Ensiled mixed foliage of taro leaves + petioles and banana pseudo-stems as replacement of rice bran for Mong Cai sows in small-holder farms in Vietnam

Hoang Nghia Duyet and T R Preston*

Hue University of Agriculture and Forestry
Hue, Vietnam
hoangnghiaduyet@gmail.com
* Finca Ecológica, TOSOLY

Abstract

The objectives of the present study were: (i) to evaluate silages made from a 50: 50 mixture (DM basis) of banana pseudo-stem and Taro foliage (leaves plus pseudo-stem) with or without additional molasses; and (ii) to determine effects on reproduction of Mong Cai sows of feeding the mixed banana-taro silage as replacement for rice bran.  In experiment 1, mixtures (50: 50 DM basis) of banana pseudo-stems and taro foliage (leaves + pseudo-stems) were ensiled with or without 1% molasses (fresh basis). This ratio was chosen as it closely resembles rice bran in the content of crude protein in DM. In experiment 2, 20 Mong Cai sows were selected in 20 different farms in Phu Da commune (Phu Vang distict, Thua Thien Hue province). They were allocated to one of 5 treatments in which banana-taro silage replaced rice bran in proportions of 0, 25, 50, 75 and 100% (DM basis).

The pH of the mixed silage decreased rapidly to 4.3 within 3 days with little further change up to 30 days. Adding molasses to the silage reduced the pH but the effect was small. It was concluded that 50: 50mixtures (DM basis) of banana pseudo-stem and taro foliage could be ensiled satisfactorily without the need for additional molasses.

The live weight gain during pregnancy and the live weight at farrowing were decreased and the live weight loss during lactation was increased, with linear trends, as the rice bran was replaced by banana-taro silage. The litter size at birth and numbers born alive were not affected by diet; however, birth weight, litter weight at weaning and litter size at weaning  were all decreased by replacing rice bran with the taro-banana silage. The period from weaning to mating was increased when the taro-banana silage replaced rice bran, thus the reproductive cycle was longer and the  predicted numbers of litters per year was deceased as the taro-banana silage replaced the rice bran. Feed intake during pregnancy was restricted to 1.5 kg/day per sow and this was all consumed on all treatments. During lactation when the offer level was ad libitum the intakes were decreased as the taro-banana silage replaced  rice bran.  The feed DM regestation, lactation,quired per kg of weaned piglet was lowest for taro-banana silage replacement of rice bran at the 50 and 25% levels.

Key words: Gestation, lactation, piglets, reproduction

Introduction

Phu Vang, Quang Dien, Phong Dien and Huong Thuy are coastal districts in Thua Thien Hue province in Central Vietnam. This is a very large area of sandy soil area of about 150,000 ha (Hoang Nghia Duyet et al 2009). It is very poor land of low fertility, Taro is the main crop being cultivated in the  raining season: from September to March. Several species of taro are grown:  such as Bac Ha (Alocasia odora), Mon Quang (Alocasia violeceum), Mon Cham (Alocasia esculenta).  Each household grows about 500m² of the taro, harvesting them for both leaves, stems and roots. The yield per crop is about 10 tonnes/ha of roots and 20 - 30 tonnes of leaves and stems  ( Hoang Nghia Duyet and Pham Khanh Tu 2009).

Banana pseudo stems are used traditionally by farmers as part of the diet of Mong Cai sows in Vietnam but there are few scientific reports on their nutritive value. According to Dao Thi My Tien et al (2010) the pseudo-stems are very low in DM but rich in soluble sugars (Table 1).

The objective of the present study was: (i) to evaluate silages made from a 50: 50 mixture (DM basis) of banana pseudo-stem and Taro foliage (leaves plus pseudo-stem) with or without additional molasses; and (ii) to determine effects on reproduction of Mong Cai sows of feeding the mixed banana-taro silage as replacement for rice bran. 

Experiment 1: Ensiling a mixture of taro foliage and banana pseudo-stems

Materials and Methods

Experimental design and procedure

Mixtures (50: 50 DM basis) of banana pseudo-stems and taro foliage (leaves + pseudo-stems) were ensiled with or without 1% molasses (fresh basis). This ratio was chosen as it closely resembles rice bran in the content of crude protein in DM. 

The foliages were chopped by hand into small pieces (1 to 2 cm for taro stems and leaves and 0.5-1 cm for banana pseudo-stems) and wilted in sunlight to reduce the moisture to about 75-80%, prior to ensiling in rigid plastic containers of 2 liters capacity. A separate container was opened at 0, 3, 8, 15 and 30 days for measurement of pH, DM, CP and soluble sugars.

Statistical analysis

The data were analyzed with the GLM option in the ANOVA program of the Minitab (2000) software. Sources of variation were: ensiling time, molasses, interaction sampling time*molasses and error.

Results and discussion

The banana pseudo-stems contained 9.83 with 4.25% crude protein in DM; the combined leaves and pseudo stem of the taro had 1.0% DM and 16.6 % crude protein in  DM, thus the 50: 50 mixture on DM basis had 13% crude protein, which is comparable to that in rice bran. The pH of the mixed silage decreased rapidly to 4.3 within 3 days with little further change up to 30 days (Figure 1). Adding molasses to the silage reduced the pH but the effect was small. It was concluded that 50: 50mixtures (DM basis) of banana pseudo-stem and taro foliage could be ensiled satisfactorily without the need for additional molasses. These results are contrary to the general recommendations for silages that supplements of fermentable carbohydrate should be added when the DM content of the ensiled material is low (McDonald et al 2002). However, they are in line with experiences elsewhere which showed that Taro foliage (leaves + puseudo-stems) could be ensiled satisfactorily without additives despite the low DM content (Rodríguez and Preston 2009; Dao Thi My Tien et al 2010).

Figure 1. Effect on pH of the silage of adding 1% molasses to a mixture of banana pseudo-stem and taro foliage (leaves + stems)

Experiment 2: Replacing rice bran with ensiled mixtures of bananas pseudo-stem and taro foliage in the diet of Mong Cai sows

Materials and Methods

Treatments and design

Twenty Mong Cai sows were selected in 20 different farms in Phu Da commune (Phu Vang distict, Thua Thien Hue province). They were allocated to one of 5 treatments in which banana-taro silage replaced rice bran in proportions of 0, 25, 50, 75 and 100% (DM basis). There were  4 replicates (individual farms) on each treatment.

Silage preparation

The silages were made in 100 liter rigid PVC containers following the procedure outlined in Experiment 1. Molasses was not added to the silages.

Sow management

The sows weighed about 80 kg and were in 3rd or later parity. They were mated by AI with the semen from the same Yorkshire boar. The sows were kept in individual concrete floor pens. Three weeks after mating, the sows were fed the experimental diets.

Feeing system

During pregnancy, the sows were fed 1.5 kg of feed/day (DM basis). The feeding level was increased after farrowing and was offered ad libitum after 5 days. Fish waste was included in the diets to raise the crude protein level (Table 2).

Because of the low DM content of the silages, the total amounts  of fresh feed offered increased markedly as the level of silage in the diet was increased (Table 2).

Statistical analysis

The data were analyzed with the GLM option in the ANOVA program of the Minitab (2000) software. Sources of variation were: ratio of silage: rice bran and error. Linear regressions were applied to the observed values (y) according to the ratio of silage: rice bran (x).

Results

The live weight gain during pregnancy and the live weight at farrowing were decreased and the live weight loss during lactation was increased, with linear trends, as the rice bran was replaced by banana-taro silage (Table 3; Figures 2 - 4). 

Figure 2. Effect of replacing rice bran with ensiled mixture of  banana pseudo-stems/taro foliage on weight gain during pregnancy	Figure 3. Effect of replacing rice bran with ensiled mixture of banana pseudo-stems/taro foliage on weight at farrowing	Figure 4. Effect of replacing rice bran with ensiled mixture of  banana pseudo-stems/taro foliage on weight loss during lactation

The litter size at birth and numbers born alive were not affected by diet; however, birth weight, litter weight at weaning and litter size at weaning  were all decreased by replacing rice bran with the taro-banana silage (Figures 5-7).

Figure 5. Effect of replacing rice bran with ensiled mixture of banana pseudo-stems/taro foliage on birth weight of piglets	Figure 6. Effect of replacing rice bran with ensiled mixture of banana pseudo-stems/taro foliage on piglet weight at weaning	Figure 7. Effect of replacing rice bran with ensiled mixture of banana pseudo-stems/taro foliage on litter weight at weaning

The period from weaning to mating was increased when the taro-banana silage replaced rice bran. As a result the reproductive cycle was longer and the  predicted numbers of litters per year was deceased as the taro-banana silage replaced the rice bran (Figuures 8-10)

Figure 8. Effect of replacing rice bran with ensiled mixture of  banana pseudo-stems/taro foliage on days to mating after weaning	Figure 9. Effect of replacing rice bran with ensiled mixture of  banana pseudo-stems/taro foliage on length of reproductive cycle	Figure 10. Effect of replacing rice bran with ensiled mixture of banana pseudo-stems/taro foliage on number of litters/year

Feed intake during pregnancy was restricted to 1.5 kg/day per sow and this was all consumed on all treatments. However, during lactation when the offer level was ad libitum the intakes were decreased as the taro-banana silage replaced  rice bran (Figure 11).  The feed DM required per kg of weaned piglet was lowest for taro-banana sikage replacement of rice bran at the 50 and 25% levels (Table 3; Figure 12).

Figure 11. Effect of replacing rice bran with ensiled mixture of  banana pseudo-stems/taro foliage on feed DM intake during lactation	Figure 12. Effect of replacing rice bran with ensiled mixture of  banana pseudo-stems/taro foliage on total feed DM consumed per 1 kg of weaned piglets

Discussion

The decrease in DM intake during lactation as the proportion of banana-taro silage in the diet increased would appear to have been the major reason for the decline in certain performance criteria such as body weight loss during lactation and reduced milk yield reflected in the slower growth rates of the piglets. This explanation is supported by the lack of differences in the reproductive rate (predicted number of litters per year) when this criterion was corrected by covariance for DM intake in lactation (Table 3). The physical characteristics of the diet of ensiled banana pseudo-stem and taro - namely the very high moisture content - could have been the reason for the decrease in DM intake as the proportion of silage in the diet was increased. .

The economic success of a pig reproduction unit is determined by: the reproductive rate in terms of numbers of piglets weaned, the numbers of litters per year, the feed required per unit weight of piglets weaned and the relative cost of the diet. In the present study, there were only small differences among diets in production criteria.  However, in terms of feed cost, the experimental system had definite economic advantages, in that almost all the ingredients were grown by the farm family using family labor, whereas rice bran had to be purchased and collected from the rice mill.

The decision to fix feed intake during gestation at 1.5 kg DM/day for all diets may also have been the wrong strategy when applied to a low cost-low energy feed such as ensiled banana pseudo stem-taro foliage. A  more appropriate system would have been to set the offer level at whatever was needed to support the same weight gain during pregnancy as was recorded for the control diet of rice bran.

Acknowledgements

The authors are grateful to the MEKARN program financed by Sida for supporting this research. The cooperation of the farmers who participted in the study is gratefully acknowledged.

References

Dao Thi My Tien, Nguyen Tuyet Giang and Preston T R 2010 A note on ensiling banana pseudo-stem with Taro (Colocasia esculenta) leaves and petioles.  (Editor: Reg Preston) International Conference on Livestock, Climate Change and Resource Depletion, Champasack University, Pakse, LAO PDR, 9-11 November 2010 . httm://www.mekarn.org/workshops/pakse/abstracts/tien_agu2.htm

Hoang Nghia Duyet and Pham Khanh Tu 2009 Use of taro leaves (Alocasia odora, Alocasia esculenta and Alocasia Xanthosoma violeceum) as protein source supplement in diets for Mong Cai sows kept in Vinh Phu commune, Phu Vang district, Thua Thien Hue province. Proceeding of “Improving food crop productivity in the coastal sandy area of Thua Thien Hue province Central Vietnam. Hue University Publishing House, page 148.

Hoang Nghia Duyet, Pham Khanh Tu, Le Duc Ngoan, Nguyen Thi Dung, Tran Van Tho and Nguyen Nhu Y 2009 Using available organic material sources for pig production- present and solutions for improving pig’s feed quality in the coastal area of Thua Thien Hue province. Proceeding of “Improving food crop productivity in the coastal sandy area of Thua Thien Hue province Central Vietnam. Hue University Publishing House, page 135.

McDonald P, Edwards R A, Greenhalgh J F D and Morgan C A 2002 Animal Nutrition. Sixth Edition. Longman Scientific and Technical, Harlow, Essex, England.

Minitab 2000 Minitab reference Manual release 13.31. User’s guide to statistics. Minitab Inc. USA

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

Received 25 February 2013; Accepted 10 March 2013; Published 2 April 2013

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