Effect of breed type and grazing performance on feedlot and carcass traits in cattle

Steers (n = 189) and heifers (n = 72) were assigned to two stocking rates (SR) at the Texas Agricultural Experiment Stations in Uvalde (UVL) and Overton (OVT) to create different growth rates in two subsequent years. Animals were either Angus, Angus × Angus Brahman, Angus × Brahman Hereford, Brahman, Brahman × Hereford, Braunvieh cross, or Bonsmara cross and stocked on TAM 90 (RG) annual ryegrass (Lolium multiflorum ) in UVL or ‘Maton’ rye (Secale cereale) and RG in OVT. Cattle were placed at the Texas Tech University Alltech research feedlot in May 2000 and May 2001 to determine the influence of grazing growth rate (GG) (High, Medium, Low), breed type (BT), and sex on feedlot performance and carcass characteristics. Cattle were randomly assigned to pens within location, BT, SR, sex, and weight with 4 to 7 animals per pen. Separate individual animal analyses were conducted for each location and sex. Feedlot performance of the UVL steers and OVT heifers was not affected by GG. OVT medium and low steers had higher final ADG than the high steers (P < 0.05). Final feedlot weights in the low and medium animals within the three groups were lower than the high animals due to an apparent failure to compensate for differences in initial feedlot weight (P < 0.05). BT influenced final ADG in the OVT steers and heifers (P < 0.05). GG affected hot carcass weight in the UVL steers, OVT heifers, and OVT steers (P < 0.05). GG did affect total carcass value in the UVL steers and OVT heifers (P < 0.05) and there was an apparent trend in the OVT steers (P = 0.06). Breed differences for carcass traits were observed in the OVT steers and heifers. Escherichia coli and Salmonella were found in the cattle at a level of 5% and 4% respectively upon entering the feedlot and at a level of 12% and 51% respectively at the completion of the finishing phase. Animal performance prior to the finishing period did affect carcass traits but had little effect on feedlot performance.