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The use of herbage n-alkanes as markers to estimate the diet composition of yaks on the Qinghai-Tibetan plateau.

INTRODUCTION

The species composition of the herbage available to and consumed by grazing animals is an important variable in studies of their nutritional status. Our understanding of the foraging behaviour of free-ranging herbivores is often constrained by our inability to make meaningful measurements of herbage diet composition. Herbage composition of feed ingested by grazing animals is difficult to assess. Direct observation of animals, use of oesophageally fistulated animals or fecal cuticle analysis have commonly been used, but all of these methods are very tedious, time consuming and/or do not allow differentiation to the level of plant species or plant parts (Dove and Mayes, 1991). Oesophageally fistulated animals have the disadvantage of requiring surgery and might be of restricted use only.

The use of n-alkanes as fecal markers for estimating the diet composition of grazing animals has provided a significant advance in such studies and has been used successfully to estimate the proportions of plant species in the diet of free-ranging herbivores (Dove and Mayes, 1991, 1996; Bugalho et al., 1999). Because the different pasture species differ in their alkane patterns, and alkanes are largely indigestible during their passage through the herbivore's alimentary tract, the composition of a mixed herbage diet can be determined from the patterns of n-alkanes found in herbage and faeces (Dove and Mayes, 1996). The n-alkane technique has been successfully applied to estimate diet composition, intake and digestibility in sheep, red deer and steer (Dove and Mayes, 1991; Duncan and Mayes, 1999; Bugalho and Myes, 2002; Ru et al., 2002; Valiente and Delgado, 2003; Walter Kelman and Miguel Bugalho, 2003; Premaratne et al., 2005).

The experimental site used in the present study lies in an alpine area, and the species composition is complex. The yaks graze in different areas of natural grassland in the different seasons. The aim of the present study was to use the n-alkane method to estimate the diet composition selected by yak when grazing alpine pastures and to explore whether the method can provide accurate assessments of dietary selection by yak under these conditions.

MATERIALS AND METHODS

Study area

The study area was an alpine grassland on the Qinghai-Tibetan plateau, and not very far from Qinghai Lake (37[degrees]18'N, 100[degrees]16'E) at an altitude of 3,275 m. The region has an alpine climate. Mean annual precipitation is around 327.1 mm and mean annual temperature is -0.5-0.1[degrees]C. The lowest temperature in January is about -31.7[degrees]C and the highest temperature in August is about 14.5[degrees]C. During autumn, the yaks' grazing pasture lies near the bank of Qinghai Lake which abuts with their spring and winter pasture. Their summer pasture is of a swamp type and lies in Qilian mountain valley.

The experiment was conducted from July to August 2004 in summer pasture, during September 2004 in autumn pasture, from October to December 2004 in winter pasture and from March to April 2005 in spring pasture.

Field measurements and preparation of sample

Herbage mass (DM g [m.sup.-2]) was measured by cutting all grass and forb species to ground level within fifteen randomly placed 0.50 m x 0.50 m quadrat frames. Thirty herbage or forb species were chosen to measure height with a ruler in different pastures. The cover of each species was measured using 10 equal grid portions with a 1 m x 1 m quadrat. Samples of the most common individual herbage species were also collected at the same time. All the samples were ground through a 1 mm screen. One sample of each species was dried in a forced draught oven at 60[degrees]C for 24 h to calculate DM, then combusted in a muffle furnace to calculate organic matter (OM). Sub-samples were air-dried before determination of acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), fat and n-alkane concentrations. The species in summer pasture were: Kobresia huimlis, Stipa aliena, Lancea tibetica, Kobresia pygmaea, Gentiana squarrosa, Leontopodium leontopodioides, Thalictrum alpinum, Oxytropis deflexa, Saussurea superba, Potentilla fruticosa, Taraxacum brevirostre, Potentilla anserine, Poa calliopsis, Potentilla multifida, Leontopodium nanum. The species in autumn pasture were: Batrachium bungei, Potentilla anserine, Kobresia pygmaea, Setaria viridis, Carex qinghaiensis, Triglochin palustre. The species in winter pasture were: Carex qinghaiensis, Stipa crylovii, Achnatherum inebrians, Pedicularis alaschanica, Heteropappus altaicus, Stellera chamaejasme, Saussurea semifasciata, Artemisia frigida, Agropyron cristatum.

Fresh faeces were collected by following eight different yaks on different days in the same period. Visible nonfaeces objects were avoided when taking fecal samples from the ground. Fecal samples were air-dried before analysis of n-alkane concentrations. One part of the fecal sample was dried in the oven at 60[degrees]C for 24 to determine DM.

N-alkane analysis

The alkane extraction procedure was carried out using a modification of the method of Mayes et al. (1986) and Dove et al. (2006). Dried and milled herbage samples (2.0 g) and fecal samples (1.0 g) were weighed along with an internal standard (tetracosane, C24 alkane), into screw-capped flasks and were heated with 1 mol [L.sup.-1] ethanolic KOH solution (13 ml) for 48 h at 90[degrees]C. After cooling to 55[degrees]C, 3 ml water and 8 ml heptane were added to each flask and the flasks were shaken vigorously. The top, non-aqueous layer was removed and evaporated to dryness, re-dissolved in 2 ml heptane and applied to a silica-gel column (Silica gel 60, Qingdao haiyang Chemical co., Ltd., 5 ml syringe). The hydrocarbons were eluted from the columns with heptane, concentrated to about 20 ml, evaporated and re-dissolved in 1 ml heptane. The solution was transferred to a centrifuge tube for injection into a gas chromatograph.

The hydrocarbons in the purified extracts were analysed by gas chromatography on a ThermoFinnigan gas chromatograph (Trace-GC2000) fitted with a flame ionization detector. The column was a 30 m x 0.53 mm inside-diameter capillary column type SPB1 with 1 [micro]m film thickness; Lanzhou Institute of Chemical Physics, China), temperature-programmed from 210 to 295[degrees]C at 6[degrees]C [min.sup.-1]. The carrier gas was nitrogen (30 ml [min.sup.-1]). The injector and detector were maintained at 300[degrees]C throughout the whole process. The chromatographic data was processed using Trace GC software (Chrom-chard). Detector response factors for individual n-alkanes were determined by injecting onto the chromatograph a standard n-alkane mixture ([C.sub.29], [C.sub.31], [C.sub.32]) after every 10 sample extracts.

Estimation of diet composition

The concentrations of the n-alkanes, from both fecal and vegetation samples, were compared iteratively within a least-squares optimization routine. The non-negative least-squares procedure was implemented using the software EATWHAT (Dove and Moore 1995).

RESULTS

Height, cover, DM and chemical composition of the herbage

The chemical composition of herbage species is presented in Table 1. Generally, the content of NDF in the species in winter and spring pasture was higher than in summer and autumn pasture. High CP contents were found in some leguminous forages, such as Oxytropis deflexa and Taraxacum brevirostre, in the summer pasture. The height, coverage and DM weight of the main species in the four pastures are presented in the four graphs (Table 2).

N-alkane concentration

Concentrations of C29 and C31 alkanes were highest in the herbage group, and the concentration of C32 alkane in most species was very low and almost zero. Particular alkanes differentiated individual species (Table 3). In summer pasture, Kobresia huimlis and Saussurea superba had the highest concentrations of C29 alkane; whilst Gentiana squarrosa and Leontopodium leontopodioides had the highest concentrations of C31 alkane, compared with other species (Table 3). In autumn pasture, the highest concentrations of C29 alkane were found in Batrachium bungei, Setaria viridis and Triglochin palustre. In the autumn, Potentilla anserina had a higher concentration of C31 alkane than any other species (Table 3). The mean concentration of n-alkanes was lower in winter pasture than in summer and autumn pasture. In winter, most species had the highest C31 concentration except for Stellera chamaejasme, Artemisia frigida and Achnatherum inebrians. Saussurea semifasciata had a higher concentration of C29 alkane than any other species (Table 3). Two species were measured in spring pasture. The higher concentration of C29 was found in Carex qinghaiensis. However, no C31 or C32 were found in this species (Table 3).

Composition of the diet

Although fifteen species were analysed from summer pasture, the EATWHAT software showed that there were two species (Kobresia huimlis, Stipa aliena) in yak diet composition (Figure 1). Kobresia humilis was 33%, and Stipa aliena was 67% of the diet. Potentilla anserine (34%) and Carex qinghaiensis (66%) were detected in the yak diet composition in autumn pasture (Figure 2). The yak diet contained three species in winter pasture (Figure 3): Heteropappus bowerii, Saussurea semifasciata, and Carex qinghaiensis. The proportion of Carex qinghainsis was the highest (52%) and that of Heteropappus bowerii and Saussurea semifasciata was 32% and 16%, respectively. In spring pasture, a high proportion (95%) of Achnatherum splendens was found in the diet composition. The other species was Carex qinghaiensis with 5% proportion (Figure 4).

DISCUSSION

The results of this study indicate that the differences between species in their cuticular wax alkane levels can be exploited successfully to estimate the main species composition of mixtures of herbage. Species other than those detected by the EATWHAT software were present in the diet, but only in small quantities. These species may be detected under the conditions of a large range of alkanes analysed. If we want to measure the major diet composition under grazing conditions, the n-alkane technique and the 'EATWHAT' software are a good choice.

The botanical composition of the diet of large herbivores can sometimes be similar to the botanical composition of the top layer of sward (Hodgson, 1986). Carex qinghaiensis was one of the most abundant browse species in autumn and winter pasture and the proportion in the diet of yak remained relatively constant. On the spring pasture, Achnatherum splendens provided the greatest cover and herbage mass of the two species present, and constituted the majority (95%) of the diet selected. The dominant species, Kobresia humilis was just a small proportion of the diet compared with Stipa aliena on summer pasture. The reason is that Stipa aliena has a good texture, and the height of Kobresia humilis is too low for yaks to graze (Table 2).

[FIGURE 1 OMITTED]

In this study we also found that yak consumed certain forbs in most circumstances, e.g. Potentilla anserine, Heteropappus bowerri, Saussurea semifasciata. The ingestion of forbs could be partially related to the requirements of yak for crude protein, a limiting factor in the nutrition of ruminants. Usually, concentrations of crude protein are very low in the herbage group layer, especially the senescent herbage layer (Fonseca, 1998). This is also proved by our results (Table 1). For example, in winter pasture, Heteropappus bowerii and Saussurea semifasciata contain relatively high levels of crude protein and are an important source of crude protein for yak. However, although Artemisia frigida also contains high levels of crude protein, the yaks rarely choose it. We found it has a strong smell which may have inhibited selection by the yak. The other forbs were not detected in the yak diet. The proportion or the height of these species is very low in the pasture. For example, the height of Stipa crylovii was lower than other herbage species; the herbage mass of Pedicularis alaschanica was lower than other species; and the cover of Pedicularis alaschanica, Stellera chamaejasme, Achnatherum inebrians and Agropyron cristatum was very low (Table 2). On the other hand, these species may contain some anti-nutritional compounds that have inhibitory effects on grazing animals. Further research remains to be investigated on this issue.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

The alpine environment is very harsh, with low oxygen, low temperature and high ultraviolet radiation. In order to maintain a sustainable grazing ecosystem, effective and reasonable grazing management is indispensable. Although summer pasture is a growing season, the stocking rate has to be controlled in order to maintain good pasture, for example, to reduce the number of livestock and retain enough forage in the ground. There is a lack of high quality food provided by winter and spring pastures when most of the herbage layer becomes senescent. Yaks are likely to suffer nutritional constraints before re-growth of the herbage layer towards the end of the spring season. Supplementary feeding at the end of the winter and in the early spring or, if economically viable, irrigation or fertilizer application to pastures, may improve the capacity of grassland by providing additional food to yak.

[FIGURE 4 OMITTED]

ACKNOWLEDGMENTS

We thank the staff of San Jiao Cheng Sheep Breeding Farm for assistance with the field work. We also wish to thank J. L. Xu for the laboratory analysis. This paper was financially supported by the key program of National Natural Science Foundation of China (No. 30730069), the key project in the National Science & Technology Pillar Program during the 11th Five-Year Plan (2007BAD63B04) and the 'Hundred Talent Program' of Chinese Academy of Sciences.

REFERENCES

Bugahho, M. N. 1999. The foraging behaviour of red deer in a mediterranean environment. Ph.D. Thesis. University of Aberdeen, Aberdeen.

Bugahho, M. N., R. W. Mayes and A. Milne. 2002. The effects of feeding selectivity on the estimation of diet composition using the n-alkane technique. Grass Forage Sci. 57:224-231.

Dove, H. and R. W. Mayes. 1991. The use of plant wax alkanes as marker substances in studies of the nutrition of herbivores: a review. Aust. J. Agric. Res. 42:913-952.

Dove, H. and A. D. Moore. 1995. Using a least-squares optimisation procedure to estimate botanical composition based on the alkanes of plant cuticular wax. Aust. J. Agric. Res. 46:1535-1544.

Dove, H. and R. W. Mayes. 1996. Plant wax components: a new approach to estimating intake and diet composition in herbivores. J. Nutr. 126:13-26.

Dove, H. and R. W. Mayes. 2006. Protocol for the analysis of n-alkanes and other plant-wax compounds and for their use as markers for quantifying the nutrient supply of large mammalian herbivores. Nat. Protoc. 1:1680-1697.

Duncan, A. J., R. W. Mayes, C. S. Lamb, S. A. Young and I. Castillo. 1999. The use of naturally occurring and artificially applied n-alkanes as markers for estimation of short-term diet composition and intake in sheep. J. Agric. Sci. Cambridge, 132:233-246.

Fonseca, M. 1998. Plasticity of mating behaviour in red deer (Cervus elaphus) in a Mediterranean environment. Ph.D. Dissertation. University of London, London.

Hodgson, J. 1986. Grazing behaviour and herbage intake. In: Grazing (Ed. J. Frame). Occasional Symposium No. 19. Br. Grassland Soc. 51-54.

Kelman, W., M. Bugalho and H. Dove. 2003. Cuticular wax alkanes and alcohols used as markers to estimate diet composition of sheep (Ovis aries). Biochem. Syst. Ecol. 31: 919-927.

Premaratne, S., J. P. Fontenot and R. K. Sharnklin. 2005. Use of n-alkane to estimate intake and digestibility by beef steers. Asian-Aust. J. Anim. Sci. 18:1564-1568.

Ru, Y. J., J. A. Kruk, M. Fischer, M. Choct and P. C. Glatz. 2002. Predicting n-alkane concentration in pastures and deer facces for dietary composition and digestibility measurement using near infrared spectroscopy. Asian-Aust. J. Anim. Sci. 15:1611-1614.

Valiente, O. L., P. Delgado, A. de Vega and J. A. Guada. 2003. Validation of the n-alkane technique to estimate intake, digestibility, and diet composition in sheep consuming mixed grain: roughage diets. Aust. J. Agric. Res. 54:693-702.

L. M. Ding (1,2) * and R. J. Long (2,3)

(1) Key Laboratory of Arid and Grassland Ecology, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China

* Corresponding Author: Long Ruijun. Tel: 931-8915650, Fax: 931-8915650, E-mail: longrj@lzu.edu.cn

(2) International Centre for Tibetan Plateau Ecosystem Management, Lanzhou University, Lanzhou, 730000, China.

(3) College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.

Received April 27, 2009; Accepted July 22, 2009
Table 1. Nutritional composition of the forages (DM basis)
(mean[+ or -]SD) (n = 3)

Species                              ADF (%)             NDF (%)

In summer pasture
  Kobresia humilis              27.83[+ or -]0.55   47.43[+ or -]0.12
  Stipa aliena                  27.40[+ or -]1.87   50.74[+ or -]3.20
  Lancea tibetica               25.44[+ or -]0.97   39.83[+ or -]7.97
  Kobresia pygmaea              21.97[+ or -]0.47   49.37[+ or -]0.40
  Gentiana squarrosa            23.23[+ or -]0.40   38.86[+ or -]0.55
  Leontopodium leontopodioides  24.91[+ or -]0.74   42.40[+ or -]0.71
  Thalictrum alpinum            23.40[+ or -]0.48   40.57[+ or -]0.16
  Oxytropis deflexa             23.43[+ or -]1.20   43.78[+ or -]0.92
  Saussurea superba             21.29[+ or -]0.88   35.05[+ or -]7.19
  Potentilla fruticosa          23.74[+ or -]0.45   40.16[+ or -]0.68
  Taraxacum brevirostre         20.72[+ or -]0.26   42.05[+ or -]0.21
  Potentilla anserina           29.57[+ or -]0.71   41.03[+ or -]0.61
  Poa calliopsis                24.40[+ or -]2.36   38.88[+ or -]0.19
  Potentilla multifida          23.68[+ or -]0.61   43.67[+ or -]1.28
  Leontopodium nanum            20.01[+ or -]1.00   39.81[+ or -]1.07
In autumn pasture
  Batrachium bungei             23.90[+ or -]2.96   40.78[+ or -]1.28
  Potentilla anserina           27.83[+ or -]1.11   46.17[+ or -]1.71
  Kobresia pygmaea              23.00[+ or -]068    44.44[+ or -]2.55
  Setaria viridis               27.36[+ or -]0.29   42.64[+ or -]0.19
  Carex qinghaiensis            26.79[+ or -]0.23   48.68[+ or -]1.49
  Triglochin palustre           23.44[+ or -]0.38   45.05[+ or -]1.92
In winter pasture
  Pedicularis alaschanica       26.77[+ or -]1.45   49.38[+ or -]0.68
  Heteropappus bowerii          27.41[+ or -]0.87   43.32[+ or -]0.55
  Stipa crylovii                27.48[+ or -]0.94   40.60[+ or -]0.09
  Stellera chamaejasme          27.35[+ or -]1.00   58.37[+ or -]0.59
  Saussurea semifasciata        26.15[+ or -]1.07   38.92[+ or -]0.02
  Artemisia frigida             28.82[+ or -]0.14   38.49[+ or -]1.00
  Achnatherum inebrians         26.31[+ or -]0.66   45.92[+ or -]0.92
  Agropyron cristatum           30.65[+ or -]1.23   51.52[+ or -]0.81
  Carex qinghaiensis            29.81[+ or -]0.23   50.21[+ or -]0.31
In spring pasture
  Carex qinghaiensis            32.11 [+ or -]0.23  53.89[+ or -]0.40
  Achnatherum splendens         24.70[+ or -]0.02   51.27[+ or -]0.83

Species                              CP (%)              OM (%)

In summer pasture
  Kobresia humilis              7.95[+ or -]0.09   93.25[+ or -]0.95
  Stipa aliena                  7.59[+ or -]0.33   94.29[+ or -]0.50
  Lancea tibetica               9.32[+ or -]0.47   94.02[+ or -]1.20
  Kobresia pygmaea              10.60[+ or -]0.54  92.06[+ or -]0.52
  Gentiana squarrosa            10.64[+ or -]0.59  91.23[+ or -]0.57
  Leontopodium leontopodioides  8.19[+ or -]0.29   90.76[+ or -]0.03
  Thalictrum alpinum            9.67[+ or -]0.29   93.43[+ or -]0.74
  Oxytropis deflexa             15.72[+ or -]0.38  92.02[+ or -]0.38
  Saussurea superba             7.02[+ or -]0.07   93.35[+ or -]1.06
  Potentilla fruticosa          7.85[+ or -]0.50   91.12[+ or -]1.42
  Taraxacum brevirostre         14.38[+ or -]1.00  91.94[+ or -]0.29
  Potentilla anserina           10.07[+ or -]0.38  91.22[+ or -]0.55
  Poa calliopsis                14.04[+ or -]0.31  91.97[+ or -]0.07
  Potentilla multifida          11.09[+ or -]1.18  92.4[+ or -]0.17
  Leontopodium nanum            8.35[+ or -]0.40   93.03[+ or -]0.23
In autumn pasture
  Batrachium bungei             8.90[+ or -]0.42   92.77[+ or -]0.19
  Potentilla anserina           9.20[+ or -]0.10   93.51[+ or -]0 69
  Kobresia pygmaea              9.33[+ or -]0.10   93.28[+ or -]0.48
  Setaria viridis               9.44[+ or -]0.10   94.02[+ or -]0.21
  Carex qinghaiensis            10.59[+ or -]0.48  91.37[+ or -]0.81
  Triglochin palustre           9.42[+ or -]0.10   93.58[+ or -]0.03
In winter pasture
  Pedicularis alaschanica       9.38[+ or -]0.57   95.50[+ or -]0.52
  Heteropappus bowerii          9.55[+ or -]0.42   93.00[+ or -]0.47
  Stipa crylovii                6.76[+ or -]0.31   94.12[+ or -]0.28
  Stellera chamaejasme          6.69[+ or -]0.40   94.83[+ or -]0.23
  Saussurea semifasciata        9.09[+ or -]0.69   92.74[+ or -]0.62
  Artemisia frigida             9.58[+ or -]0.02   92.91[+ or -]0.38
  Achnatherum inebrians         5.44[+ or -]0.38   95.50[+ or -]0.21
  Agropyron cristatum           4.88[+ or -]0.17   91.50[+ or -]0.19
  Carex qinghaiensis            8.96[+ or -]0.21   93.82[+ or -]0.36
In spring pasture
  Carex qinghaiensis            5.44[+ or -]0.38   94.05[+ or -]0.69
  Achnatherum splendens         4.07[+ or -]0.02   94.83[+ or -]0.29

Table 2. The height (cm), cover (%) and herbage dry matter mass (DM, g
[m.sup.-2]) of predominant species in summer, autumn, winter and
spring pasture (mean[+ or -]SD)

Species                              Height (cm)
                                       n = 30
In summer pasture:
  Kobresia humilis                3.03[+ or -]0.98
  Stipa aliena                    7.43[+ or -]1.31
  Lancea tibetica                 0.48[+ or -]0.49
  Kobresia pygmaea                1.50[+ or -]0.22
  Gentiana squarrosa              1.58[+ or -]0.60
  Leontopodium leontopodioides    3.16[+ or -]0.71
  Thalictrum alpinum              0.99[+ or -]0.11
  Oxytropis deflexa               3.96[+ or -]0.76
  Saussurea superba               0.87[+ or -]0.22
  Potentilla fruticosa            2.90[+ or -]0.42
  Taraxacum brevirostre           1.26[+ or -]0.33
  Potentilla anserina             1.35[+ or -]0.38
  Poa calliopsis                  1.52[+ or -]0.49
  Potentilla multifida            1.28[+ or -]0.33
  Leontopodium nanum              1.00[+ or -]0.21
In autumn pasture:
  Batrachium bungei               2.63[+ or -]0.65
  Potentilla anserina             5.03[+ or -]0.98
  Kobresia pygmaea                3.72[+ or -]0.87
  Setaria viridis                32.46[+ or -]4.30
  Carex qinghaiensis              9.41[+ or -]1.36
  Triglochin palustre             2.59[+ or -]0.71
In winter pasture:
  Pedicularis alaschanica         5.61[+ or -]0.85
  Heteropappus bowerii           13.43[+ or -]1.78
  Stipa crylovii                  2.48[+ or -]0.76
  Stellera chamaejasme           16.81[+ or -]0.54
  Saussurea semifasciata          5.92[+ or -]3.87
  Artemisia frigida              22.06[+ or -]6.21
  Achnatherum inebrians          14.77[+ or -]2.61
  Agropyron cristatum            17.55[+ or -]2.90
  Carex qinghaiensis              5.87[+ or -]0.36
In spring pasture:
  Carex qinghaiensis             12.64[+ or -]1.89
  Achnatherum splendens          65.41[+ or -]5.25

Species                               Cover (%)
                                        n = 10
In summer pasture:
  Kobresia humilis                53.83[+ or -]8.26
  Stipa aliena                     8.17[+ or -]2.25
  Lancea tibetica                  6.67[+ or -]1.42
  Kobresia pygmaea                32.00[+ or -]8.66
  Gentiana squarrosa               1.50[+ or -]0.66
  Leontopodium leontopodioides     6.13[+ or -]1.30
  Thalictrum alpinum              15.50[+ or -]1.01
  Oxytropis deflexa                0.83[+ or -]0.00
  Saussurea superba                5.83[+ or -]3.79
  Potentilla fruticosa             0.50[+ or -]0.00
  Taraxacum brevirostre            2.70[+ or -]0.00
  Potentilla anserina              1.00[+ or -]0.00
  Poa calliopsis                  10.33[+ or -]2.19
  Potentilla multifida            25.17[+ or -]6.61
  Leontopodium nanum              10.67[+ or -]2.21
In autumn pasture:
  Batrachium bungei               10.5[+ or -]1.33
  Potentilla anserina             30.4[+ or -]3.10
  Kobresia pygmaea                24.4[+ or -]1.77
  Setaria viridis                  2.40[+ or -]0.06
  Carex qinghaiensis              28.40[+ or -]4.40
  Triglochin palustre              5.20[+ or -]0.57
In winter pasture:
  Pedicularis alaschanica         12.46[+ or -]1.90
  Heteropappus bowerii            16.09[+ or -]3.38
  Stipa crylovii                  19.69[+ or -]3.95
  Stellera chamaejasme             7.53[+ or -]1.77
  Saussurea semifasciata          28.49[+ or -]6.36
  Artemisia frigida               13.81[+ or -]5.06
  Achnatherum inebrians            8.64[+ or -]2.09
  Agropyron cristatum              2.16[+ or -]0.25
  Carex qinghaiensis              43.17[+ or -]6.99
In spring pasture:
  Carex qinghaiensis              34.01[+ or -]7.50
  Achnatherum splendens           67.35[+ or -]11.52

Species                           DM (g [m.sup.-2])
                                       n = 15
In summer pasture:
  Kobresia humilis               44.64[+ or -]5.69
  Stipa aliena                    5.90[+ or -]2.83
  Lancea tibetica                11.60[+ or -]2.32
  Kobresia pygmaea               29.52[+ or -]4.26
  Gentiana squarrosa              0.47[+ or -]0.46
  Leontopodium leontopodioides    5.40[+ or -]1.36
  Thalictrum alpinum              5.70[+ or -]1.59
  Oxytropis deflexa               1.30[+ or -]0.08
  Saussurea superba               9.19[+ or -]1.43
  Potentilla fruticosa            3.04[+ or -]0.77
  Taraxacum brevirostre           1.36[+ or -]0.23
  Potentilla anserina             5.40[+ or -]0.58
  Poa calliopsis                  1.88[+ or -]0.50
  Potentilla multifida            6.45[+ or -]1.94
  Leontopodium nanum              4.08[+ or -]0.97
In autumn pasture:
  Batrachium bungei               2.72[+ or -]0.62
  Potentilla anserina            20.13[+ or -]5.38
  Kobresia pygmaea               39.70[+ or -]4.69
  Setaria viridis                 2.97[+ or -]0.89
  Carex qinghaiensis             38.18[+ or -]6.12
  Triglochin palustre             3.40[+ or -]1.08
In winter pasture:
  Pedicularis alaschanica         6.01 [+ or -]0.46
  Heteropappus bowerii           15.05[+ or -]4.96
  Stipa crylovii                 10.44[+ or -]4.14
  Stellera chamaejasme            8.77[+ or -]2.48
  Saussurea semifasciata          7.88[+ or -]1.98
  Artemisia frigida               3.43[+ or -]1.39
  Achnatherum inebrians           5.41[+ or -]0.58
  Agropyron cristatum             2.01[+ or -]1.05
  Carex qinghaiensis             26.03[+ or -]8.17
In spring pasture:
  Carex qinghaiensis             41.74[+ or -]9.45
  Achnatherum splendens          45.32[+ or -]6.89

Table 3. The n-alkane content of species in summer, autumn and winter
pasture (mg/kg DM) (mean[+ or -]SD) (n = 2)

Species                                   C29

In summer pasture
  Kobresia humilis                 368.5[+ or -]85.3
  Stipa aliena                     334.2[+ or -]23.4
  Lancea tibetica                   64.9[+ or -]6.25
  Kobresia pygmaea                 306.1[+ or -]17.1
  Gentiana squarrosa               322.3[+ or -]19.7
  Leontopodium leontopodioides     593.7[+ or -]43.1
  Thalictrum alpinum               278.9[+ or -]10.0
  Oxytropis deflexa                160.7[+ or -]9.4
  Saussurea superba                173.5[+ or -]7.4
  Potentilla fruticosa             473.6[+ or -]19.8
  Taraxacum brevirostre            476.5[+ or -]20.9
  Potentilla anserina                  0
  Poa calliopsis                   360.9[+ or -]17.1
  Potentilla multifida             347.9[+ or -]15.8
  Leontopodium nanum               693.3[+ or -]47.6
In autumn pasture
  Batrachium bungei                361.1[+ or -]8.2
  Potentilla anserina              540.5[+ or -]14.2
  Kobresia pygmaea                 125.3[+ or -]5.4
  Setaria viridis                  323.9[+ or -]6.1
  Carex qinghaiensis               717.0[+ or -]7.3
  Triglochin palustre              281.1[+ or -]6.2
In winter pasture
  Pedicularis alaschanica          223.5[+ or -]11.8
  Heteropappus bowerii             395.8[+ or -]4.7
  Stipa crylovii                   367.4[+ or -]8.3
  Stellera chamaejasme             315.7[+ or -]9.8
  Saussurea semifasciata           955.6[+ or -]10.0
  Artemisia frigida                236.4[+ or -]3.8
  Achnatherum inebrians            100.3[+ or -]4.8
  Agropyron cristatum              134.9[+ or -]7.5
  Carex qinghaiensis               284.7[+ or -]5.2
In spring pasture
  Carex qinghaiensis               603.5[+ or -]16.8
  Achnatherum splendens            113.1[+ or -]5.2

Species                                   C31

In summer pasture
  Kobresia humilis                  143.5[+ or -]11.8
  Stipa aliena                      649.5[+ or -]27.7
  Lancea tibetica                   200.4[+ or -]12.8
  Kobresia pygmaea                  454.7[+ or -]22.1
  Gentiana squarrosa              1,135.2[+ or -]29.7
  Leontopodium leontopodioides      529.7[+ or -]40.3
  Thalictrum alpinum                474.2[+ or -]18.8
  Oxytropis deflexa                 157.6[+ or -]8.2
  Saussurea superba                  60.01 [+ or -]2.91
  Potentilla fruticosa              189.7[+ or -]10.9
  Taraxacum brevirostre             300.8[+ or -]36.1
  Potentilla anserina               210.1 [+ or -]14.7
  Poa calliopsis                    181.9 [+ or -]12.5
  Potentilla multifida              169.7[+ or -]10.3
  Leontopodium nanum                962.4[+ or -]53.9
In autumn pasture
  Batrachium bungei                   0
  Potentilla anserina               163.6[+ or -]5.6
  Kobresia pygmaea                   52.3[+ or -]5.3
  Setaria viridis                     0
  Carex qinghaiensis                 58.0[+ or -]3.1
  Triglochin palustre                 0
In winter pasture
  Pedicularis alaschanica           507.8[+ or -]6.9
  Heteropappus bowerii              807.8[+ or -]8.3
  Stipa crylovii                    737.0[+ or -]7.2
  Stellera chamaejasme               16.7[+ or -]1.7
  Saussurea semifasciata            688.5[+ or -]11.8
  Artemisia frigida                  91.8[+ or -]6.3
  Achnatherum inebrians               5.2[+ or -]0.1
  Agropyron cristatum               231.2[+ or -]6.1
  Carex qinghaiensis                804.8[+ or -]8.7
In spring pasture
  Carex qinghaiensis                  0
  Achnatherum splendens             379.7[+ or -]3.3

Species                                   C32

In summer pasture
  Kobresia humilis                    0
  Stipa aliena                        0
  Lancea tibetica                    20.3[+ or -]1.5
  Kobresia pygmaea                    0
  Gentiana squarrosa                 50.1 [+ or -]4.0
  Leontopodium leontopodioides       24.9[+ or -]1.6
  Thalictrum alpinum                 28.9[+ or -]1.7
  Oxytropis deflexa                   0
  Saussurea superba                   0
  Potentilla fruticosa                0
  Taraxacum brevirostre              18.8[+ or -]0.1
  Potentilla anserina                24.7[+ or -]1.3
  Poa calliopsis                      0
  Potentilla multifida                0
  Leontopodium nanum                 36.6[+ or -]3.7
In autumn pasture
  Batrachium bungei                 252.8[+ or -]10.8
  Potentilla anserina                19.3[+ or -]2.6
  Kobresia pygmaea                    0
  Setaria viridis                     0
  Carex qinghaiensis                  0
  Triglochin palustre                 0
In winter pasture
  Pedicularis alaschanica            62.2[+ or -]5.1
  Heteropappus bowerii                2.3[+ or -]0.1
  Stipa crylovii                     16.2[+ or -]1.3
  Stellera chamaejasme               32.9[+ or -]2.7
  Saussurea semifasciata             25.7[+ or -]2.5
  Artemisia frigida                   0
  Achnatherum inebrians               0
  Agropyron cristatum                 0
  Carex qinghaiensis                175.1 [+ or -]9.3
In spring pasture
  Carex qinghaiensis                  0
  Achnatherum splendens               0
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Article Details
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Author:Ding, L.M.; Long, R.J.
Publication:Asian - Australasian Journal of Animal Sciences
Article Type:Report
Geographic Code:9CHIN
Date:Mar 23, 2010
Words:4862
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