Relationship between terrain use and performance of beef cows grazing foothill rangeland

A study was conducted on foothills rangeland to determine whether grazing p atterns differed among cow breeds and to determine whether there was a rela tionship between individual grazing patterns and performance of beef cows. Hereford (HH), Tarentaise (TT), 3/4 Hereford x 1/4 Tarentaise (3H1T), 1/2 H ereford x 1/2 Tarentaise (HT), and 1/4 Hereford x 3/4 Tarentaise (1H3T) cow s were observed during the summers of 1997 (n = 183) and 1998 (n = 159). Lo cations of individual cows were recorded two to three times per week during 1.5- to 2.5-h periods in the morning by observers on horseback. Statistica l models included cow breed, age, and nursing status. Data from each year w ere analyzed separately. During 1997 and 1998, nonlactating cows were locat ed at greater (P < 0.05) vertical distances from water than lactating cows. In 1998, nonlactating cows used steeper (P < 0.05) slopes than lactating c ows. However, nonlactating cows did not travel as far horizontally from wat er (P < 0.05) as lactating cows in 1997. Younger cows (3 yr) traveled furth er (P < 0.05) from water both vertically and horizontally than older cows ( 5+ yr) in 1997, but not during 1998. Tarentaise and 1H3T cows were observed at greater (P < 0.05) vertical distances from water than HH cows during bo th years of the study. During 1998, TT and 1H3T cows used steeper (P < 0.05 ) slopes than HH cows. Using residual correlations, there were no consisten t relationships between topographic aspects of individual grazing locations and cow weight, height, and body condition score. In 1997, cows with earli er calving dates and correspondingly heavier calf weaning weights used area s that had greater vertical distances to water; however, in 1998 there were no relationships (P > 0.05) of calving date and weaning weight with cow lo cation. During both years, pregnant and nonpregnant cows used terrain simil arly (P > 0.05), which suggests that cow reproductive performance was not r elated to terrain use. Grazing patterns in foothills rangeland varied among cow breeds. Performance of cows that used more rugged topography was simil ar to cows using gentler terrain.