Poultry

Poultry meat production has increased substantially worldwide through selection for rapid growth, feed efficiency, and high meat yield. These objectives, however, have been associated with increasing variation in muscle characteristics and meat quality, particularly in fast-growing birds. This review synthesizes the available literature on the histological characteristics of skeletal muscles in nine avian species used for meat production, focusing on muscle fiber number, size, and fiber-type composition and their relationships with muscle growth and meat quality. Literature searches were conducted in Google Scholar, PubMed, Web of Science, and Scopus up to March 2026. The available evidence indicates that muscle fiber characteristics contribute to differences in muscle function, metabolic phenotype, and postmortem muscle transformation, but their effects on meat quality cannot be considered independently of the vascular, metabolic, and connective tissue environment of the muscle. This perspective is particularly relevant in rapidly growing birds, especially broilers, in which pronounced fiber hypertrophy may exceed the capacity of surrounding tissues to maintain homeostasis and contribute to degeneration, inflammation, extracellular matrix remodeling, fibrosis, and growth-related breast muscle abnormalities. The review also highlights substantial differences in the availability, strength, and methodological consistency of histological evidence among avian species, with chicken being the most extensively studied and evidence for less-studied species remaining limited. Differences in staining procedures, fiber classification, muscle sampling, and measurement methods further restrict direct comparison among studies. Overall, muscle histology is important for understanding variation in growth and meat quality, but major knowledge gaps remain, particularly regarding direct links between muscle morphology and meat-quality characteristics.

The peak egg-laying plateau in poultry is regulated by complex genetic factors. To elucidate these, we performed a comparative ovarian transcriptome profiling (RNA-Seq) of Dekalb White hens with distinct egg production curves, using early-persistent (PP, n = 3) vs. late-degraded (DP, n = 3) birds selected by contrasting phenotypes from 60 birds per cohort at 49.5 weeks of age. PP hens showed earlier plateau onset (24 vs. 27 weeks), higher production (97.32% vs. 85.43%), lower body weight (1652.27 ± 26.19 vs. 1869.05 ± 32.18 g) and lower liver weight (34.85 ± 2.55 vs. 44.55 ± 1.10 g) than DP birds (p < 0.05). Suggestive shifts in hematological profiles (erythrocytes, hemoglobin, color index) were observed in the DP group (p < 0.05). Among 17,285 loci, 484 differentially expressed genes were identified (305 upregulated and 179 downregulated in PP). Functional enrichment analysis highlighted enzymatic activity and immune response pathways. Notably, PP hens exhibited upregulation of PNLIPRP1 (log₂FC = 1.9, p = 0.001) and downregulation of PLTP (log₂FC = −1.65, p = 0.015). Non-linear hierarchical approximation revealed a stochastic noise mode in DP (α = 45.05, p = 0.276). Network analysis identified a compact regulatory cluster (SFRP5, WNT5B, MMP13) linked to the Wnt pathway. RT-qPCR validated RNA-Seq trends for five candidate genes; SERPINB10B, MMP13 and LYG3 expression increased 3.86- to 16.00-fold in DP (p < 0.05). These signatures offer potential candidate molecular markers for future exploratory breeding programs targeting extended egg-laying plateaus.

Poultry production faces increasing challenges that directly affect animal welfare, productivity, and the sustainability of production systems. This review aimed to map the international scientific literature on housing systems for broilers and laying hens from 2014 to 2024, identifying research trends, knowledge gaps, and the main topics investigated in recent years. A total of 141 articles indexed in the Scopus and Web of Science databases were analyzed using the bibliometrix package in RStudio version 2026.08.2+200. The results revealed a significant increase in the number of publications from 2020 onward, with the United States, Brazil, and Germany emerging as the leading contributing countries. Research focused on topics such as heat stress, animal welfare, environmental control, building materials, and biosecurity. The analysis of scientific collaboration networks revealed a predominance of international publications and limited international collaboration, particularly in Brazil. Overall, the findings highlight the growing need for interdisciplinary and technology-oriented research aimed at increasing poultry productivity, thereby promoting sustainability, animal welfare, and production efficiency.