Abstract
Our objective was to determine the effects of dry and wet conditions during the preweaning on subsequent feedlot performance and carcass characteristics of beef cattle. Steers (n = 7,432) and heifers (n = 2,361) finished in 16 feedlots in southwestern Iowa through the Tri-County Steer Carcass Futurity Cooperative were used for a retrospective analysis. Cattle originated in the Midwest (Iowa, Missouri, Indiana, Illinois, and Minnesota) and were born in February, March, or April of 2002 through 2013. Feedlot performance and carcass composition data were obtained for each animal. Palmer Drought Severity Index (PDSI) values were obtained for each animal’s preweaning environment on a monthly basis. Mean PDSI values were used to classify conditions as dry (≤−2.0), normal (>−2.0 and <2.0), or wet (≥2.0) for the cool (April and May), warm (June through August), and combined (April through August) forage growing seasons preweaning. Mixed models were used to evaluate the effects of PDSI class on subsequent performance. Calf sex, date of birth (as day of year), year, and feedlot were also included as fixed effects. When considering PDSI class during the cool season, cattle from normal and wet classes had a greater feedlot delivery BW (P < 0.0001) than dry. Dry and normal classes had greater (P ≤ 0.02) delivery BW than wet during the warm and combined seasons, however. For the cool season, average daily gain was greater (P < 0.0001) for the dry class than normal and wet. Cattle from the normal class for the cool season had greater (P = 0.001) final BW than wet, but the wet class had the greatest (P < 0.04) and dry class had the lowest (P < 0.01) final BW during the warm season. During the cool season, HCW was greater (P < 0.007) for the normal than wet class, although HCW was greater (P ≤ 0.02) for wet compared with dry and normal during the warm season. Calculated yield grade was lower (P ≤ 0.006) for the normal class during the cool season compared with dry and wet. For both the warm and combined seasons, the dry class had lower (P ≤ 0.004) calculated yield grade compared with normal and wet. Carcasses from cattle that experienced normal or wet warm seasons had greater (P ≤ 0.0005) marbling scores than dry, and normal had greater (P = 0.0009) marbling score than dry for the combined seasons. In conclusion, these data indicate that both dry and wet conditions during the preweaning phase may impact ultimate feedlot performance and carcass composition.
76 Evaluating Nitrogen Management Strategies to Improve Southern Bermudagrass Grazing Systems
