Effect of sire breed on intake of grazing beef steers

摘要

A 3-year study was conducted to monitor the effects of sire breed of steers on food intake. Steers sired by high (Charoiais) or moderate (Hereford) growth potential bulls were grazed near Miles City, MT (46° 22' N, 105° 5' W). Fecal output of suckling calves and yearling steers was estimated using chromic sesquioxide in a sustained release bolus (Captec, Nufarm) as an external marker. In vitro digestibility of esophageal masticate was used to determine diet digestibility. Milk intake of calves wasmeasured by weigh-suckle-weigh. June collections were made on 68 ha of rangeland that had been seeded to Russian wildrye (Psathrostachys juncea), July collections were made on 80 ha of contour furrowed rangeland that was interseeded with alfalfa (Medicago sativa), September collections were made in a 265 ha pasture of native rangeland. Suckling calves were weaned in early October and placed on a 38-ha irrigated pasture of a wheatgrass-wildrye complex. Forage intakes of these calves were measured in late October and early December.