Effect of Long-Term, Year-Long Grazing at Moderate and Heavy Rates of Stocking on Diet Selection and Forage Intake Dynamics

Abstract

A 2-year experiment was conducted to determine the effect of 27 years of continuous grazing at moderate (7 ha/cow/yr) (MC) and heavy (5 ha/cow/yr) (HC) rates of stocking on seasonal diet selection and forage intake dynamics. Nine trials were conducted to determine differences between treatments in botanical composition and quality of diets and forage intake. Proportion of Texas wintergrass (Stipa leucothrica Trin. and Rupr.) in diets was greater (P<.05) in the MC than HC treatment whereas amounts of warmseason shortand midgrasses were less. Differences between treatments in botanical composition of diets were related to differences in seasonal availability and live:dead tissue ratios of forages. However, such differences did not generally affect diet quality. Supplementation of HC cattle with 20%/o CP breeder cube either replaced forage organic matter intake (January 1986) or substituted for insufficient forage availability (February 1987). Supplementation never stimulated forage intake. Forage organic matter intake was restricted at forage standing crops below 700 kg/ha.