Document Type : Research Paper
Authors
Abstract
Forage quality is one of the most important factors in determination of the rangeland grazing capacity and also indicates the sufficiency of nutritive requirements of grazing animals. In this research, the samples of range species (including; Acantholimon festucaceum, Andrachne fruticulosa, Artemisia sieberi, Euphorbia decipiens, Noaea mucronata, Scariola orientalis, Stachys inflate, Stipa Arabica and Stipa barbata) in Maime, which were dominant in region, were collected in three phenological stages (vegetative, flowering and seeding) in three replications, and five individual plants were collected in each replication. Then, plant samples were chemically dissolved to measure the nitrogen (N) and acid detergent fiber (ADF). A split plot in a completely randomized design was used to analyze the data. Results indicated that the mean of effective indices on forage quality had considerable changes in phenological stages and it had significant influence on the forage quality. With progress of growth stages, the amount of crude protein (CP), dray mater digestibility (DMD) and metabolism energy (ME) decreased and the amount of acid detergent fiber (ADF) increased. In addition, results showed that crude protein amounts of all studied species in vegetative and flowering stage swere more than critical level (7%) for need of daily animal requirement and in seeding stage was less than animal requirement. Mean value of dray mater digestibility (DMD) in vegetative stage was more than critical level (50%), and in flowering stage and seeding stage were less than its critical level for need of maintenance. The mean value of metabolism energy in all three phenological stages was less than critical level (8 Mj/Kg/DM) for need of maintenance of single animal unit. This suggests that desirable quality of pasture forage at different grazing times is not same and determination of daily animal unit requirement based on forage quality is needed. In general, the studied ranges are desirable in terms of supplying the required daily crude protein for animal units, grazing in rangelands, but in terms of providing metabolism energy are undesirable.
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