Associations of the epithelial mucin, PAS-1, with yield, health, and reproductive traits in Holstein dairy cows.

Five polymorphic forms of the epithelial mucin, PAS-1, were identified in milk by SDS-PAGE. The sizes of PAS-1 ranged from 194.5 to 163 kDa. Mature equivalent milk, fat, and protein yields and protein and fat percentages from 139 cows in The Pennsylvania State University herd were analyzed with two models. Both models contained a year and season combination of calving and parent average. In Model [1], yields were regressed on the mean size of PAS-1 either linearly or linearly and quadratically. Model [2] included PAS-2 phenotype as a discrete variable. Lactation mean of somatic cell scores (119 cows), number of times bred (136 cows), and days open (136 cows) were analyzed with the same two models excluding parent average (data not available). Mean size of PAS-1 was not linearly related to the traits evaluated. The effects of PAS-1 phenotypes as a discrete variable were significant for mature equivalent fat and protein yields, fat percentage, number of times bred, number of times bred restricted to 3, and days open restricted to 150 d. Overall, there was little indication of an important linear or quadratic relationship between PAS-1 size and traits measured.