Effect of bovine respiratory disease and overall pathogenic disease incidence on carcass traits.

The objective this study was to evaluate the effects of incidence of bovine respiratory disease (BRD) and overall incidence of pathogenic diseases (IPD) on carcass traits. Two independent populations were used. The first population included crossbred steers (GPE7; n = 642) derived from sires of 7 Bos taurus breeds: Angus, Charolais, Gelbvieh, Hereford, Limousin, Red Angus, and Simmental. The second population included crossbred steers (GPE8; n = 621) derived from tropically adapted Bos taurus breeds and Bos indicus-influenced breeds: Beefmaster, Brangus, Bonsmara, and Romosinuano, as well as Hereford and Angus. Treatment records for BRD, infectious keratoconjunctivitis, and infectious pododermatitis were available for these populations. Incidence of BRD was treated as an independent effect. Incidences of the 3 microbial pathogenic diseases were pooled into a single trait to represent overall pathogenic disease incidence. Traits evaluated were HCW; KPH; LM area; marbling score; fat thickness; dressing percentage; yield grade; retail, fat, and bone yields; and meat tenderness. Both BRD and IPD were associated with differences in yield grade in GPE7 and GPE8 steers. Animals treated for BRD had decreased yield grades (P = 0.003 and P = 0.02, in GPE7 and GPE8, respectively) compared with untreated animals. Animals treated for IPD had decreased yield grades (P = 0.0006 and P = 0.004, in GPE7 and GPE8, respectively) compared with untreated animals. Incidence of BRD and IPD were associated with a reduction in fat thickness in GPE7 and GPE8 steers. Animals treated for BRD had reduced adjusted fat measurements (P = 0.0007 and P = 0.01, in GPE7 and GPE8) compared with untreated animals. Animals treated for IPD also had reduced adjusted fat measurements (P = 0.0003 and P = 0.002, in GPE7 and GPE8) compared with untreated animals. Animals treated for BRD (P < 0.007) or IPD (P < 0.02) in the GPE7 population also had decreased estimated KPH measurements compared with unaffected animals. Animals affected with BRD in GPE8 had greater (P < 0.05) shear force measurements than unaffected animals. Animals affected with IPD in GPE8 had greater HCW (P < 0.03) and fat yield (P < 0.01) measurements but lesser bone yield (P < 0.03) and retail product yield (P < 0.01) measurements than unaffected animals. The relationship between disease and carcass traits should be given consideration by future studies that aim to develop selection strategies based on specific traits.