Stocking Rate Effects on ‘Jiggs’ Bermudagrass Pastures Grazed by Heifers Receiving Supplementation

Abstract

ABSTRACT‘Jiggs’ bermudagrass [Cynodon dactylon (L.) Pers.] is a productive forage in the southeastern United States; however, there is limited information on grazing management of this bermudagrass ecotype. The objective of this study was to test the effects of different stocking rates on animal performance and herbage characteristics of Jiggs pastures. The experiment was conducted in Ona, FL, from May to August 2011 and 2012. Treatments were three stocking rates, 3.0 (low), 7.5 (medium), and 12.0 animal units (AU = 450 kg liveweight [LW]) ha−1 (high). The animals received 10 g kg−1 LW concentrate supplement daily during the experimental period. Heifer weight was recorded every 28 d and herbage parameters were measured every 14 d. There was a linear decrease (P < 0.01) in herbage mass (HM, from 3.8 to 2.4 Mg ha−1), light interception (from 94 to 71%), forage height (from 17 to 9 cm), and herbage allowance (HA, from 2.3 to 0.4 kg dry matter kg−1 LW) with increasing stocking rate. There was no effect (P > 0.10) of stocking rate on herbage nutritive value. Jiggs ground cover decreased (P < 0.01) from 95 to 39% with increasing stocking rates. Heifer average daily gain decreased (P < 0.01, from 0.7 to 0.3 kg d−1) and gain per hectare (P = 0.01, from 692 to 1064 kg ha−1) increased as stocking rate increased. Despite greater gain per hectare with increasing stocking rate, continuously stocked Jiggs should not be grazed below 17‐cm stubble height during the growing season to maintain the stand.