Hendrix Genetics, Kitchener, ON, CanadaN2K 3S2.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, CanadaT6G 2P5.
J Anim Sci. 2023 Jan 3;101. doi: 10.1093/jas/skad094.
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.
生长模型对于优化火鸡的饲料配方和育种计划非常重要。本研究的目的是：1）比较雌雄和系别差异在火鸡的单和双阶段 Gompertz 生长模型参数估计中的表现；2）评估单和双相混合 Gompertz 生长模型，以确定一组雌性系火鸡公鸡的参数估计中的变异性。总共有 1056 个从 1 到 20 周龄的雄性和雌性火鸡的手动记录的每周平均体重（BW）观测值用于目标 1。从雌性系火鸡公鸡自动收集的每日中位数个体 BW 值用于目标 2，并引入与成熟体重和/或每个阶段最大增益时间相关的个体动物的随机成分到 Gompertz 模型中。雄性系公鸡、雄性系母鸡、雌性系公鸡和雌性系母鸡之间的生长曲线形状不同（P<0.001）。然而，雄性和雌性系公鸡以及雄性和雌性系母鸡之间的拐点相似（分别为 14.06 和 13.72 周和 11.22 和 10.71 周），而公鸡和母鸡之间的成熟 BW 差异分别为 6.49 和 3.81 千克。归一化生长率常数（校正成熟体重后的生长率常数）在雄性和雌性系公鸡之间大致相同（分别为 0.0031 和 0.0038），但雄性系母鸡略低于雌性系母鸡（分别为 0.0072 和 0.0091）。与单阶段模型相比，双相 Gompertz 模型在所有系别×性别组合中更好地描述了生长情况（P<0.001），混合双相 Gompertz 模型的拟合效果优于混合单相 Gompertz 模型。随机成分的相关结构表明，成熟体重较高的个体拐点较晚，生长率系数较低。这些结果为改进的育种实践提供了工具，并为评估饮食或环境因素对生长轨迹的影响提供了结构。
