Conventional feeding systems use pharmaceutical products not allowed in natural or organic systems for finishing cattle. This review of data compares the performance effects (ADG, G:F, DMI) of technologies used in conventional feeding programs that are prohibited in organic programs, natural programs, or both. The technologies evaluated were steroid implants, monensin, tylosin, endectocides, and metaphylaxis with any antimicrobial. For inclusion in this analysis, studies were conducted in North America, reported randomization to treatment group, used beef cattle, contained an untreated control group, and were sourced from peer-reviewed journals. Forest plots were used to examine the data visually for trends toward a uniform effect of the technology on the outcomes of interest (ADG, DMI, G:F). Technologies that displayed a uniform response on the forest plot compared with negative controls were then analyzed using mixed models. Examination of forest plots for endectocides, steroid implants, monensin, and metaphylaxis technologies appeared to show performance advantages for treated cattle relative to cattle in negative control groups. An insufficient number of studies met the inclusion criteria to conduct meta-analyses comparing endectocides, monensin, or tylosin with negative controls. Average daily gain in feeder cattle given metaphylaxis on arrival was 0.11 kg/d (P < 0.01) greater relative to cattle that did not receive metaphylaxis on arrival. Implanting heifers increased ADG by 0.08 kg/d compared with nonimplanted controls (P = 0.09). Implants had no effect on G:F (P = 0.14) in heifers or on DMI (P = 0.44) relative to nonimplanted control heifers. Implanting steers was associated with greater ADG, by 0.25 kg/d (P < 0.01), and DMI, by 0.53 kg/d (P < 0.01), relative to nonimplanted control steers. Implants also improved G:F in steers relative to nonimplanted steers, by 0.02 (0.17 vs. 0.15; implanted vs. controls, P < 0.01; n = 21 studies). When average estimated differences in ADG and G:F for implanted and nonimplanted steers were incorporated into a breakeven model, implanted steers had a $77/animal lower cost of production than nonimplanted steers and a $349/animal lower cost of production than organically raised steers. These data illustrate the importance of capturing premiums when operating natural and organic production systems to maintain economic viability.

Steers (n = 15,631) and heifers (n = 5,897) fed at 18 feedlots (total confinement, partial confinement, or open lots) in southwest Iowa between 2002 and 2006 as part of the Tri-County Steer Carcass Futurity sponsored by Iowa State University were used to correlate various phenotypic traits with feedlot performance and carcass traits. Dependent variables [ADG, respiratory morbidity, HCW, fat thickness, calculated yield grade, marbling score, presence or absence of lung damage, loin muscle area (LMA), and LMA x 100/HCW] were evaluated on the basis of various phenotypic traits [initial BW, disposition score (1 = calm, 6 = extremely excitable), muscle score, frame score, BCS, number of treatments for respiratory disease, presence of lung lesions, breed makeup, and percentage Angus genetics]. Subjectively evaluated phenotypic traits were evaluated by Iowa State University or USDA personnel. Cattle with greater disposition score (more excitable) had decreased initial BW, final BW, ADG, HCW, yield grade, quality grade, marbling score, and mortality (P < 0.01). Respiratory morbidity was negatively correlated with initial BW, ADG, yield grade, HCW, and marbling score (P < 0.01). As initial BW increased, final BW and HCW increased and respiratory morbidity decreased (P < 0.01). Cattle with greater BCS on arrival had greater initial BW but were lighter at slaughter (P < 0.01). Increased number of treatments for respiratory disease was associated with decreased ADG, greater mortality rate, and greater incidence of lung lesions (P < 0.01). Body weight gain was similar between English- and Continental-breed cattle (P > 0.05), although final BW and HCW were greater and yield grade and yield grade-adjusted marbling score were less for Continental-breed cattle (P < 0.01). Cattle with a poorer muscling score had reduced HCW and LMA and greater yield grade, marbling score, and quality grade (P < 0.01). Animal disposition, health, breed type, and frame score have dramatic effects on live feedlot performance and carcass traits.

An array of management tools exists within the beef industry to improve animal welfare and productivity; however, the ability to assess the outcomes of these tools is needed. Deficiencies in management commonly manifest as bovine respiratory disease complex or nutritional disorders such as acidosis; therefore, lung, liver, and rumen gross pathology lesions present at slaughter were measured as part of the Harvest Audit Program (HAP) and associations with performance determined. Individual gross pathology data from 19,229 cattle at commercial packing plants in Kansas and Texas were collected. Corresponding individual preharvest and carcass data were obtained on a subset of 13,226 cattle. Associations between lesions and performance were modeled using multivariable mixed effect models. Regression coefficients were used for estimation of lesion associative effects on continuous outcomes and odds ratios for dichotomous outcomes. Across the entire population, 67.3% of the cattle had no pulmonary lesions; 22.5 and 9.8% of cattle displayed mild and severe lesions, respectively. Severe pulmonary lesions were associated with a decreased ADG of 0.07 kg and a HCW 7.1 kg less than cohorts with no pulmonary lesions (P < 0.01). Overall, 68.6% of cattle observed had normal livers. Of cattle severely affected by liver abscesses (A+; 4.6%), 14.9% also displayed severe pulmonary lesions and 28.3% displayed mild pulmonary lesions. Rumenitis lesions were observed in 24.1% of the overall study population. Of cattle with mildly abscessed livers (A-), moderately abscessed livers (A), and severely abscessed livers, 20.6, 21.6, and 9.24% displayed mild or severe rumenitis lesions at slaughter. Severe rumenitis lesions were associated with a significant decrease in ADG and HCW (0.025 and 2.20 kg, respectively; P < 0.001). Although the majority of the cattle in this population would be considered low risk, after adjustments for cattle with multiple lesions, 22.9% of cattle in the overall population were observed with a severe lesion (lung, liver, or rumen). In conclusion, a gross pathology monitoring system is feasible and the 22.9% prevalence of severe lesions (lung, liver, or rumen) indicates that significant opportunity exists to improve beef cattle health, well-being, and productivity. Data generated using HAP may be used to support decisions concerning the implementation or removal of managerial practices and health interventions in beef cattle production systems.

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