This work aimed to evaluate the gene expression of amino acids (AA) and fatty acids (FA) sensors in the gastrointestinal tract (GIT) of chickens at two different ages (7 and 26 days post-hatch). Sixteen broilers (Ross 308) were selected, and ten sections of the GIT, including upper (tongue base, upper palate, crop, proventriculus), middle (gizzard, duodenum, jejunum, ileum), and lower GIT section (cecum, colon) were collected for analysis. Relative gene expression of AA (T1R1, T1R3, mGluR1, mGluR4, CaSR, GPR139, GPRC6A, GPR92) and FA (FFAR2, FFAR3, FFAR4) sensors were assessed using qPCR. The statistical model included age, GIT section, and gene. In addition, the correlations between gene expressions were calculated. At day 7, a significantly (p = 0.004) higher expression of AA sensors in the oral cavity and FA sensors in the lower GIT section (i.e., cecum and colon) compared to the middle section was recorded. A higher expression of AA compared to FA sensors was detected at the upper GIT section in 7 (p < 0.001) and 26-day-old chickens (p = 0.026). Thus, at day 7, AA sensors were predominantly (p < 0.05) expressed in the upper GIT section (mainly oral cavity), while FA sensors were mainly expressed in the lower GIT section, at cecum (FFR2 and 4) or colon (FFAR3). These results may indicate that in early life, both ends of the GIT are fundamental for feed intake (oral cavity) and development of the microbiota (cecum and colon). In contrast, at 26 days of age, the results showed the emergence of both AA and FA sensors in the jejunum, presumably indicating the essential role of the jejunum in the digestion absorption of nutrients and the signaling to the brain (gut-brain axis) through the enteroendocrine system. Significant positive correlations were observed between T1R1 and T1R3 (r = 0.85, p < 0.001), CaSR and T1R1 (r = 0.78, p < 0.001), CaSR and T1R3 (r = 0.45, p < 0.050), and mGluR1 and FFAR3 (r = 0.46, p < 0.050). It is concluded that the gene expression is greater in the oral cavity for AA sensors and the lower gut for FA sensors. On day 26, the role of jejunum regarding nutrient sensing is highlighted.

Fowl aviadenovirus (FAdV) is a member of the Aviadenovirus genus within the Adenoviridae family. FAdVs are divided into five species based on genomic differences: Fowl aviadenovirus A to Fowl aviadenovirus E (FAdV-A to FAdV-E). They are classified into twelve serotypes (FAdV-1 to FAdV-8a and FAdV-8b to FAdV-11) through cross-neutralization tests. FAdVs are mainly associated with hepatitis hydropericardium syndrome (HHS), adenoviral gizzard erosion (AGE), and inclusion body hepatitis (IBH). The serotypes commonly involved in IBH are FAdV-2, FAdV-11, FAdV-8a, and FAdV-8b. IBH causes significant economic losses in the poultry industry, mainly due to high mortality, reduced productivity, and immunosuppression. This is the first case report on IBH in Chile caused—according to post-mortem findings, molecular analysis, sequencing, and phylogenetic analysis—by FAdV-11. Since the serotype had not previously been reported in Chile, continued monitoring of IBH cases is required to determine the serotype of the circulating FAdVs and adapt preventative vaccination programs.

Infectious bursal disease virus (IBDV) is an important pathogen affecting the poultry industry worldwide. IBDV serotype 1, including classical virulent strains (cvIBDV), variant strains (varIBDV), and very virulent strains (vvIBDV), is pathogenic for chickens. IBDV mainly infects immature B-lymphocytes in the bursa of Fabricius, weakening the humoral immune response and leading to secondary infections and increased morbidity and mortality. The Laboratory of Avian Pathology received ten live 8-week-old pullets from a laying hen operation experiencing increased mortality, prostration, diarrhea, and sudden death. Upon necropsy, the affected birds presented swollen, hemorrhagic, and edematous bursa of Fabricius, as well as hemorrhage in the breast and thigh muscles. RT-PCR confirmed that the samples from the bursa of Fabricius were positive for IBDV. Phylogenetic analysis of the VP1 and VP2 gene nucleotide sequences classified the strain, isolated in embryonated chicken eggs, as the A3B5 genotype. Amino acid sequence analysis of the VP2 hypervariable region revealed the presence of amino acid residues commonly found in vvIBDV. Additional studies are required to investigate the epidemiological situation of this genotype in Chile and to evaluate current vaccination plans and their effectiveness against new variants.

Vertebral osteomyelitis is a re-emerging disease characterized by inflammation and necrosis of the thoracic vertebral body, caused by Enterococcus cecorum. Here, we report the first case of vertebral osteomyelitis caused by Enterococcus faecalis in Broiler Breeders, in Chile, which also causes infections in humans and is resistant to multiple antimicrobials, representing a risk to public health.

Enterococcus spp. are increasingly recognized as important opportunistic pathogens in poultry production and represent a potential One Health concern because of their virulence potential and capacity to acquire antimicrobial resistance determinants. This study characterized Enterococcus isolates recovered from clinical poultry cases in Chile, focusing on species distribution, virulence-associated genes, antimicrobial resistance patterns and genes, biofilm formation, and cytolysin activity. A total of 39 isolates were identified using the VITEK^® 2 Compact system and confirmed by PCR targeting the tuf gene. Seven Enterococcus species were detected, with E. faecalis predominating (61.5%) and E. faecium following (15.4%). The virulence-associated genes asa1, gelE, and cylA were detected in 97.4%, 97.4%, and 48.7% of the isolates, respectively. Phenotypic antimicrobial susceptibility testing showed resistance mainly to tetracycline (61.5%) and erythromycin (17.9%), whereas all isolates were susceptible to vancomycin, ampicillin, chloramphenicol, and linezolid. Molecular analysis identified tetM (71.8%), ermB (66.7%), and tetL (30.8%) as the most predominant resistance genes. A significant association was observed between tetM and phenotypic tetracycline resistance (Fisher’s exact test, p = 0.010). However, no association was found between ermB and erythromycin resistance. Biofilm formation was observed in 66.7% of the isolates, although most were weak biofilm producers. Despite the relatively high prevalence of cylA, β-hemolytic activity was detected in only 5.1% of isolates, indicating an incomplete genotype–phenotype concordance. Overall, poultry-associated Enterococcus spp. circulating in Chile harbored multiple virulence and antimicrobial resistance determinants that may contribute to their persistence and adaptation in poultry production systems. These findings provide the first baseline molecular epidemiological data on clinical poultry-associated Enterococcus spp. isolates in Chile and support the need for continued surveillance and prudent antimicrobial use in veterinary medicine.

Species of the Pasteurella genus are part of the oropharyngeal microbiota of many animal species. In poultry, Pasteurella multocida causes fowl cholera, the chronic manifestation of which can include neurological symptoms. Pasteurella canis causes osteomyelitis and other infections in humans. To the best of our knowledge, this is the first report of cranial osteomyelitis associated with Pasteurella canis in broiler chickens in Chile.