Multiphasic mixed growth models for turkeys

Area of Science:

• Animal Science
• Quantitative Biology
• Genetics

Background:

• Accurate growth modeling is crucial for optimizing turkey feed formulation and breeding programs.
• Understanding sex and line variations in growth parameters is essential for genetic selection and management.

Purpose of the Study:

• To compare parameter estimates of mono- and diphasic Gompertz growth models between sexes and lines in turkeys.
• To evaluate mono- and diphasic mixed Gompertz models for assessing parameter variations in female line turkey toms.

Main Methods:

• Utilized 1,056 manually recorded weekly body weight (BW) observations from male and female turkeys (male and female lines) from weeks 1 to 20 for objective 1.
• Employed daily median values of automatically collected individual BW of female line turkey toms for objective 2, incorporating random components into the Gompertz model.
• Analyzed growth curve shapes, inflection points, mature body weight (BW), and normalized growth rate constants across different line and sex combinations.

Main Results:

• Growth curve shapes significantly differed between male line toms, male line hens, female line toms, and female line hens (P < 0.001).
• Diphasic Gompertz models demonstrated a superior fit compared to monophasic models across all line × sex combinations (P < 0.001), with mixed diphasic models showing further improvement.
• Identified correlations where individuals with higher mature BW exhibited later inflection points and lower growth rate coefficients.

Conclusions:

• Diphasic Gompertz models offer a more accurate representation of turkey growth compared to monophasic models.
• Parameter variations in growth models provide insights for enhancing turkey breeding programs.
• The study provides a framework for evaluating dietary or environmental impacts on turkey growth trajectories.