Adjusting preweaning pig weights to a standard age

Area of Science:

• Animal Science
• Swine Genetics
• Agricultural Research

Background:

• Accurate evaluation of sow productivity requires standardized piglet weights.
• Preweaning growth varies significantly due to genetics, environment, and age.
• Existing methods may not fully capture growth curve dynamics for accurate adjustments.

Purpose of the Study:

• To derive adjustment factors for piglet and litter weights to uniform ages.
• To improve the accuracy of sow productivity evaluations using standardized weights.
• To develop a robust model for predicting piglet weights based on age.

Main Methods:

• Quadratic regression analysis applied to preweaning weight records of Duroc and Yorkshire pigs.
• Data included 3,587 pigs across 533 litters, with weights recorded at birth, 21, and 42 days.
• Weights were log-transformed, and equations fitted to litter-sex subgroups, considering year, season, breed, and sex effects.

Main Results:

• A quadratic regression equation (Y = .2127 + .07545(age) - .000558(age)^2) accurately modeled piglet weight in natural logarithms.
• Significant effects of season and year x season x breed interactions necessitated the use of quadratic coefficients.
• Multiplicative factors were calculated to adjust weights to standard ages (14, 21, 28, 35, 42 days).

Conclusions:

• The derived quadratic equation provides reliable factors for adjusting preweaning pig weights.
• These adjustment factors enhance the precision of sow productivity assessments in swine breeding.
• The study highlights the importance of considering age-related growth dynamics for accurate genetic evaluations.