Age-Specific Probabilities of Culling Under Different Culling Criteria in Nili-Ravi Buffalo

¹ Department of Animal Breeding and Genetics, University of Agriculture, Faisalabad, Pakistan
² Department of Animal Science, Iowa State University, Ames 50011

Data on 1457 Nili-Ravi buffalo in Pakistan were used to estimate age-specific probabilities of cows culled for low milk yield, reproductive failure, poor health, and old age. Reproductive failure was the principal reason for cow removal (44%). The probability of culling for reproductive problems increased with age: .006 at 3 yr to .282 at 14 yr. Low milk yield accounted for 27% of all cows removed, but there was no apparent trend based on this criterion: .063 at 3 yr and .075 at 14 yr. Cows culled for health-related problems were 22% of the total data. The probability of culling because of health gradually increased from .029 at 3 yr to .081 at 11 yr and decreased thereafter. The percentage of cows culled for old age was 7%. Age-related changes in culling for reproductive and health failures should be the subject of further research to minimize cow removal for these reasons and to allow more attention to voluntary culling for milk yield.

Culling rates for cows bred to calve first before and after 48 mo were 22 and 32; 43 and 45; 26 and 18; and 9 and 5%. respectively, for yield, reproduction, health, and old age criteria. There were larger differences in probabilities between these two groups and the pooled sample estimate at specific ages for yield than for other culling criteria. The average age of culled cows in each group was 12.49 and 11.15; 10.8 and 10.35; 12.04 and 12.66; 15 and 15; and 8.2 and 7.91 yr for yield, reproduction, health, old age, and all reasons, respectively.

Key Words: Nili-Ravi buffalo • culling probabilities • yield, reproduction

Submitted on April 22, 1991
Accepted on January 7, 1992