Estimation of economic weights for growth, feed efficiency, health, and fertility traits in a breeding program for...

The definition of breeding objectives in meat rabbits' breeding programs requires assigning economic weights to relevant traits. Our objective in this study was to estimate economic values for 12 key traits in meat rabbit production by calculating the first partial derivative of the profit function in a full-cycle production system. The model was parameterized to represent a semi-technified farm with 250 does managed in two triweekly groups, with natural mating occurring at 11 d postpartum. Economic data were expressed in U.S. dollars. Production costs were categorized into feed and non-feed costs associated with adult does, replacement does, bucks, replacement bucks, and growing rabbits. Revenues were derived from carcasses, pelts, and culled animals. Relative economic values (REV), expressed per doe per year, were obtained by multiplying the absolute economic value of each trait by its respective additive standard deviation. Feed costs accounted for 72.8% of the total. The REVs for litter size traits were $46.05 for the number of kits born alive, $42.83 for the total number of kits born, and $0.22 for the proportion of kits born alive. Efficiency traits' REV were -$6.93 for feed conversion ratio, $0.08 for feed efficiency, $2.98 for daily weight gain during the fattening period, and $0.14 for carcass yield. The functional traits' REV were $0.03 for female fertility, $0.002 for replacement doe fertility, and $0.57 for longevity. Health traits' REV were $0.18 and $0.19 for survival during lactation and fattening, respectively. Sensitivity analyses showed that increasing feed costs by 50% and carcass rabbit sale price by 40% resulted in changes ≤ 4% for most traits in the relative proportion of economic values, compared to that of the number of kits born alive. The traits with higher changes were efficiency traits (1-16%) and mainly feed conversion ratio (15-136%). The estimated economic values provide a basis for defining breeding objectives under the given production and market conditions. The methodological framework allows adaptation of selection goals to market fluctuations and the incorporation of new traits as they become relevant. Although the economic weights were relatively stable under these variations, it is recommended that they be re-estimated periodically.