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Context Exposure to maternal hormones can permanently alter an embryo’s developmental trajectory. Maternal mediated effects have significant potential in the chicken meat industry, as breeder hens are feed restricted in a bid to improve performance. Evidence suggests breeder hens are chronically stressed, resulting from periods of prolonged hunger. However, evidence linking embryonic exposure to early-life stress and altered offspring phenotype in meat chickens is lacking. Additionally, methods to alleviate the phenotypic consequences of early-life stress have not been comprehensively explored. Nutritional supplementation with amino acids, such as arginine (Arg), may provide one such option, as Arg reportedly enhances performance characteristics in chicken meat birds. Aims An in ovo study was conducted to investigate whether exposure to in ovo stress altered offspring performance in meat chickens. Additionally, Arg was supplemented post-hatch to alleviate reductions in performance, hypothesised to occur as a result of exposure to corticosterone. Method A total of 400 eggs were divided into two groups and administered a corticosterone (CORT) or control (CON) solution at embryonic Day 11. At hatch, birds were separated into four groups based on in ovo and dietary treatments: CORT-Control, CORT-Arg, CON-Arg and CON-Control. Birds fed supplementary Arg diets received an Arg:lysine inclusion of 125%. Bodyweight (bwt) and feed conversion were recorded weekly. Birds were euthanised at embryonic Day 15, Day 0, 7, 21 (n = 40 birds/time point), 28 and 35 (n = 48 birds/time point) for organ collection. A total of 12 additional female birds were euthanised and subjected to a dual-energy X-ray absorptiometry scan for body composition at Day 35. Results Neither in ovo nor diet treatments influenced bwt, bwt gain, feed conversion or plasma corticosterone at any time point, nor did any in ovo by diet interaction exist. Female birds exposed to CORT exhibited significantly greater fat mass (%bwt; P = 0.007) and reduced lean mass (%bwt; P = 0.026) compared with CON females at Day 35. Supplementary Arg did not influence bird body composition. Conclusions These findings suggest in ovo exposure to CORT may negatively influence body composition of female birds. Implications Understanding the effects of the maternal/in ovo environment may provide a novel approach to further improve carcass quality and flock uniformity.

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