PSI-5 - Effects of Two Rotational Grazing Management Systems on Forage Quality, Forage Availability, and Cow Performance

Abstract: The objective was to compare the effects of two rotational grazing systems on forage quality, forage availability, and cow performance. Multiparous, fall-calving beef cows (n = 360; BW = 613 ± 66 kg) were stratified by sire, age, body condition score (BCS), and body weight (BW), and allotted to 6 groups. Groups were randomly assigned to 1 of 2 treatments: 8-paddock system rotated every 5 d or 6-paddock system rotated every 7 d. Endophyte-infected tall fescue paddocks (6.1 ha) were grazed in two rounds of rotations from April to July. Cow BW and BCS were obtained on d 0, 28, 56, and 84. Forage heights were measured using a rising plate meter before and after grazing. Forage samples were clipped from each paddock prior to grazing for proximate analysis. Data were analyzed using the MIXED procedure of SAS 9.4. During round one, forage from the 8-paddock system tended (P = 0.07) to have greater percent dry matter (DM), but no differences were detected (P ≥ 0.12) in organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), or crude protein (CP). During round two, forage percent DM tended (P = 0.08) to be greater while CP tended (P = 0.10) to be lesser in the 8-paddock system. Additionally, the 8-paddock system had greater (P ≤ 0.05) forage NDF and ADF than the 6-paddock system, but OM was not different (P = 0.17) in round two. However, grazing system did not affect (P ≥ 0.21) forage availability after grazing in either round. Cow BW and BCS were not affected (P ≥ 0.18) by grazing system on d 0, 28, 56, or 84. Despite minor differences in forage quality, rotational grazing management system did not impact forage availability or cow performance.