Livestock Research for Rural Development 16 (12) 2004

Citation of this paper

The effect of particle size of feed on growth, reproduction and nutrient digestibility of snails (Archachatina marginata)

A J Omole, J A Sansi* and J O Osayomi*

Obafemi Awolowo University, Ile Ife, Nigeria . Institute Of Agricultural Research and Training Moor Plantation
*Federal College of Animal Health and Production Technology, I. A. R. and T., Ibadan, Nigeria
omoleboye@yahoo.com

 

Abstract

 

180 growing snails (Archachatina marginata) of mean weight 90.63.8g were used to study the effect of feed particle sizes on performance and nutrient digestibility. The treatments were diets that were ground in a hammer mill with 5, 4, 3 and 2mm diameter screen sizes.  A  completely randomized design was used to compare the four treatments.

 

All growth and reproductive traits, and digestibility coefficients, were improved or tended to improve as the particle size of the feed was reduced. 

Key words: Digestibility, particle size, performance, snails


Introduction

 

It has been reported that feed processing methods have a significant effect on feed consumption, weight gain and nutrient digestibility in pigs (Ohh et al 1983).  In broilers, the digestibility of nutrients was improved and the rate of growth  increased as a result of reduction of feed particle size (Behnke 1996). Healy et al (1994) investigated the effect of particle size of maize, hard and soft grain sorghum on growth performance and nutrient utilization in broiler chicks. They concluded that reduced particle size improved growth performance.

 

In snail production, an effort is being made to use complete balanced feeds (Stievenart 1992; Omole et al 2000; Ejidike 2001). However, there is no information on the effect of feed particle sizes on performance of snail. Moreover, the snail teeth (Radula) are very tiny and delicate, hence the objective of this study was to determine the feed particle size effect on growth, reproduction and nutrient digestibility in the snail (Archachatina marginata).

 


Materials and methods

 

The experiment was carried out at the snail unit of the Institute of Agricultural Research and Training (I.A.R.and T.), Ibadan, located on longitude 03051E, latitude 07023N and altitude 650", in the humid zone of South western Nigeria. One hundred and eighty growing snails (Archachatina marginata) of mean weight 90.63.8g were used to study the effect of feed particle size on performance and nutrient digestibility.  The snails were reared in a cage of 0.5 x 0.5 x 0.5 m compartments placed inside a well ventilated open sided house roofed with adex asbestos located under a tree. Sandy loam soil was put inside the cage to a depth of 7cm.

 

The diet was formulated to contain 24% crude protein (Table 1).


Table 1. Gross composition of the experimental diet

Ingredients, %

%

Maize

22.0

Brewer's dry grain

10.0

Wheat offal

12.6

Groundnut cake

10.0

Soya bean meal.

24.2

Fish meal

4.0

Oyster shell

9.7

Bone meal

2.15

Mineral mixture

5.0

NaCl

0.1

Premix

0.25

Total

100


The diets were ground in a hammer mill with 5, 4, 3 and 2mm diameter screen sizes P5, P4, P3 and P2, respectively. P5 was used as control diet. The treatments were replicated three times and each treatment / replicate contained 15 snails in a completely randomized design. The feed and water were given ad libitum. The feed intake and weight gain were measured on daily and weekly basis, respectively. Shell length and width were measured on weekly basis with the use of vernier callipers. The shell thickness was measured with a micrometer screw gauge on a weekly basis. Records on feed conversion ratio, number of eggs collected and size of the hatchlings were also taken. The experiment lasted for six months. The digestibility trial lasted 10 days, 3 days for adaptation and 7 days for excreta collection. The snails were fed with the same diet as used during the feeding trial. Records on feed intake was taken while excreta was collected daily from each treatment The daily excreta from each treatment was dried to constant weight at105C in the hot air oven. The dried samples were stored inside a refrigerator for subsequent analysis of proximate composition (AOAC 1990). All data were subjected to analysis of variance (SAS 1995); sources of variation were treatments and error.

 


Results

 

The crude protein, calcium and phosphorus contents of the experimental diet (Table 2) were within the range recommended for growing snails (Omole 2003).


Table 2. Chemical composition of the experimental diet

As % of air-dry feed

 

Dry Matter

87.5

As % of  DM  

Crude Protein

23.7

Crude Fibre

5.3

Ash

9.1

Ether Extract

3.6

Nitrogen Free Extract

58.3

Calcium

4.5

Phosphorus

0.6


All performance traits improved, or tended to improve, as the particle size of the feed was reduced (Table 3).


Table 3. Mean values for performance traits of  snails fed diets with different particle sizes

 

P5

P4

P3

P2

  SEM

Weekly dry matter feed intake, g

40.0b

41.0b

45.0a

45.1a

 1.84

Initial weight, g

89.4a

90.4a

90.3a

91.4 a

 2.01

Final weight, g

263.4c

339.8b

389.8a

391.2a

 11.94

Weight gain, g/week

7.25c

10.4b

12.5a

12.5a

 1.04

Weekly shell length increment, mm

2.52c

3.14b

3.56a

3.56a

 0.69

Weekly shell width increment, mm

2.13b

2.23b

2.61a

2.62a

 0.15

Weekly shell thickness, mm

0.0324

0.0325

0.0326

0.0326

 0.006

Feed conversion ratio

5.52a

3.95b

3.60c

3.61c

 0.38

Total eggs collected

12.0b

12.2b

14.3a

14.4a

 1.41

Weight of the eggs, g

4.38

4.43

4.45

4.45

 0.32

Weight of the hatchling, g

4.23

4.23

4.26

4.27

 0.3

Means with different superscripts along the same row are significantly different (p<0.05)
SEM: Standard Error of Means


The trends in the apparent digestibility coefficients (Table 4) were similar to those recorded for performance traits with positive effects due to reduced particle size.


Table 4.  Mean values for digestibility coefficients of snails fed diets with different particle sizes

 

P5

P4

P3

P2

SEM

Dry matter feed intake, g/day

  3.68c

   4.16b

   5.19a

    5.25a

0.84

Apparent digestibility, %          

Dry matter

78. 4c

 82.6b

 86.8a

  87.2a

2.94

Crude protein

84.2b

 88.8ab

 91.7a

  92.1a

3.41

Crude fibre

81.4c

 85.6b

 89.8a

  90.1a

3.21

Nitrogen free extract

74.1c

 78.7b

 83.1a

  84.2a

2.45

Means with different superscripts along the same row are significantly  different (P < 0.05)
SEM: Standard Error of Means



Discussion

 

 The improvement in feed consumption could be as a result of increase in surface area of the feed which improved the rate of digestion (Ohh et al 1983; Nir et al 1995).  Positive effects of reduced feed particle size have been observed in broilers (Behnke 1996) and pigs (Hamilton and Proudfoot 1995). The improvement in nutrient digestibility as the particle size reduced is in line with the observations of Owsley et al (1981) in pigs  The zero mortality recorded in all the treatments confirmed that snails can be fed solely on compounded rations without any adverse effect and that the feed particle sizes used in this study had no detrimental effect on health. 


Conclusions

 

When snails are to be fed on complete balanced diets there will be improvements in growth and reproductive performance due to fine grinding down to 2 mm particle size.


References

 

AOAC 1990 Association of Official Analytical Chemists. Official Methods of Analysis, 15th Edition. (K Helrick, editor) Arlington pp 1290

 

Behnke K C 1996 Factors affecting pellet quality. Proceedings of Maryland Nutrition Conference, 20 - 25 March 1994. Department of Poultry Science and Animal Science, College of Agriculture, University of Maryland, College Park. Pp 200 -207

 

Ejidike B N 2001 Comparative effect of supplemental and complete diets on the performance of African giant land snail (Archachatina marginata). Proceedings of the 26th Annual Conference of the Nigerian Society for Animal Production, Volume 26, 151 - 153.

 

Hamilton R M G and Proudfoot F G 1995 Effects of ingredient particle size and feed form on the performance of Leghorn hens Canadian Journal Animal. Science. Volume 75, pp. 109 - 114.

 

Healy B J, Hancock J D, Bramel-Cox, Behnke K C and Kennedy G A 1994 Optimum particle size of corn and hard and soft sorghum for broiler chicks. Journal of Poultry Science, pp. 96 - 114.

 

Nir I, Hillel R, Ptichi I and Shefet G 1995 Effect of particle size on performance of broiler. Grinding pelleting interaction. Poultry Science. Volume 74: 771 - 783.

 

Ohh S J, Allee G L, Behnke K C and Deyoe C W 1983 Effects of particle size of corn and sorghum grain on performance and digestibility of nutrients for weaned pigs. Journal of Animal Science Volume 57 (Supplement 1): pp.260

 

Omole A J, Tewe O O, Makinde G O, Adetoro F O, Saka J O and Ogundola I  2000 Preliminary studies on the response of growing snails (Archachatina marginata) to compounded feed as a supplementary ration. Tropical Animal Production Investigation Volume 3: 35 - 40.

 

Omole A J 2003 Nutrient requirement of different classes of snail (Archachatina marginata) at different stages of growth. Ph.D Thesis, Department of Animal Science, University of Ibadan. ( Unpublished)

 

Owsley W F, Knabe D A and Tanksley Jr T D 1981 Effects of sorghum particle size on digestibility of nutrients at the terminal ileum and over the total digestive tract of growing - finishing pigs. Journal of Animal Science 52: 557

 

SAS 1995 User's guide. Statistical analysis System Institute, Inc. Cary, N.C.

 

Stievenart C 1992 Observations on shell lip formation and reproduction in the giant African Snail (Archachatina marginata, S). Snail Farming Research Volume IV. Pp 20-29

 


Received 8 July 2004; Accepted 13 September 2004

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