Mastitis is an inflammatory response within the mammary gland caused by infection or by undue stress (Cole, 1966). Mastitis is recognized world wide as one of the most costly diseases in the dairy industry. Economic losses due to mastitis dictate that all methods of reducing infection must be explored. Tbe California Mastitis Test (CMT) was developed as a field test to detect inflammation of the mammary gland (Schalm and Noorlander, 1957). Legates and Grinnells (1952) found the incidence of mastitis of 21 first lactation sire progeny groups to vary from 0 to 40%. Significant differences between sire progeny groups for the degree of udder inflammation have been reported (Reid, 1954; Afifi, 1967; Miller et al., 1976 and Alrawi £t £l•, 1979a). Breed differences in degree of mastitis also were observed (Legosin, 1966; Filipovic et al., 1971; Tsoney et al., 1975 and Ali, 1977). Alrawi et al. (1979b) suggested that restricted selection index in which milk yield is held constant would result in genetic improvement of CMT which in turn increase milk yield phenotypically.

This study was carried out to investigate the effects of breeding groups, parity, season of the year and sires on CMT.

J.A. Al-Dabakh, A.A. Alrawi, H.J. Al-Ani

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 7. Symposia (1), , 331-335, 1982
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