Effect on growth performance of crossbred pigs fed basal diet of cassava root meal and ensiled taro foliage supplemented with protein-enriched rice or fish meal

Chiv Phiny, T R Preston*, Khieu Borin and Mao Thona

Center for Livestock and Agriculture Development (CelAgrid)
P.O Box 2423 Phnom Penh, Cambodia
chphiny@celagrid.org
* TOSOLY, AA#48 Socorro, Colombia

Abstract

Twelve crossbred male pigs with average initial body weight of 30kg were allocated randomly to 3 treatments with 4 replications in a Completely Randomized Design (CRD).  The treatments were supplements to a basal diet of cassava root meal and ensiled taro foliage (leaves plus stems) with either protein-enriched rice at 10% of diet DM or fish meal at 5% of diet DM.  . 

DM intakes were increased by protein-enriched rice and by fish meal.  Compared with the control diet, fish meal and protein-enriched rice  increased growth rate by 16.5 and 36.7%, respectively. There were no differences in DM feed conversion among treatments.

Key words: alcohol, by-product, fermentation, urea, yeast

Introduction

In Cambodia, the leaves from shrubs such as cassava and mulberry, and from vegetables such as sweet potato, Taro and water spinach, can all be used successfully in diets for pigs to replace part or all of the protein usually supplied as soybean and/or fish meal. On the basis of research so far, it appears that the foliage (leaves + stems) of Taro (Colocasia esculenta), also known as “Old Cocoyam”, offers the most potential as a protein supplement to replace fish meal and soybean meal as the digestibility of the protein and its biological value are high (Chhay Ty et al 2010). The foliage is relatively low in fiber which is reported to be of higher digestibility than the fiber in other protein-rich forages such as mulberry (Chhay Ty et al 2010). 

It is traditional practice in Cambodia for farmers to cook the leaves and stems of Taro before feeding (Buntha et al 2008), in order  to break down the needle-like calcium oxalate crystals which are present in all parts of the plant.  A similar practice was reported in Vietnam which led researchers there to study ensiling the leaves as an alternative to cooking (Tiep et al 2006). Subsequently it was found that the stems of New Cocoyam (Xanthosoma sagittifolium) (from the same family as Taro) were especially valuable as they are high in soluble sugars (Rodriguez and Preston 2009) which facilitated the process of ensiling.  It was found that the combined leaves and stems of New Cocoyam could be ensiled satisfactorily without the need for further “silage” additives (Rodríguez and Preston 2009).  This procedure has been applied to Taro by farmers in the Central coastal region of Vietnam with good growth rates of pigs even at levels of up to 70% of the diet DM (Du Thanh Hang and Preston 2010).

Rice distillers’ by-product (RWB) is the residue when rice is fermented and the products of fermentation are then distilled to produce alcohol in an artisan production system.  Rice is cooked and yeast is added to the cooked rice for fermentation. The alcohol is distilled from the fermentation liquor, after which the residue is used as a wet feed for pigs. Rice distillers’ by-product is produced in large amounts in households in the Mekong delta (Luu Huu Manh et al 2009).  The rice distillers’ by-product has a fairly high protein content (>20% crude protein in dry matter) of good quality with respect to the balance of amino acids (Luu Huu Manh et al 2009).

The hypothesis 

It was hypothesized that instead of producing alcohol from the  rice, an alternative procedure would be to facilitate the growth of the yeast by adding a source of fermentable nitrogen  and oxygen, thus producing a protein-enriched feed that would serve as a high quality protein supplement in diets for growing pigs.

Location

The experiment was done at the research farm of CelAgrid located some 20km from Phnom Penh.

Animals and experiment design

Twelve crossbred male pigs with average body weight of 30kg were allocated randomly to 3 treatments with 4 replications (Table 1). They were housed in individual pens with a concrete floor, brick walls and provided with feeders and drinking nipples.

The treatments (proportions on DM basis) were:

• Ensiled taro leaves plus stems (65%) + cassava root meal (34%) (CTL)
• Ensiled taro leaves plus stems (50%) + cassava root meal (39%) + protein-enriched rice  (10%) (PER10)
• Ensiled taro leaves plus stems (50%) + cassava root meal (44%) + fish meal (5%) (FM5)

Feeding and management

The chemical composition of the dietary ingredients is shown in Table 2. The composition  of the experimental diets is in Table 3.

Taro leaves and stems were bought from village households near CelAgrid. They were chopped into small pieces (2 to 3 cm) and wilted under sunlight for 2-3 hours to reduce the moisture content before ensiling them in plastic bags. Cassava root meal, fish meal and yeast were bought from the market. The protein-enriched rice  was produced in the laboratory of CelAgrid. A premix of minerals, vitamins and salt was added to all the diets. All the dietary ingredients were mixed together prior to feeding which was according to appetite but adjusted so as to minimize refusals. The pigs were fed three times per day, at 07.00, 12.00 and 16.00h. 

Production of protein-enriched rice

The steps in the manufacture of the protein-enriched rice were as follows:

1. 30 liters of water were added to 25 kg broken rice which was soaked over-night
2. The rice was then steamed for 1.5 hours after which 3 liters water added and the rice allowed to cool for 1h
3. Yeast was added (0.11 kg) and urea (0.275 kg) and all mixed together, after that put into a covered container
4. Fermentation was for 3 days
5. The final product was the protein-enriched rice with some alcohol.

Sample analysis

Feeds offered and refused were collected and weighed daily and once per week samples of feed offered and refused were taken for analysis. The pigs were weighed every 10 days over the experimental period of 90 days. Sub-samples of feed offered and refused were stored at -18°C and later analyzed for DM and N. The method for N was that of AOAC (1990). DM was determined by microwave radiation (Undersander et al 1993).

Data analysis

The data were analyzed using the GLM option of the Minitab (2000) ANOVA software. Sources of variation were: treatments, pigs and error.  

Results and discussion

The pigs were in good health during the trial and grew uniformly (Figure 1). There were no symptoms of discomfort from the consumption of the diets.

DM feed intake

DM intake was higher in pigs fed the supplements of protein-enriched rice and fish meal (Table 4; Figure 2).  This effect is similar to what has been observed from feeding of rice distillers' by-product as a supplement to rice bran and water spinach (Taysayavong Lotchana and Preston 2010).

Growth and feed conversion

Live weight gain was increased by 36.7% with supplementation of protein-enriched rice compared with 16.5% improvement for supplementation with fish meal (Table 5 and Figure 3). There were no differences in DM feed conversion among the treatments. The results with the protein-enriched rice appear to be similar to those reported for supplementation of pig diets with rice distillers' by-product (Luu Huu Manh et al 2003, 2009; Taysayavong Lotchana and Preston 2010).

There appear to be no reports on the use of broken rice enriched with protein by methods similar to that described in this paper.  Le Thanh Caa and Tran Thị Thu Hong (2012) described a fermentation procedure for enriching the protein content of cassava wastes, soybean wastes and rice bran using a mixed culture of micro-organisms (Yeast, Aspergillus fungi and Lactobacilli). The authors reported that the protein content was increased and the NDF reduced by the fermentation. 

Conclusions

• DM intake and growth rate were increased when a mixture of rice bran and ensiled Taro foliage was supplemented with protein-enriched rice or by fish meal.  Compared with the control diet, fish meal and protein-enriched rice  increased growth rate by 16.5 and 36.7%, respectively.

• There would appear to be considerable potential in the SE Asia region for simple fermentation procedures to produce a high quality protein from locally available carbohydrate sources such as cassava roots and broken rice, in view of the increasing prices of fish meal  and soybean and the fact that in remote rural communities these protein-rich supplements  are rarely available.

Acknowledgements

The authors wish to thanks the MEKARN project, financed by Sida/SAREC for supporting this research. Thanks are given to the staff of CelAgrid for assistance during the experiment, especially Mr. Mao Thona and Keo Srey Pao for taking care of the feeding and management of the pigs and Mr. Vor Sina for the analysis of samples in the laboratory.

References

AOAC 1990 Official Methods of Analysis. Association of Official Analytical Chemists. 15th edition (K Helrick editor). Arlington pp 1230.

Buntha P, Borin K, Preston T R and Ogle B 2008 Survey of taro varieties and their use in selected areas of Cambodia. Livestock Research for Rural Development. Volume 20, supplement. http://www.lrrd.org/lrrd20/supplement/bunt1.htm  

Chhay Ty, Borin K and Preston T R 2010 Effect of Taro (Colocasiaesculenta) leaf + stem silage and mulberry leaf silage on digestibility and N retention of growing pigs fed a basal diet of rice bran. Livestock Research for Rural Development.Volume 22, Article #109.Retrieved August 29, 2011, from http://www.lrrd.org/lrrd22/6/chha22109.htm

Du Thanh Hang and Preston T R 2010 Effect of processing Taro leaves on oxalate concentrations and using the ensiled leaves as a protein source in pig diets in central Vietnam. Livestock Research for Rural Development.Volume 22, Article #68.http://www.lrrd.org/lrrd22/4/hang22068.htm 

Le Thanh Caa and Tran Thị Thu Hong  2012 Improvement of the nutritive value of cassava residue, soybean waste and rice bran through fermentation method with different micro-organisms.  Livestock Research for Rural Development (Submitted)   

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Luu Huu Manh, Nguyen NhutXuan Dung N N, Kinh L V, Binh T C, Thu Hang B P and Phuoc T v 2009  Composition and nutritive value of rice distillers’ by-product (hem) for small-holder pig production. Livestock Researchfor Rural Development. Volume 21, Article #224. http://www.lrrd.org/lrrd21/12/manh21224.htm

Minitab 2000 Minitab Software Release 13.2 

Rodríguez L and Preston T R 2009  A note on ensiling the foliage of New Cocoyam (Xanthosoma sagittifolium).  Livestock Research for Rural Development.Volume 21, Article #183.http://www.lrrd.org/lrrd21/11/rodr21183.htm

Tiep P S, Nguyen Van Luc, Trinh Quang Tuyen, Nguyen Manh Hung and Tran Van Tu 2006 Study on the use of Alocasiamacrorrhiza(roots and leaves) in diets for crossbred growing pigs under mountainous village conditions in northern Vietnam. Workshop-seminar "Forages for Pigs and Rabbits" MEKARN-CelAgrid, Phnom Penh, Cambodia, 22-24 August, 2006. Article # 11. Retrieved February 8, 107, from. http://www.mekarn.org/proprf/tiep.htm

Taysayavong Lotchana and Preston T R 2010 Effect of rice distillers’ by-product on growth performance and digestibility in Moo Laat and Mong Cai pigs fed rice bran and water spinach. Livestock Research for Rural Development. Volume 22, Article #165. http://www.lrrd.org/lrrd22/9/lotc22165.htm

Undersander D, Mertens D R and Thiex N 1993  Forage analysis procedures. National Forage Testing Association. Omaha, pp 154. 

Received 8 March 2012; Accepted 28 March 2012; Published 2 April 2012

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