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Title: USING SIMULATION MODELS TO PREDICT FEED INTAKE: PHENOTYPIC AND GENETIC RELATIONSHIPS BETWEEN OBSERVED AND PREDICTED VALUES

Author
item Williams, Charles
item Bennett, Gary
item Jenkins, Thomas
item Cundiff, Larry
item Ferrell, Calvin

Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2005
Publication Date: 7/25/2005
Citation: Williams, C.B., Bennett, G.L., Jenkins, T.G., Cundiff, L.V., Ferrell, C.L. 2005. Using simulation models to predict feed intake: Phenotypic and genetic relationships between observed and predicted values [abstract]. Journal of Animal Science. 83(Supplement 1):13-14.

Interpretive Summary:

Technical Abstract: The objectives of this study were to evaluate the accuracy of the Decision Evaluator for the Cattle Industry (DECI) and the Cornell Value Discovery System (CVDS) in predicting individual feed intake, and the feasibility of using predicted feed intake data in genetic evaluations. Observed individual animal data on the average daily feed DMI (OFI) were obtained from postweaning records of feed consumption of 504 steers from 52 sires. The experimental data also contained individual growth performance and carcass measurements. The experimental data, and daily temperature and wind speed data were used as inputs to predict average daily kg feed DMI required for maintenance, cold stress, and ADG with the CVDS model (CFI_{mcg}_) and the DECI model (DFI_{mcg}_). Average daily feed DMI required for maintenance and ADG (CFI_{mg}_, DFI_{mg}_) were also predicted with both models. Genetic parameters were estimated by REML, using an animal model with age on test as a covariate, and genotype, age of dam, and year as fixed effects. Regression equations for observed on predicted DMI were: OFI = 1.27 +/- 0.27 + 0.83 +/- 0.04 * CFImcg (R2 = 0.44) and OFI = 1.32 +/- 0.22 + 0.8 +/- 0.03 * DFImcg (R2 = 0.53). Phenotypic correlations between OFI and CFImcg, CFImg, DFImcg, and DFImg were 0.67, 0.69, 0.73, and 0.77, respectively. Heritabilities for OFI, CFImcg, CFImg, DFImcg, and DFImg were 0.27, 0.34, 0.34, 0.34, 0.33, respectively with all SE = 0.012. Genetic correlations between OFI and CFImcg, CFImg, DFImcg, and DFImg were 0.95 +/- 0.07, 0.95 +/- 0.07, 0.96 +/- 0.07, 0.96 +/- 0.06, respectively. Genetic correlations between CFImcg and DFImcg, and between CFImg and DFImg were both 0.99 +/- 0.005. The strong genetic relationships between OFI and the predicted DMI data suggest that predicted DMI may be used in genetic evaluations. Genetically, there appears to be little difference between DECI and CVDS predicted feed intakes.