Electrical conductivity (EC) of milk is an indicator of mastitis, and could, if it shows genetic variation and is genetically correlated to mastitis, be used in a breeding program where selection for reduced mastitis resistance is included. In this study, daily measurements of EC and mastitis were analyzed with a bivariate model. For EC, the estimated heritability was high (0.22 to 0.39), while...

Introduction Mastitis is the most frequent and costly disease of dairy cattle. Losses due to mastitis can be attributed to both subclinical and clinical disease. Clinical mastitis losses are generally readily apparent and consist of discarded milk, transient reductions in milk yield and premature culling (Fetrow, 2000). Subclinical mastitis is considered the most economically important type of ...

When including clinical mastitis in the breeding goal, it is useful to know what measure of the trait is most appropriate and its relationship to the primary production traits and indicator traits in the relevant population. In this paper, genetic and phenotypic parameters for clinical mastitis, somatic cell production deviance, and protein yield were estimated for the dairy breed Danish Red. I...

The present study was conducted on the Murrah buffaloes maintained at Livestock Research Centre of ICAR-National Dairy Research Institute (NDRI), Karnal. The animals were classified into heifer, primipara and pluripara. For this experiment a total of 50 Murrah buffaloes were followed, out of which 8 were heifers, 12 were primipara and 30 were pluripara. Daytime was considered to be from 6.00 am...

Colorado State University researchers (Gutierrez and Dalsted) conducted an in-depth economic analysis of raising replacement heifers up to 31 months of age, the time at which their first calves were weaned. They calculated break-even values that were based upon all costs, minus the value of the first calf at weaning. Depending upon heifer retention rates and reproduction rates, heifer break-eve...

The aim of the present study was to compare the occurrence and duration of clinical mastitis in different seasons, stages of lactation period and parities in a Holstein dairy farm in Iran. A retrospective epidemiological survey from April 2005 to March 2008 was conducted on 884 clinical mastitis cases of 7437 lactations. Data of each case including calendar-date of mastitis onset, days in milk ...

The objective of this study was to determine the possible use of heifer pregnancy at 16 mo as a selection criterion and its possible genetic associations with hip height, yearling weight, and visual scores of conformation, finishing, and muscling. The data set contained records of 56,458 Nelore yearlings for the traits described above. Covariance components were estimated by bivariate animal mo...

This review deals with the role of viruses in the aetiology of bovine mastitis. Bovine herpesvirus 1, bovine herpesvirus 4, foot-and-mouth disease virus, and parainfluenza 3 virus have been isolated from milk from cows with clinical mastitis. Intramammary inoculations of bovine herpesvirus 1 or parainfluenza 3 virus-induced clinical mastitis, while an intramammary inoculation of foot-and-mouth ...

Thirty-eight Angus-based, crossbred, nulliparous beef heifers (BW = 280 ± 26.3 kg) sired by 2 Angus sires were used to determine if dam BW affected heifer performance, DMI, residual feed intake (RFI), and endocrine markers. Heifers were housed in individual pens (2.2 by 9.1 m) equipped with 2.2 m of bunk space and fed a diet (90.4% DM, 13.7% CP, 67.2% NDF, and 56.2% TDN) consisting of 87.2% ber...