Effects of range condition on the temporal diet selection by goats in steppe rangelands of Iran

Abstract

One of the key factors in managing a rangeland is to determine the relative preference of its major plant species by the<br />grazing livestock. Preference value of each plant species is affected by plant type, companion plants, availability by<br />animals, phenological stage, climate condition, and the livestock species. We investigated the grazing behaviour of a<br />native goat (Garizi) in the steppe rangelands of Iran, from May to November 2004. The study was conducted within or<br />outside of an enclosure, representing a Good Condition (GC) or a Poor Condition (PC) rangeland, respectively. Flocks of<br />six goats were selected randomly and their grazing behaviour was monitored by chronometers. Grazing preference was<br />considered as the time goats had spent for grazing each plant species. The grazing season was divided into 4 grazing<br />periods, 45 days each. Data recording in the GC and PC sites was repeated 3 times during each grazing period. The<br />experiment was designed as the completely randomized blocks. In the GC site, grazing pressure on the perennial grass<br />Stipa barbata and the perennial chenopod Salsola rigida was low at the beginning of the grazing period, but it was<br />increased towards the end of the grazing season. In the PC site, the main grazing pressure was on noxious plants such as<br />Scariola orientalis, Launaea acanthoides, and Cousinia deserti. For both GC and PC sites, the time of grazing had<br />significant influences on relative abundances of annual plants and plant litter, which subsequently changed diet selection<br />by the Garizi goat. One of the key factors in managing a rangeland is to determine the relative preference of its major plant species by the<br />grazing livestock. Preference value of each plant species is affected by plant type, companion plants, availability by<br />animals, phenological stage, climate condition, and the livestock species. We investigated the grazing behaviour of a<br />native goat (Garizi) in the steppe rangelands of Iran, from May to November 2004. The study was conducted within or<br />outside of an enclosure, representing a Good Condition (GC) or a Poor Condition (PC) rangeland, respectively. Flocks of<br />six goats were selected randomly and their grazing behaviour was monitored by chronometers. Grazing preference was<br />considered as the time goats had spent for grazing each plant species. The grazing season was divided into 4 grazing<br />periods, 45 days each. Data recording in the GC and PC sites was repeated 3 times during each grazing period. The<br />experiment was designed as the completely randomized blocks. In the GC site, grazing pressure on the perennial grass<br />Stipa barbata and the perennial chenopod Salsola rigida was low at the beginning of the grazing period, but it was<br />increased towards the end of the grazing season. In the PC site, the main grazing pressure was on noxious plants such as<br />Scariola orientalis, Launaea acanthoides, and Cousinia deserti. For both GC and PC sites, the time of grazing had<br />significant influences on relative abundances of annual plants and plant litter, which subsequently changed diet selection<br />by the Garizi goat.