Rotational Stocking of Tifton 85 Bermudagrass and Supplementation Level Effects on Performance of Replacement Dairy Heifers

Abstract

Use of Tifton 85 bermudagrass [Cynodon dactylon (L.) Pers. X C. transvaalensis Burtt Davy] has increased in pasture‐based dairies in the southeastern United States relative to other warm‐season grasses. A 2‐yr study was conducted to evaluate rotational stocking for two grazing rest periods (RP; 14 and 21 d) and two supplementation rates (SUP; 0.64% [low] and 0.96% [high] of heifer [Bos taurus] body weight) on pasture characteristics and animal performance. Across all treatments, pastures with 14‐d RP had greater (P < 0.05) crude protein (CP) concentration and in vitro organic matter digestibility (IVOMD) than pastures with 21‐d RP (174 vs. 161 g kg−1 and 624 vs. 602 g. kg−1, for CP and IVOMD, respectively). Herbage allowance was less in high than low SUP pastures (0.59 vs. 0.67 kg dry matter (DM) kg live weight (LW)−1, respectively). In 2010, average daily gain (ADG) was not affected by SUP (0.62 vs. 0.63 kg d−1 for heifers fed low and high amounts of SUP, respectively) or by RP. However, in 2011 ADG was greater (P = 0.07) for heifers fed high compared to low amounts of SUP (0.61 vs. 0.51 kg d−1, respectively). Although heifer ADG approached the industry target of 0.7 kg, results suggest forage allowance of < 1 kg DM kg−1 animal LW limited daily gains. The nutritive value data support the conclusion that Tifton 85 possesses high nutritive value and is suitable for use in pasture‐based systems for raising replacement dairy heifers if adequate forage allowance is maintained.