The objective of this study was to determine the relationships among daughter clinical mastitis during first and second lactations and sire transmitting abilities for somatic cell score, udder type traits, productive life, and protein yield. Data on clinical mastitis during first lactation were available for 1795 daughters (in six Pennsylvania herds, one Minnesota herd, and one Nebraska herd) of 283 Holstein sires. Data on clinical mastitis during second lactation were available for 1055 of these daughters. A total of 479 cows had 864 clinical episodes during first lactation, and 230 cows had 384 clinical episodes during second lactation. Clinical mastitis incidence and the total number of clinical episodes during each lactation were regressed on herd-season of calving (a classification variable), age at first calving, lactation length, and sire transmitting abilities taken one at a time. Linear effects, nonlinear effects, and odds ratios were estimated for sire transmitting abilities. Separate analyses were conducted on dependent variables that considered clinical mastitis from: all organisms, coagulase-negative staphylococci, coliform species, streptococci other than Streptococcus agalactiae, and the most common environmental organisms (coliform species and streptococci other than Streptococcus agalactiae). Heritability of clinical mastitis ranged from 0.01 to 0.42. Daughters of sires that transmit the lowest somatic cell score had the lowest incidence of clinical mastitis and the fewest clinical episodes during first and second lactations. Daughters of sires that transmit longer productive life, shallower udders, deeper udder cleft, and strongly attached fore udders had either fewer clinical episodes or lower clinical mastitis incidence during first and second lactations. The incidence of clinical mastitis and the number of clinical episodes per lactation may be reduced by selection for lower somatic cell score, longer productive life, shallower udders, deeper udder cleft, or strongly attached fore udders.
Bibliographical noteFunding Information:
This study was supported by a grant from the Pennsylvania Department of Agriculture. The authors thank the following cooperators for their participation: Rob Kocher of Breezy Farms (Pennsylvania Furnace, PA), Earl Lake (Pennsylvania Furnace, PA), Ed Quigley of Luzerne Farms (Spruce Creek, PA), Doyle Waybright of Mason Dixon Farms (Gettysburg, PA), Ray Burk-holder of Statler Farms (Chambersburg, PA), George Marx and Marlyn Jacobson of the University of Minnesota Northwest Experiment Station (Crookston), Erin Marotz of the University of Nebraska-Lincoln, and Mark Amsler, Howard Wiggan, Bob Hoffman, Walker McNeill, and Myron Rudy of The Pennsylvania State University Dairy Production Research and Teaching Center (University Park). Appreciation is expressed to the following matriculated students of The Pennsylvania State University, College of Agricultural Sciences for their assistance with data entry: Suzanne Cadwal-lader Beinlich, Lynette Goodling, Mark Swartz, and Derrice Ward. The authors thank Ryan Starkenburg of Holstein Association, USA for retrieval of data contributed by the Animal Improvement Programs Laboratory at USDA.
- Clinical mastitis
- Productive life
- Somatic cell score
- Udder type traits