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Argentina is one of South America's leading milk and pork producers, yet the data for antimicrobial usage and resistance in these sectors is extremely limited. Here we report third-generation cephalosporin resistance (3GC-R) rates among E. coli from pigs and dairy cattle in two Argentinian regions (La Plata and Rio Cuarto) and the resistance mechanisms found. Samples were from effluent and faecally-contaminated near-animal environments collected using sterile boot-socks, submerged in 10x w/v PBS and made to 25% v/v glycerol; 20μL was spread on Chromagar-3GCR. Up to two 3GC- R isolates representing each positive sample were sequenced (Illumina) following deduplication at farm level using multiplex β-lactamase gene PCR. A total of 413 samples across 40 pig farms (291 La Plata, 122 Rio Cuarto) and 404 samples across 30 dairy cattle farms (286 La Plata, 118 Rio Cuarto) were collected. In La Plata, 29.7% of cattle and 51.2% of pig samples were positive for 3GC-R E. coli. In Rio Cuarto, resistance was more prevalent: 55.1% and 77.9% positivity in cattle and pig samples, respectively. Sequencing 131 representative 3GC-R isolates revealed a wide range of 3GC-R mechanisms, dominated by CTX-M variants (73% of isolates); specificity at the level of animal species was seen. CMY-2 accounted for 3GC-R in 24.4% of pig but only 4.4% of dairy isolates (χ2=8.14, p=0.004). 25.6% of pig isolates but only 8.9% of dairy carried CTX-M-8 (χ2=5.17, p=0.02). 6.9% of pig but 40% of dairy isolates carried CTX-M-15 (χ2=21.5, p<0.001). There was only one significant difference in 3GC- R mechanism prevalence seen between regions: CTX-M-14 was more common in isolates from farms around Rio Cuarto than La Plata (χ2=7.45, p=0.006). Nine 3GC-R isolates from pigs and one from cattle did not carry any known 3GC-R mechanism. There is a considerable burden of 3GC-R in Argentina which varies significantly by region and animal. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the association between progesterone concentration on Days 4 and 9 of the estrus cycle and endometrial transcriptome at Day 9 in lactating grazing dairy cows. Blood samples were obtained on Days 0, 4, and 9 for progesterone measurement by chemiluminescence. Cows were assigned to one of the following groups (n = 3 per group): cows with low physiological progesterone on Day 4, cows in anestrous, cows with high physiological progesterone on Day 4, and superovulated cows. Endometrial biopsy samples were obtained on Day 9 for RNA sequencing. Quality control and determination of differentially expressed genes (false discovery rate <0.05) were determined using the edgeR package for R software. We identified 3,042 differentially expressed genes among the 4 groups. Cows having high physiological progesterone and superovulated cows showed high similarities and clustered apart from those in anestrus or having low physiological progesterone. Functional analysis using Database for Annotation, Visualization, and Integrated Discovery revealed that endometrial genes upregulated by low progesterone concentration are enriched genes involved in the immune system and inflammatory response. Conversely, cows with high physiological progesterone concentration presented an endometrial transcriptome with similarities to cows with good genetic merit for fertility, showing upregulation of genes related to uterine relaxation–contraction, focal adhesion, GnRH signaling pathway, and epidermal growth factor–like related terms, suggesting a favorable embryo environment. In conclusion, our results support the concept that there is a threshold of progesterone concentration at the beginning of the luteal phase associated with endometrial expression of critical genes involved in the preparation of the uterine environment for embryo implantation. • Progesterone and endometrial global gene expression on Day 4 and 9 were studied. • Cows with high progesterone clustered apart from cows with low progesterone. • Cows with low progesterone had an endometrial transcriptome of an inflammatory response. • Cows with high progesterone had an endometrial transcriptome like cows with good fertility. [ABSTRACT FROM AUTHOR]