Differences among beef sire breeds and relationships between terrain use and performance when daughters graze foothill rangelands as cows

A study was conducted on foothill rangeland to determine if breed of sire affected grazing distribution patterns and to evaluate relationships between individual grazing patterns and performance of beef cows. Angus (AN), Charolais (CH), Piedmontese (PI), and Salers (SA) sires were mated to dams with Hereford and Tarentaise breeding to produce cows observed during the summers of 1998–2001. Locations of individual cows were recorded two to three times per week during 1.5–2.5-h periods in the morning by observers on horseback. Terrain use was analyzed using a mixed statistical model that included breed of sire, dam terrain use category as fixed effects and cow as a random effect. Piedmontese-sired cows were observed farther (P < 0.05) horizontally from water and showed a tendency toward higher (P = 0.09) pasture ratios (PR) of terrain use than AN-sired cows. Cows from dams that used steeper slopes and areas farther from water grazed farther (P < 0.05) vertically from water, tended to be observed farther (P = 0.09) horizontally from water, and had a PR greater (P < 0.05) than cows from dams that used gentle terrain near water. Relationships between terrain use and animal performance were evaluated each year using residual correlations from a model that included sire breed, dam breed, cow age, and pasture. In 1998 and 2001, cows that were heavier (P < 0.05) and in 1998 taller (P < 0.05) traveled farther horizontally from water than did lighter cows. Relationships between cow weight or hip height and horizontal distance to water were not observed during other years. No other relationships between terrain use and cow performance were found (P > 0.05). Terrain use was not correlated (P > 0.05) to calving date, actual weaning weight, or age-adjusted weaning weight. Pregnant cows used steeper (P < 0.05) slopes in 2001, but no differences were detected in the other 3 years (P > 0.05). Cows sired by bulls from breeds developed in mountainous terrain appeared to use rugged extensive pastures more uniformly than cows sired by bulls from breeds developed in gentler terrain. As observed in an earlier study, terrain use of cows grazing foothill rangeland was not consistently related to their weight, hip height, body condition, reproductive performance, or calf weight.