Abstract: In this study, total nutrient and Selenium (Se) content of 84 pasture grass samples taken from 15 locations around Van Lake and were analyzed. The samples were collected every 15 days between May 15th 1996 and August 15th 1996 for seven different periods. Sampling was performed in 1 location for 3 periods, in 5 locations for 5 periods, in 7 locations for 6 periods and in 2 locations for 7 periods. The differences between periods were not significant in Crude Ash (CA%) (p>0.05) but were significant in Dry Matter (DM%), Crude Protein (CP%), Ether Extract (EE%), Crude Fiber (CF%) and Nitrogen Free Extract (NFE%) (p<0.05). There were significant differences between locations in DM, CP, EE, CA, CF and NFE% (p<0.05). Regression analysis results showed no relationship between DM, CP, EE, CA, CF and NFE% and Se (mg kg^-1) content.

INTRODUCTION

The importance of animal food stuffs in human consumption has become the main reason in the interest of human to animals.

In animal feeding, meadows and pastures have an important part in animal husbandry; therefore, studies on them are very effective on animal production.

Due to the fact that Eastern Anatolia is an important region for animal production, determining both nutrient content and Se content, said problematic in the region of the meadows and pasture of Lake Van Basin will fill the gap in the region.

Although, Se has been known as a toxic element since 1817, it was determined as an essential nutrient in 1957. It has been reported that the deficiency or excess of Se in meadows and pastures cause several diseases and negative nesses in animals (Beale et al., 1990).

Selenium is an essential micro element. As reported in Pehrson et al. (1993) Schawanz and Folltz revealed that Se prevented the lung degeneration in rats fed whit inadequate vitamin E; therefore, showed that it is an essential nutrient. Moreover, when Se is taken up over the requirement, it becomes toxic. It has been known as a toxic element far many years. On the other hand, inadequate Se causes many diseases and negative nesses in many animal species Sevgican (1977) and Spallholz (1994) retorted the deficiencies caused by inadequate Se as fatigue, weakness, decrease in wool and offspring production, weak teeth, white muscle disease in sheep and fatigue, weakness and problem in placenta removal (throw) in cattle. Se has important roles in cell respiration. In an organism, Se content is the most abundant in liver and kidneys, but the least abundant in blood, pancreas, spleen, hair and horns. Se accumulation increases in some period based on the consumed amount and then a balance is established between the up taken and removed Se (Spallholz, 1994). Rotruck and Fhale independently determined that Se is an indents able building material of GSH Px in 1973 and is was the most important biochemical role of Se. With this property, Se protect from oxidative pressure (Zachara et al., 1992).

Due to the complexity of deface mechanisms related whit the oxygen poisoning and lipid oxidation in cell level, three functions of Se-GSH-Px have been demonstrated only experimentally up until now. These functions are, Se-GSH-Px prevents oxidation by destroying H₂O₂ and hydrocyperoxide in erythrocytes, Se-GSH-Px regulates the H₂O₂ concentration in cells when katalaz activity is low or absent and Se-GSH-Px blocks lipid peroxsidation in liver and destroys H₂O₂.

In the study, no certain criteria has been determined in order to find out the suitable levels of Se compounds. In contrast to white muscle disease and problems in plesenta throw, it is difficult to find adequate experimental results for total Se concentration in serum, tissue and blood. Another negative situation is that different diagnostic methods have been applied in Se measurements such as the determination of Se levels in serum or plasma, the determination of peroxides activity in plasma or blood (Galgan and Frank, 1993).

Food and Drug Administration in the USA stated that 0.1 ppm of Se level in pigs and chickens and 0.2 ppm of Se level in turkey’s feed provided safety in 1974. On the other hand, in 1987, it was concluded that the minimum 0.3 ppm Se for each kg of dry matter of feed should have given to chickens, turkeys, pigs, sheep and cattle in order to prevent health problems and other negative consequences (Ullrey, 1992).

The results on the Se uptake in ruminants were all different. These differences were caused by the various criteria taken into consideration such as the form of Se, the Se reserve of the animal, various factors in feed (proteins and the structure and concentrations of heavy metals) and the structure of mixed feed. According to the World Health Organization reports 0.2 ppm Se concentration for each kg dry matter of ruminants’ feed was enough to prevent Se inadequacy. On the other hand, Conrad and Smith recommended the use of 0.03 mg Se addition per kg dry matter of feed. However, nowadays it is agreed that 0.01 ppm Se addition is adequate (Zachara et al., 1992).

The 68.7% of protein and 62.2% of starch in crude feed is supplied from meadows and pastures in plateaus. The starch, crude protein and crude fiber levels of the dry matter contents of plant species in Turkey’s meadows and pastures were 45.1, 9.4 and 35.6%, respectively in gramineae species, 40.9, 19.9 and 25.1%, respectively leguminosea species and 49.6, 33.0 and 22.1%, respectively other species (Genckan, 1985).

MATERIALS AND METHODS

Total 84 meadow plant samples from 12 towns of Van province (Erek-Central, Fidanlik-Central, Edremit, Gevas, Catak Gurpinar, Baskale, Ozalp, Saray, Muradiye, Caldiran, Ercis) and 3 towns of Bitlis province (Adilcevaz, Ahlat, Tavan) were evaluated from 15th May to the end of vegetation period in fifteen day intervals.

Se analysis of samples were carried out at the beginning middle and end of the vegetation period, but when there was inadequate samples in that periods, samples from the close dates were used. In some regions, samples couldn’t collect in some periods due to various reasons.

The exact places of meadows were determined after fixing the subject of this study. The Staff of Province Agricultural Managements and 9th village Support Management was interviewed on April 20th and 21st 1996. By taking into consideration the soil structure and meadows’ characteristics of the regions, representative meadows were chosen on the maps and these regions were visited on the first three days of May 1996 and samples were taken in 15 days intervals from May 15th to end of the vegetation period in the selected meadow parcels.

Samples were put into the plastic bags and carried to the laboratory were some parts of the samples were dried immediately at 105°C and analyzed. The rest of the samples were naturally dried in laboratory condition. Dried samples were sieved in a 1 mm-mesh size grinder and saved in plastic bags. All nutrient matters except crude starch were analyzed by the method of Weende (Akyildiz, 1984). Crude cellulose was analyzed by the method published in Official News Paper in 21 January 1992 (Anonymous, 1992).

The hydrur formation method was used in the Se analysis. The Se amount was determined by atomic absorption spectrophotometer in heated quartz tubes after Se (IV) was transformation into SeH₂. External calibration technique and standard addition method was used in this analysis (Anonymous, 1997).

All data were subjected to analysis of variance using General Linear Model procedure of SAS (1982). Mean treatment differences were determined by Duncan’s multiple range tests with a level of statistical differences of 5% (Duzgunes et al., 1978).

RESULTS AND DISCUSSION

The main objective of this study was to determine the Se and nutrient content of meadows located in 15 regions of Lake Van Basin and collected in 15 days intervals (Table 1). The sample sizes were different in these regions. Table 2-10 demonstrate the nutrient contents of meadows.

Crude nutrient content results were determined for each period (from 1-7) in the Table 2-10.

Based on the analysis it was seen that the meadows of Lake Van Basin had general crude nutrient content characteristics of meadows even some had better crude nutrient content (9). Crude nutrients were presented as percentage in dry matter content. While, the highest CP level (20.06%) was obtained from the first period in Adilcevaz region, the lowest one (4.63%) was obtained from the 6th period in Muradiye region. The highest CL (3.76%) was obtained from the 6th period in Gurpinar, while the lowest one (1.08%) was obtained from 2nd period in Edremit. The highest CA (17.01%) was obtained from the 3rd period of Ercis, while the lowest one (4.92%) was obtained from the 4th period in Baskale. While, the highest CC value (42.40%) was obtained from the 4th period in Saray, the lowest one (22.18%) was obtained from the 1st period in Ercis. The highest NFE (62.17%) was obtained from the 6th period Fidanlik-Central, the lowest one was obtained from the 4th period in Ercis.

Table 1:	The regions, the numbers and dates of samples
*Taking the samples began on 01.06.1996; **Taking the samples didn’t made in Baskale because of security reasons on 16.05.1996 and 16.06.1996; ***Taking the samples didn’t made the last 4 period becous of kuraklik

Table 2:	Parameter estimates for 1st period
*Dray matter in fresh matter; **Because the vegetation wasn’t starting, samples weren’t taken in this period

Table 3:	Parameter estimates for 2nd period
*Dray matter in fresh matter

There was significant (p<0.05) differences for DM, CP, CL, CC and NOM in the regions and periods. The regions, but not periods were significantly (p<0.05) different for CA. Se content was insignificant in the regions and periods. The highest Se content (0.0301 ppm) was obtained from the second period and lowest one (0.226 ppm) was obtained from the 6th period. Average essential Se content for ruminants is between 0.02-0.30 ppm. However, in this study the Se content never reached to the upper limit (0.3 ppm). However, in some places and periods (2nd periods of Erek, Edremit, Fidanlik, Ahlat, Muradiye, Caldiran 4th periods of Ercis and Ahlat) it dropped below the lower limit (0.02 ppm).

Based others results, it was shown that there was no constant inadequacy for the some region, but there were some inadequacy in some periods of some regions. The highest two Se contents (0.0634 ppm and 0.0421 ppm) was obtained from the 2nd period in Muradiye and the 4th period in Saray, respectively.

Table 4:	Parameter estimates for 3rd period
*Dray matter in fresh matter; **Taking the samples didn’t made in Baskale because of security reasons

Table 5:	Parameter estimates for 4th period

Table 6:	Parameter estimates for 5th period

Table 7:	Parameter estimates for 6th period
*Dray matter in fresh matter; **Because the vegetation finished, samples weren’t taken in this period

Table 8:	Parameter estimates for 7th period
*Dray matter in fresh matter; **Because the vegetation finished, samples weren’t taken in other location

Table 9:	Parameters (%) of the all periods and standard error
a-f: Values with different letters in the same line differ significantly (p<0.05)

Table 10:	Parameters of Se (mg kg-1)
*Because vegetation in Saray town was short, samples were collected in only 5 periods; **There was drought in Caldiran town and after the first three periods, there were no samples

Table 11:	Correlations among DM, CP, EE, CA, CF, NFE and Se
*Significant at p<0.05; **Significant at p<0.01; a: Insignificant relationship with Se (+/-) b: Percentage value

The lowest two Se contents (0.0149 ppm and 0.0150 ppm) were obtained from the 6th period in Ahlat and the 6th period in Fidanlik-Central-Van.

When evaluating the correlations among DM, CP, CL, CA, CC, NFE and Se there were insignificant correlations among these combinations; DM-CL, DM-CA, DM-Se, DM-NFE, CP-CL, CP-CA, CP-NFE, CL-CA, CL-Se, CP-Se, CA-Se and NFE-Se. There were very significant (p<0.01) positive correlations between DM and CC and between CA and NFE.

There were also significant (p<0.05) and negative correlations between CC and Se and between CP and Se. There were also significant (p<0.05) and positive correlation between CA and CC and between CL and CC (Table 11).

CONCLUSION

Obtained from the region of the basic nutrient content of pasture grasses in general reflected the topical characteristics. However, some differences were observed in the basic nutrient content between the periods and the region due to soil structure and climate in the study area. Expected the maximum and minimum levels of selenium in ruminant feed rations are 0.30-0.02 mg kg^-1. In this stud, selenium values were found near the lower limits. There were found same negative and positive correlations between selenium and other nutrients but those are statistically insignificant.

In this study, it was concluded that good for ruminant animal production activities selenium should be added to the ruminant rations in the region.

ACKNOWLEDGEMENT

This research was financially supported by TUBITAK Project no: TOGTAG-1536