Native warm-season grasses (NWSGs) have demonstrated potential to reduce summer forage variability, and furthermore, there has been growing interest in the use of NWSGs as lignocellulosic biomass crops. Th e objective of this research was to determine if there was a diff erence in net returns for full-season summer grazing beef steers (Bos taurus) on three NWSGs. Additionally, the expected price for biomass that a beef producer would need to break even between using the dual-purpose early-season grazing and biomass system and the full-season grazing system was calculated for these three NWSGs. Weaned beef steers grazed switchgrass (Panicum virgatum L.) (SG), a big bluestem (Andropogon gerardi Vitman) and indiangrass [Sorghastrum nutans (L.) Nash] mixture (BBIG), and eastern gamagrass [Tripsacum dactyloides (L.) L.] at Grand Junction (AP) and Highland Rim (HR), TN, from 2010 to 2012. Th e dual-purpose grazing occurred for 30 d beginning in early May, with subsequent growth harvested as biomass post-dormancy, and full-season grazing occurred for 90 d beginning in early May. Budgets were developed for each NWSG to calculate net returns, and mixed models were used to determine diff erences in beef yield and net returns across each NWSG and location. Expected yield and net returns to full-season grazing were not diff erent among NWSGs at AP. However, net returns to full-season grazing were higher for BBIG than SG at HR. A profi t-maximizing, risk-neutral individual would increase net returns by grazing any of the NWSGs over marketing calves at weaning. Th e breakeven biomass prices ranged between US$10 and US$98 Mg-1 depending on the NWSG and location.

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Heifer rearing is one of the largest production expenses for dairy cattle operations, which is one reason milking operations outsource heifer rearing to custom developers. The cost of harvested feedstuffs is a major expense in heifer rearing. A possible way to lower feed costs is to graze dairy heifers, but little research exists on this topic in the mid-south United States. The objectives of this research were to determine the cost of feeding bred dairy heifers grazing native warm-season grasses (NWSG), with and without legumes, and compare the cost of grazing with the cost of rearing heifers using 3 traditional rations. The 3 rations were corn silage with soybean meal, corn silage with dry distillers grain, and a wet distillers grain-based ration. Bred Holstein heifers between 15- and 20-mo-old continuously grazed switchgrass (SG), SG with red clover (SG+RC), a big bluestem and Indiangrass mixture (BBIG), and BBIG with red clover (BBIG+RC) in Tennessee during the summer months. Total grazing days were calculated for each NWSG to determine the average cost/animal per grazing day. The average daily gain (ADG) was calculated for each NWSG to develop 3 harvested feed rations that would result in the same ADG over the same number of grazing day as each NWSG treatment. The average cost/animal per grazing day was lowest for SG ($0.48/animal/grazing d) and highest for BBIG+RC ($1.10/animal/grazing d). For both BBIG and SG, legumes increased the average cost/animal per grazing day because grazing days did not increase enough to account for the additional cost of the legumes. No difference was observed in ADG for heifers grazing BBIG (0.85 kg/d) and BBIG+RC (0.94 kg/d), and no difference was observed in ADG for heifers grazing SG (0.71 kg/d) and SG+RC (0.70 kg/d). However, the ADG for heifers grazing SG and SG+RC was lower than the ADG for heifers grazing either BBIG or BBIG+RC. The average cost/animal per grazing day was lower for all NWSG treatments than the average cost/animal per day for all comparable feed rations at a low, average, and high yardage fee. Results of this study suggest that SG was the most cost-effective NWSG alternative to harvested feeds for bred dairy heifer rearing.

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