Effect of rice-wine distillers’ byproduct and biochar on growth performance and methane emissions in local “Yellow” cattle fed ensiled cassava root, urea, cassava foliage and rice straw

Sengsouly Phongphanith and T R Preston¹

Animal Science Department, Faculty of Agriculture and Forest Resource Souphanouvong University Lao PDR
ssl.souphanouvong@gmail.com
¹ Investigador Emérito, Centro para la Investigación en Sistemas Sostenibles
de Producción Agropecuaria (CIPAV), Carrera 25 No 6-62 Cali, Colombia

Abstract

Twelve local “Yellow” cattle with initial body weight of 80-100kg and 1.5 to 2 years of age were assigned to a feeding trial in a farmer household in Phonexay village, Phieng District, Xayabouly Province. The trial was arranged as a 2*2 factorial with 3 replications. The factors were: Biochar: 0 or 1% of DM intake; and Rice distillers’ byproduct: 0 or 4% of DM intake. The experiment was carried out for 120 days from January to June 2016, with an extra 15 days for adaptation to the pens and diets. The basal diet was ensiled cassava root supplemented with urea at 2% of ensiled root DM, fresh cassava foliage (sweet variety) at 25% of the DM of the basal diet, and rice straw at 1% of live weight. At the end of trial, concentrations of methane and carbon dioxide were determined in eructed gas mixed with air in a closed chamber in which the animals were kept for 20 minutes prior to measurement of the gases.

Supplementation of a basal diet of ensiled cassava root – urea and fresh cassava foliage with rice wine by-product (RDB) improved the growth rate of local “Yellow” cattle by 37% and feed conversion by 21%. Improvements due to supplementation with biochar were lower (15 and 15% respectively for live weight gain and feed conversion. The combined effect of RDB and biochar was to increase the live weight gain by 60% (from 300 to 500 g/day). The improvement in feed conversion was 38% (from 11.5 to 7.86).

Key words: climate change, feed conversion, greenhouse gases, live weight gain, rumen ammonia

Introduction

The government of Lao PDR focuses on poverty reduction, in particular on income generation in the rural areas under its national development policy (FAO 2003). Agriculture is the mainstay of the economy in Lao PDR, contributing 41% of GDP and employing more than 80% of the population. For the rural smallholders, who contribute most of the country’s agricultural output, livestock keeping is often a vital source of cash income, a means to accumulate assets, and a provider of inputs to crop production (manure and draught power). Cattle, buffaloes, pigs, chickens and goats are the most important livestock species in the country. Demand for meat is increasing, and there is growing potential for exporting livestock and their products to neighboring countries. The government has adopted a livestock development plan to strengthen and promote animal production and enhance national food security. Lao PDR has a comparative advantage in large ruminant production over neighboring countries, with scope for further development of cattle, buffalo and goat production in the uplands (FAO 2007).

Large ruminant production is one of the most important economic sectors in Lao PDR, with current number of local “Yellow” cattle 1,714,400 in 297,000 households. Due to population growth and changing diets, there is strong market demand for Lao local “Yellow” cattle products from neighboring countries of the People’s Republic of China and Vietnam as well as domestically. Available information suggests that current exports are less than 10% of potential demand, while annual domestic demand is rising at 4.5%. The price of beef in the Vientiane market increased from 43,500 kip/kg in 2010 to 85,000 kip/kg in 2014.

Despite the market opportunities, production systems are poorly developed. The main feed resources for the ruminants in Lao PDR are native grasses, legumes and tree leaves that are available in the natural grassland and forests (Phonepaseuth Phengsavanh and Ledin 2003). The availability of these feed resources is seasonally limited and both feed quantity and quality are low, especially in the cropping season. Cattle lose body weight in the dry season when forage resources are low in both nitrogen and minerals.

Preston and Leng (2009) and Leng (1997) have emphasized that the most appropriate ways to improve feed resources for ruminants in the tropics are through efficient utilization of crop byproducts and residues and tree/shrub foliages. However, to optimize performance correct feeding methods need to be applied ensuring that rumen function is efficient and secondly ensuring efficient assimilation of nutrients by providing a source of bypass nutrients (Preston and Leng 2009).

Rice straw is the most abundant crop residue in Asia, particularly in Lao PDR. It is the main feed in the dry season when natural grasses are in short supply to animals. However, it is characterized by high fiber levels and nutrient deficiencies, especially protein (2 to 4% crude protein), vitamins, minerals and soluble carbohydrates.

Cassava (Manihot esculenta Crantz) is an annual crop grown widely in the tropical and subtropical regions. Roots of cassava are rich in energy (75 to 85% of soluble carbohydrate) but with minimal levels of crude protein (2 to 3% in DM) (Feedipedia 2016).

The development of the starch industry in Lao for export to China and other neighboring countries has increased the market for cassava roots. As a result, cassava is currently the third most important crop in Laos, after rice and maize.

The varieties used for industrial starch production are known as “bitter” varieties due to the high content of cyanogenic glucosides that are converted into the highly toxic hydrocyanic acid when consumed by animals and people. The cassava varieties that are planted for human consumption are known as “sweet” varieties as they have a lower content of cyanogenic glucosides.

For every tonne of roots that are harvested there are an additional 600 kg of stems and leaves. However, the farmers in the cassava factory area have no experience in the utilization of cassava leaves as the protein supplement to feed to animals, especially cattle.

The foliage of cassava has been shown to be an effective source of bypass protein for fattening steers (Ffoulkes and Preston 1978; Keo Sath et al 2008; Wanapat et al 1997) and goats (Ho Quang Do et al 2002).). It is thus logical forage to provide the additional protein required in diets rich in carbohydrate but low in protein. Cassava leaves are known to contain variable levels of condensed tannins; about 3% in DM according to Netpana et al (2001) and Bui Phan Thu Hang and Ledin (2005). Condensed tannins are also reported to decrease methane production and increase the efficiency of microbial protein synthesis (Makkar et al 1995; Grainger et al 2009). Reductions of CH₄ production of 13 to 16% have been reported (Carulla et al 2005, Waghorn et al 2002, Grainger et al 2009, Woodward et al 2004), apparently through a direct toxic effect on methanogens.

Another potential source of protein for livestock in Lao is fresh brewers’ grains. However, availability is limited to areas close to the breweries, which are located in Vientiane, Pakse and Savannakhet provinces. Recent research has shown that small quantities of brewers’ grains (4% of diet DM) increased growth rates of cattle fed cassava root pulp and foliage of bitter cassava (Le Binh Phuong, personal communication). Further support for the idea that brewers ‘grains have a synergistic effect on cattle performance was provided by Inthapanya et al (2016) who reported improvements in N retention in cattle of almost 50% when 5% of brewers’ grains were added to a basal diet of ensiled cassava root, urea and sweet cassava foliage. Major increases in growth rate of goats (from 80 to 160 g/day) were reported by Vor Sina (personal communication) when a basal diet of fresh cassava foliage was supplemented with 4% (of diet DM) of fresh brewers’ grains.

Feeding of fresh brewers’ grains to cattle is only feasible in areas in close proximity to beer factories. However, a similar product “Kilao” is produced in almost all villages in rural areas of Lao, when rice is fermented and distilled to produce rice “wine”. It was hypothesized that “Kilao” (henceforth referred to as “rice distillers’ by-product [RDB]” would have a similar positive effect on growth of cattle as the brewers‘ grains when ensiled cassava root and cassava foliage were the basis of the diet.

Biochar is the carbon-rich residue when fibrous biomass is carbonized at high temperatures. It has been shown to play an active role in systems involving microbial fermentation (Lehmann and Joseph 2009). It is believed that the biochar, which is highly porous, may act as “habitat” for biofilms that facilitate the functioning of consortia of micro-organisms and their nutrients, allowing interspecies transfer of nutrients produced in a food chain such as in the glycolytic degradation of complex organic matter to VFA and production of  methane  or producing habitat (by the formation of biofilms) for microbes that degrade compounds that are in solution in the bulk fluid (Leng R L 2016, personal communication).

In previous experiments in Souphanouvong University with cattle fed urea-treated rice straw (Inthapanya et a al 2015) and goats fed Bauhinia acuminata tree foliage (Silivong et al 2015) addition of 1% of biochar to the diet increased growth rates and reduced methane production. It was hypothesized that similar benefits would be obtained by feeding biochar to cattle fed ensiled cassava root and cassava foliage.

Materials and methods

Animals, housing and location

Twelve local “Yellow” cattle with initial body weight of 80-100kg and 1.5 to 2 years of age were assigned to a feeding trial in a farmer household in Phonexay village, Phieng District, Xayabouly Province. They were confined in separate pens make from wood, bamboo and cement with the area 100*150 cm) (Photo 1). Vaccination was done against epidemic diseases and animals were drenching against internal parasites before the commencement of the experiment.

Photo 1. The cattle kept in individual pens

Treatments and experimental design

The experiment was carried out for 120 days (from January to June 2016), with an extra 15 days for adaptation to the pens and diets. The cattle were assigned in individual pens to a 2*2 factorial arrangement of four treatments with 3 replications. The factors were:

· Biochar: 0 or 1% of DM intake

· RDB: 0 or 4% of DM intake

The basal diet was ensiled cassava root supplemented with urea (2% of ensiled root DM), fresh cassava foliage (sweet variety) at 25% of the DM of the basal diet, and rice straw at 1% of live weight.

Feeding and management

Animals were adapted to the experimental feeds for 15 days before collection of data. The cassava root was bought from farmers in Xayabouly province. It was chopped into small pieces by machine and then stored in a plastic bag for ensiling over 7 days (Photo 2). Rice straw and rice distillers’ byproduct were purchased from farmers in the village (Photo 3). Cassava foliage was planted in the farmer areas (Photo 4). The biochar was produced locally by burning rice husks in a top lit updraft (TLUD) gasifier stove (Olivier 2010). It was ground to a particle size that passes through a 1 mm sieve and was mixed with the basal diets.

Feeds were given two times per day at 7:00am and 4:30pm and put in individual feeder troughs. The ensiled cassava root was mixed with urea (previously diluted with water) and with the biochar and RDB (according to the treatment design). Cassava foliage and rice straw were fed separately. The ensiled cassava root was fed ad libitum. Water was freely available. Feeds offered and refusals were weighed every morning.

Photo 2. Ensiled cassava root in the plastic bag	Photo 3. Rice distillers’ byproduct	Photo 4. Cassava at the time of harvesting the foliage

Data collection and measurements

The cattle were weighed before feeding in the morning at the beginning of the experiment and every 15 days, using an electronic balance. At the end of the experiment samples of rumen fluid were taken by a stomach tube, two hours post feeding in the morning for determining rumen ammonia and pH. At the end of the experiment, a sample of mixed eructed and respired gas from each animal was analysed for methane: carbon dioxide ratio using the Gasmet equipment (GASMET 4030; Gasmet Technologies Oy, Pulttitie 8A, FI-00880 Helsinki, Finland), based on the approach suggested by Madsen et al (2008). The cattle were held for 20 minutes in wooden crates covered with polyethylene film before taking the measurements, so that the gases emitted from the animal could equilibrate with the air in the box (Photo 5). Samples of air in the animal house were also analyzed for the methane: carbon dioxide ratio.

Photo 5. Wooden crates enclosed in plastic used to house the cattle during the 20 minute period of adaptation/measurement using the GASMET infra-red analyzer

Chemical analysis

Samples of feeds offered and residues were collected every 15 days to determine dry matter (DM), ash, crude protein (CP) according to AOAC (1990) methods. Rumen pH was measured immediately after taking rumen fluid from the animal with a digital pH meter. Rumen ammonia was measured by steam distillation and titration with 0.1 N H₂SO₄.

Statistical analysis

The data were analyzed by the general linear model option of the ANOVA program in the Minitab (2000) software (version 16.0). The sources of variation were: replicates, RDB, biochar, interaction RDB*biochar and error. Live weight gains were calculated from the linear regression of live weight (Y) on days in the experiment (X).

Results and discussion

Chemical composition of the feeds (see Table 1)

Feed intake

DM intake as percent of live weight was increased both by RDB and biochar although the effects were small (3% and 6% for biochar and RDB, respectively; Table 2, Figures 1 and 2).

Figure 1. Effect of rice distillers’by product with or without biochar on DM intake	Figure 2. Effect of biochar with or without rice distillers” byproduct on DM intake

Growth rate and feed conversion

Supplementation with RDB improved the growth rate by 37% and feed conversion by 21% (Table 3; Figures 3, 4, 5 and 7). Improvements due to supplementation with biochar were lower (15 and 15% respectively for live weight gain and feed conversion (Figures 6 and 8). The combined effect of RDB and biochar was to increase the live weight gain by 60% (from 300 to 500 g/day; Figure 3) the improvement in feed conversion was 38% (from 11.5 to 7.86; Figure 4).

Figure 3. Effect of supplementation with biochar and rice distillers byproduct on live weight gain of cattle feed ensiled cassava root with urea, straw and cassava foliage

Figure 4. Effect of supplementation with biochar and rice distillers’ byproduct on feed conversion of cattle fed ensiled cassava root with urea, straw and cassava foliage

Figure 5. Effect of rice distiller with or without biochar on live weight gain	Figure 6. Effect of biochar with or without rice distiller on live weight gain
Figure 7. Effect of rice distiller with or without biochar on feed conversion	Figure 8. Effect of biochar with or without rice distiller on feed conversion

Rumen parameters

Rumen pH values were similar on all treatments (Table 4). Rumen ammonia was not affected by biochar but was increased by RDB.

Methane production

There was an interaction between the effects of RDB and biochar. RDB had no effect on methane: carbon dioxide ratios in the absence of biochar but decreased the methane: carbon dioxide ratio by 36% when combined with biochar (Figures 9 and 10). Similarly, biochar reduced methane production in the presence of RDB but had the opposite effect in the absence of RDB. A positive effect on methane reduction was observed by Vor Sina (2016, personal communication) in growing goats when 4% brewers’ grains were added to a basal diet of cassava foliage.

Figure 9. Effect of rice distiller with or without biochar on ratio of methane and carbon dioxide	Figure 10. Effect of biochar with rice distiller on ratio of methane and carbon dioxide

Conclusions

• Supplementation of a basal diet of ensiled cassava root – urea and fresh cassava foliage with rice wine by-product (RDB) improved the growth rate of local “Yellow” cattle by by 37% and feed conversion by 21%. Improvements due to supplementation with biochar were lower (15 and 15% respectively for live weight gain and feed conversion.
  
  
• The combined effect of RDB and biochar was to increase the live weight gain by 60% (from 300 to 500 g/day). The improvement in feed conversion was 38% (from 11.5 to 7.86).

Acknowledgements

This research was done by the senior author as part of the requirements for the MSc degree in Animal Production "Improving Livelihood and Food Security of the people in Lower Mekong Basin through Climate Change Mitigation" in Cantho University, Vietnam. The author expresses gratitude to the MEKARN II project, supported by Sida, for financial support for this research. Special thanks are given to Mr Khamchanh Thammalangka who provided valuable help in the farm. We also thank the farmers at Phonexay village, Phieng District, Xayabouly Province, Lao PDR for providing the facilities to carry out this research.

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Received 10 September 2016; Accepted 15 September 2016; Published 1 October 2016

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