Noetzold Thiago L, Obi Etseoghena A, Fancher Bryan, Silva Marcelo, Thomson Alan, Zuidhof Martin J
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Poult Sci. 2024 Dec;103(12):104414. doi: 10.1016/j.psj.2024.104414. Epub 2024 Oct 12.
This study aimed to evaluate the effect of early growth (EG) and time of maximum pubertal growth peak (I2) on development, feed efficiency, carcass composition, and sexual maturation of broiler breeder females. Target BW trajectories were designed by changing coefficients of a 3-phase Gompertz model fit to the recommended BW target of Ross 308 breeders, [Formula: see text] . In each phase i, biologically relevant coefficients describe the amount of BW gain (g), the rate of growth (b), and the inflection point (I), which is the time when the growth rate for that phase is at its maximum rate. The study consisted of a 6 × 2 factorial arrangement, with six I2 levels (I from phase 2) and two EG levels. The I2 coefficients were 15, 17, 19, 21 (standard), 22, and 23 in wk. The EG treatments were: EG0, where g and g coefficients estimated from the standard from the breeder recommended BW were unchanged; and EG20, where 20% of the gain (g) in phase 2 (pubertal phase) was shifted to phase 1 (g; prepubertal phase). Two-hundred-eighty-eight Ross 308 pullets were randomly assigned to the twelve BW growth trajectories and fed using a precision feeding system from 0 to 28 wk of age. Body composition variables were submitted to three-way ANOVA, with EG, I2, and age as fixed sources of variation. Analysis of covariance was conducted on the remaining dependent variables with EG as fixed effect, I2 as a continuous fixed effect, and age as continuous random effect. Differences were reported at P ≤ 0.05. The BW of females followed their target BW, and ADFI differed depending on the amount of feed required to achieve their respective BW targets. Breast fleshing score was 0.2 greater in the EG20 compared to EG0. The number of juvenile primary wing feathers and age at first egg decreased by 0.4 and 0.9 d, respectively, per wk of earlier I2. Advancing I2 resulted in birds with increased carcass fat deposition from 16 to 28 wk of age. Carcass fat was 1.3- to 1.6-fold greater in the EG20 only from 4 to 16 wk of age. Early growth increased mostly pullet muscle and skeletal characteristics whereas advancing I2 advanced sexual maturity and increased carcass fat deposition around sexual maturation time.
本研究旨在评估早期生长（EG）和最大青春期生长高峰时间（I2）对肉种鸡育成母鸡的发育、饲料效率、胴体组成和性成熟的影响。通过改变拟合罗斯308种鸡推荐体重目标的三相冈珀茨模型的系数来设计目标体重轨迹，[公式：见原文]。在每个阶段i，生物学相关系数描述体重增加量（g）、生长速率（b）和拐点（I），拐点即该阶段生长速率达到最大值的时间。该研究采用6×2析因设计，有六个I2水平（来自第2阶段的I）和两个EG水平。I2系数在第15、17、19、21周（标准）、22周和23周。EG处理为：EG0，其中根据种鸡推荐体重标准估计的g和g系数不变；EG20，其中第2阶段（青春期阶段）20%的体重增加量（g）转移到第1阶段（g；青春期前阶段）。288只罗斯308小母鸡被随机分配到12种体重生长轨迹中，并从0至28周龄使用精确饲喂系统进行饲喂。对体成分变量进行三因素方差分析，将EG、I2和年龄作为固定变异来源。对其余因变量进行协方差分析，将EG作为固定效应，I2作为连续固定效应，年龄作为连续随机效应。当P≤0.05时报告差异。母鸡的体重遵循其目标体重，且平均日采食量因实现各自体重目标所需的饲料量而异。与EG0相比，EG20的胸肌丰满度评分高0.2。I2每提前一周，雏鸡初级翼羽数量和初产蛋年龄分别减少0.4天和0.9天。I2提前导致16至28周龄鸡的胴体脂肪沉积增加。仅在4至16周龄时，EG20的胴体脂肪比EG0高1.3至1.6倍。早期生长主要增加了小母鸡的肌肉和骨骼特征，而I2提前则使性成熟提前，并在性成熟时间前后增加了胴体脂肪沉积。
