Reducing the carbon dioxide footprint of goat production with green tea (Camellia sinensis), Jackfruit (Artocarpus heterophyllus) foliage and coconut oil

Nguyen Thi Ngoc Trang¹ and Nguyen Thi Thu Hong^2,3

¹ Faculty of Natural Resources - Environment, Kien Giang University, Vietnam
ntntrang@vnkgu.edu.vn
² An Giang University, An Giang, Vietnam
³ Vietnam National University, Ho Chi Minh City, Vietnam

Abstract

Four growing male goats (14.9±1.0kg) were used in a 4*4 Latin square arrangement to determine feed intake, N retention and rumen methane production on a basal diet of water spinach (Ipomoea aquatica) supplemented with two sources of dietary tannin:Camellia sinensis leaves or Jackfruit (Artocarpus heterophyllus) foliage with or without coconut oil. The treatments had no effect on DM or protein digestibility but increased N retention and reduced methane production. There appeared to be a negative relationship between N retention and the concentration of methane in the rumen gas.

Key words: methane, N retention, tannin, water spinach

Introduction

Climate change seriously affects ecological balance, human health, and sustainable living (Najeh Dali 2008). Methane emissions from ruminant livestock have contributed significantly to this process (Watson 2008).

Tiemann et al (2008) reported that the inclusion of tannin-rich shrub legumes species Callinadra calothyrsus and Fleminga macrophylla in the diet of lambs reduced CH₄ emissions by up to 24%. Tannins are also present in leaves of green tea (Camellia sinensis) and are readily available at tea processing factories in Vietnam. Chu Manh Thang et al (2016) fed different levels of green tea leaves to growing cattle and found that they decreased rumen methane emissions.

In our research, we studied the effects of green tea leaves compared with leaves of another tannin plant Artocarpus heterophyllus as supplements for growing goats fed a basal diet of water spinach, h a plant known to produce high levels of methane when fed to goats (Silivong et al 2013).

Material and methods

Location

The experiment was carried out in the farm of An Giang University from January to June 2019.

Experimental animals, treatments and design

Four growing male goats (14.9±1.0kg) were hired from smallholder goat keepers in the area. The trial was a 2*2 factorial arrangement of four treatments with 4 replications. The experiment was designed with two factors: (i) Camellia sinensis or Jackfruit (Artocarpus heterophyllus) as sources of condensed tannin (at approximately 50g tannin/kg diet DM); and (ii) supplementation with or without coconut oil at 10g/kg DM intake.

Individual treatments were:

WM: Water spinach plus Camellia

WMC: Water spinach plus Camellia with coconut oil

WL: Water spinach plus Jackfruit

WLC: Water spinach plus Jackfruit with coconut oil

Feeds and management

The goats were vaccinated against foot and mouth disease and de-wormed before the start of the experiment. They were individually fed in metabolism cages with free access to water and mineral blocks. New feed was offered daily at 08:00 and 16:00. All treatments included 50g rice bran/day as the carrier for the coconut oil.

Branches of Jackfruit growing in nearby fields were collected every day. Water spinach was grown on plots on the University farm and was harvested after 21 days of regrowth. It was put in the feed trough at an offer level of about 120% of recorded intake. The branches of Jackfruit were tied in bunches suspended above the feed troughs in amounts that would provide approximately 50 g condensed tannin per 1 kg DM intake.

Green tea meal (by-products) was mixed with rice bran.

Photo 1. The goat is feeding on rice bran	Photo 2. Suspending the branches of Jackfruit (Artocarpus heterophyllus) to simulate browsing

Each experimental period lasted 20 days. For the first 10 days in each period, the goats were adapted to the new diets. From 11 to 15 days feces and urine were collected, and feeds offered and refused were recorded. The urine was acidified with 10% H2SO4 to prevent ammonia-N loss. Samples of feces and urine. and of feeds offered and refused were pooled over the 5-day collection period and refrigerated (-18°C) prior to analysis. On the 15th day of each period of the experiment, the carbon dioxide and methane in eructed gases were measured. The gases were collected in the morning by placing the goats in a glass chamber and after a period of 5 minutes for equilibration with the air in the chamber, the concentrations of methane and carbon dioxide were determined using a Greenhouse Gas Analyzer, model number 908 - 0011. There were rest periods of 5 days between experimental periods when the goats were fed only grass.

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 24h; organic matter (OM) by ashing at 550⁰C for 4h; and crude protein (CP) by Kjeldahl technique. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were analyzed using the method of Van Soest and Robertson (1985). The condensed tannin content of feeds was determined by the Lowenthal method (AOAC 1936). Protein solubility was determined by the method described by Whitelaw and Preston (1963).

Statistical analysis

The data were analyzed using the general linear model in the ANOVA program of the Minitab software release 16.20. Sources of variation in the model were: source of supplementary foliage (Camellia and Jackfruit), supplementation with coconut oil, interaction foliage*coconut oil, animals, periods, and error.

Results and discussion

Condensed tannin was 20% higher in leaves of Camellia than in leaves of Jackfruit (Table 1). There was no tannin in water spinach. NDF was higher in Jackfruit than in Camellia leaves The solubility of the protein was high in the water spinach and low in the jackfruit leaves.

DM intake and DM digestibility were not affected by the source of tannin nor by supplementation with coconut oil (Table 2). N retention tended to be higher (p=0.09) for supplementation with green tea leaves compared with Jackfruit leaves but was not affected by the addition of coconut oil (Table 2).

The methane: carbon dioxide ratio in expired gas was lower when green tea was the supplement compared with Jackfruit and can be assumed to be lower than in the basal diet of water spinach for which methane emissions are known to be very high (Preston et al 2019; Sengsouly et al 2016). The high solubility of the protein in the water spinach (78%) has also been shown to be directly related to the comment of methane in expired gas (Do H Q et al 2013).

Discussion

Production of methane in the rumen involves a reduction in the nutritive value of the diet (Johnston and Johnston 1995) as methanogens compete for hydrogen in the rumen fermentation with reduced production of propionic acid an important precursor of glucose in the ruminant animal.

A trend was observed in the present experiment for N retention to be decreased as the as methane: carbon dioxide ratio in rumen gas was increased (Figure 1).

Figure 1. Relation ship between N retention and methane:carbon dioxide ratio in the expired breath of the goats

Tavendale et al (2005) suggested two modes of action of tannins on methanogens: directly affecting activity or population of methanogens, resulting in lower methane emission, and indirectly by reduced hydrogen production by lowering feed degradation.

Conclusions

• The present study shows that supplemented tannin-rich meals in diets of growing goats increase CP digestibility and N retention. Supplementing the diets with coconut oil led to a reduction in rumen methane but had no effect on performance traits.

References

AOAC 1936 Official and Tentative Methods of Analysis, 4th ed. p. 196.

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

Chu Manh Thang, Nguyen Đinh Tuong and Tran Hiep 2016 Effects of supplementation of tannin from green tea meal (Camellia sinensis) in the diet for growing cattle on animal productivity and enteric methane production. Journal of Animal Science and technology. Vol 63: 68-76.

Do H Q, Khoa T D, Hao T P and Preston T R 2013 Methane production in an in vitro rumen incubation is lower for leaves with low compared with high protein solubility. Livestock Research for Rural Development. Volume 25, Article #134. Retrieved August 5, 2021, from http://www.lrrd.org/lrrd25/7/hqdo25134.htm

Johnson K A and Johnson D E 1995 Methane emissions from cattle. Journal of Animal Science, vol. 73, 1995, p. 2483–2492.

Minitab 2010 Minitab reference manual release 16.20. Minitab Inc.

Najeh Dali 2008 Principal guidelines for a National Climate Change Strategy: Adaptation, mitigation and international solidarity. Pp:1-5. In Proceedings of International Conference on Livestock and Global climate Change, 2008, Editors: P Rowlinson, M Steele and A Nefzaoui,17-20 May, 2008, Hammamet, Tunisia Cambridge Univesity press, May, 2008

Preston T R, Silivong P and Leng R A 2019 Methane production in rumen in vitro incubations of ensiled cassava (Manihot esculenta Cranz) root supplemented with urea and protein-rich leaves from grasses, legumes and shrubs. Livestock Research for Rural Development. Volume 31, Article #112. http://www.lrrd.org/lrrd31/7/silv31112.html

Sengsouly P, Preston T R and Leng R A 2016 Effect of water spinach (Ipomoea aquatica) and cassava leaf meal (Manihot esculenta Crantz) with or without biochar on methane production in an in vitro rumen incubation using ensiled or dried cassava root meal as source of carbohydrate. Livestock Research for Rural Development. Volume 28, Article #112. Retrieved August 5, 2021, from http://www.lrrd.org/lrrd28/6/seng28112.htm

Silivong P, Onphachanh X, Ounalom A and Preston T R 2013 Methane production in an in vitro rumen incubation is reduced when leaves from Mimosa pigra are the protein source compared with Gliricidia sepium. Livestock Research for Rural Development. Volume 25, Article #131. Retrieved August 5, 2021, from http://www.lrrd.org/lrrd25/7/sili25131.htm

Tavendale M H, Meagher L P, Pacheco D, Walker N, Attwood G T and Sivakumaran S 2005 Methane production from in vitro rumen incubations with Lotus pedunculatus and Medicago sativa, and effects of extractable condensed tanin fractions on methanogenesis. Animal Feed Science and Technology, Vol 123-124: 403-419

Tiemann T T, Lascano C E, Wettstein H R, Mayer A C, Kreuzer M and Hess H D 2008 Effect of the tropical tannin-rich shrub legumes Calliandra calothyrsus and Flemingia macrophylla on methane emission and nitrogen and energy balance in growing lambs. Animal 2: 790–799

Van Soest P J and Robertson J B 1985 Analysis of forages and fibrous foods. Ithaca: Cornell University. 202p.

Watson R 2008 Climate Change: An environmental, development and security issue. Pp: 6-7. In Proceedings of International Conference on Livestock and Global climate Change, 2008 , Editors: P Rowlinson, M Steele and A Nefzaoui,17-20 May, 2008, Hammamet, Tunisia Cambridge Univesity press, May, 2008

Whitelaw F G and Preston T R 1963 The nutrition of the early-weaned calf. III. Protein solubility and amino acid composition as factors affecting protein utilization. Animal Science Volume 5, pp 131-145 DOI: https://doi.org/10.1017/S0003356100033882