Traits for Sire Selection Related to Udder Health and Management

Abstract

Traits related to udder health were discussed: bacteriological measures, clinical frequency, and milk properties (somatic cell count, enzymes, etc.). Bacteriological testing of quarters maximizes information on infection but is impractical on a population scale. Clinical recording is an objective measure but fails to indicate subclinical cases and is not available in most countries. Cell counts are economical to obtain but are highly variable, difficult to interpret, and not sensitive indicators of subclinical infections. Several milk enzymes are possible indicators of tissue damage. Heritabilities are about .2 for cell counts and .1 for other measures, reflecting genetic variation in teat defenses, phagocytosis, or immune response. There appears to be genetic antagonism between cell count and milk yield (positive gentic correlation of .1 to .2) in contrast to the negative phenotypic relationship between milk yield and cell count. A program to select sires whose progeny have lowest cell counts should be formulated carefully; more needs to be known about interpretation of cell count as a defense mechanism. Heightened cell counts decrease the probability of infection upon subsequent challenge with pathogens. Is there heritable variation in cell count of cows before exposure? A combined criterion of cell count, lactose, and enzyme concentration should be studied.

Investigation into the production and conformation traits associated with clinical mastitis using artificial neural networks

“…For instance, the estimated genetic correlations between milk yield and indicators of mastitis suggest that genetic proofs for production traits might be an important source of information for improving an ANN's ability to predict mastitis (Miller 1984;Banos and Shook 1990;Simianer et al 1991;Schutz 1994). Furthermore, SCC itself has a high genetic correlation with mastitis (0.6 to 0.8), indicating that a pattern may exist (Shook and Schutz 1994).…”

An Epidemiological and Genetic Study on Registered Diseases in Finnish Ayrshire Cattle

“…As expected, the heritability estimates were relatively low. In the review by Miller (1984) the heritability estimates of clinical mastitis ranged from -0.03 to 0.5, with average 0.12. T a b 1 e 4.…”

“…AU countries recommended mastitis control measures (IDF 1985). According to Miller (1984), the mastitis control centers on sanitation, antibiotics and, as a lasit resort, culiling. In spite of control, intensified treatments with antibiotios, and extensive research, mastitis is the most important disease problem in the dairy industry (Dodd 1985).…”

“…To some extent, modern dairy management with liberal use of antibiotics and an aim to save labour, conflicts. with mastiitis control (Miller 1984). More exact knowledge of the epidemio 1 lo•gy and genetics of mastitis is needed for creating an appropriate preventive and control program.…”

Linear programming applied to dairy cattle selection

“…Further research in these areas is required before national selection programs for SCS should be commenced. Miller (1984) reviewed the estimates of heritability for somatic cell count and reported an average estimate (Emanuelson etal., 1988;Coffey etal., 1985). Declines in milk yield with increases in somatic cell concentration have been reported by Raubertas and Shook (1982) and Bartlett et al (1990).…”