The objectives of this study were to compare milk coagulation ability (MCA) and the prevalence of noncoagulation of milk within the main Finnish dairy breeds, Finnish Ayrshire (FA) and Holstein-Friesian (HOL), as well as to study the herd effect on MCA. Data used in the statistical analyses consisted of individual milk samples of 959 FA, 399 HOL, and 50 crossbred cows from 84 herds. Data were collected before the grazing season in the spring 1999. Milk samples were analyzed for the milk coagulation traits (milk renneting time, R and curd firmness, E(30)) and pH. In addition, information on the 305-d milk production traits from the year 1999, and background information about feeding and management regimes of the herds were obtained. Variance components for the random herd and animal effects were estimated using REML methodology and an animal model. Breed, parity, lactation stage (for R, E(30) and pH only), and a measuring unit (for R and E(30) only) were included as fixed effects in the model. When the effects of concentrate feeding frequency and type of concentrate were studied, the random effect of herd was excluded from the model. A relationship matrix included parents, grandparents, and great grandparents of the cows with observations. The HOL cows were superior to FA cows in MCA when both the proportion of poorly coagulating (PC) and noncoagulating (NC) milk, and the differences in curd firmness were considered. About 30% of the FA cows and 12% of the HOL cows produced PC milk. Only 1.3% of the HOL cows and 8.6% of the FA cows produced NC milk. Herd effect explained only a minor part of the variation in MCA (8%) compared with that in 305-d milk production traits (about 43%). Frequent feeding of the concentrate was associated with good MCA as well as for the high milk, protein and fat yields, but it was not associated with the prevalence of the NC milk.

Pedigree data from national breeding value evaluations were used in calculation of the coeffi cient and rate of inbreeding, average coeffi cient and rate of relationship and generation intervals for the Finnish Ayrshire and Holstein-Friesian dairy cattle populations. The data had 1,366,555 Ayrshire and 377,869 Holstein-Friesian animals. The mean coeffi cient of inbreeding for Ayrshire and Holstein-Friesian animals born in the 1990s was 2.29% and 0.90%, respectively, and the trend was towards higher inbreeding values. The average coeffi cient of relationship, mean increase in inbreeding and generation interval was calculated for bulls born between 1976 and 1999, and for cows born between 1986 and 1999. The mean coeffi cient of relationship of Ayrshire bulls increased 2.22 %-units per generation and inbreeding increased 0.20 %-units per generation during the years studied. The mean coeffi cient of relationship of Finnish Holstein-Friesian bulls increased 0.96 %-units per generation and inbreeding 0.17 %-units per generation. The mean coeffi cient of relationship and inbreeding of Ayrshire cows increased 0.38 %-units and 0.31 %-units per generation, respectively. For Holstein-Friesian cows the mean coeffi cient of relationship and inbreeding increased 0.25 %-units and 0.11 %-units per generation, respectively. Results show that inbreeding is low and it is increasing slowly in both breeds. However, especially the coeffi cients of relationship of Ayrshire bulls are high in some age classes and this may lead into faster increase in coeffi cients of inbreeding.

ei saatavilla