ANSC 4405 Exam with Right Answers

Describe how days on feed, dressing percentage and cattle end weight have changed over the past 10 years. - days on feed = longer Dressing percentage = higher Cattle end weight = heavier Explain why days on feed, dressing percentage, and cattle end weight have changed - ration prices lower, genetics are better for heavier cattle, longer days on feed allows for more gain and a higher dress percentage During the last 30 days on feed, ______% of tissue accretion is on the ____________. - 80, carcass How are the majority of fed cattle marketed today? - on carcass basis What is a CAFO? - animals are stabled or confined for 45 days of more in any 12 month period What is the definition of a large- scale CAFO? - greater than 1,000 head What are factors in livestock facilities that impact gas and dust production, and how can these factors be regulated to reduce these emissions? - -Climate = temperature/humidity, airflow -Animal factors = number/size, diet (DDS 30% protein), activity - Manure management = composting - Retention ponds, cleaning pens regularly ____% of nutrients consumed by cattle are converted to product, why? - 20%, a lot of nutrients are lost to gas or excretion What are the primary air quality contaminants in manure? - H2S, N2O, methane, particulates, ammonia Aside from gaseous emissions from manure, what other components of the feedyard contribute to gaseous emissions? - pen surface, cattle, roads, feed mill, manure stock piles, retention ponds What are the sources of N losses in feedyards? - NH3, N2O, N2, Amines How are NH3, N2O, CH4, and H2S produced? - - NH3 = Hydrolyzed from urea and urine, rapid. Of mineralized from feces, slow. - N2O = bacteria ferment N substrate in feces, nitrification/denitrification - CH4 = from fermentation of CHO - H2S = decomposition of manure via anaerobic conditions What factors influence emissions of NH3? - CP of diet, higher amounts of CP mean higher NH3, hot temperatures, seasonality summer How does ammonia produced by urine differ from ammonia produced from manure? - - urine = rapid hydrolysis - feces = mineralized slowly