Estimated Culling Probabilities, Age Distribution, and Expected Herd Life 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 were from 1457 buffalo cows in a herd under development for dairy production since 1935. The probability of cows entering and remaining in the herd increased from .037 at 2 yr to .873 at 5 yr and decreased gradually thereafter. The probability of cows being culled increased with age from .098 at 3 yr to .423 at 14 yr. The maximum age of culling was 15 yr. Average ages of culled cows and of cows in the herd were 7.92 and 6.58 yr, respectively. The proportions of young (<6 yr), mature (6 to 9 yr), and old cows (>9 yr) were 42.6, 41.7, and 15.7%, respectively, for cows in the herd and 25.4, 45.7, and 28.9%, respectively, for culled cows. Expected additional herd life was 4.64, 3.18, 2.24, 1.50, and .30 yr for cows aged 3, 6, 9, 12, and 15 yr, respectively.

Age at first calving did not affect the overall trend in age-specific culling probabilities. Cows calving for the first time before 42 mo were culled in about equal proportions as old cows (28.5%) to cows calving first at 42 to 54 mo (28.5%) and after 54 mo (25.9%). The relatively infrequent culling of cows at an early age within this herd may have been detrimental to genetic improvement. Therefore, efforts to improve the genetic merit of buffalo cows should focus on performance of younger cows.

Key Words: Nili-Ravi buffalo • culling probabilities • age distribution • expected herd life

Submitted on April 11, 1991
Accepted on January 7, 1992