Abstract Profitable seasonal calving dairy production systems require a cow that will establishpregnancy early in the breeding season implying a quick return to service post-calving and good pregnancy rates. Genetic selection provides an opportunity to achieve this goal so therefore the objective of this study was to estimate the necessary geneticparameters for fertility traits, pertinent to seasonal calving herds, in order to facilitate genetic selection for fertility. The data, following editing, consisted of parity 1 to 3 records on up to 397,373 Holstein-Friesian dairy cows in Ireland. Variance components for the defined interval fertility traits (age at first calving, calving to first service interval, calving interval), binary fertility traits (submission rate in the first 21 days of thebreeding season, pregnant to first service, pregnant in the first 42 days of the breedingseason, calved in the first 42 days of the calving season) and the count fertility trait(number of services) were estimated using univariate animal models and covariancesamong traits were estimated using bivariate sire models. Heritability estimates of thenine fertility traits (including age at first calving and survival) varied from 0.01 to 0.07 within parity one to three. The coefficient of genetic variation for the fertility traits varied from 3.3% to 15.3%. Calving to first service interval, within parity, was moderately positively genetically correlated (0.54 to 0.75) with calving interval and was, in general,moderately negatively correlated with both submission rate (-0.68 to -0.29) and pregnantin the first 42 days of the breeding season (-0.36 to -0.14). Calving interval wasmoderately positively correlated (0.24 to 0.68) with number of services. Irrespectiveof parity, the genetic correlations between calving interval with calving in the first 42days of the calving season, and submission rate with pregnant in the first 42 days ofthe breeding season were all negative. The genetic correlations among calving in thefirst 42 days of the calving season, submission rate and pregnant in the first 42 days of the breeding season were all positive. All fertility traits were generally antagonistically genetically correlated with lactation milk yield, but most were moderate to stronglyfavourably correlated with survival to the next lactation. This study provides the necessary genetic parameters to undertake national genetic evaluations for fertility to help achieve the fertility targets in seasonal calving herds.

Url http://hdl.handle.net/11019/445

Collections Ireland -> Teagasc -> IJAFR, volume 52, no1, 2013
Ireland -> Teagasc -> Animal & Bioscience
Ireland -> Teagasc -> Animal & Grassland Research & Innovation Programme
Ireland -> Teagasc -> Irish Journal of Agricultural & Food Research