Citation of this paper

Potential nutritive value and anti-methanogenic potential of some fallen tree leaves in Turkey

Adem Kamalak and Cagri Ozgur Ozkan

Department of Animal Science, Faculty of Agriculture, University of Kahramanmaras Sutcu Imam, Kahramanmaras, Turkey
akamalak@ksu.edu.tr

Abstrac

The aim of the current experiment was to determine the potential nutritive value and anti-methanogenic potential of some fallen tree leaves used for small ruminant animals in Turkey.

Species had a significant effect on the chemical composition, in vitro gas production and methane (CH₄) production of fallen tree leaves. The crude protein (CP) contents of fallen tree leaves ranged from 2.9 to 7.9%. The CP contents of Aesculus hippocastanum and Ficus carica leaves were significantly higher than those of other tree plants. The neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents of fallen tree leaves ranged from 26.7 to 54.8% and 16.4 to 30.3% respectively. The NDF and ADF contents of Aesculus hippocastanum and Platanus orientalis were significantly higher than the other tree leaves. The condensed tannin (CT) contents ranged from 1.0 to 19.0 %. The CT contents of Platanus orientalis and Aesculus hippocastanum were significantly higher the other tree leaves. The CP contents of fallen tree leaves except for Aesculus hippocastanum are not sufficient to meet minimum level of protein requirement. Therefore protein supplementation is required for optimum rumen function and feed intake in ruminant animals when large amount of fallen tree leaves were included into ruminant diets. However due to high CT content, Aesculus hippocastanum, Rhus coriaria and Platanus orientalis leaves might be used as a feed additive in ruminant diets to decrease the enteric CH ₄ production. However it should be tested in vivo before large implication.

Key words: chemical composition, fallen tree leaves, gas production, methane, nutritive value

Introduction

Small ruminant animals in the most parts of developing countries meet their requirement from shrub and tree leaves. Potential nutritive value and anti-methanogenic potential of tree leaves have been evaluated for small ruminant animals using the chemical composition and in vitro gas production technique. (Karabulut 2006; Kamalak 2006; Karabulut et al 2007; Kamalak et al 2010; Temel and Tan 2011; Kaya and Kamalak 2012, Guven 2012). Recently considerable amount of research has been diverted into determination of potential nutritive value of fallen or senescent tree leaves for ruminant animals (Sanon et al 2005; Kamalak et al. 2010; Mishra et al 2013, Kaya et al. 2016). However there is limited information on potential nutritive value and anti-methanogenic potential of some fallen leaves of tree grown in Turkey. Therefore the aim of the current experiment was to determine potential nutritive value and anti-methanogenic potential of some fallen tree leaves using the chemical composition and in vitro gas production technique.

Materials and methods

Fallen Tree leaves

Fallen leaves from Ficus carica, Paulownia tomentosa, Aesculus hippocastanum, Rhus coriaria, Platanus orientalis, Morus albus were collected in December, 2020 by hand from at least 10 different trees in Kahramanmaras, Turkey.

Chemical analysis

Fallen tree leave samples were pooled and dried at 65 ^oC using a forced air oven. Dry leaves were ground using a laboratory mill with 1 mm screen size for subsequent analysis. Dry matter (DM) of leave samples was determined by drying the samples at 105 ^oC overnight and ash by igniting the samples in muffle furnace at 525 ^oCfor 8 h. Nitrogen (N) content of leaves was measured by the Kjeldahl method (AOAC, 1990). Crude protein content of leaves was calculated as N X 6.25. Ether extract contents of leaves were determined according to AOAC (1990). Cell wall contents (NDF, and ADF) were determined by the method of Van Soest et al (1991). Condensed tannin contents of samples were determined by butanol-HCl method as described by Makkar et al (1995). All chemical analyses of samples were carried out in triplicate.

In vitro gas and methane production

Approximately 0.200 gram fallen leave samples were incubated with buffered rumen fluid for 24 h in a water bath at 39 ^oC in triplicate using the methods of Menke et al (1979). Rumen fluid was obtained from three fistulated sheep fed twice daily with a diet containing alfalfa hay (60 %) and concentrate (40 %). Net gas productions of samples were determined at 24 h after incubation and corrected for blank and hay standard (University of Hohenheim, Germany).

Methane contents (%) of total gas produced at 24 h fermentation of leave samples were measured using an infrared methane analyzer (Sensor Europe GmbH, Erkrath, Germany) (Goel et al 2008). After measuring gas produced at 24 h incubation, gas samples was transferred into inlet of the infrared methane analyzer with the plastics syringe. The infrared methane analyzer displays methane as percent of total gas. Methane production (mL) was calculated as follows.

Methane production (mL) = Total gas production (mL) X Percentage of Methane (%)

Statistical analysis

One-way analysis of variance (ANOVA) was used to determine the effect of species on the chemical composition, metabolisable energy, organic matter digestibility, gas and methane production of fallen tree leaves. Significance between individual means was identified using the Tukey’s multiple range tests. Mean differences were considered significant at p<0.05.

Result and discussion

Effect of species on the chemical composition of fallen leaves

Effect of species on the chemical composition of fallen leaves is presented in Table 1. Species had a significant effect on the chemical composition of fallen leaves. The crude ash contents of Morus albus and Ficus carica leaves were significantly higher than those of other tree plants. The CP contents of fallen tree leaves ranged from 2.9 to 7.9%. The CP contents of Aesculus hippocastanum and Ficus carica leaves were significantly higher than those of other tree plants. Van Soest (1994) suggested that CP content browse species should be higher than the minimum level of 7-8% of DM for optimum rumen function and feed intake in ruminant animals. In the current study The CP contents of fallen tree leaves except for Aesculus hippocastanum is not sufficient to meet minimum level of CP requirement. Therefore protein supplementation is required for optimum rumen function and feed intake in ruminant animals when large amount of fallen tree leaves were included into ruminant diets. The EE contents ranged from 4.6 to 12.9 %. The EE contents of Rhus coriaria and Morus albus were significantly higher the other tree leaves. There are significant variations among fallen tree leaves in terms of cell wall contents. The NDF and ADF contents ranged from 26.7 to 54.8% and 16.41 to 30.34% respectively. The NDF and ADF contents of Aesculus hippocastanum and Platanus orientalis were significantly higher than the other tree leaves. The CT contents ranged from 1.0 to 19.0 %. The CT contents of Platanus orientalis and Aesculus hippocastanum were significantly higher the other tree leaves. Even if CP content of leaves of Aesculus hippocastanum is higher than the minimum level of 7-8% of DM for optimum rumen function and feed intake in ruminant animals, CT content of Aesculus hippocastanum is very high. The high level of CT in Aesculus hippocastanum leaves may hamper the protein utilization.

Table 1. Effect of species on the chemical composition of some fallen leaves (n=3)
Tree species	DM	CA	CP	EE	NDF	ADF	CT

Aesculus hippocastanum	90.4^b	12.2^c	7.9^a	8.5^c	54.8^a	30.3^a	16.6^a
Ficus carica	86.4^d	19.3^b	6.2_b	4.5^e	28.9^d	16.2^c	1.0^b
Paulownia tomentosa	89.0^c	11.0^d	5.3^c	7.9^d	32.7^c	23.4^b	1.5^b
Platanus orientalis	91.7^a	9.2^e	4.5^d	4.6^e	47.8^b	32.8^a	19.0^a
Morus albus	91.3^a	21.5^a	4.5^d	11.5^b	39.1^c	16.2^c	1.1^b
Rhus coriaria	91.1^ab	9.4^e	2.9^e	12.9^a	26.7^d	16.4^c	1.8^b
SEM	0.227	0.202	0.201	0.103	2.000	0.817	0.791
Prob.	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
^abc Column means with common superscripts do not differ (p>0.05); SEM: Standard error mean DM: Dry matter (%), CA: Crude ash (%), CP: Crude protein (%), NDF: Neutral detergent fiber (%), ADF: Acid detergent fiber (%), EE: Ether extract (%), CT: Condensed tannin (%)

Effect of species on in vitro gas production and methane production of fallen tree leaves

The effect of species on in vitro gas and CH₄ productions of fallen tree leaves is given in Table 2. Species had a significant effect in vitro gas and CH₄ productions of fallen tree leaves. The gas and methane production ranged from 17.2 to 38.2 ml and 1.9 to 2.3 ml respectively. The gas and methane productions of fallen tree leaves of Platanus orientalis and Aesculus hippocastanum were significantly lower than the other tree species. The percentage of methane in total gas ranged from 10.4 to 14.8 %. The percentage of methane from leaves of Aesculus hippocastanum , Rhus coriaria and Platanus orientalis were significantly lower than the other tree species.

Table 2. The effect of species on in vitro gas production, methane production, metabolisable energy and organic matter digestibility of fallen tree leaves (n=3)
Tree species	Gas(ml)	CH₄(ml)	CH₄(%)

Rhus coriaria	30.1^b	3.1^b	10.4^b
Platanus orientalis	17.2^d	1.9^c	11.2^b
Aesculus hippocastanum	20.0^c	2.3^c	11.5^b
Morus albus	37.5^a	5.3^a	14.1^a
Ficus carica	38.2^a	5.6^a	14.6^a
Paulownia tomentosa	37.8^a	5.6^a	14.8^a
SEM	0.533	0.178	0.584
p	<0.001	<0.001	<0.001
^abc Column means with common superscripts do not differ (P>0.05); SEM: Standard error mean

Figure 1. Tree species listed according to methane production after 24h incubation with rumen fluid

Gas production is reported to be negatively correlated with cell wall contents of diets (Kamalak 2006; Karabulut et al 2007; Kamalak et al 2010). This was also the case in the present experiment (Figure 2 and 3).

Figure 2. Relationship between NDF contents of tree leaves and gas production

Figure 3. Relationship between ADF contents of tree leaves and gas production

Gas and methane production are reported to be negatively correlated with condensed tannin content of diets (Singleton 1981; Silanikove et al 1996; Waghorn 2008). This was also the case in the present experiment (Figure 4 and 5).

Figure 4. Relationship between condensed tannin contents of tree leaves and gas production

Figure 5. Relationship between condensed tannin contents of tree leaves and methane production

Lopez et al (2010) suggested that CH₄ percentage of total gas produced after 24 hour fermentation can be used to determine the anti-methanogenic potential of any feedstuffs and the feedstuffs can be classified in three groups, low anti-methanogenic potential (% methane in gas between >11% and ≤14%), moderate anti-methanogenic potential (% methane in gas between >6% and <11%), high anti-methanogenic potential (% methane in gas between >0% and <6%). Therefore it seems to be likely that Aesculus hippocastanum, Rhus coriaria and Platanus orientalis leaves had low methane reduction potential since the percentages of methane for leaves are between >11% and ≤14%.

Conclusions

Species had a significant effect on chemical composition, in vitro gas and methane production of fallen tree leaves.
The CP contents of fallen tree leaves except for Aesculus hippocastanum are not sufficient to meet minimum level of protein requirement.
Protein supplementation is required for optimum rumen function and feed intake in ruminant animals when large amount of fallen tree leaves were included into ruminant diets.
Due to high CT content, Aesculus hippocastanum, Rhus coriaria and Platanus orientalis leaves might be used as a feed additive in ruminant diets to decrease the enteric CH₄ production. However it should be tested in vivo before large implication.

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