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Short Communication: Genetic Analysis of Nonreturn Rate and Mastitis in First-Lactation Norwegian Red Cows

B. Heringstad^*,,1, I. M. Andersen-Ranberg, Y. M. Chang and D. Gianola^*,

^* Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, N-1432 Ås, Norway
Geno Breeding and A. I. Association, N-1432 Ås, Norway
Department of Dairy Science, University of Wisconsin, Madison 53706

¹ Corresponding author: bjorg.heringstad{at}umb.no

Associations between clinical mastitis (CM) and nonreturn rate within 56 d after first insemination (NR56) were examined in Norwegian Red (NRF) cows. Records on absence or presence of CM within each of the intervals, –30 to 30, 31 to 150, and 151 to 300 d after first calving, and records on NR56 for 620,492 first-lactation daughters of 3,064 NRF sires were analyzed with a Bayesian multivariate threshold liability model. Point estimates of genetic correlations between NR56 and the 3 CM traits were between –0.05 and –0.02. Residual correlations were close to zero, and correlations between herd-5-yr effects on NR56 and CM in the 3 lactation intervals ranged from –0.15 to –0.17. It appears that CM and NR56 in first lactation are independent traits.

Key Words: female fertility • genetic correlation • mastitis • multivariate threshold model