Rice distillers’ byproduct and biochar as additives to a forage-based diet for growing Moo Lath pigs; effects on growth and feed conversion

Bounlerth Sivilai, T R Preston¹, R A Leng², Du Thanh Hang³ and Nguyen Quang Linh³

Department of Livestock and Fisheries, Faculty of Agriculture, National University of Laos, Vientiane Capital, Lao PDR
lerth_si@yahoo.com
¹ Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria(CIPAV), Carrera 25 No 6-62 Cali, Colombia
² University of New England, Armidale NSW, Australia
³ Department of Animal Husbandry, Faculty of Animal Husbandry and Veterinary Medicine, University of Agriculture and Forestry, Hue University, Vietnam

Abstract

Native Moo Lath pigs (n=20; initial live weight 15.8 ± 1.3 kg) were housed in individual concrete pens (1.2 *0.6m). They were fed a basal diet of ensiled banana pseudo stem and ensiled taro foliage supplemented with broken rice and soybean meal. There were four dietary treatments arranged as a 2*2 factorial in a completely randomized design with 5 replications. The treatments (% in diet DM) were: no additive (CTL), 4% rice distillers’ byproduct (RDB), 1% biochar (BIO) and the combination of RDB and BIO (RDB-BIO).

Growth rate tended to be better (p=0.089) and feed conversion was improved (p=0.048) for both additives, fed separately or together, when compared with the control diet. The improvements in weight gain were 20.1 and 22.9% for biochar and RDB added separately and 22.9% for the combined additives. For feed conversion the relative degrees of improvement were 10.6, 12.2 and 9.30%.  There were no benefits from combining both additives compared with feeding each one separately.  Whilst considerable research needs to be done, the possibility is that biochar and distillers’ byproducts bind toxins from the feed which are either excreted in the feces or degraded by some organisms in the animal’s gut microbiome.

Keywords: banana pseudo-stem, native pig, prebiotic, taro foliage

Introduction

Rice distillers’ byproduct (RDB) is the residue derived from yeast fermentation of rice to make rice wine usually at household level. Rural smallholder farmers in Vietnam and Laos have successfully used RDB as a protein source for pigs (Manh et al 2009; Taysayavong and Preston 2010; Manivanh et al 2012). Recently it has been hypothesized that RDB fed in small quantities (4% of the diet) also acts as a prebiotic safeguarding cattle from potential toxicity caused by hydrocyanic acid in cassava foliage (Binh et al 2017), increasing N retention in growing pigs (Sivilai and Preston 2017) and improving growth and feed conversion in pregnant-lactating gilts and in the growth rate of their piglets to weaning (Sivilai et al 2018).

Biochar is the residue from the carbonization of fibrous biomass at high temperatures (500-1000 °C) in a downdraft gasifier (Rodriguez and Preston 2010; Orosco et al 2018) or in an updraft gasifier stove (Philavong et al 2017). It has been extensively researched as a means of sequestering carbon in soils (Lehman 2007) with associated beneficial effects on crop and plant growth (Lehman and Joseph 2015; Preston 2015).

Feeding biochar to animals is a recent development arising from the finding that 1% of biochar in a cassava-based diet enhanced growth rate of cattle (Leng et al 2012a; Sengsouly and Preston 2016) and reduced the release of methane in an in vitro rumen incubation (Leng et al 2012b). The potential of feeding biochar to fish was indicated by the superior growth rates in striped catfish fed 1% biochar in their diet and the associated improvement in water quality in the fish tank (Lan et al 2016).

The objective of the research described in this paper was to evaluate the effect of biochar on the growth rates of indigenous Moo Lath pigs fed a high forage diet, and to compare it with rice distillers’ byproduct already shown to be effective as a prebiotic in diets of Moo Lath pigs (Silivai and Preston 2017, Sivilai et al 2018).

Materials and Methods

Location and duration

The experiment was conducted in the farm of the Department of Livestock and Fishery, Faculty of Agriculture, National University of Laos, Vientiane capital, Lao PDR. The temperature during the experiment ranged from 24 to 35 °C. The experiment was carried out for four months from 27 November, 2017 to 27 February, 2018.

Experimental design

Twenty native Moo Lath pigs with 15.8 ± 1.3 kg initial live weight were housed in individual concrete pens (1.2 *0.6m). They were fed a basal diet of ensiled banana (Musa spp) pseudo stem and ensiled taro (Colocasia esculenta) foliage supplemented with broken rice and soybean meal. There were four dietary treatments arranged as a 2*2 factorial in a completely randomized design with 5 replications. The treatments (% in diet DM) were: no additive (CTL), 4% rice distillers’ byproduct (RDB), 1% biochar (BIO) and the combination of RDB and BIO (RDB-BIO).

Feeding and management

The pigs were vaccinated against hog cholera and de-wormed with Ivermectin (1 ml/20 kg LW) and adapted to the new feeds for 12 days prior to collection of data. The daily allowances were prepared immediately prior to feeding at 7:30 am and 4:30 pm; water was freely accessed through nipple tap drinkers in each pen.

Photo 1. The biochar was the residue from rice husks used as fuel in a gasifier stove

The rice distillers’ byproduct (RDB) was bought from traditional rice wine producers, mostly smallholder farmers, in the area surrounding Vientiane city. It was stored in closed containers to maintain the quality and avoid mold growth. The biochar was made from rice husk combusted in a gasifier stove (Photo 1). The water retention capacity (volume of water retained per unit weight of dry biochar) was ??? which is similar to the value (5.6) reported for biochar produced from rice husks in a down-draft gasifier (Orosco et al 2018).

Taro foliage (leaves + petioles) were collected from ponds in the local village where waste water was stored;. The banana pseudo stems were obtained from farmers’ gardens after harvesting the fruit. Each foliage was chopped into small particles of 1-2 cm and wilted under shade for 24 h prior to being stored in closed plastic bags in which they were preserved for 14 days before being fed to the pigs.

Data collection and proximate analysis

The pigs were weighed every 14 days during the 90-day experiment. Average daily weight gain was determined from the linear regression of live weight (Y) against days in the experiment (X). Feeds offered and refused were recorded daily. Representative samples were stored at -18°C until the end the experiment when they were bulked on an individual animal basis for determination of DM, crude protein, crude fiber and ash according to AOAC (1990) procedures.

Statistical analysis

The data of DM feed intake, live weight change and feed conversion were analyzed by the general linear model option in the ANOVA program of the Minitab software (Minitab 2016). Sources of variation in the model were rice distillers’ byproduct (RDB), biochar (BIO), interaction of RDB*BIO, replicates and error.

Results

Composition and proximate analysis of the diets

Approximately 55% of the protein in the diets came from the taro silage with soybean meal accounting for 26%. When RDB was added, it represented about 6% of the total protein supply (Tables 1 and 2). The value of 4.73 for water retention capacity of the biochar (weight of water adsorbed per unit weight of biochar) was less than that (5.60) reported for rice husk carbonized in a contiuous-flow downdraft gasifier (Orosco et al 2018).

Dry matter intake, growth rate and feed conversion

There was no effect of the additives on feed intake (Table 3: Figure 1). Growth rate tended to be better (p=0.089) and feed conversion was improved (p=0.048) for both additives, fed separately or together, when compared with the control diet. The improvements in weight gain were 20.1 and 22.9% for biochar and RDB added separately and 22.9% for the combined additives. For feed conversion the relative degrees of improvement were 10.6, 12.2 and 9.30%.  There were no benefits from combining both additives compared with feeding each one separately.  

Figure 1. Effect of additives (DM basis) of rice distiller’s byproduct (4%) and biochar (1%) on DM intake of Moo Lath pigs fed a basal diet of ensiled banana pseudo stem, ensiled taro foliage and broken rice

Figure 2. Effect of additives (DM basis) of rice distiller’s byproduct (4%) and biochar (1%) on live weight gain of Moo Lath pigs fed a basal diet of ensiled banana pseudo stem, ensiled taro foliage, broken rice and soybean meal.

Figure 3. Effect of additives (DM basis) of rice distiller’s byproduct (4%) and biochar (1%) on DM feed conversion of Moo Lath pigs fed a basal diet of ensiled banana pseudo stem/taro foliage, broken rice and soybean meal

Discussion

The positive effect of rice distillers’ byproduct on growth rates and feed conversion of the Moo Lath pigs agrees with previous results in our laboratory where: (i) 4% (as DM) of rice distillers byproduct improved N retention in growing Moo Lath pigs by 36% and the biological value of the nitrogen by 18% (Sivilai and Preston 2017): and (ii) 4% (as DM) of rice distillers byproduct increased the litter weight of weaned pigs from Moo Lath gilts by 67% and the overall feed conversion (feed consumed in pregnancy and lactation/weight of weaned piglets) by 64% (Sivilai et al 2018).

To our knowledge, the feeding of biochar to pigs has not previously been reported. The degree of response observed in this experiment with growing pigs (20-23% and 11-14% for growth and feed conversion) is similar to the 15 and 18% improvements in growth and feed conversion reported for biochar fed to cattle (Sengsouly and Preston 2016) and the 27 and 13% improvements in growth and feed conversion when biochar was fed to goats (Silivong and Preston 2016).

Distillers’ by-products contain the remains of the yeast that produce the alcohol., The cell wall of S cerevisiea contains a scaffold of β-glucans attached to highly glycoslylated mannoproteins (see Shetty et al 2006) that can bind numerous compounds ,microorganisms or provide habitat for biofilm formation. Biochar is relatively inert but also has sites for microorganisms, sorption of chemicals and is known to provide habitat for biofilm formation (Leng 2017). So both additives have numerous sites for absorption and binding of compounds and microorganisms and potentially also provide habitat for biofilm attachment.

Biochar and rice distillers’ by-product each increase pig growth rate and efficiency of feed utilization but the effects were not additive when they were combined. It is possible that both additives are controlling or preventing reactions that removed whatever caused the lowered production in their absence. It is possible that the feed used in the present study had become contaminated with molds that produce a variety of mycotoxins. The silage component although high in moisture, with a low pH can contain molds on the herbage before and after harvesting and even in the ensiling process before acidification causes the fermentative process to cease. Leng (2017) hypothesized that given time the rumen microbiome has an enormous capacity to degrade many phytotoxins and mycotoxins provided a specific habitat is available together with the toxin. Similarly, the caecum/colon of the pig may have the same capacity. Whilst considerable research needs to be done, the possibility here is that biochar and distillers’ byproducts bind toxins from the feed which are either excreted in the feces or degraded by some organisms in the animal’s gut microbiome. This concept is supported by the report of Prasai et al (2017) that: “supplementation of feed fed to hens with biochar, zeolite or bentonite improved egg yield and feed conversion ratio, with these additives potentially acting as detoxifiers or inhibiting growth of microbial pathogens, slowing digestion or altering the gut anatomy and microbiota to improve feed conversion ratio”. Leng (2017) argued a similar case for the detoxification of mimosine and fluoroacetate in ruminants that had never been exposed to these in their feed.

The related issue is the extent to which the soil ameliorating properties of biochar will be observed when the excreta of biochar-fed animals is returned to the soil as fertilizer. This expectation is conditional on the animals being fully integrated in the farming system.

Conclusions

• In pgs, growth rate tended to be better (p=0.089) and feed conversion was improved (p=0.048) for both additives, fed separately or together, when compared with the control diet. The improvements in weight gain were 20.1 and 22.9% for biochar and RDB added separately and 22.9% for the combined additives.
  
  
• For feed conversion the relative degrees of improvement were 10.6, 12.2 and 9.30%.There were no benefits from combining both additives compared with feeding each one separately.
  
  
• It is postulated that biochar and distillers’ byproduct bind toxins from the feed which are either excreted in the feces or degraded by some organisms in the animal’s gut microbiome.

Acknowledgement

This research was done by the senior author as part of the requirements for the PhD degree in Animal Science of the University of Agriculture and Forestry, Hue University, Vietnam. The authors acknowledge support for this research from the MEKARN II project (Improving Livelihood and Food Security of the people in Lower Mekong Basin through Climate Change Mitigation), financed by Sida and co-research fund of the National University of Laos. Special thanks are given to animal science students (Bounphan Sitthaphone and Saysomphone Kaiyalath) for their assistance in field work and the laboratory during the experiment. The Faculty of Agriculture, National University of Laos is acknowledged for providing the facilities to carry out this research.

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Received 22 April 2018; Accepted 18 May 2018; Published 1 June 2018

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