A retrospective study was undertaken to examine monthly rates of carcass condemnation for bovine malignant lymphoma in adult dairy cows slaughtered between January 1979 and December 1982, in 2 plants (A and B) in the southern San Joaquin Valley of California. Extremes (mean) of monthly rates for slaughterhouse A were 41 to 100 (65.9) per 10,000 slaughtered and for slaughterhouse B, 39 to 113 (94.1) per 10,000. The overall monthly mean rate was 80 per 10,000 slaughtered. Equations for long-term trend lines for condemnation rates for slaughterhouses A and B were T = 0.398 + 0.0176t - 0.0002t2 and T = 0.314 + 0.0378t - 0.0007t2, where t = month. A difference in patterns of trends was not apparent, although slaughterhouse A tended to have lower rates of condemnation than did slaughterhouse B. Seasonal components of trend lines, estimated by time-series analysis, were not consistent between plants, except for the month of August, during which time seasonally adjusted rates were low for both slaughterhouses. For slaughterhouse A, 2 classic cyclical components were identified--between January 1981 and September 1981 and between September 1981 and September 1982. For slaughterhouse B, the cyclical components were between November 1979 and July 1981 and between July 1981 and August 1982. The later cycle resembled the second cycle of rates from slaughterhouse A. Rates remained stable through 1979 and then increased steadily for 2.5 years. During the last 6 months of 1982, rates leveled off and perhaps began to decline.
|Original language||English (US)|
|Number of pages||5|
|Journal||American Journal of Veterinary Research|
|State||Published - Jun 1985|
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