Giant taro leaves (Alocasia macrorrhiza) for replacement of soybean meal in diets for Mong Cai sows in Central Vietnam

Hoang Nghia Duyet

Hue University of Agriculture and Forestry, Hue, Vietnam
hoangnghiaduyet@gmail.com

Abstract

A total of 104 households was selected for a study of the potential benefits from growing Taro. The results showed that even on the low-fertility,  sandy soil in Vinh Phu commune in the coastal region of central Vietnam, yields of foliage and roots can be very high (200 and 20 tonnes/ha fresh basis, respectively in 200 days. The benefits were as high as 100 million VND (about USD 5,000)/ha, almost five times more than from rice.

In a feeding trial with 18 Mong Cai sows, mated by AI with semen from a Yorkshire boar,  boiled leaves of Giant taro (Alocasia odora) replaced 50% or all the protein from soybean meal in diets based on rice bran and broken rice.

Litter size at birth and at weaning, and piglet survival to weaning, did not differ among treatments.  With increasing replacement of soybean meal by boiled taro leaves, there were slight decreases in piglet weight at birth and at weaning but no differences in litter weight at weaning. There was slightly poorer lactation performance (lower litter weights of piglets at 21 days, greater loss of live weight during lactation, increased time to re-mating), due to replacement of soybean meal by boiled taro leaves, but the differences were relatively small, and were most noticeable between the 50 and 100% levels of the boiled taro leaves.

It was concluded that the boiled leaves of the Giant taro can be a complete replacement for soybean meal in the diets of Mong Cai sows with only a slight increase in time to re-mating (from 7.2 to 12.7 days) and a reduction of 3.5% in litter weight at weaning. Economic benefits were increased threefold from complete replacement of soybean meal by the boiled taro leaves.

Keywords: Agronomy, birth weight, crossbreeding, lactation, local breeds, reproduction, re-mating, sandy soil, weaning weight

Introduction

In the sandy soil coastal areas of Thua Thien Hue province (Phu vang, Phong Dien, Huong Thuy districts), farmers traditionally cultivate several species of taro; Bac Ha (Alocasia odora), Quang (Xanthosoma violeaceum) and Cham (Colocasia esculenta) The roots are used mainly for human consumption while the leaves and stems are boiled and fed to pigs. .

In Vietnam there are about one million Mong Cai (MC) sows, concentrated in the North and Central region of Vietnam (Hoang Nghia Duyet 1992). The traditional way of feeding MC sows in Central Vietnam is to use a large proportion of vegetables in the diet such as sweet potato leaves, taro leaves and water spinach, mixing them with rice bran, cassava root meal, broken rice and then cooking the mixed feed before offering it to the pigs.

Recently (http://www.mekarn.org/proprf/content.htm), increasing attention has been given to improving the utilization of vegetative plants as a replacement  for soybean and fish meal  in pig diets, in view of the increasing cost of these conventional  protein sources. Sweet potato leaves  were studied by Hoang Nghia Duyet et al (2003) and shown to be a suitable replacement for up to 50% of the soybean meal in diets of Yorkshire and Mong Cai sows. At higher levels (100% replacement). the reproductive performance of the Yorkshire sows was markedly compromised; by contrast, the Mong Cai sows were found to be less less affected by the high forage levels. More recent research has focused attention on the foliage of the plants of the Colocacia family (Colocacia, Alocacia and Xanthosoma spp) which appear to offer most potential as protein sources for pigs (Pham Sy Tiep et al 2006; Rodríguez et al 2009a,b;  Du Thanh Hang and Preston 2009, 2010; and Chhay Ty et al 2010). However,  these studies have been mostly with growing pigs  and so far there is only limited research on feeding of taro foliage to pigs during pregnancy and lactation (Chittavong Malavanh et al 2008; Sivilai et al 2010).

The objective of this study was to assess the agronomic characteristics of the Taro species commonly grown by small-holder farmers in the coastal region of Central Vietnam and to evaluate the use of the foliage as a replacement for soybean meal in the diets of Mong Cai sows.

Material and methods

Agronomic features of taro growing in Vinh Phu commune

A total of 104 households in Vinh Phu commune was selected for evaluation of the potential benefits of growing Taro in the sandy soils of the coastal area of Central Vietnam. Data were collected on the agronomic features of the cultivation and use of three species of Taro:  Bac Ha (Alocasia odora), Mon Quang (Xanthosoma violeaceum) and Mon Cham (Colocacia esculenta).

Boiled leaves of Giant taro (Alocacia odora) as replacement for soybean meal in the diets of Mong Cai sows

Experimental design:

Three dietary treatments were applied to 18 Mong Cai sows (Table 1) in a completely random design:

• SBM: 100 % protein supplement from soybean meal
• SBM-GT: 50% protein supplement from soybean meal and 50 % from Giant taro leaves
• GT: 100% protein supplement from Giant taro leaves

 Growing and processing of the foliages:

Leaves of Giant taro were purchased from farmers who traditionally grow the forages in their fields or gardens. The foliages (leaves and stems) were harvested by taking only the mature leaves and stems from the taro plants. The taro leaves were chopped finely with a knife (3 -5 mm length) and mixed with the rest of the diet ingredients in the ratios shown in Table 2. The mixtures were then cooked in the early early morning (at 5 o’clock), by boiling for 10 minutes. Feeding was twice daily during pregnancy (at 10.00 and 17.00h) and 3 times daily during lactation (07.00, 12.00 and 17.00h). During  pregnancy the feeding level was 1.2 kg (DM) daily. In the lactation period the sows were given increasing amounts of feed after farrowing and then ad libitum after 5 days in lactation.

Animals:

Eighteen Mong Çai sows (>3rd parity and live weight about 80 kg) were selected in small-holder farms (one sow per farm) in Vinh Phu commune (Phu Vang distict). On each farm, the sows were kept in individual concrete floor pens. All were mated by AI with the same semen of a Yorkshire boar. Three weeks after mating, the sows were fed the experimental diets (Table 2; Figure 1).

Figure 1. Dietary sources of crude protein

Measurements:

·         For the Taro:

• Growing time, time start harvesting, time for finishing in the sandy soil of Vinh Phu commune

• The yield of stems, leaves and roots

• Benefit of growing taros (income for a Sao = 500 m²)

·         For the Mong Cai sows:

• Litter size at birth and at weaning

• Live weight of the piglets at birth and at weaning

• Litter weight of piglets at 21 days of age

• FCR and price for produce 1 kg of weaning piglet

• Economic benefits

 The experiment was carried out from September 2007 to May 2008

Results and discussion

Agronomic features of taro growing in Vinh Phu commune

The taro species growing in the sandy soil of Vinh Phu commune are Bac Ha (Alocasia odora), Mon Quang (Xanthosoma violeaceum) and Mon Cham (Alocasia esculenta) (Table 3).

These species are very well adapted and give a very high yield of leaves and roots, useful for pigs and for people (Table 4).

 Reproductive and lactation performance of Mong Cai sows

Litter size at birth and at weaning, and piglet survival to weaning, did not differ among treatments (Table 5; Figure 2).  There were slight decreases in piglet weight at birth and at weaning but no differences in litter weight at weaning (Figures 3 and 4).

Figure 3. Birth weights of crossbred piglets from Mong Cai sows when soybean meal (SBM) was replaced by cooked taro leaves (GT)	Figure 4. Weaning weights of crossbred piglets from Mong Cai sows when soybean meal (SBM) was replaced by cooked taro leaves (GT)

There were slightly poorer lactation traits (lower litter weights of piglets at 21 days, greater loss of live weight during lactation, increased time to re-mating), due to replacement of soybean meal by boiled taro leaves (Table 6; Figures 5 and 6), but the differences were relatively small, and were most noticeable between the 50 and 100% levels of the boiled taro leaves. Similar findings were reported by Chittavong Malavanh et al (2207) and Sivilai et al (2010) from feeding mixtures of ensiled leaves of taro (Colocacia esculenta) and water spinach to Mong Cai gilts.

Figure 5. Weight after farrowing and at  weaning of Mong Cai sows when soybean meal was replaced by cooked taro leaves		Figure 6. Loss of live weight in lactation and days to re-mating of Mong Cai sows when soybean meal was replaced by cooked taro leaves

The benefits from feeding the boiled leaves of the Giant taro were considerable (Table 7; Figure 7), increasing threefold for the 100% replacement of the soybean meal. This degree of economic benefit from replacing completely the soybean diet more than compensates for the slightly  poorer lactation performance.

Figure 7. Benefits from savings in feed cost to produce one litter of weaned crossbred piglets from Mong Cai sows.

Conclusions

•         Boiled leaves of the Giant taro can be a complete replacement for soybean meal in the diets of Mong Cai sows with only a small increase in time to re-mating (from 7.2 to 12.7 days) and a reduction of 3.5% in litter weight at weaning

•         Economic benefits were increased threefold from complete replacement of soybean meal by the boiled taro leaves.

Acknowledgements

This study was financed by the MEKARN project, supported by the Sida - SAREC agency. Ms Pham Thi Loan is gratefully acknowledged  for her technical help. Thanks are also due to the 18 small-holder farmers in Vinh Phu commune, Phu Vang Distric, Thua Thien Hue province, who shared their experiences and participated actively in this study.  and tubers to others seasons for

References

Chittavong Malavanh, Preston T R and Ogle B 2008 Effect of replacing soybean meal by a mixture of taro leaf silage and water spinach on reproduction and piglet performance in Mong Cai gilts. Livestock Research for Rural Development. Volume 20, supplement. http://www.lrrd.org/lrrd20/supplement/mala2.htm  

Chhay Ty, Khieu Borin and Preston T R 2010 Effect of Taro (Colocasia esculenta) 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. http://www.lrrd.org/lrrd22/6/chha22109.htm

Du Thanh Hang and Preston T R 2009 Taro (Colocacia esculenta) leaves as a protein source for growing pigs in Central Viet Nam. Livestock Research for Rural Development. Volume 21, Article #164. http://www.lrrd.org/lrrd21/10/hang21164.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

Hoang Nghia Duyet, 2003 The effect of sweet potato stems levels in the diet on productivities of Mong Cai sows. Science and Technology Journal of Agriculture and Rural Development, N0 6- 2003.

Hoang Nghia Duyet, Nguyen Dinh Son, Nguyen Van An and Truong Thi Thuan 2003  Effect of high dietary levels of sweet potato leaves on the reproductive performance of pure and crossbred Mong Cai sows; In: Proceedings of Final National Seminar-Workshop on Sustainable Livestock Production on Local Feed Resources (Editors: Reg Preston and Brian Ogle). HUAF-SAREC, Hue City, 25 – 28 March, 2003. Retrieved , from http://www.mekarn.org/sarec03/duyethue2.htm

Pham Sy Tiep, Nguyen Van Luc, Trinh Quang Tuyen, Nguyen Manh Hung and Tran Van Tu 2006 Study on the use of Alocasia macrorrhiza (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. http://www.mekarn.org/proprf/tiep.htm

Rodríguez Lylian, Preston T R and Peters K 2009a Studies on the nutritive value for pigs of New Cocoyam (Xanthosoma sagittifolium); digestibility and nitrogen balance with different levels of ensiled leaves in a basal diet of sugar cane juice. Livestock Research for Rural Development. Volume 21, Article #27. http://www.lrrd.org/lrrd21/2/rodr21027.htm

Rodríguez Lylian, Peniche Irina, Preston T R and Peters K 2009b Nutritive value for pigs of New Cocoyam (Xanthosoma sagittifolium); digestibility and nitrogen balance with different proportions of fresh leaves and soybean meal in a basal diet of sugar cane juice. Livestock Research for Rural Development. Volume 21, Article #16. http://www.lrrd.org/lrrd21/1/rodr21016.htm

Sivilai B, Chittavong M and Preston T R 2010 Reproduction and piglet performance in Mong Cai gilts fed a mixture of taro leaf silage and water spinach. Livestock Research for Rural Development. Volume 22, Article #79. http://www.lrrd.org/lrrd22/4/boun22079.htm

Received 21 June 2010; Accepted 21 July 2010; Published 1 August 2010

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