Antimicrobial resistance (AMR) has emerged as a major One Health threat driven by inappropriate antimicrobial use (AMU) in humans, animals, and the environment. Poultry production is recognized as a key reservoir of antimicrobial-resistant bacteria, yet few studies in Kenya examine AMU and AMR across interconnected human–animal–environment domains. This study assessed AMU patterns among poultry farmers in Kiambu County and characterized phenotypic resistance in Escherichia coli and Enterococcus spp. isolated from humans, chickens, and chicken environments.  A cross-sectional study was conducted from May to September 2024, involving 102 poultry farms. Farm demographics and AMU data were collected using a semi-structured questionnaire. Archived E. coli (n = 92) and Enterococcus spp. (n = 101) isolates from chicken handlers’ hands, chickens, and environmental samples were subjected to antimicrobial susceptibility testing using the Kirby–Bauer method per Clinical and Laboratory Standards Institute (CLSI) 2024 guidelines. Descriptive and inferential statistics, including logistic regression with false discovery rate correction, were used to assess associations between AMU and phenotypic resistance.  Macrolides (69%), tetracyclines (48%), and sulfonamides (21%) were the most commonly used antimicrobials; 7% of farms reported colistin use. Among E. coli isolates, resistance was highest to ampicillin (77%), tetracycline (72%), and trimethoprim–sulfamethoxazole (49%), with 35% exhibiting multidrug resistance (MDR). No carbapenem resistance was detected. Enterococcus isolates showed high erythromycin resistance (61%) and moderate ciprofloxacin resistance (26%), with 6.9% exhibiting MDR; no vancomycin-resistant enterococci (VRE) were observed. Penicillin use strongly predicted ampicillin resistance in both organisms, whereas sulfonamide use was associated with reduced trimethoprim–sulfamethoxazole resistance. Macrolide use did not correlate with erythromycin resistance.  High AMU in poultry farming, particularly of macrolides, tetracyclines, and sulfonamides, has created significant selection pressure, contributing to MDR emergence across One Health interfaces. Detection of resistance in humans, poultry, and shared environments underscores the bidirectional risk of AMR transmission. Strengthened antimicrobial stewardship, regulation of critically important antimicrobials, and enhanced farm hygiene are essential to mitigate AMR. These findings directly support Kenya’s Vision 2030 and SDGs targeting health, responsible production, and environmental protection. 

Propranolol is a widely used non-selective beta-adrenergic blocker in human medicine, with well-characterized pharmacokinetics (PK) in humans but virtually no data available for pigs, a species of growing biomedical relevance. Furthermore, no validated bioanalytical methods exist for propranolol or its primary metabolite, 4-hydroxypropranolol, in porcine matrices. This study aimed to develop and validate a rapid, sensitive, and reliable liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the simultaneous quantification of propranolol and 4-hydroxypropranolol in pig plasma and dried blood spots (DBS), and to apply it in a preliminary PK investigation in pigs.  Sample preparation involved simple protein precipitation (plasma) or solvent extraction (DBS) using acetonitrile–water mixtures, followed by chromatographic separation on a Bridged ethyl hybrid C18 column (50 × 2.1 mm, 1.7 μm; 4-min run). Detection was performed in Multiple reaction monitoring mode with propranolol-d7 as the internal standard. Validation followed EMA ICH M10 guidelines, assessing linearity, accuracy, precision, matrix effects, recovery, and stability. The method was then applied to plasma samples from five juvenile female pigs receiving oral propranolol (3 mg/kg, q8 h).  The method demonstrated excellent linearity (r2 > 0.99) and acceptable accuracy and precision (±15%) across 2–500 ng/mL (propranolol) and 1–400 ng/mL (4-hydroxypropranolol). Recoveries ranged from 83% to 116% (plasma) and 81%–113% (DBS), with no matrix interference or carry-over. In vivo PK data revealed rapid absorption (Tmax 1.14 ± 0.63 h), moderate elimination (t½ 2.19 ± 0.86 h), and a mean Cmax of 112.02 ± 81.87 ng/mL. Notably, 4-hydroxypropranolol was undetectable in all plasma samples, suggesting species-specific metabolic differences.  This study reports the first validated LC–MS/MS assay for propranolol and 4-hydroxypropranolol in pigs and demonstrates its successful application in a PK study. The method’s simplicity, short runtime, and compatibility with DBS microsampling make it ideal for preclinical and veterinary research, minimizing animal stress and sampling volume. Absence of 4-hydroxypropranolol highlights interspecies metabolic variability and warrants further investigation into propranolol biotransformation pathways in swine and other translational models. 

Heat stress (HS) substantially impairs dairy goat productivity in Mediterranean climates by disrupting metabolic, endocrine, and cellular homeostasis. High-yielding Saanen goats are particularly vulnerable because of elevated metabolic heat production, yet age-specific physiological responses to prolonged natural HS remain unclear. This study aimed to characterize age-dependent adaptations to progressive summer HS by evaluating changes in triiodothyronine (T3), thyroxine (T4), cortisol (CORT), and heat shock protein 70 (HSP70), and their relationship to daily average milk yield (DAMY). We hypothesized that increasing temperature–humidity index (THI) would suppress T3 and T4, moderately elevate CORT, and stimulate HSP70 expression, particularly in young goats.  Thirty clinically healthy, lactating Saanen does were grouped into young, middle-aged, and old age groups (n = 10 per group). The study was conducted from May to August under natural Mediterranean field conditions. Ambient temperature, relative humidity, and THI were recorded daily. DAMY was measured automatically using a radio-frequency identification-linked milking system. Blood samples were collected twice monthly to quantify serum T3, T4, CORT, and HSP70 using commercial enzyme-linked immunosorbent assay kits. A repeated-measures general linear model evaluated the effects of age, month, and their interaction; significance was set at p < 0.05.  THI increased from “no HS” in May to “severe HS” in July and August, confirming sustained heat-load. DAMY declined from 2.59 ± 0.43 kg in May to 1.88 ± 0.40 kg in August. T4 decreased significantly in young and middle-aged goats, with the sharpest decline in middle-aged goats (92.96 to 61.82 nmol/L; p < 0.01). T3 also decreased significantly in young and middle-aged groups (p < 0.01), whereas older goats showed modest, nonsignificant reductions. CORT showed a mild, nonsignificant upward trend. HSP70 increased across all groups, with a significant rise in young goats (13.32 to 17.85 ng/mL; p < 0.05). T4 showed a strong positive correlation with DAMY (r = 0.78, p = 0.0027), whereas CORT showed a moderate negative correlation with DAMY (r = −0.58, p = 0.047).  Lactating Saanen goats exhibit age-dependent dual adaptations to summer HS: endocrine suppression of thyroid activity, stronger in middle-aged goats, and cellular upregulation of HSP70, most evident in young goats. Monitoring T3, T4, CORT, HSP70, and DAMY can help identify thermally vulnerable life-stage groups and guide targeted cooling, nutritional, and breeding interventions in heat-stressed dairy systems. 

Essential oils (EOs) are promising natural modifiers of rumen fermentation and methane production; however, their volatility and rapid degradation limit their effectiveness. Microencapsulation can shield bioactive compounds and allow controlled release. Insect-derived proteins, especially from black soldier fly (BSF; Hermetia illucens L.), offer a sustainable and functional wall material, yet their use for rumen-targeted delivery remains unexplored. This study aimed to assess the effects of microencapsulated-lemongrass oil (M-LEO) using BSF protein as a biopolymer wall on gas kinetics, nutrient degradability, rumen fermentation parameters, microbial populations, and methane output in vitro.  A completely randomized design was used with five dietary treatments containing M-LEO at 0, 2, 4, 6, and 8% of total dry matter (DM) substrate. In vitro rumen fermentation was performed using rumen fluid from Holstein-crossbred dairy cattle. Fermentation was measured at 12, 24, and 48 h for gas kinetics, in vitro dry matter degradability (IVDMD) and in vitro organic matter degradability (IVOMD), pH, ammonia-nitrogen (NH₃-N), volatile fatty acids (VFAs), methane production, and microbial populations quantified by real-time polymerase chain reaction.  M-LEO showed high encapsulation efficiency (85.2%) and significant bioactive content. Supplementing with M-LEO notably improved gas production kinetics and nutrient degradability, with optimal effects at 6% of total DM. At this level, IVDMD and IVOMD increased by up to 11.5% and 10.5%, respectively. Total VFA and propionate concentrations rose significantly (p < 0.05), while acetate proportion and the acetate-to-propionate ratio decreased. Rumen pH and NH₃-N levels stayed within optimal ranges and were unaffected by treatment. Methane production was substantially reduced, with decreases of up to 48.8% at 48 h compared to the control. Additionally, M-LEO boosted populations of key cellulolytic bacteria (Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens) and Megasphaera elsdenii, while significantly suppressing methanogenic archaea (Methanobacteriales).  Microencapsulation of lemongrass oil with BSF protein effectively enhances rumen fermentation efficiency and significantly decreases methane emissions in vitro. This innovative insect-protein delivery system provides a sustainable and climate-friendly feed additive approach, deserving further validation in vivo.