Citation of this paper

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

Nguyen Van Thu, T R Preston¹ and R Leng²

Dept. of Animal Science, College of Agriculture, Can Tho University
nvthu@ctu.edu.vn
¹ Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria (CIPAV), Cali, Colombia
² University of New England, Armidale, NSW, Australia

Abstract

A feeding trial with growing cattle was carried out to test the hypothesis that a supplement of yeast-fermented rice – as a proven source of Beta-glucan – would stimulate the rumen microbiota to increase the production of propionic acid as an alternative to methane as an electron sink for hydrogen.

Five Ongle cattle were fed ad libitum elephant grass and restricted protein supplement in a 5*5 Latin square design in which the treatments were 5 levels of yeast fermented rice (YFR) of 0, 1.5, 3, 4.5 and 6%. The experimental periods were of 14 days with measurements over the last seven days of each period.

The YFR increased the proportion of propionic acid in the rumen VFA, decreased emissions of methane and improved growth and feed conversion

All the reported responses to YFR supplementation showed curvilinear trends with optimum values recorded when the YFR was between 3 and 4% of the diet dry matter.

Key words: climate change, greenhouses, rumen, Saccharomyces cerevisiae

Introduction

The series of events that lead to the design of this experiment were:

Brewers’ spent grains fed to growing cattle at 4% of the diet reduced the toxicity caused by feeding foliage from a bitter variety of cassava (Binh et al 2014);
The byproduct from the yeast fermentation of polished ice to make “rice wine”, improved the liveweight gain and feed conversion of growing cattle increased the proportion of propionic acid in the rumen VFA and reduced the emissions of methane (Sangkhom et al (2018), and;
The total product of the yeast fermentation of polished rice was as efficient as the rice wine byproduct in reducing methane in vitro rumen incubation (Sangkhom et al (2018).

Materials and methods

Experimental design

The objective of the experiment was to show that supplementing the diet of growing cattle with yeast fermented rice (YFR) would: (i) modify the rumen fermentation to favor formation of propionic acid rather than methane: , and that (ii) such changes would result in improved live weight gain and feed conversion of growing cattle.

The experiment was arranged as a 5x5 Latin square with five male Ongle cattle of 279 ± 9.0 kg. The treatments were five levels (0, 1.5, 3.0, 4.5 and 6.0 % (based on DM) of yeast-fermented rice (YFR).

Preparation of yeast fermented rice

Broken rice was soaked in water (80% rice; 20% water) for 30 minutes. Yeast (Saccharomyces cerevisiae) was added (0.5% of the soaked rice) and the mixture enclosed in a plastic bag for anaerobic fermentation during three days.

Feeding procedure

Elephant grass was fed ad libitum, The protein-rich supplement (37.7% CP) was fed at 240 g DM/100kgLW. The protein supplement included soybean meal rice bran and broken rice. The YFR was mixed with the protein supplement before feeding. Drinking water was always available.

Measurements

The experimental period was 14 days with 7 days for adaptation and then 7 days for takking sampled of rumen fluid and recording enissions of methane and carbon dioxide inexpired gases. During the 7 days collection period, feeds offered and refused, were recorded and samples taken for analysis. Rumen fluid was collected using an esophagus tube before and 3 hours post feeding, Smples were weighed ad pooled over ‘day collection period. Rumen ammonia was measured by the Kjeldahl method. VFAs analysis was done by Gas-liquid chromatography according to Pirondini (2012). Methane and carbon dioxide concentrations in expired gas were recorded using a ventilated hood in which the heads of the animal were enclosed. Concentrations of methane and carbon dioxide in the expired gasses were measured with an infrared gas analyzer (Model IR200, Style S3; YOKOGAWA, Japan (Sakai 2016).

Photo 1. Male Ongle cattle in ventilated hoods for measuring GHG emissions

Chemical analysis

Proximate analysis of feeds (Table 1) was done according to AOAC (2000) procedures. NDF was determined by the methods of Van Soest et al (1991).

Table 1. Chemical compositions of feeds in the experiment (as % in DM except for DM which is on air-dry basis)
Feeds	DM	OM	CP	NDF	EE	Ash

Elephant Grass	13.6	89.5	9.06	70.1	2.45	10.5
SBM^#	87.5	90.7	37.7	38.6	7.15	9.35
Broken rice (BR)	88.1	91.0	8.80	13.0	1.48	9.0
YFR	70.2	92.0	8.90	13.2	1.64	8.0
^#Contained 91 SBM and 99% broken rice

Statistical analysis

The recorded data were analysed using the ANOVA software of Minitab Reference Manual Release16.0 (Minitab 2016). Microsoft Office (Excel) software was used to calculate Polynomial relationships between inputs (treatments) and outputs (recorded data).

Results and discussion

Feed intake

Supplementation no effect on feed intake (Table 2).

Table 2. Feeds and nutrients intakes of Ongle cattle in different treatments of the experiment
Item	YFR, % in the diet					SEM	p
Item	0	1.5	3	4.5	6	SEM	p

Elep. grass, kg	3.94	3.9	3.85	3.97	3.88	0.91	0.39
Concentrate, kg	0.74	0.74	0.74	0.74	0.74	0.01	0.91
Broken rice, kg	0.30	0.21	0.14	0.08	0	0.02	0.00
YFR, kg	0	0.07	0.14	0.22	0.29	0.01	0.00
CP, kg	0.66	0.66	0.65	0.67	0.68	0.00	0.42
EE, kg	0.15	0.16	0.17	0.18	0.19	0.00	0.02
NDF, kg	3.08	3.06	3.01	3.11	3.05	0.03	0.34
Ash, kg	0.51	0.5	0.51	0.51	0.51	0.01	0.28

Live weight gain and feed conversion

There are two ways in which a supplement (eg. YFR) may affect growth rate and feed conversion in ruminants. One way is for the supplement to increase feed intake thus more nutrients are available for production relative to maintenance. The other way is when feed intake is not affected but when the supplement improves the balance of nutrients available for productive purposes.

In the present experiment the feeding of YFR did not affect feed intake (Table 2) but improved liveweight gain and feed conversion (Figures 1 and 2). Thus, it can be assumed that in the present experiment the effect of YFR was to change the balance of nutrients available for productive purposes (eg. an improvement in live weight gain and feet conversion. (Table 3, Figures 1 and 2).

Table 3. The live weight and daily weight gain of the cattle in the experiment
Item	YFR, % in the diet					SEM	p
Item	0	1.5	3	4.5	6	SEM	p

DM intake, kg/d	4.98	5.02	4.87	5.04	4.95	0.06	0.25
Initial LW, kg	304	300	299	302	304	2.21	0.38
Final LW, kg	310	311	308	315	312	2.02	0.20
DWG, kg	0.50	0.79	0.64	0.93	0.57	0.25	0.11
FCR	9.96^a	6.39^ab	7.57^ab	5.43^b	8.67^ab	0.78	0.01


Figure 1. Effect of YFR on liveweight gain	Figure 2. Effect of YFR on Feed conversion

Figure 3. Effect of YFR on methane production

Rumen function

Supplementing the diet with YFR had no effect on rumen pH, ammonia and total VFA (Table 4). However, the proportion of propionic acid increase as YFR was increased from 0 to 3% of the diet DM (Table 4; Figure 4).

Table 4. Mean values in rumen fluid of pH, ammonia and volatile fatty acids according to levels of YFR in the diet
Item	YFR, % in the diet					± SE	p
Item	0	1.5	3	4.5	6	± SE	p

pH_0h	6.98	6.92	6.98	6.94	6.97	0.07	0.96
pH_3h	6.72	6.73	6.76	6.75	6.72	0.05	0.59
N-NH3_0h, mg/100 ml	16.4	16.1	15.4	15.0	15.0	0.97	0.78
N-NH3_3h, mg/100 ml	19.9	19.6	18.5	19.9	19.2	0.81	0.72
TVFA_0h, mM	80.0	81.3	79.1	82.1	79.6	2.09	0.84
TVFA_3h, mM	88.9	95	94.7	93.9	91	1.84	0.06
Acetic acid, mM	60.1	62.6	64.0	63.5	62.6	1.53	0.44
Propionic acid, mM	13.9^b	15.3^ab	16.9^ab	16.6^ab	16.5^ab	0.63	0.03
Butyric acid, mM	9.55	9.44	9.67	9.65	9.66	0.24	0.84

Table 5. Effect of dietary concentration of YFR on production of methane and carbon dioxide and on the ratios of the two gases
Item	YFR, % in the diet					SE	p
Item	0	1.5	3	4.5	6	SE	p

CH₄, L/d	170	151	138	140	160	10.5	0.21
CO₂, L/d	1863	1765	1733	1703	1803	51.2	0.40
CH4/CO₂	0.09	0.09	0.08	0.08	0.09	0.00	0.07


Figure 4. Effect of YFR on the cocentration of propionic acid in the rumen VFA	Figure 5. The inverse relationship between the proportion of propionic acid in the rumen VFA and the production of methane in the rumen

Conclusions

Supplementing the diet of growing cattle with yeast-fermented rice increased the proportion of propionic acid in the rumen VFA, decreased emissions of methane and improved growth and feed conversion.
All the reported responses to YFR supplementation showed curvilinear trends with optimum values recorded when the YFR was between 3 and 4% of the diet dry matter.

References

AOAC 2000 Official methods of Analysis of AOAC International. 17^th edition. AOAC International. Gaithersburg, Maryland, USA. Vol 1, Chapter 5, pp. 5-15.

Bhatta R, Enishi O and Kurihara M 2007 Measurement of methane production from ruminants.Asian-Australasian Journal of Animal Sciences, 20(8), pp. 1305-1318.

Binh P L T, Preston T R, Duong K N and Leng R A 2017 A low concentration (4% in diet dry matter) of brewers’ grains improves the growth rate and reduces thiocyanate excretion of cattle fed cassava pulp-urea and “bitter” cassava foliage. Livestock Research for Rural Development. Volume 29, Article #104. http://www.lrrd.org/lrrd29/5/phuo29104.html

Inthapanya S, Preston T R, Phung L D and Ngoan L D 2017 Effect of supplements of yeast (Saccharomyces cerevisiae), rice distillers’ by-product and fermented cassava root on methane production in an in vitro rumen incubation of ensiled cassava root, urea and cassava leaf meal. Livestock Research for Rural Development. Volume 29, Article #220. http://www.lrrd.org/lrrd29/12/sang29220.html

Minitab 2016 Minitab reference manual release 16.1.0 Minitab Inc.

Pirondini M, Malagutti L, Colombini S, Amodeo P and Crovetto G M 2012 Methane yield from dry and lactating cows diets in the Po Plain (Italy) using an in vitro gas production technique. Ital. J. Anim. Sci. 11:330–335

Sakai T, Tran Kim Chi, Nguyen Van Thu, Suzuki T, Hayshi K and Higuchi K 2016 Ventilated Hood System for Measurements of Enteric Methane Emissions in Vietnam. Working Paper · March 2016. DOI: 10.13140/RG.2.2.34692.9408. https://www.researchgate.net/publication/317002110

Sangkhom I, Preston T R, Leng R A, Ngoan L D and Phung L D 2017 Rice distillers’ byproduct improved growth performance and reduced enteric methane from “Yellow” cattle fed a fattening diet based on cassava root and foliage (Manihot esculenta Cranz). Livestock Research for Rural Development. Volume 29, Article #131. http://www.lrrd.org/lrrd29/7/sang29131.html

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for dietary fiber, neutral detergent fiber and non-starch polysaccharides in relation to animal nutrition J. Dairy Sci. 74, pp. 3583 – 3598.