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ARS Home » Research » Publications at this Location » Publication #124089
Title: PHYSIOLOGICAL AND GENETIC FACTORS THAT INFLUENCE THE COWS RESISTANCE TO MASTITIS, ESPECIALLY DURING EARLY LACTATION

Author
item BURVENICH, C - U GHENT BELGIUM
item DETILLEUX, J - U LIEGE BELGIUM
item PAAPE, MAX
item MASSART-LEEN, A - U GHENT BELGIUM

Submitted to: Flemish Veterinary Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2001
Publication Date: 2/1/2002
Citation: BURVENICH, C., DETILLEUX, J., PAAPE, M.J., MASSART-LEEN, A.M. PHYSIOLOGICAL AND GENETIC FACTORS THAT INFLUENCE THE COWS RESISTANCE TO MASTITIS, ESPECIALLY DURING EARLY LACTATION. FLEMISH VETERINARY JOURNAL. 2002.

Interpretive Summary: Susceptibility to intramammary infection (IMI) is the probability that an animal can be infected. Sensitivity refers to the clinical reaction to IMI (mild, moderate, severe). A resistant animal is less sensitive to IMI. Bacterial, cow and environmental factors, facilitate susceptibility to mastitis. The impact of each factor depends on the pathogen. Sensitivity is sespecially dependent on cow factors and the pathogen. Mastitis incidence i the frequency of newly occurring events in a population over a given time period. It depends on susceptibility and sensitivity to IMI. Some cows exhibit a greater or lesser susceptibility and sensitivity to the same IMI infectious pathogen than others, and within a lactation cycle cows may behave differently depending on the stage of lactation (early vs. established lactation). Twenty years ago, the mechanisms that controlled the sensitivity of the mammary gland to infection were poorly understood. Since then much progress has been made. Results of endocrine and genetic studies may lead to a better insight into the susceptibility for mastitis. the challenge is to integrate effectively the information from molecular and quantitative genetics into existing breeding programs. Genetic selection for cows resistant to mastitis could become an important alternative for prophylactic measures of mastitis in the future,

Technical Abstract: The first line of defence against infection in the bovine udder is the mechanical and anti-microbial barrier of the teat canal. In the gland, protection is only effective if rapid influx of neutrophils from the circulation and subsequent phagocytosis and killing of bacteria occurs. The second line of defence against infection consists of a network of memory cells and immunolglobulines, and there is no doubt that complex interactions exist with the first line of defence. In order to minimise mammary tissue damage caused by bacterial toxins and oxidative products released by neutrophils, elimination of invading bacteria should proceed quickly. First and second line of defences have a genetic basis. Heritability of teat and udder conformation, milkability, alpha and beta receptors in the teat, somatic cell count and defence mechanisms have been investigated. Milkability is highly heritable and has been related to penetrability of the teat canal. The number of blood neutrophils in health cows after parturition is also highly heritable and has been related to susceptibility to clinical mastitis. Under normal conditions, circulating neutrophils do not have the same genetic ability to ingest and kill bacteria. In vitro ingestion of Escherichia coli by blood neutrophils is, however, not an appropriate predictive marker for mastitis susceptibility and the heritability for percentage of Staphylococcus aureus ingested per cell is close to zero. Although significant genetic variation among cows in resistance to mastitis is found, differences in intramammary infections between BLAD carriers and non-carriers were not observed.