Production and Quality of Forage and Economics of Grazing a Hay Meadow in the Spring

An experiment was conducted to determine the effects of spring grazing on forage DM production and nutritive value, as well as the economics of spring grazing a flood-irrigated hay meadow. Two vegetation types were present: predominantly ‘Garrison’ fcreeping foxtail (Alopecurus arundinanceus Poir) and a complex mixture with both introduced and native species. With use of cages, samples of ungrazed and grazed treatments were collected before and after grazing and also in August. Eighty-eight Angus × Gelbvieh rotationally-crossed heifers (average BW = 361.3 kg) were allowed to graze from May 27 to June 8 at 5.4 heifers/ha. A sampling date effect (P < 0.0001) occurred for forage DM production. Forage DM production was not different (P = 0.90) between native species and creeping foxtail. Also, grazing treatment did not alter (P = 0.23) forage DM production. Vegetation types were not different (P . 0.19) in ash, NDF, ADF, and CP, but creeping foxtail was greater (P = 0.02) in in vitro DM digestibility than the native species group. The loss of 12,025kg of forage due to early grazing treatment, at a hay price of $0.0772/kg, resulted in a replacement hay value of $928. Forage plants were able to adequately recover from grazing despite atypical environmental conditions; however, expected improvements in quality did not occur with the early grazing treatment. It is concluded that although spring grazing by beef heifers did not affect forage production and most indices of forage quality, less harvestable nutrients in late summer were more costly than feeding harvested forage or renting pasture for the spring-grazing period.