By Cue, R. I. and Durr, J. W. and Monardes, H. G. and Philpot, J. C., Canadian Journal of Animal Science, 1997
Description
1558 080 lactation records were collected from "Programme d'Analyse des Troupeaux Laitiers du Quebec" Holstein cows which calved between November 1979 and March 1995. Differences in culling trends between official milk recorded and owner-sampler herds, between parities and between agricultural regions were compared. Statistical analysis was carried out using a logistic regression model, and the significance of trends was tested by linear contrasts. Involuntary culling increased from 23% in 1981 to 32% in 1994, as opposed to culling for low milk production (voluntary), which decreased from 16% in 1981 to 4.5% in 1994. The increase in involuntary culling was mainly due to increasing trends in culling for reproductive problems, mastitis, and feet and leg problems. Official herds had a greater proportion of cows that were sold and fewer cows culled for mastitis than owner-sampler herds. In official herds the percentage of cows sold tended to increase over time whereas in owner-sampler herds the proportion did not tend to change. A greater proportion of cows were culled for low productivity in the 1st lactation than in later lactations, but all parities showed a descending trend over time. The proportion of cows that were sold decreased with parity number. The proportion of cows culled for all involuntary reasons increased with parity number. All agricultural regions had similar trends for the major reasons for culling over the whole study period. [For Pt. I see pp. 593-600 of the same number of the journal.]
1558 080 lactation records were collected from "Programme d'Analyse des Troupeaux Laitiers du Quebec" Holstein cows which calved between November 1979 and March 1995. Differences in culling trends between official milk recorded and owner-sampler herds, between parities and between agricultural regions were compared. Statistical analysis was carried out using a logistic regression model, and the significance of trends was tested by linear contrasts. Involuntary culling increased from 23% in 1981 to 32% in 1994, as opposed to culling for low milk production (voluntary), which decreased from 16% in 1981 to 4.5% in 1994. The increase in involuntary culling was mainly due to increasing trends in culling for reproductive problems, mastitis, and feet and leg problems. Official herds had a greater proportion of cows that were sold and fewer cows culled for mastitis than owner-sampler herds. In official herds the percentage of cows sold tended to increase over time whereas in owner-sampler herds the proportion did not tend to change. A greater proportion of cows were culled for low productivity in the 1st lactation than in later lactations, but all parities showed a descending trend over time. The proportion of cows that were sold decreased with parity number. The proportion of cows culled for all involuntary reasons increased with parity number. All agricultural regions had similar trends for the major reasons for culling over the whole study period. [For Pt. I see pp. 593-600 of the same number of the journal.]
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