The Use of Cowpea as Forage for Cow-Calf Production in Florida.

The increased cost of N fertilizer stimulates producers to search for warm-season legumes adapted to grazing conditions in Florida. The objective of this study was to evaluate the use of cowpea (Vigna unguiculata L.) on forage production and animal performance of cow-calf pairs grazing bahiagrass (Paspalum notatum Flugge) pastures during the summer in Florida. The study was conducted in Ona, FL from May to August 2007 and 2008. Treatments were planting ‘Iron Clay’ cowpea on half of the pastures, cowpea planted on creep grazing area (0.1 ha), creep feeding with concentrate (1% BW, 14% CP, 76% TDN), or control (bahiagrass pasture only) in a completely randomized design with three replicates. Pastures (1.0 ha) were sampled to determine herbage mass (HM), crude protein (CP), and in vitro digestible organic matter (IVDOM) every 28 d.  Exclusion cages were used to measure herbage accumulation. Pastures were continuously stocked using a fixed stocking rate with three cow-calf pairs per experimental unit. Pasture planted with cowpea in half of the area had decreased HM (1.8 vs. 3.7 Mg ha^-1) and herbage allowance (0.8 vs. 1.4 kg DM kg^-1 liveweight) when compared to the other treatments. Cow pea had greater CP (160 g kg^-1) and in IVDOM (600 g kg^-1) than bahiagrass (110 and 490 g kg^-1 for CP and IVDOM, respectively), however, HM was only 0.9 Mg ha^-1 in May, 0.7 Mg ha^-1 in June, and did not persist in July and August. There was no difference in average daily gain (ADG) of the cows among treatments. Calves receiving the creep feeding treatments had greater ADG (0.8 vs. 0.7 kg d^-1) than calves on other treatments. There was no difference in animal performance between the cowpea treatments and the control. Cowpea has limited use as forage for cow-calf operations in Florida because of the decreased persistence under grazing on continuous stocked pastures.