Influence of Breed on Forage Intake of Range Beef Cows

Abstract

We estimated forage intake of Hereford (HH) and 75% Simmental-25% Hereford (3S1H) cows grazing in northcentral Montana during the summer grazing season of 1982. Cows ranged freely over a 81-ha pasture of rough fescue (Festuca scabrella)-dominated rangeland. Intake was estimated for 6 lactating (March calved) and 6 nonlactating cows of each breed type in June, July, August, and September, 1982. Fecal output of dry cows was measured with total fecal collections and was also estimated with the chromic oxide dilution technique. Only the chromic oxide technique was used for lactating cows. Three to 4 esophageal-fistulated cows of each breed type were used for collection of dietary material suitable for in vitro digestibility analysis. Organic matter intake (as a percentage of body weight per day, %BW/D) of nonlactating HH and 3S1H cows did not differ (P is greater than or equal to 10), averaging 1.3% BW/d (using total fecal collection estimates). Chromic oxide derived forage intake estimates were 15% higher (P<.10) than total fecal collection estimates. Breeds responded similarly (P4 1/4.10) to both fecal output estimation techniques. Forage intake estimates for lactating cows were adjusted for this overestimation, and lactating 3S1H cows consumed more (P<.10) forage than lactating HH cows (1.9 vs. 1.7% BW/d, and 10.9 vs. 7.8 kg/d, respectively).