Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 6/22/2003
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: The objectives of this study were to estimate genetic correlations among body condition score (BCS), dairy form (DF), days open (DO), ME milk, ME fat and ME protein production. Body condition score and DF obtained from the Holstein Association USA Inc. were merged with DO and production data from the Animal Improvement Programs Laboratory at USDA. Edits applied to the data included: a valid BCS observation, a minimum of 20 daughters per sire, a minimum of 10 cows per herd-classification visit (HV) or herd-year-season of calving (HYS), age between 24 and 60 months at classification, less than 336 days in milk (DIM) at classification and minimums of 25 days open and 4,537 kg of ME milk. Only one record per cow was used and DO greater than 250 were set to 250. The final data set included 166,222 records. Fixed effects were age within lactation group, 5th order polynomials of DIM and HV for BCS and DF, age within lactation group and HYS for production traits and lactation number and HYS for DO. Random sire and error were included for all traits and all analyses were performed with ASREML. Heritability estimates ranged from 0.04 for DO to 0.30 for ME protein. The genetic correlation estimate between BCS and DO was -0.33. The genetic correlation estimate between DF and DO was 0.51. The genetic correlation estimate between BCS and DO was -0.10 when DF was included as a covariable and the genetic correlation estimate between DF and DO was 0.49 when BCS was included as a covariable. Genetic correlation estimates among BCS and production traits ranged from -0.20 to -0.30, whereas genetic correlation estimates among DF and production traits ranged from 0.41 to 0.52. Dairy form could be included in a fertility index for reduced DO to increase the reliability of DO evaluations for newly proven bulls in the US.