Nutrient composition of forest based foliages consumed by Mithun (Bos frontalis) under Imphal district of Manipur

B Prakash, S S Rathore*, K Khate** and C Rajkhowa**

Project Directorate on Poultry, Indian Council of Agricultural Research, Rajendranagar, Hyderabad-500030, Andhra Pradesh
drbhukyaprakash@gmail.com
* Directorate of Rapeseed-Mustard Research, Indian Council of Agricultural Research, Sewar, Bharatpur -321303, Rajasthan
** National Research Centre on Mithun, Indian Council of Agricultural Research, Jharnapani, Medziphema -797106, Nagaland

Abstract

The aim of the current study was to determine the micronutrient content in important forest based foliages that are available in some parts of Imphal districts of Manipur. The foliage species were selected because they are abundantly available, and highly preferred by mithun in its natural habitat, and because farmers strongly believe that these foliage species are highly nutritious. The collected samples were subjected for estimation of dry matter (DM), crude protein (CP), ether extract (EE), crude fibre (CF), ash and condensed tannins (CT). The foliages were also estimated for some of the macro and micro minerals using standard procedures.

The DM, CP, EE, CF, ash and CT ranged from 11.0 to 42.3, 9.20 to 26.3, 0.7 to 4.0, 12.1 to 33.8, 3.60 to 17.6 and 0.30 to 12.0%, respectively. The macro mineral i.e. Ca, P, Mg, Na and K content ranged from 1.47 to 3.10, 0.11 to 0.34, 0.07 to 0.95, 0.01 to 0.08 and 0.95 to 2.44%, respectively. Similarly, the micro mineral i.e. Zn, Fe and Cu content ranged from 37.0 to 92.0, 146 to 302 and 5.0 to 19.0 mg/kg, respectively. Therefore, it has been concluded that the nutrient contents were adequate in most of the foliages. However, the Na was deficient in majority of the foliages and may explain observed salt seeking behavior of Mithun reared under free grazing systems.

Key words: ecosystems, foliages, India, nutrient composition

Introduction

Mithun is a unique free-range domesticated bovine found mainly in the subtropical rain forest of Northeastern Hilly Region (NEHR) of India ) (Photo 1). This species is also found in many pockets of Southeast Asia (Simoons 1984). Mithun is an important component of the cultural and socio-economical life of its rearers, and thrives on natural vegetation and tree fodders as its major feed resources (Prakash et al 2008). In general, farmers do not provide any feed supplements except common salt (Photo 2).

Photo 1. Mithun cattle in the study area	Photo 2. In general, farmers do not provide any feed supplements except common salt

The NEHR of India is mega biodiversity region of the world and harbors great floral diversity (Myers et al 2000). The evergreen forest of NEHR is a potential source of tree fodders throughout the year. Despite their potential as feeds, meager information is available on their nutrient composition. However, the previous report indicates that some of the tree foliages have high feeding value (Prakash et al 2009). Further, as the topography of the mithun habitat is undulating, leaching of minerals is a common phenomenon (Kleinman et al 1996) and soils are prone to mineral deficiencies, which could affect vegetation (Prasad et al 1986). This may be the reason why mithuns reared under free grazing conditions exhibit salt licking behavior. Therefore, it is imperative to study the nutrient status of the important browse species in order to develop a suitable feeding strategy for mithun.

The objective was to determine the nutrient composition and to relate the analysed nutrient values to those recommended by the National Research Council (1978) and summarized by McDowell (1997). The experimental foliage species were selected because they are abundantly available and highly preferred by mithun in its natural habitat. Further, the farmers strongly believe that these foliage species are highly nutritious.

Materials and methods

Sample collection

The samples of the selected foliage species were collected from various packets of Imphal district of Manipur. Approximately 1 kg of the foliage was harvested from each species as a single sample of leaves harvested from a single tree. The samples were mixed thoroughly and a representative sample of 200 g was finally collected, dried and stored for further laboratory analysis. All samples were collected within 25 days to minimize effects of sampling time on nutrient composition.

Chemical analysis

Dry matter (DM), crude protein (CP) (N × 6.25), ether extract (EE), crude fibre (CF) and ash were determined  according to AOAC (1980). Condensed tannin (CT) was analysed according to Porter et al (1986), wherein 200 mg of ground sample was placed in a 50 ml conical flask and mixed thoroughly with 20 ml of diethyl ether containing 10 g/l acetic acid and kept for 5 min. Diethyl ether was removed by decantation and the residue dried at 30º C for 30 min. Dried residue was mixed with 10 ml aqueous acetone and incubated in an orbital shaker (30º C, 130 rpm) for 2 h. Following incubation, the content was centrifuged (20 min at 5000 × g) at 4º C and the supernatant was collected for analysis. For CT fractionation, the extract was treated with butanol–HCl in the presence of ferric ammonium sulphate and expressed as leucocyanidin equivalent (A_{550 nm} × 782.6/wt. of sample DM; A _{550 nm} is the absorbance at 550 nm assuming that the effective E^1%,^1cm, 550 nm of leucocyanidin is 460).

For mineral estimation, 1 g of dried sample was ignited in a muffle furnace at 550º C for 3 h. The ash was dissolved in hydrochloric acid (337 g/l) and filtered through filter paper (Whatman ® Grade no. 1), and the final volume was made to 250 ml with Milli-Q water (Millipore Corporation, Bedford, MA, USA). All minerals (i.e., Ca, P, Mg, Na, K, Cu, Fe, Mn Zn) were estimated using an atomic absorption spectrophotometer (AAS; Thermo Electron Corp., Cambridge, UK) according to methods suggested by the manufacturer. A specific lamp was used for each mineral and the AAS was calibrated with various concentrations of mineral standards. The standards and samples were positioned and injected using the furnace auto-sampler (GFS 97; Thermo Electron Corp.). The concentration of each element was retrieved using the Solaar software (Version 10.11; Thermo Electron Corp.). To determine the content of Ca and Mg, processed samples were further diluted with 87 g/l lanthanum chloride to mask interferences of Al, Be, P, Si, Ti, V and Zn.

Results and discussion

Most of the foliages are perennial and deciduous or evergreen those are highly preferred by mithun in their natural habitat. The traditional forest based foliages have a wide variation in DM, CP, EE, CF, ash and CT content occurred among the foliages (Table 1). However, nutrient compositions of the foliages are constant with previous reports of chemical composition of foliages (Prakash et al 2009) from Nagaland. Most of the foliages contained acceptable levels of CT (i.e., <5% on DM [Waghorn et al 1990]), which reduces the excess ruminal ammonia production and increases the protein availability at the lower gastro-intestinal tract. This will leads to increase the production potential in the animals. Further, most of the evaluated foliage have sufficient CP (i.e., >14%, Subba 1999) to support growth and maintenance of mithun under its natural habitat.

Majority of the foliages contained high Ca, Mg, K, Fe, Mn and Zn relative to requirements (Table 2).

Therefore, deficiencies of these minerals are unlikely in mithun those are maintained exclusively on these foliages. It is also a rare chance that toxic effects of Fe would occur as ruminants tolerate comparatively high levels of Fe (>1000 ppm), if consumed in natural foliages (NRC 1978). However, it has been reported that the high levels of Fe may interfere with Cu absorption and metabolism (Youssef et al 1999). The content of P and Cu was within the required range for ruminants (McDowell 1997). The Na content varied widely and, in all the foliages, it was deficient compared to the required range. It is well known in the NEHR that Mithun shows salt-hunger behavior extensively under free-grazing condition (Simoons 1984), which might be due to the deficiency of Na in the foliages as it has been recorded in the present study. The higher Ca and Mg contents in the foliages might be due to relatively higher uptake of these elements from coarse textured soils with low cation exchange ability (Sillanpaa 1982). These type of the soils generally found in the NEHR of India. The Ca:P ratio was much wider in all foliages, compared to those recommended for ruminants (McDowell 1997), which may create problem with vitamin D metabolism (ARC 1984). However, it can be overcome by supplementing with the foliages with higher P that are recorded in the present study and Tithonia diversifolia like foliages, which contain higher P (Olabode et al 2007).

Conclusions

• The results of the current study revealed that all the foliage species contained adequate nutrients. But were deficient in Na in all the foliages and this may be the reason why the Mithun seek salt liking behavior those are reared on the traditional forest based foliages under free grazing systems.
  
  
• It is first and foremost important to conserve the natural habitat of the mithun through use of local knowledge, which will help in maintaining the quality of the environment and conserving the traditional feed resources.
  
  
• Conservation and judicious use of diversified feed resources will lead to increased animal productivity, population and will help in developing the improved feeds for feeding the animals.

Acknowledgement

Authors are highly thankful to the Indian Council of Agricultural Research for granting the A.P. Cess Fund Scheme (F. No. 8 (29) 2004-ASR-II. Dated 03.05.2005) to conduct the study and the villagers of Waiphei (Leimakhong) surrounding areas of Imphal district of Manipur for helping in documentation of the work.

References

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Received 30 August 2013; Accepted 23 September 2013; Published 1 October 2013

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