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In recent years, the livestock production industry has been receiving pressure to assess and improve production practices in two seemingly unrelated areas: environmental quality and animal welfare. In this article, we argue that the nexus of these two areas of study should be a priority for future research and that the integration of these disciplines in research, extension, and education efforts has the potential to improve the sustainability of production livestock agriculture.

Increased animal productivity has the potential to reduce the environmental impact per unit of consumable product and is believed to be the most promising and sustainable mitigation technique to meet increasing demand for high quality protein. The feedlot industry uses ionophores, antibiotics, growth implants, and β2-adrenergic agonists to improve health and growth performance of cattle. These technologies not only increase productivity but also alter microbes in the rumen and increase nitrogen retention in the animal, which may lead to changes in greenhouse gas (GHG), volatile organic compound (VOC), and ammonia (NH3) emissions from feedlot cattle. The present study investigated GHG, VOC, and NH3 emissions from 160 Angus crossbred steers. Steers were blocked by weight in a randomized block design and assigned to 16 pens of 10 animals each. Treatments applied were 1) control (CON; no technology application), 2) monensin and tylosin phosphate (MON), 3) monensin, tylosin phosphate, and growth implant (IMP), and 4) monensin, tylosin phosphate, growth implant, and zilpaterol hydrochloride (fed during the last 20 d of the feeding period; BAA). Cattle were on feed for an average of 107 d. Performance variables (DMI, BW, ADG, and G:F) and carcass traits (HCW, dressing percent, KPH, LM area, fat thickness, marbling score, yield grade, and quality grade) were measured. Gaseous emissions were measured during the last 10 d of the feeding period when animals were housed in 4 totally enclosed identical cattle pen enclosures. To quantify gaseous emissions a 4×4 Latin square design (n=4) was used. Gaseous emissions were analyzed using Proc Mixed in SAS and reported in grams per kilogram HCW per day and grams per kilogram per animal per hour. Treatment with IMP and BAA increased (P<0.05) ADG, final BW, and HCW. Cattle on BAA had greater HCW and LM area (P<0.05) and had lower (P<0.05) CH4, methanol, and NH3 emissions per kilogram HCW than cattle on the remaining treatments. Methane emissions were similar for CON and IMP treated cattle. Nitrous oxide emissions were similar across CON, MON, and IMP treated cattle and were higher in BAA treated cattle (P<0.05). The present study provides a better understanding of how application of growth promoting technologies to feedlot steers affects GHG, VOC, and NH3 emissions per kilogram of product.

Life Cycle Assessments (LCA) are useful tools to analyze a product's "carbon footprint" (e.g., the net greenhouse gas (GHG) emissions expressed as standardized carbon dioxide equivalents per unit of product) considering all phases of the production chain. For beef, an LCA would include the GHG emissions from feed production, from the enteric fermentation of the cattle, from the cattle's waste, and from processing and transportation. Identifying the scope and scale of the LCA is critical and key to preventing inappropriate applications of the analysis (e.g., applying a global LCA for beef to the regional or national scale). Ideally, a LCA can integrate the complex biogeochemical processes responsible for GHG emissions and the disparate animal and agricultural management techniques used be different phases of the beef production chain (e.g., feedlot vs. cow-calf) and different production systems (e.g., conventional vs. organic)., (Copyright © 2012 Elsevier Ltd. All rights reserved.)