Browse selection by Karakul sheep in relation to plant composition and estimated metabolizable energy content

Abstract

Large areas of the Central Asian Republic of Kazakhstan are classified as desert and semi-desert rangelands and are subjected to severe climatic extremes. The sparse vegetation of these rangelands supports mainly grazing sheep, which are raised for wool and meat production. These two products are important to the national economy and the livelihood of the rural population. The extremes of climate cause periodic shortages of fodder availability that, together with the lack of drinking water and adequate animal shelters, can cause severe animal loss, particularly during the winter but also in other seasons. Desert rangeland improvements have been instigated by the introduction and planting out of palatable drought-resistant fodder shrubs to augment the natural species, many of which appear to have survived only because they are unpalatable and/or inedible. To determine the edibility of 15 natural species, Karakul sheep were observed grazing and/or browsing them and identified those species that were edible. It was predicted that the sheep would selectively browse from shrubs with low phenolic concentration, high estimated metabolizable energy content, high crude protein content and low fibre content. To test this prediction, the shrub foliage was analysed and edibility by sheep was related to chemical composition and estimated metabolizable energy content. Six of the 15 plant species were edible. The only significant factor in determining whether plants were eaten was total phenolic content – plants eaten had a content of 17·7±6·3 g/kg DM whereas plants not eaten had a content of 66·4±129·6 g/kg DM. Metabolizable energy, protein and fibre contents did not affect edibility of the plants.