Multiphasic mixed growth models for turkeys

Abstract Growth models are important for optimization of feed formulation and breeding programs in turkeys. The objectives of this study were 1) to compare sex and line differences in turkeys in parameter estimates of mono- and di-phasic Gompertz growth models, and 2) to evaluate mono and diphasic m...

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Bibliographic Details
Published in:Journal of animal science 2023-01, Vol.101
Main Authors: van der Klein, Sasha A S, Willems, Owen W, Zuidhof, Martin J
Format: Article
Language:English
Subjects:
Animal Models
Animals
Body Weight
Breeding
Breeding methods
Chickens
Environmental factors
Estimates
Feed formulation
Female
Females
Growth models
Growth rate
Inflection points
Male
Males
Mathematical models
Parameter estimation
Sex
Turkeys
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Summary:Abstract Growth models are important for optimization of feed formulation and breeding programs in turkeys. The objectives of this study were 1) to compare sex and line differences in turkeys in parameter estimates of mono- and di-phasic Gompertz growth models, and 2) to evaluate mono and diphasic mixed Gompertz growth models to determine the variation in parameter estimates in a group of female line turkey toms. A total of 1,056 manually recorded weekly average body weight (BW) observations from male and female turkeys of a male and female line from weeks 1 to 20 were used for objective 1. Daily median values of automatically collected individual BW of female line turkey toms were used for objective 2 and random components associated with individual subject animals related to mature weight and/or timing of maximum gain during each phase were introduced in the Gompertz model. Growth curve shapes were different between male line toms, male line hens, female line toms, and female line hens (P < 0.001). However, inflection points were similar between male and female line toms and between male and female line hens (14.06 vs. 13.72 wk and 11.22 and 10.71 wk, respectively), while mature BW differed between lines by 6.49 and 3.81 kg for toms and hens, respectively. The normalized growth rate constant (growth rate constant corrected for mature weight) was around the same magnitude between male and female line toms (0.0031 vs. 0.0038, respectively), but slightly lower in male line hens compared to female line hens (0.0072 vs. 0.0091, respectively). Diphasic Gompertz models described growth better in all line × sex combinations compared to the monophasic models (P < 0.001) and mixed diphasic Gompertz models showed improved fit over mixed monophasic Gompertz models. The correlation structure of the random components identified that individuals with a higher mature weight had a later inflection point and lower growth rate coefficients. These results provide tools for improved breeding practices and a structure to evaluate the effects of dietary or environmental factors on growth trajectories. Not all turkeys grow the same. Find out how divergent selection changed the way they grow. Lay Summary Turkeys have been bred for several purposes over the past decades. We studied growth patterns of turkeys of two genetic lines bred for either meat production or egg production. Mathematical equations were designed and fitted to describe the average bodyweight of several consecut
ISSN:0021-8812
1525-3163
DOI:10.1093/jas/skad094