87. Effect of Alternative Beef Heifer Grazing Management on Synchronized Fixed-time AI and Delayed Feedlot Entry of Non-pregnant Heifers.

Abstract

Non-traditional beef heifer reproductive management procedures are being evaluated at the NDSU Dickinson Research Extension Center. Using a synchronized fixed-time AI procedure, drylot control heifers with cleanup bulls (CTL) were compared to two fixed-time grazing protocols without cleanup bulls. Treatments: 1) Drylot Control (CTL) with clean-up bulls, 2) Grazing within a diverse annual forage cropping system (IAF – no clean-up bulls), and 3) Grazing native range (NR – no clean-up bulls). For finishing of non-pregnant heifers, following an 85-day ultrasound pregnancy determination, the heifers were transferred to the University of Wyoming (SAREC) feedlot and grid marketed in the meat at the Cargill Meat Solutions, packing plant, Ft. Morgan, CO. The MIXED procedure of SAS was used for data analysis. Four years of heifer reproductive management data is summarized in this abstract. Grazing days for the total four-year study for the CTL, IAF, and NR were 101-, 150-, and 150-days, respectively, and synchronized pregnancy rates were 50.0, 56.0, and 50.0%, respectively. CTL cleanup bulls added 15.6% for total pregnancy of 65.6%. Grazing ADG was greater for IAF heifers (0.84 kg, P = 0.001) compared to the CTL and NR (0.35, 0.76 kg), respectively. Non-pregnant CTL, IAF, and NR feedlot heifer performance was: start weight (CTL 431, IAF 482, NR 448 kg, P = 0.001), end weight (CTL 649, IAF 655, NR 627 kg, P = 0.28), gain (CTL 218.4, IAF 173, NR 179 kg, P = 0.035), and ADG (CTL 1.84, IAF 1.43, NR 1.51 kg, P = 0.031). Daily DM feed intake was similar for the CTL (18.1 kg) compared to IAF 16.8 and NR 17.2 kg (P = 0.539) and G: F (CTL 0.1015, IAF 0.0850, NR 0.0875 kg, P = 0.45). Daily feed cost for CTL, IAF, and NR was $4.42, $4.13, and $4.23/d, respectively. Total feed and yardage cost per heifer was similar for the CTL $565.55, lowest for the IAF $543.70, and NR was intermediate at $557.40/heifer (P = 0.91). HCW (CTL 375, IAF 388, NR 372 kg, P = 0.15) and dressing percent (CTL 60.25, IAF 59.8, NR 59.9%, P = 0.84) did not differ. Carcass marbling score (P = 0.19), USDA YG (P = 0.35), quality grade (100% Choice or better, P = 1.0), and gross carcass value (P = 0.63) did not differ. Economically, the CTL system heifers had the highest net return after accounting for expenses compared to the integrated system heifers (IAF) and native range system heifer (NR) returns were intermediate. Reduced net return for the IAF was due to farming, feedlot feed and yardage, and freight to the feedlot and packing plant. Similarly, the NR system net return was reduced due to feedlot feed and yardage as well as freight to the feedlot and packing plant, but no farming. Each system has advantages and disadvantages depending on a particular ranches’ infrastructure and available labor.