Impact of economic parameters on economic values in dairy sheep

The impact of variation in economic conditions on the economic values of fourteen production and functional traits was examined for the Improved Valachian breed using a bio-economic model implemented in the ECOWEIGHT software. The following economic parameters were investigated: market prices of lambs, milk, and cheese (variation ± 40%), costs for roughage, concentrates, and total feeding rations , costs for labour and veterinary care, fixed costs (variation ± 20% for all costs), and discount rate of revenues and costs (0 and 3%). Results of the analyses were presented in detail for the marginal and relative economic values of the four most important traits: milk yield in the 150-day milking period, conception rate of ewes, litter size per lambed ewe, and productive lifetime of ewes. Furthermore, cumulative relative economic values of the four trait complexes - milk production, growth, functional, and wool traits - were presented. Prices for sheep products were found to be the most important factor for both the marginal and the relative economic values of the evaluated traits. The four traits with the highest relative economic values in the base calculation stayed the most important for all investigated economic parameters ranges. The relative economic values of the remaining 10 traits did not exceed 6.1%. The relative economic values of milk yield and litter size were the most sensitive to the variation in economic circumstances. For the investigated range of economic parameters, the relative economic value for the complex of milk production traits ranged 30.6-48.1%, for growth traits 6.3-9.4%, and that for functional traits 45.4-59.7%. The relative economic value for the wool trait did not exceed 0.3%.