Early-life cold stress and broiler breeder age: effects on metabolism and performance in broiler chicks

Context Understanding the interaction between breeder age and environmental stressors, such as cold, is crucial for poultry production. Previous research has highlighted the impact of these factors on chick development, but there is limited information on how breeder age specifically influences stress resilience and growth performance in broilers, particularly under suboptimal conditions. Aims The study aimed to assess the impact of broiler breeder age and 8-h exposure to cold stress on chicks during the first 7 days of rearing. Methods A total of 600 male chicks from two Cobb flocks were divided into groups based on breeder age (29 or 42 weeks) and rearing temperature (thermoneutral or cold-stressed for 8 h/day during the first week). Key results Chicks from 42-week-old breeders exhibited faster yolk sac absorption under thermal comfort conditions (P < 0.05). Corticosterone levels were higher in chicks from 29-week-old breeders exposed to cold stress (P < 0.05). Cold-exposed birds showed elevated heterophil/lymphocyte ratios regardless of breeders’ age (P < 0.05). Feed intake and weight gain were superior in birds from 42-week-old breeders up to 35 days, whereas cold stress negatively impacted the feed conversion ratio (P < 0.05). Viability was lower in chicks from 29-week-old breeders and those subjected to cold stress (P < 0.05). Conclusion Although cold stress did not affect weight gain at 35 days, it impaired the feed conversion ratio. Moreover, chicks from 29-week-old breeders were more susceptible to cold stress during the first week of life compared with those from 42-week-old breeders. Implications The study reveals that breeder age significantly influences chick resilience to cold stress, with older breeders (42-week-old) producing more robust offspring. The findings suggest that optimizing the management of thermal conditions is critical for enhancing feed efficiency, growth performance and overall viability in broiler production.