial analysis showed no consistent effect of the level of snailmeal on the taste of broiler thigh meat.

It is concluded that snail meal (Achatina fulica) can be used as a protein source in broiler diets in Côte d’Ivoire.

Key words: chemical analysis, côte d’ivoire, poultry, sensoriel analysis, snail meal, zootechnical performances

Introduction

During these last days, different raw materials not often used by the human being have been used in the fowls living in the tropics (Bassuel 1983; Gualtiéri and Rapaccini 1990; Barcelos and Barcello 1991; June et al 1991; Hardouin and Stiévenart 1991; Gicogna 1992; Agbede et al 1994; Kamatali 1996; Munyuli and Balezi 2002). Indeed the fish and  meat meals frequently used as protein source in these diets have a high cost and this urged tropical countries like Côte d’Ivoire to import those dietary components for their fowl production. So it seems judicious to consider the use of local sources of animal proteins which are available and whose costs are lower. Thus, Agbede et al (1994) have conducted some tests with fowls fed on a diet containing 3.6% of meal from Edrillus engeniae in comparison with some chickens fed on a diet containing 5% of meat meal.  These studies showed that the chickens fed on Edrillus engeniae had the same feed intake, the same average daily gain and the same body weight.  The introduction of the snail or the meat meal in the fowls’ diet was studied by different teams. Barcelos and Barcello (1991) determined the chemical composition of the meat of the gilded snail (Pila leopoldoilleusis) which on the one hand was raw and then on the other hand was cooked. Those snail meals were given to broilers fed on fish meal. These experiments showed that on the one hand that the cooked snail weal was more eaten by the chickens than the meal of raw snail, and on the other hand that the weight put on by the chickens fed on the snail meal and the weight put on by the chickens fed on the fish meal were identical. June et al (1991) have also conducted a dietary experiment about broilers first fed on snail meal (Pomecea caniculata) compared to the second group fed on fish meal and bone and  meat meal . These experiments underlined the fact that the snail meal which is less expensive than the fish and bone and meat meal can easily replace the last two feeds in the fowls' diet. However, attempts to use snail (Achatina fulica ) in the broilers’diet are limited or even absent in Côte d’Ivoire.

This research aims at finding the best way of introducing snail (Achatina fulica) meal as an important source of protein and as a cheap feed in broiler diets in Côte d’Ivoire and also aims at revealing the impact of such meal on the sensorial quality of the chicken meat.

Material and methods    

Snail meal production

The snails (Achatina fulica) collected in the parish called Anyama (a suburb of Abidjan in Côte d’Ivoire) were extracted from their shells with an iron stick. The flesh that came out of the shells was put in plastic bags with holes and squeezed by means of a squeezer machine. Squeezed as it was the snail flesh was then cut into pieces which in their turn were put into aluminium containers. Next the whole stuff was set in the hot room at a temperature of 70° C. Twenty four hours later, the dried snail pieces were then ground in a grinder equipped with separation grates and many propellers. Thus, the obtained meal was incorporated into the chicken diet.

Chemical analysis of snail and fish meal

From the snail meal and the fish meal bought at market, five samples of each, weighing 100g were analysed and the analysis was repeated three times for each sample. The bromatological analysis of snail meal (Achatina fulica) was about the estimation of the whole nitrogen by way of the Kjeldhal method, the crude fibre and fat by the methods of AOAC 1980). The  level of dry matter  was estimated on a fraction of the sample which had been dried in the hot room. The ashes were determined after incineration of the dry material under 550°C for 24 hours.  The content of  the sugars  was determined (AOAC 1980). 

Experimental diets

Eleven different diets were prepared (Tables 1 and 2).  

A sample of 100g of each diet was analysed. The metabolic energy was estimated after the equation  of Larbier and Leclercq  (1992):

ME= 3951 + 54.4F - 88.8CF - 40.8A

with ME: metabolisable energy, F: fat , CF: crude fiber,  A: ash.

Management of the experiment

The 330 chicks of a day old weighing between 32 and 35 g were andomly put in eleven cages on wood shaving litter, and were fed at will on the 11 dietary treatments (SM0 to SM10).   Each treatment included 3 repetitions. The starter diet was fed up to 28 days, followed by the grower diet from 29 to42 days. Before the beginning of the test a 3 days period of adaptation during which the chickens consumed the experimental diet and clean water was observed. The feeding was ad libitum with natural lighting. At the end of the experiment, 4 chickens randomly chosen in each repetition were slaughtered after they had been fasted for 24 hours in order to estimate the characteristics of the carcasses. We focused on the empty carcass, the yield of the carcass and the abdominal fat. All these details were translated into the percentage of the body weight.

Economic evaluation of experimental diets

The costs of the diets have been calculated in taking into account, the respective proportion of each ingredient, the average price of raw materials and the cost in relation to their transformation, especially for the snail meal.

Sensorial evaluation of the chickens’ meat

The thighs of the 4 slaughtered chickens per cage were cooked in oil for 20 minutes. The tasting staff was composed of people chosen randomly in the commune of Adjame (Abidjan) with 10 men and 10 women. The hedonic approach was used. The scale of  5 points was chosen ( 5-very pleasant, 4-pleasant, 3-neither pleasant nor unpleasant, 2- unpleasant, 1-very unpleasant).

Statistical analysis

The collected data were analysed using the ANOVA program in the statistics software (SAS, version 6.12). The means were separated using the test of Newman Keuls (SAS/STAT  1996).

Results 

Chemical composition of snail meal, fish meal and diets

The snail meal was higher in protein (62.4 vs. 58.2%) in ash (22.7 vs. 20.0%) and in calcium (7.7 vs. 7.0%) than the fish meal. The snail meal was on the contrary poorer in fat (4.3 vs. 10.0) than the fish meal. The dry matter levels of the meals were appreciably identical (Table 3).

The levels of crude protein, ash and calcium increased with the increase of the content of snail meal in the diets (Tables 4 and 5). 

Growth performance and feed conversion

At the starting period, the diet with 3, 4 and 5% of snail meal showed some signs of consumption which were higher (1.4 and 1.6 %) whereas the others had lower signs of consumption (1.2 to 1.4 %) during the first week. But from the 2^nd week, the signs of consumption were appreciably identical and constant (Table 4). Growth rates in the starter phase showed a negative curvilinear response to increasing proportions of snail meal (Figure 1; R² = 0.90). Growth rates were maintained as snail meal replaced up to 30% of the fish meal followed by a steady decline up to 100% replacement of the fish meal. In the grower stage (Table 5) there was also an indication of a curvilinear response with a slight decrease as the snail meal was raised from 0 to 30% replacement of fish meal followed by an increase as snail meal replacement increased from 30 to 100% of fish meal (Figure 2; R² = 0.44).

Figure 1. Effect of level of snail meal in the diet on growth rate during the starter phase	Figure 2. Effect of level of snail meal in the diet on growth rate during the grower phase

 The diet with 6, 7, 8, 9 and  10% of snail meal revealed the lowest abdominal fat level of chicken (1.8 to 0.6) whereas for those diets with 0, 1, 2, 3, 4 and 5% of snail meal the fat decreased from 3 to 2% (Table 6).

The yields in carcass were higher for the diets with more than 60% replacement of fishmeal by snail meal (Table 6).

Sensorial characteristics of the chickens’ meat

There were differences (p<0.05) in the taste of the broiler meat among treatments but the trends were not consistent (Table 6).

Discussion 

There is no obvious explanation for the reduction in broiler growth rate caused by replacing fish meal with snail mal in the starter phase, other than a poorer amino acid balance possibly caused by partial denaturation of certain essential amino acids during the drying of the snail meat. . The positive response to the higher levels of snail meal in the grower phase, when amino acid requirements are lower, supports this suggestion.  Similar nutritive values for snail meat and fish meal in pig diets were reported by Kaensombath Lampheuy and Ogle (2005). These authors  replaced fish meal with ensiled or fresh meat from Golden Apple Snails (Pomacea spp) in the diets of growing - finishing pigs and reported no differences in growth rate. It was concluded that the meat of the Golden Snail was comparable in nutritive value to fish meal.

Conclusions

• Meal from snails (Achatina fulica) can be included in diets for broilers at up to 3 % replacing fish meal (starter  phase), and at 10% in the grower phase replacing fish meal completely, with no reduction in growth performance but a saving in feed costs.

  
  

• The sensorial quality of broiler meat was not affected by the presence of snail meal in the diet..

References 

Agbede G, Nguekam et Mpoame M 1994 Essai d’utilisation  de la farine de vers de terre, Eudrilus engeniae dans l’alimentation de poulets de chair en finition. Tropicultura 12: 3-5

AOAC 1980 Official Methods of Analysis. Editor: Horowitz W. Association of Official Analytical Chemists, Washington, D.C. 

Barcelos P M and Barcello J R 1991 The potentiel of snail (Pila leopoldoilleusis) meal as supplement in broilers diets. Tropicultura 9:11-13

Bassuel F M 1983 Processing toad (Buffo marinus) as protein source on the performance of broiler and layer rations. Ph. D.Dissertation, University of Philippines at los Bagnos College, Lagima. Philippines 154 p.

Gicogna M 1992 First international Seminar on faming of invertebrales and other minilivestock (18-19 novembre 1992). Tropicultura 10: 155-159

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Kaensombath Lampheuy and Ogle B 2005 Effect of ensiled or fresh Golden Apple Snails (Pomacea spp) on pig growth performance and production economics.
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June L, Ulep P and Buanefe M M 1991 Performance of broilers fed with snail (Pomecea caniculata) meal as substitute to fish meal or meat and bone meal. Tropicultura 9: 58-60

Kamatali P 1996 Note de cours d’alimentation des monogatriques. Faculté des sciences agronomiques et de l’environnement, Département de Zootechnie, U. E. A, Bukavu (République Démocratique du Congo) 430p.

Larbier M et Lecclercq B 1992 Nutrition et alimentation des volailles In : INRA. Paris 355p.

Munyuli B M T et Balezi N 2002 Utilisation des blattes et des termites comme substituts potentiels de la farine de viande dans l’alimentation des poulets de chair au Sud Kivu , République Démocratique du Congo, Tropicultura 20: 10-16 http://www.bib.fsagx.ac.be/tropicultura/pdf/v20n1.pdf

SAS/STAT  1996 User’s guide, Version 6.12. In : Cary NC, USA, SAS Institute

Received 24 March 2008; Accepted 28 October 2008; Published 5 December 2008

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