Document Type : Research Paper
Authors
1 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.
3 ,Department of animal science, Golpayegan Branch, Islamic Azad University, Golpayegan, Iran
Abstract
Objective: Golestan Province, possessing valuable rangelands, faces challenges from climate change and human activities, leading to reduced productivity and disrupted 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 particular importance. Recent field studies indicate the occurrence of metabolic disorders in the region's sheep, likely stemming from mineral deficiencies at various levels of this food chain. This research was conducted to investigate the correlation between the minerals present in the soil and forage of Golestan Province's rangelands and the serum element levels in lactating Dall lambs. A secondary objective was to examine the correlative relationships between the levels of these elements across different matrices and to analyze the impact of environmental variables on their bioavailability.
Material and Methods: The present study was conducted in June 2024 in Golestan Province. Fifty soil samples were collected from five distinct areas of the province (Maraveh Tappeh, Incheh Borun, Ghaleh Miran, Chahar Bagh, and Gomishan). Fifty samples of mature rangeland forage, each comprising a uniform mixture of forage species from the area with a dry weight of 50 grams, were harvested, packaged, and transferred to the laboratory for measurement of the target elements. To investigate serum element concentrations in sheep, blood samples were collected from 50 heads of Dalagh sheep in the study areas (10 per area) and transported to the laboratory. Data obtained from laboratory analyses were statistically evaluated 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.
Results and Discussion: Based on soil analysis results, the macro-elements, including calcium, magnesium, potassium, and sulfur, showed significant differences among rangelands, indicating greater sensitivity of these elements to the ecological and soil characteristics of different regions. Forage analysis revealed that only phosphorus concentration differed significantly among rangelands, while the concentrations of other macro and micro-elements were within a similar range and showed no significant regional differences. The concentration of elements in animal blood serum followed a similar pattern, with only calcium and phosphorus showing significant differences among rangelands. Correlation analysis results indicated that the pattern of association between mineral elements in the soil-forage-animal serum chain was not uniform and was dependent on the element type. The metallic micronutrients include iron, zinc, copper, and manganese exhibited stronger and more consistent correlation coefficients among soil, plant, and animal blood serum compared to macro-elements. In contrast, correlations for macro-elements within this chain were generally weaker and more variable.
Conclusion: Considering the totality of mineral elements examined in this study, differences in the nutritional status of grazing animals were observed among the studied rangelands. Based on the overall pattern of elements in soil, forage, and blood serum, the Ghaleh Miran and Gomishan rangelands demonstrated greater stability and harmony in mineral concentration throughout the soil-forage-serum chain compared to other areas. In contrast, the Chahar Bagh rangeland, despite the availability of some elements in soil and forage, showed signs of macro-element imbalance, particularly in the calcium-to-phosphorus ratio, at the serum level in animals, likely due to absorption or homeostatic regulation of these elements in the livestock. Overall, the Ghaleh Miran and Gomishan rangelands exhibited more favorable conditions. In contrast, the Maraveh Tappeh and Incheh Borun rangelands showed greater fluctuations and a less stable pattern in the concentration of certain elements, and the Chahar Bagh rangeland displayed a different pattern regarding mineral balance at the animal serum level.
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