Developmental Morphology of Smooth Bromegrass Growth Following Spring Grazing
2003
Brueland, B. A. | Harmoney, K. R. | Moore, K. J. | George, J. R. | Brummer, E. C.
The timing of initial spring grazing of smooth bromegrass (Bromus inermis Leyss.) pastures affects regrowth potential and subsequent forage yield and quality. This study was conducted to quantify the effects of the timing of the initiation of spring grazing on these factors. A field experiment was conducted at the Rhodes Research and Demonstration Farm in central Iowa from April through July in 1996 and 1997. Treatments were an undefoliated control and four initial dates of defoliation that were applied weekly, beginning when one fully collared leaf per tiller was present. Defoliation was done using two mature cattle (Bos taurus) to quickly (12–24 h) graze the sward to a height of 5 to 10 cm. Regrowth was sampled weekly for 8 wk, staged, and analyzed for forage quality. Early grazing of smooth bromegrass pastures did not delay sward development. Initiation of grazing at the later dates caused short delays in both development and the ability to regrow rapidly, but allowed utilization of a larger quantity of forage for the initial grazing event, with minimally decreased forage quality. Sward development differed between years. Tiller density and mean stage count did not differ among treatments during the 7 wk after defoliation in 1996 but did so in 1997. However, by the end of 8 wk, development was similar for all treatments. On the basis of this study, initiation of grazing when one fully collared leaf per tiller was present, followed by an adequate recovery period before beginning rotational grazing would give producers an early start on pasturing with limited impact on sward yield and health.
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