title: Effects of production circumstances on expected responses for growth and carcass traits to selection of bulls in Japan.
abstract: Economic values of growth and carcass traits in Japanese beef cattle for production systems with various types of integration of levels/ stages (cow-calf and feedlot segments and the integrated system) and production circumstances (including 20% higher genetic levels of the traits, management, and economic alternatives) were used to examine responses to selection. Discounted economic values with interest rates of 0, 4.2 (Japanese average), and 8.4% were obtained to investigate the effect of discounting on selection efficiency. Traits considered were daily gain in the feedlot, marbling score, birth weight, weaning weight, and mature weight. The effects of discounting were small. Correlated responses to selection were not always economically favorable for all situations. Selecting bulls for the base situation (i.e., the typical biological and economic conditions for the production of Japanese Black cattle) resulted in negative genetic changes in weaning weight and mature weight in the feedlot segment. Higher genetic levels of daily gain and weaning weight affected efficiency of selection. Although effects of management and economic alternatives on responses to selection were generally small, lighter market weight influenced responses to selection. The results indicate that predicted correlated responses to selection are sensitive to production systems and some production circumstances.
authors.affiliation: Faculty of Economics, Ryukoku University, Kyoto, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Hirooka
authors.forename: A F
authors.initials: AF
authors.lastname: Groen
mesh_terms: D000818:Animals; D001824:Body Constitution; D001947:Breeding / Q000191:economics / Q000379:methods*; D002417:Cattle / Q000254:growth & development*; D007564:Japan; D008297:Male; D008460:Meat / Q000191:economics*