Effects of starter feeding strategies and hatching systems on performance, intestinal health, and bone mineralization in broiler chickens

• Study compared on-farm hatching and early feeding strategies in broiler chickens. • On-farm hatching improved early growth, bone strength, and intestinal health. • Early feed access boosted genes for nutrient uptake, immunity, and gut health. • Enhanced starter diets improved later performance across hatching systems. • Hatching system growth gaps vanished by day 10, showing compensatory growth. Broiler chicks of the same batch typically hatch over 24-48 h, not simultaneously. After hatching, exposure to suboptimal ambient temperatures, together with practices such as sexing, vaccination, and transport, delay their first feed and water intake, negatively impacting nutrient absorption and immune system development. Early nutrition strategies using lower Ca levels and highly digestible ingredients, like spray-dried porcine plasma, may mitigate these effects. This study compared a conventional hatchery system (CH) vs. on-farm hatching system (OFH) and three early feeding programs on performance (pen-based), tibia mineralization, and intestinal gene expression measured in representative male birds in Ross 308 broilers. Eggs from one breeder flock were divided as follows: 2 880 eggs at 18-day incubation were transported to the farm for OFH (initially 60 eggs/pen; 48 pens). At 21-day incubation (day 0), OFH pens were standardized to 39 chicks/pen (1 872 chicks total) to match conventional hatchery stocking density; surplus chicks were not enrolled. In parallel, 1 872 CH chicks from the same flock were transported ∼6 h (492 km) and placed in 48 pens. The study followed a three-way factorial design, including three starter feeding programs—S1: standard starter (0-10 days); S2: enhanced pre-starter (0-4 days) followed by standard starter (4-10 days); and S3: enhanced pre-starter (0-4 days) followed by enhanced starter (4-10 days)—by two hatching systems (CH vs. OFH), and by two sexes (female vs. male). All birds received common grower (10-28 days) and finisher (28-42 days) diets. During the starter phase, OFH chicks showed higher BW and greater tibia weight, ash weight, length, and breaking strength ( P 0.05) with few differences in bone properties. Feeding program S3 improved overall performance ( P < 0.05) compared to S1 in both systems. Chicks fed the enhanced pre-starter diet exhibited upregulation of OCLN ( P < 0.05), a gene associated with gut barrier integrity, compared with those on the standard diet. Chicks from CH showed higher expression ( P < 0.05) of genes associated with immune response, barrier function, and stress adaptation, whereas OFH chicks showed gene expression patterns consistent with earlier intestinal maturation associated with immediate post-hatch feed access. Overall, optimized early feeding strategies based on low-Ca levels and highly digestible ingredients improved broiler growth performance and supported intestinal and bone development, whereas the effects of hatching system were mainly confined to the early post-hatch period.