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Analysis of culling probability in dairy buffalo using survival models
P M Galeazzi1, M E Z Mercadante, J A Ii V Silva
11Animal Science Department, São Paulo State University, Jaboticabal, São Paulo, Brazil.
Animal : an International Journal of Animal Bioscience
|March 27, 2012
Summary
Environmental factors significantly impact dairy Murrah buffalo longevity. Higher first-lactation milk yield increases stayability, while older age at first calving reduces it in the first year. These factors are crucial for genetic breeding programs.
Area of Science:
- Animal Science
- Dairy Production
- Genetics
Background:
- Herd management and genetic improvement programs for buffaloes require understanding factors influencing female longevity.
- Stayability (ST) is a key trait for dairy herd productivity and economic viability.
Purpose of the Study:
- To investigate the influence of environmental effects on the stayability (ST) of dairy female Murrah buffalo.
- To identify key environmental factors impacting buffalo herd retention for genetic breeding programs.
Main Methods:
- Survival analysis was employed using data from 1016 Murrah buffaloes.
- The LIFEREG procedure in SAS was used to fit parametric models to failure time data (culling).
- Fixed effects analyzed included farm, birth year/season, first-lactation milk yield, and age at first calving.
Main Results:
- Breeding farm, year of birth, and first-lactation milk yield significantly influenced buffalo stayability (P < 0.0001).
- Older age at first calving increased culling probability within the first year post-calving.
- Higher first-lactation milk yield was associated with lower culling probability and longer herd retention.
Conclusions:
- Environmental factors, specifically breeding farm, birth year, and first-lactation milk yield, are critical determinants of buffalo stayability.
- These significant factors should be incorporated into genetic models for analyzing buffalo stayability.
- Understanding these influences can optimize breeding strategies for improved dairy buffalo herd management.
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