Effects of incorporating cowpea in a subtropical grass pasture on forage production and quality and the performance of cows and calves

Abstract

AbstractThe increasing cost of N fertilizer has stimulated an interest in sourcing protein from warm‐season legumes among beef cattle producers in the tropical/subtropical areas of the world. The objective of this study was to evaluate effects of two strategies of incorporating cowpea [Vigna unguiculata (L.) Walp.] into bahiagrass (Paspalum notatum Flügge) pastures on the herbage characteristics and performance of grazing cow–calf pairs. The study was conducted in Ona, Florida, USA, from May to August in 2007 and 2008. Experimental units were 1·0 ha. Treatments were bahiagrass pasture alone (control), 50:50 bahiagrass–cowpea pasture (cowpea), bahiagrass pasture with a cowpea creep grazing area (0·1 ha, creep grazing) and bahiagrass pasture with a creep‐fed concentrate [(creep feeding; 10 g kg−1 body weight (BW)]. The cowpea pastures had lower herbage mass [HM, 1·8 vs. 3·7 t ha−1] and herbage allowance [HA, 0·8 vs. 1·4 kg DM kg−1 live weight (LW)] compared with the other treatments. Cowpea had greater CP (CP, 160 g kg−1) and in vitro digestible organic matter (IVDOM), (600 g kg−1) than bahiagrass (110 and 490 g kg−1 respectively); however, cowpea HM was only 0·9 t ha−1 in May and 0·7 t ha−1 in June, but it did not persist in July and August. Calves receiving the creep feeding treatments had greater average daily gain (0·8 vs. 0·7 kg d−1) than calves in other treatments. Further research is necessary to exploit the superior nutritive value of cowpea in grazing systems in the south‐eastern USA.