Document Type : Research Paper
Authors
1 Department of Soil Science, Gorgan university of Agricultural Sciences and Natural Resources, Gorgan, Iran. E-mail: pooria.pezeshknejad_s00@gau.ac.ir
2 Department of Animal Sciences Research, Agricultural and Natural Resources Research and Education Center of Gorgan, Gorgan, Iran. E mail: Mohammad.asadi_s97@gau.ac.ir
3 ,Corresponding Author, Department of animal science, Golpayegan Branch, Islamic Azad University, Golpayegan, Iran. E mail: smirhabibi@iau.ac.ir
Abstract
Objective: the Golestan Province has rangelands of high value but these are threatened by climate change and human activities that can lower productivity and ecosystem function. Since soil is the primary substrate for supplying mineral elements to the soil-plant-livestock food chain, assessing the status of macro and micro-elements within this system is of special interest. Recent field studies indicate that there may be metabolic disorders in the sheep of the region, which may be caused by mineral deficiencies at various levels of this food chain. The present study was aimed at investigatingthe association ofthe minerals in the soil and forage of rangelands Golestan Province with the serum element levels in lactating Dall lambs and also correlating the levels of these elements across different matrices and to determining the effect of environmental factors on their bioavailability.
Method: The present study was conducted in June 2024 in Golestan Province, Iran. Fifty soil samples were collected from five different areas of the province (Maraveh Tappeh, Incheh Borun, Ghaleh Miran, Chahar Bagh, and Gomishan). Fifty samples of mature rangeland forage, containing a uniform mixture of forage species from the area and a dry weight of 50 g, were harvested, packaged, and transferred to the laboratory to measurethe target elements. To determine serum element concentrations in sheep, blood samples were taken from 50 heads of Dalagh sheep in the study areas (10 per area) and sent to the laboratory. The data were statistically analyzed in a completely randomized design with 5 treatments and 10 replications using SAS 9 software (Tukey; P<0.05). Pearson correlation analysis was performed using R software (version 4.5.1).
Results: Soil analysis results indicated the macro-elements calcium (P=0.0001), magnesium (P=0.0001), potassium (P=0.0311), and sulfur (P=0.0017), differed significantly among rangelands and were more sensitive to to ecological and soil characteristics of the regions, whereasonly phosphorus concentration (P=0.0033) differed significantly among rangelands in forage analysis and theother macro and micro-elements were in the same range and were not significantly different among the rangelands. Concentration of elements in animal blood serum also reflected this pattern, except for calcium (P=0.0217) and phosphorus (P=0.0011) which were significantly differentamong rangelands. Correlation analysis indicated that the correlation pattern between mineral elements in the soil-forage-animal serum chain was not consistent and varied based on element type. The metallic micronutrients (iron, zinc, copper, and manganese) showing stronger and more consistent correlation coefficients among soil, plant, and animal blood serum than the macro-elements, and correlations for macro-elements were generally weaker and more variable within this chain.
Conclusion: Among the rangelands studied, based on the general pattern of mineral elements in soil, forage, and blood serum, the Ghaleh Miran and Gomishan rangelands were more stable and balanced in terms of mineral concentration throughout the soil-forage-serum chain, while the Chahar Bagh rangeland, although some elements were available in soil and forage, had a macro-element imbalance (e.g., calcium-to-phosphorus ratio) at the serum level in animals, possibly due to absorption or homeostatic regulation of these elements in livestock.. The Ghaleh Miran and Gomishan rangelands, on the other hand, had more favorable conditions, whereas the Maraveh Tappeh and Incheh Borun rangelands showed greater fluctuations and a less stable pattern in the concentration of some elements, and the Chahar Bagh rangeland displayed a different pattern with regard to mineral balance at the animal serum level. The results support the conclusion that the stability and biological balance of the mineral transfer chain is more important than soil richness in determining the health and efficiency of this chain in rangelands.
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