Associations between somatic cell score of milk and fertility traits in Polish Holstein-Friesian cows
Journal Title: Animal Science Papers and Reports - Year 2009, Vol 27, Issue 1
Abstract
The study aimed at estimating the association between somatic cell score (SCS) and two fertility traits: non-returns to oestrus by 56 days (NR56), and number of days from calving to first insemination (CFI). The data were records of 298,016 test-day observations from 190,279 first and second lactation of Polish Holstein-Friesian (PHF) cows. The model used to evaluate the effect of preceding test-day SCS on NR56 included random herd effect and fixed effects of parity, year of calving, lactation stage at first insemination, month of first insemination, interval between preceding test-day and day of first insemination, and linear regression of NR56 on SCS. A similar model including fixed effects of parity, year of calving, month of first insemination, linear and quadratic regressions of CFI on SCS, and random herd effect was applied to analyse the relation between test-day SCS and CFI. All fixed effects except the number of days from preceding test-day to first insemination significantly affected NR56. Fixed effects included in the linear model for CFI analysis, i.e. parity, year of calving, and month of first insemination, were also significant. Negative regression coefficients of NR56 on preceding test-day SCS, by interval between day of preceding test and first insemination, showed that within each interval an increase in test-day SCS caused a decrease in the non-return rate. The significant linear and quadratic regressions of CFI on SCS indicate that high SCS might delay the first insemination.
Authors and Affiliations
Małgorzata Morek-Kopeć, Andrzej Żarnecki, Wojciech Jagusiak
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