PSXI-23 Modelling environmental impacts associated with use of implants in pre-weaned calves.

Abstract The performance and environmental sustainability advantages of implanting backgrounded and finished cattle have been well documented. The objective of this research is to explore the environmental sustainability of implanting pre-weaned calves in Canada. Greenhouse gas (GHG) emissions, and land and water use intensities were modeled in a cow-calf to finish system in which pre-weaned steer calves were raised with (IM) or without (NIM) implants. Pre-weaned calves (n=130) received Synovex C at 30 days of age while the remaining 130 steers were not implanted. Greenhouse gas emissions (including enteric and manure CH4, direct and indirect N20 and energy C02) were calculated using the Holos model for three eco-regions in Manitoba, Canada. Land and water use were calculated using spreadsheet models. Due to the increased liveweight (LW) of IM compared to NIM calves at weaning (255 vs 245 kg), GHG emission intensity (kg CO2e kg LW-1) was 3.79% lower for the former. Land use (ha kg LW-1) and water use (L kg LW-1) intensities were also lower by 3.86% and 3.92%, respectively. In addition, estimated revenue from IM calves at weaning was $94.10 greater per calf compared to NIM calves. Using hormonal implants in pre-weaned steers reduced the environmental footprint and generated greater economic returns than those not implanted before weaning.