Effect of rice distillers’ by-product on growth performance and digestibility of Moo Laat and Mong Cai pigs fed rice bran and water spinach

Taysayavong Lotchana and T R Preston^*

Champasack University
Champasack province, Lao PDR
Lotchanasouks@yahoo.com
*UTA - TOSOLY - Finca Ecológica, AA
# 48, Socorro, Santander, Santander del Sur, Colombia

Abstract

Sixteen growing female pigs (8 Moo Laat and 8 Mong Cai) with an initial weight of 11 to 13 and 25 to 26 kg, respectively, were allocated to a 2*2 factorial arrangement with four replications of four treatments in a Completely Randomized Design (CRD). The factors were: breed of pigs and supplementation with or without rice distillers’ by-product. The basal diet was a mixture of rice bran and fresh water spinach. The diets were offered in amounts based on an expected DM intake of 4 % of live weight. For the control diets (no distillers’ byproduct) the water spinach comprised 30% of the diet DM. For the diets with rice distillers’ by-product the proportions (% DM) were 70, 20 and 10 for rice bran, water spinach and rice distillers’ byproduct, respectively.

Mong Cai pigs grew faster than Moo Laat pigs but the latter tended to have better feed conversion. There was an interaction between breed and rice distillers’ supplementation for DM intake per unit LW and live weight gain. Supplementation increased the intake and growth rate in the Mong Cai pigs. During the 6 weeks of the experiment the Moo Laat pigs fed the rice distillers’ product grew more slowly than those not fed the supplement. During the final 6 weeks the response of the Moo Laat pigs was reversed with higher gains observed for the pigs fed the supplement. Coefficients of digestibility determined by the insoluble ash method were not affected by supplementation with rice distillers’ by-product but appeared to be higher for the Mong Cai compared with the Moo Laat.

Key words: Acid insoluble ash, adaptation, forages, local breeds

Introduction

Farmers in Laos traditionally keep pigs of predominantly indigenous breeds in foraging systems. The number of pigs kept by a household varies between 1.4 and 3.7 animals, depending on the region (Knips 2004). There are several breeds of local pigs called: Moo Chid, Moo Laat, Moo Daeng and Moo Nonghaet. They are slow growing with high fat content in the carcass. Mature body weight in sows ranges from 60 to 90 kg except for the Moo Chid that is smaller. The litter size is usually small (7 to 8) and the farrowing interval about 1.5 litters per year. The native breeds are hardy, well adapted to a free-ranging system and can survive in a hot climate on low quality feed, and with a high resistance to diseases (Vongthilath and Blacksell 1999). A small number of farmers use exotic breeds or crossbreeds, but compared to local breeds they are considered to be less resistant in smallholder farming conditions and do not perform as well. The type of feed given depends on the farming system, the availability of labor and suitable natural vegetation. Feeds include rice bran, broken rice, banana pseudostem, taro, yams, maize, cassava, by-products (especially rice distillers’ waste) and vegetation collected in fallow fields and forests (Stur Werner et al 2002)

Lon Mong Cai (Mong Cai pig) is an indigenous breed that originated from Quang Ninh province, in northern Vietnam. The breed is very well adapted to the harsh conditions in the region and is known for its early puberty, good litter size and maternal ability. The Mong Cai have been shown to perform better than Large White sows when the diet is based on forages (Nguyen Van Lai 1998 and Hoang Nghia Duyet et al 2006).

In Lao villages, where most farmers are growing paddy rice for sale, the feed for pigs is based on rice bran, which is fed together with a small amount of green feed. Thus rice bran is available in most farm households. The main problem is the supply of protein as soybean and fish meals are not available in rural areas. Phengsavanh and Stür (2006) showed that growth rates were increased from 100 to 200 g/day by providing some protein-rich forage in the form of stylosanthes. However, other forages appear to have more potential in pig diets based on rice bran. Thus Bounhong Norachack et al (2004) reported that N retention was two times higher when cassava leaves replaced stylosanthes.

Water spinach (Ipomoea aquatica) is a vegetable cultivated for food and also used as pig feed throughout Southeast Asia. The fresh leaves and stems of water spinach are rich in protein. They have been used successfully to replace part of the protein in diets based on rice by-products (Chhay Ty et al 2005; Chittavong Malavanh et al 2008a).

Another potential source of high quality protein in rural areas of Laos is the waste after distilling the alcohol derived by yeast fermentation of sticky rice. The waste is called “Khilao” and is used as a wet feed for pigs. Rice distillers’ by-product or “hem” is traditionally used by farmers in Vietnam. Luu Huu Manh (2000) and Luu Huu Mamh et al (2009) showed that the protein content ranged from 17 to 33% (mean of 23%) in dry matter (DM) and that it had a well-balanced array of amino acids. Luu Huu Manh et al (2003) reported that this product can replace completely the fish meal in growing and fattening pig diets with no loss of performance.
 

Materials and methods

Location

The experiment was carried out at the Integrated Farming Demonstration center of Champasack University, situated about 13 km from Pakse city, Pakse District, Champasack Province; Laos PDR. The temperature in the area averages 27⁰C (range 22 to 32). The experiment began on 14 September and finished on 14 December 2009.

Experimental design

Four treatments were compared in a 2*2 factorial, Completely Randomized Design (CRD) (Table 1). The factors were:

• Breed: (Moo Laat or Mong Cai) (Photos 1 and 2)
• Diet:    (With or without rice distillers’ by-product)

The individual treatments were:

• ML-RW: Moo Laat fed rice bran and water spinach

• MC-RW: Mong Cai fed rice bran and water spinach

• ML-RWDB:  Moo Laat fed rice bran, water spinach and rice distillers’ by-product

• MC-RWDB:  Mong Cai fed with rice bran, water spinach and rice distillers’ by-product

Animals and management

The local pigs (Moo Laat) were bought from the market in Pakse district with initial weights ranging from 11 to 13 kg. The Mong Cai pigs were imported from the Government pig farm in Hue province, Vietnam, with initial weights ranging from 25 to 26 kg. Both two breeds were the same age (1 year), the pigs were housed in individual pens (2*2 m) with concrete floors; and provided with feeders, and automatic water drinkers. The pigs were vaccinated against salmonella disease and de-wormed with Ivermectin before the start of the experiment.

Feeds and feeding

The diets (Table 2) were formulated to contain 11% crude protein in the diet DM. They were supplemented with a mineral-vitamin premix (Table 3). The diets were offered in amounts based on an expected DM intake of 4 % of live weight. For the control diets (no distillers’ byproduct) the water spinach was given at 30% of the diet DM. For the diets with rice distillers’ by-product the proportions (% DM) were 70, 20 and 10 for rice bran, water spinach and rice distillers’ by-product, respectively.

The rice bran (Photo 3) and water spinach (Photo 4) were bought in the market. The distillers’ waste (Photo 5) was purchased every three days directly from farmer households. The water spinach was chopped into small pieces (0.5 cm) and then all the diet ingredients were mixed together before feeding the pigs, which was done in two meals per day at 07.00 and 16.00 hours.

Measurements

Growth and feed conversion

The pigs were weighed every 2 weeks during the experiment which lasted 84 days. Live weight gains were calculated from the linear regression of live weight (Y) on days in the experiment (X). Feeds offered and residues were recorded daily. Samples of feeds and residues were taken weekly and stored at -16 °C until analysis.

Apparent digestibility

The acid-insoluble ash (AIA) method was used (Van Keulen and Young 1977). Samples of feed and feces were taken over 5 consecutive days. Samples of feces were collected from the floor of the pens 3 to 4 hours after the first feed in the morning and stored at -18°C. This procedure was repeated for 5 days after which the samples were bulked according to individual animals. Feed samples were taken over the same time period.

Chemical analysis

Samples of feeds and refusals were analyzed for dry matter (DM) by micro-wave radiation (Undersander et al 1993), and nitrogen (N), crude fibre (CF) and ash following AOAC (1990) procedures. The samples taken during the digestibility trial were analysed for acid-insoluble ash (AIA) according to the method of Van Keulen and Young (1977). Samples (5g) were ashed for 4-6 hours in a muffle furnace at 450°C. The ash was transferred to a 600 ml beaker and extracted with 100 ml of a solution of HCl (178 ml concentrated HCl and 1 litre of water) and boiling for 5 minutes. The suspension was then filtered and the solid residue transferred to filter paper and ashed again at 450°C for 6h. Acid insoluble ash (AIA %) was calculated as:

• % AIA = [initial weight of ash-final weight of ash]/initial weight*100

Calculations of apparent digestibility were made as follows:

• Digestibility of DM = 100-[(100*%AIA in feed)/%AIA in feces]

• Digestibility of nutrients = 100- [[(%AIA feed) x % concentration of nutrient] x 100%]/ %AIA Feces x % concentration of nutrient

Statistical analysis

The data were analyzed using the General Linear Model (GLM) in the Analysis of variance (ANOVA) program of the Minitab software (version 13.1. The sources of variation in the model were: breeds, diet, interaction breed*diet and error.
 

Results and discussion

Chemical composition of diets

The rice bran was of low quality (only 7.3% CP in DM); the CP in the water spinach was also low compared to other published data (e.g.: 23%, 26%, 27%, 29% and 32% CP in DM) (Le Thi Men et al 2005, Chiv Phiny 2008, Le Thi Men et al 2000, Thim Sokha et al 2008 and Chhay Ty and Preston 2006, respectively). The average CP in the rice distillers’ byproduct was a little higher than the average (23% in DM) of the samples reported by Luu Huu Manh et al (2009) in Vietnam.

Feed intake, growth rate and feed conversion

There was an interaction between breed and rice distillers’ supplementation for both DM intake per unit LW and live weight gain (Table 6, Figures 1 and 2). Supplementation increased the intake and growth rate in the Mong Cai pigs but decreased the weight gain and had no effect on DM intake in the Moo Laat pigs.

For live weight gain the Mong Cai pigs were superior to the Moo Laat (Table 7). By contrast, feed conversion was better for the Moo Laat.

Apparent total tract digestibility

The results of the estimation of apparent digestibility by the acid insoluble ash method (Tables 9 and 10) appeared to show major advantages to the Mong Cai breed over the Moo Laat, It is not possible to explain the reason for such a difference, which needs to be confirmed or disproved in a subsequent experiment. Supplementation with rice distillers’ by-product did not affect the coefficients of digestibility. The coefficients for DM and OM were lower than those (81.1% for DM and 84% for OM) reported by Chittavong et al (2008b) for Mong Cai gilts. In contrast for crude protein the coefficient of apparent digestibility was higher in our study than the value (59%) recorded by these authors. The methods used were similar (Acid insoluble ash in each case) but Chittavong et al (2008b) fed diets in which the energy component was a mixture of ensiled cassava root and broken rice, ingredients with negligible fiber content as compared with the rice bran used in the present study.

The interaction between breed and supplementation in DM intake (per unit LW) and growth rate is not easy to explain. Supplementation increased feed intake and growth rate in Mong Cai but had no effect on intake yet decreased growth rate in the Moo Laat. There were indications from the growth curves (Figure 3), that in the case of the Moo Laat, those fed the rice distillers’ by-product took a long time to adapt to this supplement. During the last part of the trial they appeared to be growing faster than those not supplemented.

Analyzing the growth rates and DM intakes (as g/kg LW) separately for the periods 0-6 weeks and 7-12 weeks (Tables 11 and 12), shows clearly that:

1.      During each of the successive periods of 6 weeks, the Mong Cai fed the rice distillers’ by-product had higher DM intakes (P = 0.15 and 0.001 for the successive periods) and faster growth than their control mates not fed the supplement (Tables 11 and 12; Figures 2-5).

2.      During the first 6 weeks, the Moo Laat fed the rice distillers’ by-product had the same DM intake but grew more slowly than their control mates not fed the supplement (Table 11; Figures 2 and 4). In contrast, during the final 6 weeks (Table 12; Figures 4 to 7), the Moo Laat fed the rice distillers’ by-product had the same DM intake but grew at a faster rate than their control mates not fed the supplement.

The reasons for the apparent need for adaptation of the Moo Laat pigs to the rice distillers’ by-product do not appear to be due to the introduction of a new feed (the rice distillers’ by-product) as DM intakes expressed as a function of live weight were not depressed by feeding the by-product; however, neither were they increased, which is in contrast with the response of the Mong Cai that responded with increased intakes due to the supplement.

The better feed conversion of the Moo Laat pigs compared to the Mong Cai was also unexpected as they grew more slowly, which normally would influence negatively the conversion rate. The smaller size, and hence reduced maintenance requirement, would appear to be the reason for the good feed conversion of the Moo Laat breed.  From observation it also appeared that the Moo Laat was laying down less fat than the Mong Cai, another factor that would have benefited the feed conversion rate.

Conclusions

• Supplementation of a basal diet of rice bran and water spinach with rice distillers’ by-product increased the feed intake and growth rate of Mong Cai pigs but decreased the weight gain and had no effect on DM intake in Moo Laat pigs.
• The Mong Cai pigs grew faster than the Moo Laat pigs but the latter had the better feed conversion
• The coefficients of digestibility as measured by the acid indigestible ash method were not affected by supplementation with rice distillers’ by-product but appeared to be higher for the Mong Cai compared with the Moo Laat.

Acknowledgements

We would like to acknowledge the support of the Swedish International Development Agency (Sida) in funding this experiment as part of the MSc program in the regional MEKARN project. We also thank the students of the Faculty of Agriculture of Champasack University for their help in the management and feeding of the animals.

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