Feed Intake Specifications in Defining Breeding Objectives

SUMMARY Development of selection objectives for beef cattle requires tion of the available feed resources. In production systems \Ji th to li~eral quantities of harvested feeds of relatively high quality to improve economic eff iciency ~lill normally favor animals ~li th high potentials for the primary production traits. Hovlever , these highly types may also have relatively high maintenance requirements and be efficient when nutrient restrictions prevent expression of genetic in appetite. 'l'hus , important genotype :~ environment interactions may observed. In range environments, animals may be restricted in the of forage that can be harvested. These restrictions usually arise from inability of the animal to increase grazing times or feed intake rates certain levels imposed by the sl-lard and by innate animal requirements rest and rumination. In addition, maintenance requirements are often in range environments , thereby further limiting the increases in capacity that can be accommodated. Under conditions of nutrient antagonistic phenotypic relationships may also be observed among traits (such as milk production and reproduction). The nature of tionships must be considered in the development INTRODUCTION