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Controlling body weight in broiler breeder farms is achieved through feed restriction. The degree of feed restriction depends on the target growth curve. It is valuable to investigate the intergenerational impact of lesser growth restriction and earlier pubertal growth. Most of the research pertaining to consequences of maternal effects in chickens have focused on nutrient composition of the diet; however, there is little data on effects of alterations of the maternal prepubertal BW gain (MW) and pubertal inflection (MI) on progeny performance in the literature. The objective of the current study was to investigate the effect of a reduced degree of maternal prepubertal phase growth restriction and earlier maternal pubertal phase growth on offspring growth and development.
In a randomized controlled trial, a total of 40 female broiler breeders were randomly assigned to 10 unique growth trajectories with 2 levels of maternal BW gain (MW) in prepubertal phase and 5 levels of maternal pubertal growth inflection (MI) for each level of the MW. Growth parameters (MW and MI) were estimated by fitting a 3-phase Gompertz model to the breeder-recommended BW target (Standard MW; SMW), or 10% higher (HMW). Maternal pubertal inflection was advanced by 0, 5, 10, 15, or 20% in both SMW and HMW groups. Maternal growth trajectories were implemented from 0 to 42 wk of age using a precision feeding (PF) system. The current study consisted of two cohorts that varied in maternal age (MA) of 35 and 42 wk. The broiler chicks were fed to 35 d of age, also with the PF system. Analysis of covariance was conducted on all dependent variables (body weight, feed conversion ratio, carcass traits) with maternal age (MA), MW, and offspring sex as categorical variables and MI as a continuous predictor variable.
Chicks from 42 wk old hens had higher 0 (hatch), 14, 21, and 28 d BW, liver, and heart weight, and lower FCR from 7 to 35 d of age than those from the 35 wk old hens. Compared to SMW hens, HMW hens produced female offspring with lower FCR, and male offspring with heavier gut weight. Advancing MI increased hatch BW in both sexes and 35 d BW in male broilers. For every week that the MI was advanced, hatch BW increased by 0.26 g in females and 0.39 g in males; however, 21 and 35 d BW decreased by 6.85 and 17.29 g/wk in females and increased by 10.53 and 25.94 g/wk in males, respectively. Overall, a lesser degree of growth restriction during prepubertal and earlier pubertal growth increased male offspring growth.
To investigate the effects of maternal growth patterns downstream in the broiler supply chain, the current experiment focused on relaxed maternal growth restriction during the prepubertal growth phase and earlier pubertal growth in breeders on their offspring growth and carcass traits. To our knowledge, this is the first investigation of the maternal effects of strategically designed growth trajectories based on advancing the timing of the pubertal growth phase in breeders. Overall, the current results indicate that increasing maternal prepubertal phase BW gain by 10% and advancing maternal pubertal phase inflection from 22 to 18 wk of age can increase male broiler growth rate and some carcass components weight in offspring chicks.