A stochastic model for the derivation of economic values and their standard deviations for production and functional traits in dairy cattle
Nielsen, H.M. ; Groen, A.F. ; Ostergaard, S. ; Berg, P. - \ 2006
Acta Agriculturae Scandinavica Section A-Animal Science 56 (2006)1. - ISSN 0906-4702 - p. 16 - 32.
feed-intake capacity - selection indexes - production circumstances - profit-functions - breeding goals - herd - bias
The objective of this paper was to present a model of a dairy cattle production system for the derivation of economic values and their standard deviations for both production and functional traits under Danish production circumstances. The stochastic model used is dynamic, and simulates production and health in a dairy herd. Because of indirect effects between traits, the phenotypic levels of (related) traits can change as a result of genetic changes. Economic values for milk production and body weight were 0.28 and -0.76 euro/kg per cow-year respectively. For incidence of milk fever, mastitis, retained placenta and laminitis economic values were -402.1, -162.5, -79.0 and -210.2 euro/incidence per cow-year. The economic values for involuntary culling rate, stillbirth and conception rate were -6.66, -1.63, and 1.98 euro/% per cow-year, respectively and the economic value for days from calving to first heat was -0.94 euro/day per cow-year. Standard deviations of economic values expressing variation in realised profit of a farm before and after a genetic change were computed using a linear Taylor series expansion. Expressed as coefficient of variation, standard deviations of economic values based on 1000 replicates ranged between 0.07 (milk production) to 16 (retained placenta)
Economic values for production and functional traits in Holstein cattle in Costa Rica
Vargas, B. ; Groen, A.F. ; Herrero, M. ; Arendonk, J.A.M. van - \ 2002
Livestock Production Science 75 (2002). - ISSN 0301-6226 - p. 101 - 116.
feed-intake capacity - dairy-cattle - production circumstances - output limitations - production systems - breeding goals - live weight - situations - selection - model
Economic values for production traits (carrier, fat, protein, and dressing percentage) and functional traits (conception rate, survival rate, body weight, and rumen capacity) were calculated for Holstein cattle of Costa Rica. Economic values were derived using a bio-economic model that combined genetic potential performance, feeding strategies and optimum culling and insemination policies to obtain actual phenotypic performance. Two evaluation bases were considered: fixed herd-size and fixed milk-output. With a fixed herd-size economic values were 0.04 (carrier), 5.25 (fat), 3.95 (protein), 0.92 (dressing percentage), 1.30 (conception rate), 2.42 (survival rate), 0.81 (body weight) and 84.53 (rumen capacity). With a milk-output limitation, economic values for all traits except survival rate were lower than for fixed herd-size. The respective values were -0.04, 3.53, 2.91, 0.88, 0.85, 3.18, 0.51 and 45.59. Sensitivity analysis indicated that economic values of fat, protein and rumen capacity increased significantly with higher prices of milk solids. Other traits were less sensitive to a change in price of milk solids. Changes in price of concentrate did not alter economic values significantly. Under a fixed feeding strategy, economic values for functional traits increased substantially, while those for production traits decreased. The results of this analysis suggest that genetic improvement of fertility, health and cow-efficiency traits will have a clear positive effect on profitability of Holstein cows in Costa Rica, especially when feeding conditions are not optimal. (C) 2002 Elsevier Science BY All rights reserved.