Poultry

In ovo injection has emerged as a targeted strategy for delivering essential nutrients or vaccines during avian embryogenesis, yet the effects of vitamin D (VitD) metabolites delivered prior to hatch remain incompletely understood. This review summarizes the available evidence describing the embryonic and post-hatch responses of broilers when VitD is administered in ovo and highlights the opportunities and limitations for improving their performance in association with each VitD source, including vitamin D₃ (VitD₃), 25-hydroxyvitamin D₃ (25OHD₃), 1α-hydroxyvitamin D₃ (1α-OHD₃), 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), and 24,25-dihydroxyvitamin D₃. Greater post-hatch improvements in broiler performance and skeletal development have been observed when in ovo 25OHD₃ was combined with dietary 25OHD₃ or minerals. The in ovo delivery of 1.2 to 2.4 µg of water-soluble 25OHD₃ alone or in combination with Marek’s disease vaccine between 17.5 and 18 days of incubation (doi), has been found to be effective in improving hatchability, post-hatch performance, bone mineralization, meat yield, intestinal histomorphology, and immune function. In contrast, in ovo administration of 1α-OHD₃ and 1,25(OH)₂D₃ at low doses has resulted in inconsistent performance and remains unsuitable for practical in ovo application. The physiological responses to in ovo VitD sources are highly dependent on metabolite form, dose, solubility, vehicle, embryonic age at administration and post-hatch environmental conditions. Nevertheless, 25OHD₃ is a promising candidate for integration into commercial in ovo platforms. Furthermore, knowledge gaps remain for defining optimal dose ranges, understanding metabolite interactions, and evaluating long-term impacts across different production systems.

Native Mexican turkeys (Meleagris gallopavo gallopavo) are an important genetic resource in family-based production systems exposed to marked regional and seasonal environmental variation. This study evaluated the associations between environmental gradients, diet composition, and hematological responses in native Mexican turkeys (Meleagris gallopavo gallopavo) raised under traditional family-based production systems. Fifty approximately six-month-old males were evaluated in a 5 × 2 factorial design including five physiographic regions and two seasons (rainy and dry). Crop content composition, estimated dietary nutrient composition, body weight, and hematological profile were analyzed using multivariate analysis of variance, principal component analysis (PCA), and multiple regression. Grains and energy-rich by-products predominated in the diet (58.2–76.2%), whereas the dry season increased dry plant fragments and crude fiber while reducing crude protein from 17.5 to 14.3% (p < 0.001). Body weight was greatest in the Neovolcanic Axis region (5.20 kg) and lowest in the Coast region (4.35 kg) (p < 0.001). Erythrocyte-related variables were higher in temperate, high-altitude regions, whereas leukocyte-related variables predominated in warmer regions (p < 0.05). PCA explained 71.3% of the total variation, identifying nutritional–productive and immunological–adaptive components. Physiographic region was the factor most strongly associated with the diet composition and hematological responses, whereas the dry season intensified nutritional constraints and their effects on physiological adaptation.

A novel fungal phytase (NFP) was evaluated for its effects on growth performance, phosphorus (P) metabolism, tibia development, and nutrient digestibility in broilers. A total of 420 one-day-old Arbor Acres broilers were randomly assigned to seven treatments: a negative control (basal diet without phytase), a positive control (500 U/kg commercial phytase), and five groups supplemented with NFP at 250, 500, 1000, 1500, or 2000 U/kg. Increasing inclusion of dietary NFP linearly improved average daily gain and feed conversion ratio (FCR) during days 22–42 and overall, with NFP outperforming commercial phytase at equivalent doses in FCR reduction. NFP increased the digestibility of crude fiber and P, linearly increased crude protein digestibility, and dose-dependently enhanced ileal digestibility of several amino acids (especially at 1000–2000 U/kg). NFP dose-dependently increased plasma inorganic P while reducing alkaline phosphatase and parathyroid hormone. Tibia weight, midshaft width, bone density, breaking strength, and P content increased linearly with NFP, peaking at 1000–2000 U/kg. NFP also upregulated tibial mRNA expression of the phosphate-regulating gene with homology to endopeptidase on the X chromosome, dentin matrix protein 1, and osteocalcin. In conclusion, NFP optimizes broiler growth, nutrient utilization, and skeletal development via dose-dependent modulation of P metabolism and osteogenic pathways.