Effects of supplementing yeast-fermented broken rice in diets on digestibility and nitrogen balance of crossbred wild growing pigs

Nguyen Thi Thu Hong^1,2, Nguyen Thi Ngoc Trang³ and Thomas R Preston⁴

¹ An Giang University, An Giang, Vietnam
ntthong@agu.edu.vn
² Vietnam National University Ho Chi Minh City, Vietnam
³ Faculty of Natural Resources - Environment, Kien Giang University, Vietnam
⁴ Fundación CIPAV Cali, Colombia

Abstract

Yeast-fermented broken rice (YFBR) was fed to growing pigs at: 0, 2,4, 6 and 8% (DM basis) of a forage-based diet. The pigs were hybrids (Wild boar*Large White) with initial live-weight of 11.0±0.7kg.

The YFBR increased the biological value of the dietary protein as reflected in the retention of nitrogen and the improved biological value of the protein with positive implications for the nutritive value of the diet.

Keywords: climate change, feed intake, indigenous breeds, Saccharomyces cerevisiae

Introduction

Improved rates of growth and better feed conversion have been reported in cattle (Nguyen Van Thu et al 2022), goats (Nguyen Thi Thu Hong et al 2023) and broiler chickens (Nguyen Thuy Linh et al 2021) when their diets were supplemented with polished rice which had been fermented (YFR) with yeast (Saccharomyces cerevisiae).

A rumen in vitro study of a forage-based diet showed that supplementation with YFR stimulated the formation of propionic acid with reduced emissions of methane (Phuong et al 2023).

The following experiment was conducted to determine the effect of YFR on the digestibility and nitrogen retention of a forage-based diet fed to hybrid pigs (Wild Boar x Large White).

Materials and methods

Location

The experiment was conducted from April to August 2024, on an experimental farm of An Giang University in Long Xuyen city, An Giang province.

Design and treatments

Five castrated male pigs used in this experiment were the product of cross-breeding Large-White females with “Wild Boar” males. They were from a private farm in An Giang province. The average body weight was 11.0±0.7kg. The pigs were vaccinated against hog cholera and foot and mouth disease and were treated for roundworms before starting the experiment. They were fed a forage-based diet according to a 5*5 Latin square design with five levels of YFBR: 0, 2, 4, 6 and 8% in DM (Table 1).

Preparing YFBR

Broken rice was soaked in water (1kg broken rice; 1.0 liter water) for 5 hours and wet-milled in a blender. Yeast (Saccharomyces cerevisiae) was added at 3% (DM basis) and the mixture was enclosed in a plastic bag for anaerobic fermentation for three days.

Measurements and chemical analysis

The pigs were weighed in the morning, before being fed, at the beginning of the trial and after each period of 15 days. From 11 to 15 days, feces and urine were collected, and feeds offered and refused were recorded.

Samples of feeds refused and feces were pooled over the 5-day collection period. Samples were dried in a forced-air oven at 60°C for 48 hours and then ground to pass a 1 mm screen and refrigerated at -18°C prior to analysis. Feces were collected every day and were kept frozen in plastic bags until analysis. A representative sample (10% of total amount voided) was obtained from every animal. The urine was acidified with 10% H₂SO ₄ to prevent ammonia-N loss.

The samples of feed offered and refused and of feces were analyzed by AOAC (1990) methods for: dry matter (DM) by drying at 105⁰C for 24 hours; organic matter (OM) by ashing at 550⁰C for 4h; and crude protein (CP) by the Kjeldahl technique.

Statistical analysis

The data were analyzed by the general linear model in the Minitab software (Minitab 2010). Sources of variation were: treatments, repetitions and error.

Results and discussion

The fermentation of broken rice with yeast resulted in an increase in crude protein content from 8.64% to 9.94% in DM (Table 2)

There was a linear increase in nitrogen retained as the level of yeast-fermented broken rice in the diet was increased (Table 3 and Figure 1). Further support for the positive effect of YFBR on nitrogen metabolism is shown in Figure 2.

Figure 1. Effect of YFBR on N retention	Figure 2. Relationship between YFBR and N retention as percent of digested N

There is no obvious explanation for why incorporation of yeast-fermented rice in a diet fed to pigs should increase the nitrogen retention and specifically the biological value of the retained nitrogen.

The only model that appears to be relevant is that part of the excreted fecal material is recycled in the cecum. This process takes place in rabbits and has been shown to result in improved growth rates (Pok Samkol et al 2006), as it improves the biological value of the ingested protein. The assumption is that the contents of this part of the digestive tract are richer in protein as a response to bacterial action in the cecum. However, this explanation implies some form of recycling of cecal contents, but this would appear to be difficult for pigs confined individually in metabolism cages.

The results show that the inclusion of YFBR in the diet had a positive effect on N retention (Table 3 and Figure 1). Nitrogen retention as a percentage of nitrogen digested, which indicates the biological value of the protein, increased with YFBR inclusion (Figure 2).

The results show that the inclusion of YFBR in the diet has a positive effect on the digestion and retention of dietary protein, with significant improvements in CP digestibility and biological value of protein. This enhanced YFBR utilization is supported by the results of Nguyen Thuy Linh et al (2021), which demonstrated a positive curvilinear response in growth rate and feed conversion efficiency in broiler chicken, achieving a 20% improvement over the control with 4% YFBR in the diet.

Similar results were reported by Tran Trung Tuan et al (2023) when they supplemented broiler chickens with yeast-fermented cassava root, which supported similar growth responses to yeast-fermented rice.

This indicates that incorporating yeast-fermented broken rice into the diet at levels up to 8% has a positive impact on the nutrition of pigs, supporting an increase in nitrogen retention and therefore improved growth rates of the pigs.

Conclusions

Including yeast-fermented broken rice at levels of up to 8% of a forage-based diet fed to growing pigs had a positive effect on the biological value of the protein as reflected in the increased retention of nitrogen as a percentage of nitrogen digested, and the improved biological value of the protein with positive implications for the nutritive value of the diet.

Acknowledgements

This research is funded by An Giang University (AGU), Vietnam National University HoChiMinh City (VNU-HCM) under grant number 24.03.NN

References

AOAC 1990 Official Methods of Analysis, 15 ^th edition. Association of the Official Analytical Chemists, Washington D.C.

Minitab 2010 Minitab Reference Manual, Release 16.1 for WindoT. Minitab Inc., USA.

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Nguyen Thi Thu Hong, Nguyen Thi Ngoc Trang and Le Tran Minh Hieu 2023 Effects of a supplement of yeast-fermented broken rice on nitrogen retention and methane emissions in growing goats fed Para grass (Brachiaria mutica). Livestock Research for Rural Development. Volume 35, Article #47. http://www.lrrd.org/lrrd35/5/3547hong.html

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Nguyen Van Thu, Preston T R and Leng R 2022 Supplementing the diet of growing cattle with yeast-fermented rice (YFR) increased the production of rumen propionate, decreased emissions of methane and improved growth and feed conversion. Livestock Research for Rural Development. Volume 34, Article #113. Retrieved August 4, 2024, from http://www.lrrd.org/lrrd34/12/34113thuv.html

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