Livestock Research for Rural Development 30 (9) 2018 Guide for preparation of papers LRRD Newsletter

Citation of this paper

Effect of biochar on growth performance of local “Yellow” cattle fed ensiled cassava roots, fresh brewers’ grains and rice straw

Bounthavy Vongkhamchanh, T R Preston1, R A Leng2, Le Van An3 and Duong Thanh Hai3

Faculty of Agriculture and Forestry, Champasack University, Champasak, Lao PDR
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 Faculty of Agriculture and Forestry, Hue University, Vietnam


In a 56-day experiment with 6 local Yellow cattle fed ensiled cassava root-urea, brewers’ grains and rice straw, there were indications (p=0.08) that after an initial 4-week adaptation to the diet, the cattle were growing faster when 1% of biochar (derived from rice husk) was incorporated in the diet.

Keywords: biofilms, habitat, mycotoxins, rice husks


Biochar is a carbonized plant material produced by high-temperature (>500°C) pyrolysis of fiber-rich biomass, preferably as a co-product with producer gas, as in an updraft gasifier stove (Photo 1) or in a downdraft gasifier (Rodríguez et al 2009; Lanh et al 2016; Orosco et al 2018).

Photo 1. Producing biochar from rice husk in a gasifier stove (from Thuy Hang et al 2018)

Biochar is becoming increasingly important in agricultural systems (Kammann et al 2017) as a means of improving soil fertility (Bouaravong et al 2017) and sequestering atmospheric carbon (Lehmann 2007). The principal virtue of biochar is thought to be in its surface area which is reported to range from 100 to 460 m2/g (Park et al 2013). It was postulated (Leng 2014) that this characteristic of biochar enables it to act as a support mechanism for biofilms that provide habitat for microbial communities which bind and degrade phytotoxins. Support for this idea is provided by the results of an initial study in Laos (Leng et al 2012), in which growth rates of local Yellow cattle fed fresh cassava root, urea and cassava foliage were increased 20% by adding 1% biochar to the diet. In the light of recent knowledge (Leng 2017), it is hypothesized that mycotoxins may have proliferated in the stored cassava roots and that the improved animal response from feeding biochar may have been due its action in binding the mycotoxins This concept is supported by the report of Prasai et al (2017) that: “supplementation of laying hens’ diets 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”.

The rationale for conducting the following experiment was to obtain further evidence concerning the potential benefits from feeding biochar as an additive in cattle fattening diets based on ensiled cassava roots and brewers’ grains.

Materials and Methods

Location and duration

The experiment was conducted in the Integrated Demonstration Station, Faculty of Agriculture and Forestry, Champasak University, Lao PDR.

Treatments and experimental design

The treatments were absence or presence of biochar (1% as DM) in a diet of ensiled cassava root supplemented with urea, brewers’ grains and rice straw. Six local Yellow cattle (initial weights from 90 to 100kg) were housed in individual pens, three on each treatment. The experiment lasted 56 days. They were vaccinated against endemic diseases and drenched against internal parasites before starting the experiment.

Feeds and feeding system

The basal diet was ad libitum ensiled cassava root (with 3% urea on DM basis added prior to feeding) with supplements of fresh brewers’ grains and rice straw (both at 1% of live weight as DM).

Feeding management

The rice straw was collected from farmers’ fields in the area. Brewers’ grains were donated by the local beer factory. Cassava roots were purchased from farmers, chopped and ensiled in plastic bags for five days before feeding, Urea was purchased from the market. A mineral mixture containing salt (NaCl) 40%, sulphur 5% and lime (calcium carbonate) 35% was provided ad libitum. Water was freely available. Biochar was made from rice husks in a gasifier stove (Photo 1).

Data collection

The cattle were weighed before feeding in the morning at the beginning of the experiment and at 14-day intervals. Feeds offered, and residues, were recorded daily; samples of each were collected every 14 days and stored at -18 C. At the end of the experiment, the samples were bulked on an individual animal basis prior to analysis.

Chemical analysis

Feed samples were analyzed for dry matter (DM), ash and nitrogen following the procedures of AOAC (1990).

Statistical analysis

Live weight gain was determined from the linear regression of live weight (Y) on days in the experiment (X). The recorded data were analyzed by the general linear model option in the ANOVA program of the Minitab software (MINITAB 2000). Sources of variation in the model were were treatments and error. As there appeared to be an improvement in growth response to biochar in succeeding months (Figure 1), separate analyses were run for each of the two months of the experiment.


Chemical composition of feeds

The analyzed values were in the range of those reported in

Table 1. Chemical composition (CP is crude protein) of diet ingredients
(% DM basis, except for DM which is on % fresh basis)






Rice straw






Ensiled cassava root






Brewers’ grains






Feed intake

More rice straw was eaten when the diet was supplemented with biochar (Table 2), but total DM intake was not affected.

Table 2. Mean values for intake of diet components (kg DM) during the 56-day trial

No biochar




Rice straw





Ensiled cassava root





Brewers' grains










Growth and feed conversion

It was apparent from the trends in live weight with time on experiment (Figure 2) that there was an adaptation period of some 3-4 weeks before there was a response to the biochar additive.

Figure 1. Trends in live weight of the cattle over the 56 days of the experiment
according to the treatment with or without biochar additive

When growth rates were calculated separately for the two periods: 0-28d and 28 to 56d (Table 3) there was a strong indication (p=0.08) of improvement due to the biochar additive (Figure 3).

Table 3. Mean values for live weight, DM intake and feed
conversion for local Yellow cattle fed ensiled cassava root-urea,
brewers’ grains and rice straw with and without biochar

No biochar




Live weight, kg














LW gain, kg/d
















DMI, kg





FCR, kg/kg





DMI, DM intake, FCR, feed DM conversion

Figure 2. Live weight gain over successive 28-day periods of local Yellow cattle fed ensiled cassava
root-urea, brewers’ grains and rice straw with and without 1% biochar in the diet


The experiment could not be continued beyond 56 days for reasons beyond the control of the authors. However, the indications of a positive production response from feeding the biochar are in line with previous reports with cattle (Leng et al 2012; Sengsouly and Preston 2016), goats (Silivong et al 2018; Thuy Hang et al 2018), pigs (Sivilai et al 2018), hens (Prasai et al 2017) and fish (Lan et al 2016).

Further support for incorporating biochar in livestock feeds is in the report by Joseph et al (2015) where it was shown that the excreta from cattle fed biochar mixed in molasses had ameliorating effects on plant growth when recycled to the soil.

Added to the diverse positive effects of biochar on animal and plant growth are the findings of the reduction in rumen methane production both in vitro (Leng et al 2013; Vongkhamchanh et al 2015; Saleem et al 2018) and in vivo (Leng et al 2012; Sengsouly and Preston 2016) when biochar was added to the substrate/feed.



This research is part of the requirement by the senior author for the degree of PhD at Hue University of Agriculture and Forestry. The support from the MEKARN II project, financed by Sida, is gratefully acknowledged, as is that from the Faculty of Agriculture and Forestry, Champasack University for providing laboratory facilities to carry out this research.


AOAC 1990 Official methods of analysis. 15th ed. AOAC, Washington, D.C.

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Silivong P, Preston T R, Van N H and Hai D T 2018 Brewers’ grains (5% of diet DM) increases the digestibility, nitrogen retention and growth performance of goats fed a basal diet ofBauhinia accuminata and foliage from cassava (Manihot esculenta Crantz) or water spinach (Ipomoea aquatica). Livestock Research for Rural Development. Volume 30, Article #55. Retrieved June 22, 2018, from

Sivilai B, Preston T R, Leng R A, Hang D T and Linh N Q 2018 Rice distillers’ byproduct and biochar as additives to a forage-based diet for growing Moo Lath pigs; effects on growth and feed conversion. Livestock Research for Rural Development. Volume 30, Article #111. Retrieved June 23, 2018, from

Thuy Hang L T, Preston T R, Leng R A and Ba N X 2018 Effect of biochar and water spinach on feed intake, digestibility and N-retention in goats fed urea-treated cassava stems. Livestock Research for Rural Development. Volume 30, Article #93. Retrieved June 23, 2018, from

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Received 2 July 2018; Accepted 31 July 2018; Published 3 September 2018

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