Livestock Research for Rural Development 28 (11) 2016 Guide for preparation of papers LRRD Newsletter

Citation of this paper

Effect of coconut (Cocos nucifera) meal on growth and rumen methane production of Sindhi cattle fed cassava (Manihot esculenta, Crantz) pulp and Elephant grass (Pennisetum pupureum)

Nguyen Thanh Duy and Duong Nguyen Khang

Research and Technology Transfer Center of Nong Lam University, Ho Chi Minh City, Viet Nam


This study focused on the effect of coconut oil meal on growth performance and methane emissions in growing cattle fed Elephang grass and cassava pulp. Twenty female Sindhi cattle were allocated to five treatments in five pens according to a randomized complete block design (RCBD). The treatments were levels of coconut oil meal of: 0, 0.25, 0.5, 0.75 and 1.0 percent of live weight per day. The basal diet was fresh cassava pulp and elephant grass fed at levels of 1 and 2% of live weight (DM basis), respectively.

Growth rate was increased, feed conversion was improved and eructed methane decreased with increasing amounts of coconut oil meal in the diet. The solubility of the diet protein was reduced when the coconut meal concentration in the diet increased and was directly related to the reduction in eructed methane. A direct effect of the oil in the coconut meal reducing methanogenesis through indirect effects on rumen protozoa population may also have contributed to the reduction in methane when Elephant grass was supplemented with  coconut meal.

Key words: byproducts, feed conversion, oil, protein solubility, protozoa


Cassava is one of the major crops planted in the tropics. It is cultivated in Viet Nam mainly for food (sweet varieties) and industrial starch (bitter varieties), and recently for feeding to livestock. The increasing demand for cassava for industrial use has resulted in the production of large quantities of byproducts and residues. Cassava pulp is the major byproduct accounting for some 30% of the original root. It is composed almost completely of non-structural carbohydrate, 65% of which is starch according to Sriroth et al (2000). It is very low in crude protein (less than 3% in the dry matter) and in minerals. To take advantage of the high carbohydrate content of cassava pulp it is recommended (Phanthavong et al 2016) that it should be supplemented with:

The coconut tree is an important source of edible oil in Vietnam; the area planted is of the order of 163,200 ha, with oil production of around 968 thousand tonnes (Statistical book 2002). Coconut meal is the byproduct from the extraction of oil, representing from 34 to 42% of the weight of the nut (Hutagalung 1981). It contains 18 to 25 % crude protein in DM. When the mechanical expeller process is used to extract the oil, the protein-rich byproduct is likely to be a good source of “bypass” protein, as the combination of the heat produced in processing, and the presence of residual oil, will tend to protect the protein against degradation in the rumen, thus conferring rumen “bypass” or “escape” properties to the protein (Preston and Leng 1987).

Elephant grass is considered to be the fastest growing plant in the world (Karlsson and Vasil 1985). However, when fed as the sole compoonent of the diet of fattening cattle, growth rates were low (111 to 260 g/day; Antari et al 2016). of weverThe protein content ranges from 4.4 to 20.4% in dry matter (DM) with the mean around 12%; the average NDF and ADF values are around 67 and 42%, respectively (Rusdy 2016). It could thus provide the fermentable protein and the fiber needed to optimize rumen microbial fermentation of the cassava pulp.

The purpose of the research reported in this paper was to evaluate the effects on growth rate, and on enteric methane production in Sindhi cattle, when Elephant grass was supplemented with a combination of cassava pulp and coconut oil meal.

Materials and methods


The experiment was conducted in the cattle farm of the Research and Technology Transfer Center of Nong Lam University from February to May 2016.

Treatments and experimental design

Twenty female Sindhi cattle were allocated to five pens according to live weight and fed a basal diet of Elephant grass and fresh cassava pulp (2 and 1% of live weight, as DM, respectively). Each pen received one of the following treatments according to a completely randomized block design:

• COM0: control (basal diet) (no supplementation)

• COM0.25: basal diet plus coconut meal 0.25% of LW/day

• COM0.5: basal diet plus coconut meal 0.5% of LW/day

• COM0.75: basal diet plus coconut meal 0.75% of LW, day

• COM1.0: basal diet plus coconut meal 1.0% of LW, day

Animals and housing

The cattle had an initial weight in the range of 140 to 244 kg and were allocated to 5 pens so that mean live weights within each pen were similar (Photo 1). Vaccination was done against epidemic diseases and the cattle were drenched against internal parasites before the commencement of the experiment.

Photo 1. The Sindhi cattle housed in group pens Photo 2. The coconut meal collected from
the processing factory
Feeding and management

The cattle were adapted gradually to the experimental feeds for two weeks prior to starting the experiment. The cassava pulp was collected from the Wuson cassava factory in Binh Phuoc province. Elephant grass was harvested from the cropping areas in the Center for Research and Technology Transfer, and chopped by machine prior to offering it to the cattle. Coconut meal was purchased from a coconut milk factory in Ho Chi Minh city. The feeds were offered two times a day, at 7.30 am and 3.30 pm. Water was always available.

Data collection and measurements

The cattle were weighed at the beginning and every 14 days, using an electronic balance. Feeds offered were weighed before giving them to the cattle. Feed refusals were collected each morning prior to offering fresh feed and weighed to measure the feed intake. Samples of feeds offered and refused were collected every 14 days to determine DM and crude protein according to AOAC (1990) methods. 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 1 hour in a closed chamber before taking the measurements, so that the gases emitted from the animal could equilibrate with the air in the environment (Photo 4). Samples of air in the animal house were also analyzed for the methane: carbon dioxide ratio.

Photo 3.  Electronic scale for weighing the cattle Photo 4. Closed chamber used to measure
enteric methane production
Chemical analysis

Samples of feeds offered and residues were analyzed for DM and crude protein (CP) following AOAC (1990) procedures. Protein solubility was measured by weighing 3 g of sample (DM basis), followed by shaking in 100 ml of M NaCl for 3 h. The suspension was then filtered through Whatman No. 4 filter paper and washed 3 times with distilled water. All the filtrate was then transferred to a kjeldahl flask for digestion, distillation and titration according to AOAC (1990). Protein solubility was calculated as the N content of the filtrate as a percentage of the N in the original sample.

Statistical analysis

Response curves were fitted to the data using linear and quadratic equations in Microsoft Office Excel software, with level of coconut meal as the independent variable (X) and the response component (eg: feed intake, weight gain …..,) as dependent variable (Y).

Results and discussion

Chemical composition of feeds

There were major differences in the solubility of the protein with much lower values for coconut meal and cassava pulp than for Elephant grass (Table 1).

Table 1. Composition of dietary ingredients


CP in DM

Soluble protein,
% of total protein

Cassava pulp




Elephant grass




Coconut meal




Feed intake

DM intake increased with a curvilinear trend as the supplementation with coconut meal increased, the peak value being reached when coconut meal was fed at 0.5% of live weight (Table 2; Figure 1). The overall level of dietary crude protein increased with the level of supplementation of coconut meal from 8.96% of diet DM with zero coconut meal to 11.7% in diet DM with coconut meal at 1% of live weight. The overall solubility of the dietary protein showed the opposite trend declining from 49.8% on the control diet of elephant grass and cassava pulp to 37.6% at the highest level of coconut meal supplementation (Table 2).

Growth rate increased with the level of supplementation of coconut meal with a curvilinear trend (R2 = 0.93) indicating that the optimum level of supplementation was with coconut meal providing about 50% of the dietary crude protein. Feed conversion was improved by supplementation with coconut meal with a linear trend (R= 0.88), the high values in general (28.7 – 20.5) reflecting the low rates of live weight gain (0.205 – 0.329 kg/day). The declining rate of response in live weight gain to increasing levels of coconut meal supplementation is in accordance with similar studies in which protein-rich supplements were fed in increasing quantities in diets rich in carbohydrates (eg: fish meal and molasses-urea, Preston and Leng 1987; cottonseed cake and ammoniated wheat straw, Weixian et al 1994).

Coconut oil meal is rich in oil (18% in DM). At the highest level of coconut oil meal supplementation the contribution of coconut oil to the diet would be 4.5%, leading to an overall level of ether-extract in the diet of 5.7%. This could explain the tendency to lower feed intake at the highest level of supplementation, as suggested by Beauchemin et al (2007). However, Phengvilaysouk and Wanapat (2008) reported no effect on feed intake when coconut oil was added to urea-treated rice straw (equivalent to 7.4% oil in diet DM) fed to buffaloes.

Table 2. Mean values for changes in live weight, DM intake, DM conversion and crude protein in diet DM and for cattle

Level of coconut meal, % of LW/day








Live weight, kg

















Daily gain








DM intake, kg/d

Coconut meal






Cassava pulp








Elephant grass














DM conversion






Crude protein
% in diet DM






% soluble*






* Protein solubilized by extraction with M NaCl

Figure 1. Proportion of the dietary intake as elephant grass (EM), cassava pulp (CP) and coconut meal (CLO) according to the dietary treatments Figure 2. Effect of coconut meal on DM intake of cattle fed elephant
grass and cassava pulp as basal diet

Figure 3. Effect of coconut meal on live weight gain of cattle fed
elephant grass and cassava pulp as basal diet
Figure 4. Effect of coconut meal on DM conversion of cattle fed
elephant grass and cassava pulp as basal diet

Table 3. Mean values for methane to carbon dioxide in eructed gas from cattle fed increasing levels of coconut
oil meal in a basal diet of elephant grass and cassava pulp

Level of coconut meal, % of LW/day















< 0.001

The ratio of methane to carbon dioxide in eructed gas was reduced with a curvilinear trend (R2 =0.97) by feeding increasing levels of coconut meal (Table 3; Figure 5). There are two possible explanations for the reduction in methane with increasing levels of coconut meal in the diet. Replacing the elephant grass with coconut meal led to an overall decrease in the solubility of the dietary protein (from 50 to 40%) and this was directly related (R 2 = 0.94) to the methane: carbon dioxide ratio (Figure 6). A similar relationship between methane production and solubility of the dietary protein was reported by Silivong et al (2016) and was attributed to the shift in metabolic disposal of hydrogen from methane to acetate when the balance of fermentative digestion was changed as in the case of feeds escaping from the rumen to be fermented in the cecum-colon (Leng 2016, personal communication). The increasing levels of oil from the coconut meal may also have had a direct effect in reducing rumen methanogenisis associated with the oil decreasing rumen protozoa as reported in an earlier paper (Nguyen Thanh Duy et al 2016).

Figure 5. Effect of coconut meal on the ratio of methane to carbon dioxide in eructed
gas from cattle fed elephant grass and cassava pulp as basal diet

Figure 6. Relationship between solubility of diet protein and ratio of methane to carbon dioxide in eructed gas from cattle
fed elephant grass and cassava pulp as basal diet supplemented with increasing levels of coconut meal



This research was done by the senior author as part of the requirements for the MSc degree in Animal Production "Specialized in Response to Climate Change and Depletion of Non-renewable Resources" of Cantho University, Vietnam. The authors acknowledge support for this research from the MEKARN II project financed by Sida. They also acknowledge the Research and Technology Transfer Center, Nong Lam University, Vietnam for providing infrastructure support.


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Received 3 October 2016; Accepted 6 October 2016; Published 1 November 2016

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