LIFE CYCLE EFFICIENCY OF BEEF PRODUCTION: VI. RELATIONSHIP OF COW EFFICIENCY RATIOS FOR PROGENY SLAUGHTERED TO GROWTH, CONDITION, FERTILITY AND MILK PRODUCTION OF THE DAM 1'2'3

Summary Weights and individual feed consumptions of 160 beef, dairy and beef  dairy darns and their progeny were used to estimate several measures of life cycle cow efficiency. Efficiency was expressed as the ratio of output to input, where output included relative values for slaughter weights, carcass weights and trimmed wholesale cut weights of progeny and weight of the dam, and inputs were pre- and postweaning feed consumption of progeny plus lifetime feed con- sumption of the dam. In the first approach, inputs and outputs were weighted by their probability of occurrence; probabilities were a function of the age distribution of the cow herd and calf crop percentage in a theoretical herd. The second approach involved dividing the sum