Greenhouse Gas Emissions from Calf- and Yearling-Fed Beef Production Systems, With and Without the Use of Growth Promotants

摘要: A spring calving herd consisting of about 350 beef cows, 14-16 breeding bulls, 60 replacement heifers and 112 steers were used to compare the whole-farm GHG emissions among calf-fed vs. yearling-fed production systems with without growth implants. Carbon footprint ranged from 11.63 13.22 kg CO₂e per live weight (19.87-22.52 carcass weight). Enteric CH₄ was largest source (53-54%), followed by manure N₂O (20-22%), cropping (11%), energy use CO₂ (9-9.5%), (4-6%). Beef cow accounted for 77% 58% in yearling-fed. Feeders second highest (15% calf-fed; 35-36% yearling-fed). Implants reduced carbon 4.9-5.1% compared hormone-free. Calf-fed 6.3-7.5% When expressed as year 73.9-76.1% lower than production, implanted 85% hormone-free Reducing may be accomplished improving feed efficiency herd, decreasing days on low quality feeds, reducing age at harvest youthful cattle.