Chemical composition and in vitro gas production characteristics of several tannin containing tree leaves

A Kamalak, O Canbolat*, Y Gurbuz, O Ozay, C O Ozkan and M Sakarya

Kahramanmaras Sutcu Imam University, Faculty of Agriculture, Department of Animal Nutrition, Kahrmanmaras, Turkey.
^*Bursa Uludag University, Faculty of Agriculture, Department of Animal Nutrition, Bursa, Turkey.
akamalak@ksu.edu.tr

Abstract

The aim of the present work was to determine the chemical composition including condensed tannin contents of leaves of some trees used for small ruminant animals in Turkey, and examine their relationships with in vitro gas production parameters.

Crude protein content ranged from 5.62 to 14.1 %, with Morus alba having the highest content. The content of neutral (NDF) and acid detergent fiber (ADF) ranged from 42.3 to 56.9% and 28.3 to 34.2 % respectively. The NDF content of Juniperus communis was significantly higher than the others. The ash content ranged from 4.99 to 15.8 % with Morus alba having highest ash. Total condensed tannin (TCT) content of tree leaves ranged from 1.42 to 21.3% with Juniperus communis having the highest TCT, most of which was in the soluble form. Gas production at 96 h incubation for leaves of Quercus libari was significantly higher than the others. The rank order in terms of potential gas production was Quercus libari ≥ Populus nigra ≥ Morus alba > Juniperus communis. There was no significant difference among tree leaves in terms of the rate of gas production from insoluble but fermentable fraction. The gas volume of Quercus libari obtained from soluble fraction was significantly higher than the other tree species. The gas production from the insoluble but degradable fraction was significantly higher for Quercus libari than the other tree leaves whereas the potential gas production of Quercus libari was significantly higher than those of Morus alba and Juniperus communis. Total and soluble condensed tannins, NDF and ADF were negatively correlated with estimated parameters of gas production.

Key Words:Tree leaves, chemical composition, condensed tannin, in vitro gas production

Introduction

Tree and shrub leaves have the potential for alleviating some of the feed shortages and nutritional deficiencies experienced in the dry season on smallholder farms. Tree leaves are an important component of goats and sheep diets (Holecheck 1984; Papachristou and Nastis 1996) and play an important role in the nutrition of grazing animals in areas where few or no alternatives are available (Meuret et al 1990). However the use of tree and shrub leaves by herbivores is restricted by defending or deterring mechanisms related to high tannin content (Provenza 1995).

Although tree and shrub leaves are important sources of forage for small ruminants in most parts of Turkey during the critical periods of year when quality and quantity of pasture herbages are limited, there is little information on the nutritive value of tree and shrub leaves.

In vitro estimations of feed degradation are important tools for ruminant nutritionists. These methods measure either substrate disappearance or fermentation products (Blümmel et al 1997). It has been suggested that the gas production technique is more reliable than the nylon bag method for determining nutritive value of feeds containing anti-nutritive factors (Khazaal et al 1993). Gas production is associated with volatile fatty acid production following fermentation of substrate (Blummel and Ørskov 1993). In addition, the application of models permits the fermentation kinetics of the soluble and readily degradable fraction of the feeds, and more slowly degradable fraction to be described (Gatechew et al 1998). Moreover the gas production parameters of trees might demonstrate differences in their nutritional value that may be closely related to their chemical composition (Cerrillo and Juarez 2004).

The aim of the present work was to determine the chemical composition including condensed tannin contents of leaves of some trees used for small ruminant animals in some part of Turkey, and examine their relationships with in vitro gas production parameters.

Materials and methods

Forage samples

Leaves from four trees were harvested in 2003 from the city called Kahramanmaras, in the South of Turkey. The area is located at altitude of 630 m above sea level. The mean annual rainfall and temperature are 857 mm and 16.2 °C respectively. Leaves were hand harvested from at least 10 different trees, then pooled and oven-dried at 60 °C for 48 h (Abdulrazak et al 2000). The samples were ground to pass a 1 mm sieve for later analysis and determination.

Chemical analysis

Dry matter was determined by drying the samples at 105 °C overnight and ash by igniting the samples in muffle furnace at 525 °C for 8 h. Content of nitrogen (N) was measured by the Kheldal method (AOAC 1990). The crude protein (CP) was calculated as N x 6.25. Contents of neutral detergent fiber (NDF) of leave samples were determined by the method of Van Soest et al (1991). Acid detergent fibre (ADF) of leave samples were determined following the method of Van Soest (1963). Total condensed tannin (TCT), soluble condensed tannin (SCT) and bound condensed tannin (BCT) were determined by the butanol-HCL method (Makkar et al 1995). Mimosa tannin (MT; Hodgson, England) was used as an external standard.

In vitro gas production

Rumen fluid was obtained from two fistulated sheep fed twice daily with a diet containing alfalfa hay (60%) and concentrate mixture (40%). The samples were incubated using calibrated glass syringes following the procedures of Menke and Steingass (1988). Approximately 200 mg of OM sample was weighed in triplicate into glass syringes. The syringes were pre-warmed at 39 °C before the injection of 30 ml rumen fluid-buffer mixture into each syringe followed by incubation in a water bath at 39 ^ºC. The syringes were gently shaken at 30 min after the start of incubation and every hour for the first 10 h of incubation. Gas production was recorded before incubation (0) and 3, 6, 12, 24, 48, 72 and 96 h after incubation. Total gas values were corrected for blank and hay standards with known gas production. Cumulative gas production data were fitted to the model of Ørskov and McDonald, (1979) using the Fig P program.

p = a + b (1-exp ^{-c t})

Where:
             p represents gas volume (ml) at time t,
            a the gas produced from soluble fraction (ml),
            b the gas produced from insoluble but fermentable fraction (ml),
            (a+b) the potential gas production (ml), and
            c the rate constant of gas production during incubation (ml h^-1).

Statistical analysis

One-way analysis of variance (ANOVA) was carried out to compare the chemical composition and in vitro gas production with species as the main factor using the General Linear Model (GLM) (Stastica 1993). Significance between individual means was identified using Tukey's multiple range test (Pearse and Hartley 1966). Mean differences were considered significant at P<0.05. Standard errors of means were calculated from the residual mean square in the analysis of variance. A simple correlation analysis was used to establish the relationship between chemical composition and in vitro gas production parameters.

Results and discussion

There were significant differences in the chemical composition among tree leaves. The CP content in DM ranged from 5.62 to 14.1 % with Morus alba having the highest content. The CP content of Morus alba was significantly lower than that reported by Liu et al (2001) and Phiny et al (2003), who found the CP of 18.5 and 23.0 % of DM.

The NDF and ADF content ranged from 42.3 to 56.9% and 28.3 to 34.2% respectively. The NDF content of Juniperus communis was significantly higher than the others. The ash content ranged from 4.99 to 15.8 % with Morus alba having highest content. The TCT content of tree leaves ranged from 1.42 to 21.3% with Juniperus communis having the highest TCT, most of which was in the soluble form. Chemical composition is influenced by seasonal, environmental, soil and other factors (Khanal and Subba 2001).

Gas production of tree leaves increased with increasing incubation time (Figure 1). There were significant differences among the four tree leaves in gas production at all incubation times. Gas production of leaves of Quercus libari was significantly (P<0.001) higher than the others at 96 h incubation.

Figure 1. Cumulative gas production of four tree leaves

Fermentation parameters for leaves from the four different trees are presented in Table 2. There was no significant difference among tree leaves in the rate (c) of gas production. The gas volumes from soluble fraction (a) and fraction (b) were significantly higher in Quercus libari than in the other tree species. The rank order in terms of potential gas production performance was Quercus libari ≥ Populus nigra ≥ Morus alba > Juniperus communis.

The intake of a feed is mostly explained by the rate of gas production (c) which affects the passage rate of feed through the rumen, whereas the potential gas production (a +b), is associated with degradability of feed (Khazaal et al 1995). Therefore the higher values obtained for the potential gas production in the Quercus libari and Populus nigra might indicate a better nutrient availability for rumen microorganisms.

There were significant correlations between estimated parameters and the chemical composition of tree leaves from four different species (Table 3). Contents of NDF and ADF were negatively correlated with most of the estimated parameters. This result is in agreement with findings of Abdulrazak et al (2000), and Ndlovu and Nherera (1997). Rate of gas production was not related to TCT, BCT and SCT. The lack of correlation between these parameters has been observed in previous studies (Khazaal et al 1994). Rate of gas production did not correlate with NDF and ADF content. This result is not in agreement with findings of Ndlovu and Nherera (1997). There is no obvious explanation for these anomalies.

TCT and SCT were also negatively correlated with most of the estimated parameters. This result is consistent with findings of Frutos et al (2002). On the other hand, Larbi et al (1998) reported a weak relationship between TCT and gas production parameters of tree leaves during wet and dry season in West Africa. A possible reason could be differences in the nature of tannins between browse species (Jackson et al 1996). The negative correlation between potential gas production and NDF, ADF, TCT, or SCT may be a result of the reduction of microbial activity from increasingly adverse environmental conditions as incubation time progress (Abreu et.al 1998; Wood and Plumb 1995).

The tree leaves had low contents of CT (less than 6.51 g / kg DM) which would generally be considered unlikely to significantly affect digestion of nutrients in ruminants (Frutos et al 2002). There was, however, one exception to this in tree leaves collected from Juniperus communis, which showed high TCT contents.

NDF and ADF explained 61.1 and 55.5 % of the variation of cumulative gas production respectively whereas the TCT and SCT content explained 72.4 and 87.0 % of variation of cumulative gas production. Cerrillo and Juarez (2004) reported that 81 % of the variation in potential gas production could be explained by the changes in ADF content. The low predictive values in the current experiment could be due to species variation in quantity and quality of fibre content as well as variation in complexation of fibre with polyphenolics (Ndlovu and Nherera 1997).

Conclusion

• It was concluded that there were significant variations in chemical composition and gas production characteristics of tree leaves studied in this experiment.
• Total condensed tannin, soluble condensed tannin and cell wall content (NDF and ADF) adversely affected cumulative gas production and estimated parameters of tree leaves from four different species.

References

Abdulrazak S A, Fujihara T, Ondiek J K and Ørskov E  R 2000 Nutritive evaluation of some Acacia tree leaves from Kenya. Animal Feed Science Technology. 85:89-98.

 

Abreu J M F and Bruno-Soares A M 1998 Chemical composition, organic matter digestibility and gas production of nine legume grains. Animal Feed Science Technology, 70:49-57.

 

 AOAC 1990 Official Method of Analysis. Association of Official Analytical Chemists pp.66-88. 15th.edition Washington, DC. USA.

 

Blümmel M, Makkar H P S and Becker K 1997 In vitro gas production: a technique revisited. Journal of Animal Physiology and Animal Nutrition, 77:24-34.

 

Blummel M and Ørskov E.R 1993 Comparison of an in vitro gas production and nylon bag degradability of roughages in predicting feed intake in cattle. Animal Feed Science Technology. 40:109-119.

 

Cerrillo M A and Juarez R A S 2004 In vitro gas production parameters in cacti and tree species commonly consumed by grazing goats in a semiarid region of North Mexico. Livestock Research for Rural Development. 16 (4) 2004, http://www.lrrd.org/lrrd16/4/cerr16021.htm

 

Frutos P, Hervas G, Ramos G, Giraldez F J and Mantecon A R 2002 Condensed tannin content of several shrub species from a mountain area in northern Spain, and its relationship to various indicators of nutritive value. Animal Feed Science Technology, 95:215-226.

 

Getachew G, Blümmel M, Makkar H P S and Becker K 1998 In vitro gas measuring techniques for assessment of nutritional quality of feeds: A review. Animal Feed Science and Technology, 72:261-281.

 

Holecheck J L 1984 Comparative contribution of grasses, forbs, and shrubs to the nutrition range ungulates. Rangelands, 6:261-263.

 

Jackson F S, Barry T N, Lascona C and Palmer B 1996 The extractable and bound condensed tannin content of leaves from tropical tree. Journal of. The Science of Food and Agriculture, 71:103-110.

 

Khanal RC and Subba D B 2001 Nutritional evaluation of leaves from some major fodder trees cultivated in the hills of Nepal. Animal Feed Science Technology, 92:17-32.

 

Khazaal K A, Boza J and Ørskov E R 1994 Assessment of phenolic-related anti-nutritive effects in Mediterranean browse: a comparison between the use of in vitro gas production technique with or without insoluble polyvinylpolypyrrolidone or nylon bag. Animal Feed Science Technology, 49: 133-149.

 

Khazaal K A, Dentinho M T, Ribeiro R and Ørskov E R 1993 A comparison of gas production during incubation with rumen contents in vitro and nylon bag degradability as predictors of the Apparent digestibility in vivo and voluntary intake of hays. Animal Production, 57: 105-112.

 

Khazaal K A, Dentino M T, Ribeiro J M and Ørskov E R 1995 Prediction of apparent digestibility and voluntary intake of hays fed to sheep: comparison between using fibre components, in vitro digestibility or characteristics of gas production or nylon bag degradation. Animal Science, 61:527-538.

 

Larbi A, Smith JW, Kurdi IO, Adekunle I.O, Raji AM and Lapido D O 1998 Chemical composition, rumen degradation and gas production characteristics of some multipurpose fodder tree shrubs during wet and dry season in the humid tropics. Animal Feed Science Technology, 72: 81-96.

 

Liu J X, Yao J, Yan B, Yu, J Q and Shi Z Q 2001Effects of mulberry leaves to replace rapeseed meal on performance of sheep feeding on ammoniated rice straw diet. Small Ruminant Research, 39: 131-136.

 

Makkar H P S, Blümmel M and Becker K 1995 Formation of complexes between polyvinily pyrorolidones or polyethylene glycols and their implication in gas production and true digestibility in vitro techniques. British Journal of Nutrition, 73:897-913.

 

Menke K H and Steingass H 1988 Estimation of the energetic feed value obtained from chemical analysis and gas production using rumen fluid. Animal Research Development, 28: 7-55.

 

Meuret M, Boza J, Narjisse N and Nastis A 1990 Evaluation and utilization of rangeland feeds by goats. In: Morand-Fehr, P (Editors). Goat Nutrition, PUDOC. Wageningen, The Netherlands, pp.161-170.

 

Ndlovu L R and Nherera F V 1997 Chemical composition and relationship to in vitro gas production of Zimbabwean browsable indigenous tree species. Animal Feed Science Technology, 69:121-129.

 

Orskov E R and McDonald P 1979 The estimation of protein degradability in the rumen from incubation measurements weighed according to rate of passage. Journal of Agricultural Science, 92: 499-503.

 

Papachristou T G and Nastis A S 1996 Influence of decidues broadleaved woody species in goat nutrition during the dry season in Northern Greece. Small Ruminant Research, 20: 15-22.

 

Pearse E S and Hartley H O 1966 Biometrika tables for statisticians. Volume1. pp 1-270. Cambridge University Press.

 

Phiny C, Preston T R and Ly J 2003 Mulberry (Morus alba) leaves as protein source for young pigs fed rice-based diets: Digestibility studies. Livestock Research for rural development. 15 (1), 2003. http://www.lrrd.org/lrrd15/1/phin151.htm

 

Provenza F D 1995 Post ingestive feedback as an elementary determinant of food selection and intake in ruminants. Journal of Range Management, 48: 2-17.

 

Stastica 1993 Stastica for windows release 4.3, StatSoft, Inc. Tulsa, OK

 

Van Soest P J 1963 Use of Detergents in the analysis of fibrous Feeds. II. Rapid method for the determination and lignin. Journal of Association of Analytical Chemist, 46: 830.

 

Van Soest P J, Robertson, J D and Lewis, B A 1991 Methods for dietary fibre, neutral detergent fibre and non-starch polysaccharides in relation to animal nutrition. Journal of Dairy Science, 74: 3583-3597.

 

Wood C D and Plumb V E 1995 Evaluation of assays for phenolic compounds on the basis of in vitro gas production by rumen micro-organisms. Animal Feed Science Technology, 56:195-206.