Chymosin-induced gelation properties of the milk of around 400 Swedish Red dairy cows was investigated with the aim of identifying genetic protein variants that influence chymosin-induced gelation for optimisation of cheese milk through breeding practices. The variation in chymosin-induced gelation properties was shown to be large in the milk of Swedish Red and there was a high frequency of cows producing non-coagulating milk, 18%. The present study showed that the common composite beta-kappa-casein genotypes A(1)A(2)/AE and A(2)A(2)/AA were associated with both poor gelation properties and non-coagulation in the milk of Swedish Red. The present study suggests that if the frequencies of composite genotypes A(1)A(2)/AE and A(2)A(2)/AA were decreased in the Swedish Red population in favour for A(1)A(1)/AA and A(1)A(1)/AE, this could have a positive effect on the rennetability of the milk. (C) 2014 Elsevier Ltd. All rights reserved.