Effect of housing system and milk yield on cow fertility

Abstract. The effect of housing system (tethered vs. loose) and milk yield of 10 358 cows on their fertility was analysed in 1 721 farms from the Pomerania and Kujawy regions of Poland. The GLM, FREQ and CORR procedures of the SAS package were used for statistical calculations. The housing system significantly affected cow fertility, which also depended, both in the first reproductive cycle and over the cows‘ lifetime, on milk production level after the first calving. A stronger relationship (unfavourable for breeders) between milk production and fertility was found for tethered cows compared to their loose-housed contemporaries. Regardless of the milk production level of first calvers, loose-housed cows showed better fertility.