Research Article
Nutritive Value of Some Herbages for Dromedary Camel in Iran
Department of Animal Science, Faculty of Agronomy and Animal Science, University of Tehran, P.O. Box 31587-4111, Karaj, Iran
To determine the nutritive value of feedstuffs for camel, the first step is to analyse chemical composition of different species plants which preferred by camels and then, to measure digestibility and palatability. Chemical composition of many feedstuffs have been obtained from different ecosystems in the Arab region in Asia and Africa (Wardeh et al., 1990). In India, nutritive value of different tree leaves and green lucerene fodder for camels in north semi-arid zone were determined (Bhagwat et al., 2001). They suggested that tree leaves were palatable to camel and can serve as good and nutritive fodder for camel.
In Iran, Javan (2001) has reported the digestibility some arid rangelands plants by bovine rumen liquor. The determination of in vivo digestibility of wheat straw imply that camel apparently digested poor quality roughages more than cattle and sheep (Hedi and Khamais, 1990; Cianci et al., 2004). Therefore, It is required to measure the in vitro digestibility of herbages by camel rumen liquor.
It has been documented which there is a reverse relationship between digestibility and palatability of forages with NDF content (Lascano et al., 2003; Bagg, 2003). While there is a positive correlation between preferred rating of herbages and nitrogen and mineral concentration in sheep (Reid et al., 1992). There are no data from dromedary camel.
However, little information is known about the nutritive value of range herbage consumed by camel in arid and semi-arid zone of Iran. The objectives of the current study were to determine 1) the chemical composition, gross energy of the most consuming plant species including Atriplex lentiformis, Alhagi persarum, Seidlitzia rosmarinus, Saueda fruticosa, Haloxylon ammodendron, Tamarix kotschyi, Hammada salicornica, Salsola yazdiana, Salsola tomentosa, Tamarix aphyllaand Artemisia sieberi, 2) in vitro digestibility of the plants by camel rumen liquor 3) the possible relationship between the palatability (preferred rating) with digestibility or chemical composition of the herbages in dromedary camel.
The plants samples were collected in autumn 2002 based on stratified random sampling from the rangelands of Yazd province in Iran. Thirty samples from the browsing parts prepared, pooled and dried at room temperature and milled. Chemical composition of samples including dry matter (DM), crude fiber (CF), Neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE), total ash (TA), macro elements (Ca, P, Mg, K)and microelements (Fe, Mn, Cu, Zn)and gross energy (GE) were analyzed by standard methods (AOAC, 1990; Wiseman and Cole, 1990; Undersander et al., 1993) in Animal Science Research Institute, Karaj.
To determine the digestibility of the plants, four mature male camel were fitted with fistula in the rumen under anesthesia. The in vitro digestibility was measured in duplicate by camel rumen liquor and pepsin in Tilley and Terry 1963 method. Percentage of dry matter digestibility (%DMD), organic matter digestibility (%OMD), organic matter digestibility in dry matter (%DOMD) were calculated.
The palatability of plants were determined by three mature camels in cafeteria trials. The camels were placed in individual pen and offered simultaneously the choice of 11 fresh plant species. The plant samples were collected from the browsing parts from the rangelands. No apparent stress or anxiety was observed from individual penning of the camels. Camels were fed each morning for one hour during six consecutive days. Each feed was weighed and offered in three separates containers. Sufficient feed was placed in each container so that feed would not be depleted. Feed remaining from the previous feeding was weighed to determined amount consumed and the containers were refilled. The location of the containers in the pen was randomizes at each feeding. To compare the preferred rating based on a defined standard, a sample of each collected samples were dried at room temperature for one month.
Data from feed preference trials were analyzed by GLM method in SAS software (1996). The means were compared by duncans test.
RESULTS AND DISCUSSION
The results of Table 1 showed that highest CP (18.3%)and the lowest NDF (40.4%) and ADF (35.4%) were related to Tamarix aphylla. The lowest CP (5.5%)and the highest NDF (72.8%) and ADF (59.6%) were related to Artemisia sieberi.
Little information is known about the digestibility of herbages in camel. The digestibility of CP and CF of tree leaves and green lucerene fodder were measured (Bhagwat et al., 2001). In situ DM and fiber degradation in camel and in vitro gas production of four grasses irrigated with sea water have been reported (Alhadrami et al., 1998; Abdel-Gawad and Alhadrami, 1998).
Present data are the first report about the in vitro digestibility of the some Iranian herbages which obtained by camel rumen liquor. The highest and the lowest %DOMD were related to Haloxylon ammondendron and Artemisia siberi, respectively (Table 2). We will be able to calculate metabolizable energy of the plants based on MEF = 0.15% DOMD as MEF is metabolizable energy of forage (Orskov, 1984).
% DOMD of Haloxylon ammondendron (57.9%), Seidlitzia rosmarinus (20.6) and Hammada salicornica (48.7) have measured with bovine rumen liquor by Javan (2001). The different result apparently is caused the kind of animal's liquor or phytogenic stage of the plants.
Lower fiber (NDF and ADF) is associated with higher digestibility and higher dry matter intake in sheep (Lascano et al., 2003). There was no correlation between our data in dromedary camel. Previous studies have been shown NDF indigestibility increased nonlinearly as the lignin concentration of the NDF increased (Jung et al., 1997; Traxler et al.,1998). However, we did not measure lignin concentration or indigestible NDF in this experiment.
Table 1: | Chemical composition and gross energy of different plant species based on dry matter |
Table 2: | In vitro digestibility of different plant species |
Table 3: | Mean±SD intake of different plant species as air-dried or fresh |
* The values which did not have a common letter (s) are significantly different (p<0.05) |
The results indicated that species of plant had a significant effect (p<0.01) on intake. Mean intake of Atriplex lentiformis was significantly (p<0.05) greater than the other plant species based on air-dried. As fresh, relative intake of Atriplex lentiformis and Alhagi persarum was not significantly different, but their intake were significantly (p<0.05) more than the other plant species. Relative intake was greater (p<0.01) for fresh Seidlitzia rosmarinus and fresh Sueda fruticosa and air-dried Seidlitzia rosmarinus than for the others plant species (Table 3).
Considering to results, we could divided the plants to three groups: 1) most palatable including Atriplex lentiformis and Alhagi persarum; 2) palatable including Seidlitzia rosmarinus, Sueda fruticosa, Haloxylon ammondendron and Salsola tomentosa; 3) less palatable or undesirable including Hammada salicornica, Tamarix kotschi, Salsola yazdiana, Tamarix aphylla and Artemisia siberi.
In the current study, there was not any consistent relationship of plants palatability to measured chemical composition or digestibility. In camel, there was a little information about herbage preference and grazing behavior of camel (Wardeh, 1990). In that study, it was not reported any relationship between palatability to chemical composition or digestibility. In cattle, Increased NDF indigestibility will result in higher energy values and perhaps more importantly, increased forage intake. Relatively small improvements in fiber digestibility can significantly increase dry matter intake (Bagg, 2003). In sheep, the palatability was associated with lower NDF and a greater concentration of nitrogen content and generally greater concentration of minerals (K, Ca, Mg, S, Fe) (Reid et al., 1992; Lascano et al., 2003). It has been suggested that sheep were able to select a diet meeting their CP requirements and avoid, at least to a certain extent, excess of protein intake (Reid et al., 1966; Kyriazakis and Oldham, 1993).
It has been shown that the animal needs to be aware of the nutritional differences between the feeds which differ in taste, colour or some other sensory discriminating factor. Social interactions between animals also can have influences on food selection (Forbes and Kyriazakis, 1995). It must be considering that the presence of a toxin in one food can markedly reduce the animals preference for that food. For example, Ralphs et al. (1990) indicated that the presence of a toxin alkaloid swainsonine in locoweed resulted in the ewes did not select it if the other feeds were offered. However, We did not measured toxins in the plants.
Diet selection theory is extremely complex and has been reviewed for grazing and browsing livestock, for example, Malechek and Balph (1987) and Milne (1991). In this study, specific points of interest were whether palatability or preference ratings were related to chemical composition and (or) nutritional characteristics of the herbages.
Forbes and Kyriazakis (1995) have suggested that preferred foods, or the preferred ratio of two or more foods, are tuned to provide a diet which promotes maximum metabolic comfort. Hence, it is reasonable to presume that the camels selected a combination of feeds/plants which provided animals metabolic requirements and, no based on the chemical composition.
IMPLICATION
This is the first report on the in vitro digestibility by camel rumen liquor and the palatability of some herbages in Iran. There were no consistent patterns between the palatability with chemical composition or the digestibility of the plants. For further study, it is suggested to investigate the relationship between the other contents of plants, for example lignin, toxin etc., with the palatability.