New approaches for enhancing grazing productivity: Meeting the challenges of variable environments1.

Livestock management on rangelands is challenging because rangelands are characterized by inherently low and variable precipitation, a complex native forage base that varies widely in nutritive value and toxicity, and topographic variation encompassed by large pastures. One approach to managing the consequent low and variable forage supply is to exploit the natural abilities of animals. Livestock adapted to low forage supply are those with low relative maintenance requirements. Livestock management systems can be designed to respond to distinct seasonal plant growth patterns by ensuring that peak nutrient demand coincides with the period of nutritious available forage. Herbivores vary substantially in their ability to harvest and digest range-land forages. Making efficient use of existing forage resources can therefore be accomplished by selecting the species and breed of animal that has the natural ability to eat the available forage. The differences between herbivores in landscape use patterns could also be exploited to create livestock enterprises that best meet the topographic character of a specific ranch. Livestock well adapted to rangeland conditions can be selectively culled and bred for desired characteristics and given opportunities to learn about the grazing resource. The flexible and opportunistic strategies necessary for successful management in variable ecosystems are rooted in a clear understanding of the challenges facing the grazing animal and its natural abilities to meet these challenges. The livestock manager's role is to facilitate and exploit these natural abilities to efficiently convert forage into saleable livestock products. [ABSTRACT FROM AUTHOR]