Replacing rice distiller’ by-product with protein-enriched cassava root as a protein source for growing local pigs fed basal diet of rice bran

Nouphone Manivanh, Vongpasith Chanthakhoun and Vanhnasin Phoneyaphon

Faculty of Agriculture and Forest Resource, Souphanouvong University, Luangn Prabang, Lao PDR
noumanivanh@gmail.com

Abstract

Sixteen local pigs, weighing on average 11.6 kg, were arranged in a completely randomized block design (RCBD) with four treatments and four replications. Individual treatments were 30% of Protein-enriched cassava root (PECR) and rice distillers’ by-product (RDB) and the mixed PECR and RDB 15% (DM basis) with rice bran as a basal diet (RB) compared with control diet (100% of rice bran). The trial was conducted in the experimental area of Department of Animal Science, in Luang Prabang Province, Laos.

Fresh cassava roots were supplemented with urea and di-ammonium phosphate and fermented aerobically with yeast (S. cerevisiae) to increase the content of protein from 2 to 10.8%. In a growth trial with sixteen local pigs, there were indications of positive effects of the replacing protein-enriched cassava root and rice distillers’ by-product in the diets increased DM intake and growth rate and improved feed conversion in Local pigs fed a basal diet of rice bran.

Keywords: fermentation, yeast, local pigs, growth rate

Introduction

Pig production constitutes a vital component of livestock farming in the Lao People’s Democratic Republic (Lao PDR), particularly among rural smallholders practicing traditional mixed farming systems Most pigs are raised in small-scale, low-input systems that use local feed sources like rice bran, cassava, maize, and household by-products (Phengsavanh et al 2010; Phengsavanh and Stür, 2011).Despite involving little investment, offering restricted access to veterinary care, and yielding low productivity, these systems still play an essential role in supporting rural communities by providing income, food security and a means of livelihood (International Labor Organization [ILO], 2024).

In these systems indigenous pig breeds play a significant role due to their high adaptability to the environmental conditions, low quality of local feed resources and animal husbandry. The most common local pig breed reared is the Moo Lath or native Lao pig, (Phengsavanh et al 2010; Huyen et al 2011). While these pigs exhibit slow growth rates, lower reproductive performance, and higher fat deposition compared to exotic breeds, they are valued for their superior meat quality, disease resistance, and resilience (Viengsavanh et al 2021).

In most regions of Laos, livestock feeding practices are based on the use of agricultural by-products such as rice bran, along with natural grasses (ILRI, 2002). In rural areas where growing paddy rice is the primary form of farming, pigs are typically fed a diet of rice bran supplemented with a small amount of green forage. However, a major limitation in pig production is the insufficient supply of protein, since soybean meal and fish meal are almost unavailable in rural areas.

Phengsavanh and Stür (2006) demonstrated that supplementing pig diets with protein-rich forage, such as Stylosanthes, improved average daily growth rates from 100 g to 200 g per day. Nevertheless, other forage species may offer even greater potential when included in rice bran–based pig diets (Preston, 2006). Research has shown that adding rice distillers’ by-product (RDB) as a dietary supplement can improve animal performance in growing pigs (Sivilai and Preston, 2017), cattle (Sengsouly & Preston, 2016; Sangkhom et al 2017) and goats (Silivong and Preston, 2016).

These positive responses are believed to result from the presence of prebiotic compounds, particularly β-glucans found in the cell walls of cereal grains and yeast. When rice wine is made, β-glucans are released during fermentation and distillation. These active compounds help improve the gut health of livestock and make it easier for them to use nutrients. Cassava (Manihot esculenta Crantz) ranks as the third most important crop in Lao PDR, and its cultivation has expanded rapidly with the growth of industrial starch production for export. Cassava root mainly consists of carbohydrates and contains exceptionally low levels of protein, which restricts its nutritional value as a livestock feed. Previous research by Manivanh and Preston (2016a) demonstrated that the true protein content of cassava root could be increased to 14% of dry matter through aerobic fermentation with yeast, supplemented with urea and di-ammonium phosphate. Live weight gain of the pigs were increased by 46% with a linear trend as the protein-enriched cassava root was increased from zero to 15% of the diet (Manivanh N and Preston T R, 2016b).

Materials and methods

Location

The experiment was conducted at the Faculty of Agriculture and Forest Resources, Souphanouvong University. The site is situated approximately 7 km from Luang Prabang City, Lao PDR. During the experimental period, the mean daily temperature was 27°C, ranging from 22 to 32°C.

Experimental design, treatments and management

Protein-enrichment of cassava root

Cassava roots were peeled and chopped by machine into small pieces (1-2 cm) and steamed for 30 minutes. The substrate was cassava root 93.6% + di-ammonium phosphate (DAP) 2%+ urea 1.4%+ yeast 3% (DM basis). The mixed substrate was then transferred to plastic tank covered with plastic netting to allow free entrance of air, after seven days, the protein-enriched cassava root was fed to the pigs.

The rice distillers’ by-product (RDB) was purchased from traditional rice wine producers, primarily smallholder farmers, in areas surrounding Luangprabang City.

Experimental design

The experiment was arranged in a completely randomized block design (RCBD) with four treatments and four replications.

Individual treatments were 30% of Protein-enriched cassava root (PECR) and rice distillers’ by-product (RDB) and the mixed PECR and RDB 15% (DM basis) with rice bran as a basal diet (RB):

T1: Rice bran 100%

T2: Rice bran 70% + PECR 30%

T3: Rice bran 70% + RDB 30%

T4: Rice bran 70% + RDB 15% + PECR 15%

Sixteen local pigs (Moo Lat breed) with a mean body weight of 11.6 kg (10 males; 6 females). All were vaccinated against swine fever and treated for roundworms with Ivermectin (1ml per 20kg live weight) before the experiment began. The pigs were housed in individual pens (with 1m and length 1.2m) made from local materials. The pigs were provided with unrestricted access to water and allowed a one-week acclimation period to both the pens and the diet prior to the start of the experiment, which was conducted over 90 days.

Diet ingredients were mixed and fed twice daily at 6:30 am and 5:00 pm, with amounts set to 40g DM per kg of body weight.

Data collection

The pigs were weighed in the morning before feeding at the start of the trial and subsequently at 15-day intervals. Average daily live weight gain was calculated from the linear regression of live weight against time (days on trial). Samples of feed offered and feed refusals were collected daily, weighed, and sub-sampled. The sub-samples were stored at 4 °C in a refrigerator and later pooled for the analysis of dry matter (DM), nitrogen (N), and ash contents.

Chemical analysis

The sub-samples of feed offered, feed refused, and feces were analyzed for dry matter (DM), nitrogen (N), and ash using standard procedures described by AOAC (1990). Urine samples were analyzed for nitrogen content following the same reference methods. The true protein content of the enriched cassava root was determined by treating the samples with trichloroacetic acid (TCA) prior to nitrogen estimation.

Statistical analysis

Data for feed intake, N intake, live weight were analyzed with the General Linear Model option of the ANOVA program in the MINITAB software (Minitab 2000).

Results and discussion

Chemical composition

After adding the urea, DAP and yeast to the cassava root, prior to the start of the fermentation, the CP in the mixture was calculated to be 13.8%, a value similar to that reported by Manivanh et al (2016), Sengxayalth and Preston (2017) and Vanhnasin and Preston (2016).

Feed intake, growth rate and feed conversion

DM intake was increased 30% with the rice distillers’ by-product in the diets and proportion of the mixed level of protein-enriched cassava root and rice distillers’ by-product 15%. The lowest DM intake -g/day- was in the 100% of rice bran treatment T1 (Table 3; Figure1).

Figure 1. Effect of replacing rice distiller’s by-product with protein enriched cassava root as a protein source on DM intake.

Table 4 shows the live weight gain and DM feed conversion of pigs; both parameters increased with the addition of the mixed level of protein-enriched cassava root and rice distillers’ by-product, (Figure 2 and Figure 3).

Figure 2. Live weight gain,-g/day- by replacing rice distiller’ by-product with protein-enriched cassava root as a protein source

Figure 3. Feed conversion ratio by replacing rice distiller’ by-product with protein-enriched cassava root as a protein source

Discussion

Fermenting cassava root with yeast, urea and DAP increases its protein content, as shown in previous studies Nouphone et al (2016a) reported a similar result when fresh cassava root was fermented using DAP, urea, and yeast, leading to an increase in crude protein content from 3.2% to 21.1% (DM basis), with about 90% of the crude protein present as true protein. Likewise, Antai and Mbongo (1994) found that fermentation of cassava peels with a pure culture of Saccharomyces cerevisiae raised the protein content from 2.4% to 14.1%. Similarly, Oboh and Kindahunsi (2005) observed an increase in the protein level of fermented cassava flour from 4.4% to 10.9% (DM basis) when S. cerevisiae was used as the fermenting organism.

The increase in growth rate by replacing protein-enriched cassava root and rice distillers’ by-product 15% in the diets was higher that (30% protein source of PECR) reported in an experiment (Manivanh and Preston 2015). DM feed conversion in the present experiment by replacing protein-enriched cassava root and rice distillers’ by-product 15% in the diets (3.9) was also better than in the previous experiment (5.7). The positive impact of rice distillers’ by-product on the growth performance and feed efficiency of local pigs is consistent with earlier reports. Sivilai and Preston (2017) demonstrated that dietary inclusion of 4% rice distillers’ by-product (DM basis) improved nitrogen retention by 36% and increased the biological value of nitrogen by 18% in growing local pigs. Similarly, Sivilai et al (2018) reported that supplementation at the same level enhanced the litter weight of weaned piglets by 67% and improved overall feed conversion efficiency (feed intake during pregnancy and lactation per weight of weaned piglets) by 64%.

Conclusions

There were indications of positive effects of the replacing protein-enriched cassava root and rice distillers’ by-product in the diets increased DM intake and growth rate and improved feed conversion in Local pigs fed a basal diet of rice bran.

Acknowledgments

The authors would like to express sincere gratitude to Souphanouvong University who supporting the budget for this experiment. We are very grateful to Mr. Bounkham Sinthason, the student of Faculty of Agriculture and Forest Resources (FAF), Lao PDR for he helps collecting data during the experiment.

References

Antai S P And Mbongo P N 1994 Utilization of cassava peels as substrate for crude protein formation. plant foods for human nutrition, V.46, P.345-351.

AOAC 1990 Official methods of analysis. Association of official analytical chemists, Arlington, Virginia, 15^thedition, 1298 pp.

Huyen L T T, Ogle B And Stür W 2011 Performance of local and crossbred pigs under smallholder conditions in northern Lao PDR. Animal production science, 54, 600-606.

ILRI 2002 Improving the livelihoods of the poor through improved livestock technologies: Annual report 2002. International livestock research institute (ILRI). Nairobi, Kenya.

International livestock research institute [ILRI] 2021 Production diseases in smallholder pig systems in rural Lao PDR. https://www.ilri.org

Manavanh N And Preston T R 2016a Protein enrichment of cassava (Manihot esculenta crantz) root by fermentation with yeast, urea and di-ammonium phosphate. Livestock research for rural development, 28(12). Retrieved from https://www.lrrd.org/lrrd28/12/noup28222.html

Manivanh N And Preston T R 2016b Replacing taro (Colocasia esculenta) silage with protein-enriched cassava root improved the nutritive value of a banana stem (Musa spp.) based diet and supported better growth in local pigs (Moo Laat breed). Livestock research for rural development. Volume 28, Article #97, from http://www.lrrd.org/lrrd28/5/noup28097.html

Manivanh N And Preston T R 2015 Protein-enriched cassava root meal improves the growth performance of moo Lat pigs fed ensiled taro (Colocasia esculenta) foliage and banana stem. Livestock research for rural development. Volume 27, Article #44, from http://www.lrrd.org/lrrd27/3/noup27044.html

Oboh G And Akindahunsi A A 2005 Nutritional and toxicological evaluation of saccharomyces cerevisiae fermented cassava flour. Journal of food composition and analysis, V.18, p.731-738,

Phengsavanh P And Stür W W 2006 The use of stylosanthes as a protein source for growing pigs in smallholder systems in Laos. in W. W. Stür, P M. Horne, J. B. hacker, & P. C. Kerridge (eds.), working with farmers: the key to adoption FF forage technologies (pp. 115-118). Aciar.

Phengsavanh P, Ogle B And Stür W W 2010 Feeding and performance of local pigs under smallholder conditions in northern Laos. Tropical animal health and production, 42 (5), 901-908.

Preston T R 2006 Forages as protein sources for pigs in the tropics. Livestock research for rural development, 18(8). Retrieved from https://www.lrrd.org/lrrd18/8/pres18112.htm

Sangkhom R, Sengsouly P And Preston T R 2017 Effect of rice distillers’ by-product and biochar on growth rate and feed conversion of local yellow cattle fed a diet of ensiled cassava root, urea, and cassava foliage. Livestock research for rural development, 29 (5). Retrieved from https://www.lrrd.org/lrrd29/5/sagkh29094.html

Sengsouly P And Preston T R 2016 Growth performance and methane emissions from local “yellow” cattle fed ensiled cassava root supplemented with rice distillers’ by-product and biochar. Livestock research for rural development, 28 (9). Retrieved from https://www.lrrd.org/lrrd28/9/seng28161.html

Sengxayalth P And Preston T R 2017 Fermentation of cassava (Manihot esculentacrantz) pulp with yeast, urea and di-ammonium phosphate (dap). Livestock research for rural development. volume 29, article #177. Retrieved august 17, 2018, from http://www.lrrd.org/lrrd29/9/pom29177.html

Silivong P And Preston T R 2016 Effect of biochar and rice distillers’ by-product on growth performance and methane emissions in goats fed a basal diet of cassava foliage and ensiled cassava root. Livestock research for rural development, 28(10). Retrieved from https://www.lrrd.org/lrrd28/10/sili28183.html

Sivilai B And Preston T R 2017 A low concentration of rice distillers’ byproduct, or of brewers’ grains, increased diet digestibility and nitrogen retention in native moo lath pigs fed ensiled banana pseudo-stem (Musa spp) and ensiled taro foliage (Colocasia esculenta). Livestock research for rural development. volume 29, article #123. http://www.lrrd.org/lrrd29/6/lert29123.html

Sivilai Bounlerth, Preston T R, Du Thang Hang and Nguyen Quang Linh 2018 Effect of a 4% dietary concentration of rice distillers’ byproduct, or of brewers' grains, on growth rate and feed conversion during pregnancy and lactation of native moo lath gilts and their progeny. Livestock research for rural development. Volume 30, article #20. http://www.lrrd.org/lrrd30/1/lert30020.html

Vanhnasin P, Manivanh N And Preston T R 2016 Effect of fermentation system on protein enrichment of cassava (Manihot esculenta) root. Livestock research for rural development. volume 28, article #175. Retrieved december 18, 2016, from http://www.lrrd.org/lrrd28/10/vanh28175.html

Viengsavanh S, Phengsavanh P And Sihavong P 2021 Reproductive performance of indigenous sows in northern Lao PDR. Archives animal breeding, 64, 365-373.

Sivilai P and Preston T R 2017 Rice distillers’ by-product and biochar as additives to a forage-based diet for growing moo lath pigs. Livestock research for rural development, 29 (8). Retrieved from https://www.lrrd.org/lrrd29/8/sivi29154.html