Performance and economic comparison of conventional and non-conventional post-weaning calf management systems
A two-year study was conducted to evaluate three feeding management systems based on starting weight at weaning: Heavy (HV) = direct-entry finish, 295 kg average, Medium (MD) = short background to finish, 250 kg average, Light (LT) long background to finish for weaned steers, 205 kg average, (n=4 in year 1 and 2, respectively) using conventional (CONV) or natural (NAT) management. The usage of performance enhancing technology (PET) including hormone implants, monensin and tylosin was included in CONV treatments, but not NAT. Each year of the study, 240 steers were allocated into three weight brackets and randomly allocated to CONV or NAT management and raised to a target weight of 635 kg.. In the backgrounding phase, the ADG of MD and LT-CONV steers was 19-22% better than MD and LT-NAT steers (P<0.01). Dry matter intake was 12% higher for CONV steers among all groups (P<0.01). Feed efficiency (G:F) was not different among treatments for MD calves, but G:F was 25% better for LT-CONV steers (P<0.01). The cost of gain (COG) for raising MD/LT-CONV animals in winter backgrounding was 11-15% lower than MD/LT-NAT. In the finishing phase, there were 25% more DOF for NAT steers taken to the same end weight as CONV counterparts (P<0.01). The Heavy, MD and LT CONV treatments had 19%, 34% and 40% better ADG than their NAT counterparts (P<0.01). There was no difference in DMI across all treatments (P=0.12). There was a 25% improvement in G:F for CONV animals in finishing compared to NAT (P<0.01). The MD weight group exhibited the poorest feed efficiency of all weight groups (P<0.05). For overall performance, Heavy, MD and LT NAT groups had a 25%, 20% and 17% more DOF from weaning to slaughter (P<0.01). The three CONV treatment groups had equal cost/kg gain overall from weaning to slaughter (P<0.01). The Heavy CONV had equal cost/kg gain as their NAT counterparts, but the MD and LT CONV groups had 17% and 13% reduced cost/kg gain than their NAT counterparts, respectively (P<0.01). The economic and production disparity between CONV and NAT treatments in the Heavy weight class was less pronounced than the backgrounded weight groups. For carcass characteristics, the Heavy CONV group had the highest HCW and REA, and the other two CONV groups did not grade better than NAT in this area (P<0.01). Marbling, backfat thickness and yield scores were higher for NAT management. Natural animals had 29% more AAA grades (P<0.01) and CONV cattle had more AA grade (P<0.01). Overall, NAT cattle exhibited a higher proportion of liver abscesses (P<0.01). In the backgrounding period the MD and LT-CONV steers had 11% and 15% lower COG than their NAT counterparts (P<0.01). In the finishing period the H, MD and LT-CONV groups had 7%, 29% and 28% better COG than their NAT counterparts (P<0.01). Overall, raising NAT beef under western Canadian conditions will have lower ADG and more DOF to reach a target finish weight, resulting in higher overall COG. Animals under a NAT long-backgrounding system that are grazed previous to fall feedlot entry will be most efficient when compared to the H or MD management systems. The results of this study indicate that natural beef production in Canada will require an 8-11% premium to break even on a cost basis if calves are slaughtered at similar live body weights as conventionally raised calves.
beef cattle conventional non-conventional implants
Master of Science (M.Sc.)
Animal and Poultry Science