Escherichia coli, a major opportunistic pathogen in chickens, poses a serious threat to poultry production and public health via potential zoonotic transmission of ESBL-producing strains. Therefore, this study aimed to emphasize broilers as early carriers of ESBL E. coli and provide deeper insights into antimicrobial resistance of these bacteria. Prevalence and antimicrobial resistance (MIC) testing of ESBL E. coli in cloacal and environmental samples from one-day-old and five-day-old broilers was conducted on three different growth cycles from a conventional poultry farm in Lithuania. Confirmed prevalence of ESBL E. coli in cloacal samples ranged from 0% to 57.5%, and in environmental swabs from 0% to 25%. All 102 ESBL E. coli isolates were susceptible to meropenem, imipenem, fosfomycin, and colistin. However, 93.14% of the strains were resistant to ceftriaxone (89.06–100%, depending on bacteria isolation source), 97.06% to ciprofloxacin (95.31–100%), and 66.67% to tetracycline (26.09–100%). Additionally, 80.39% of ESBL E. coli strains exhibited multidrug resistance. In total, 23 different antimicrobial resistance profiles were confirmed, with CRO/AMS/AUG/CIP/SXT/TE and CRO/CIP being the most common, detected in 18 of the 102 strains. The detection of widespread antimicrobial-resistant ESBL E. coli in five-day-old broilers emphasizes the need to implement control strategies early in the broiler production cycle.

The use of animal by-products to produce bioactive peptides is a promising and sustainable approach in the food and nutrition industry. Meat by-products can be used as a key raw material for the production of high-value-added components, such as bioactive peptides, to ensure sustainability. Porcine livers and hearts classified as category three by-products were selected for the study, together with those intended for human consumption, in which no changes were observed after veterinary post-mortem examination. Hydrolysis was performed at three different times 3 h, 6 h, and 24 h, using pepsin and papain. The influence of different hydrolysis times and enzymes on the degree of hydrolysis (DH) value was determined. The highest value of DH was found in porcine hearts after 24 h following hydrolysis with pepsin enzymes (33.56 ± 0.31). The antiradical activity was assessed by measuring the absorbance of DPPH• and ABTS•+ in hydrolysates obtained from porcine meat by-products. Porcine livers hydrolysates treated with papain for 24 h showed the highest radical scavenging abilities ABTS•+ (97.2 ± 1.79%) and DPPH• (92.07 ± 2.23%). The identification and quantification of peptides from porcine livers and hearts were conducted using SWATH-MS technology. The most abundant peptides that showed a relationship with antioxidant capacity were WGKVNVDEVGGEALGRL, WGKVNVDEVGGEAL, and GLWGKVNVDEVGGEALGRL from beta hemoglobin.