Bacterial resistance has been increasingly reported worldwide and is one of the major causes of failure in the treatment of infectious diseases. Natural-based products, including plant secondary metabolites (phytochemicals), may be used to surpass or reduce this problem. The objective of this study was to determine the antibacterial effect and mode of action of selected essential oils (EOs) components: carveol, carvone, citronellol, and citronellal, against Escherichia coli and Staphylococcus aureus. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were assessed for the selected EOs components. Moreover, physicochemical bacterial surface characterization, bacterial surface charge, membrane integrity, and K + leakage assays were carried out to investigate the antimicrobial mode of action of EOs components. Citronellol was the most effective molecule against both pathogens, followed by citronellal, carveol, and carvone. Changes in the hydrophobicity, surface charge, and membrane integrity with the subsequent K + leakage from E. coli and S. aureus were observed after exposure to EOs. This study demonstrates that the selected EOs have significant antimicrobial activity against the bacteria tested, acting on the cell surface and causing the disruption of the bacterial membrane. Moreover, these molecules are interesting alternatives to conventional antimicrobials for the control of microbial infections.

Growth promoters have been widely used as a strategy to improve productivity, and great benefits have been observed throughout the meat production chain. However, the prohibition of growth promoters in several countries, as well as consumer rejection, has led industry and the academy to search for alternatives. For decades, the inclusion of phytochemicals in animal feed has been proposed as a replacement for traditional growth promoters. However, there are many concerns about the application of phytochemicals and their impact on the various links in the meat production chain (productive performance, carcass and meat quality). Therefore, the effects of these feed additives are reviewed in this article, along with their potential safety and consumer benefits, to understand the current state of their use. In summary, the replacement of traditional growth promoters in experiments with broilers yielded benefits in all aspects of the meat production chain, such as improvements in productive performance and carcass and meat quality. Although the effects in pigs have been similar to those observed in broilers, fewer studies have been carried out in pigs, and there is a need to define the types of phytochemicals to be used and the appropriate stages for adding such compounds. In regard to ruminant diets, few studies have been conducted, and their results have been inconclusive. Therefore, it is necessary to propose more in vivo studies to determine other strategies for phytochemical inclusion in the production phases and to select the appropriate types of compounds. It is also necessary to define the variables that will best elucidate the mechanism(s) of action that will enable the future replacement of synthetic growth promoters with phytochemical feed additives.

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The aim of this study was to evaluate effects of free ferulic acid (FA) supplementation on productive performance, some blood metabolite concentrations, and carcass characteristics of ewe lambs finished in a feedlot. Dorper×Pelibuey ewe lambs (n=20; BW=28.5±0.5 kg; age=5 mo) were individually housed in pens and assigned under a randomized complete block design to the following dietary treatments (n=10): daily feeding without (control) or with 300 mg of FA/animal. The feedlot feeding period lasted 34 d and then all ewe lambs were slaughtered. Free FA did not affect (P≥0.16) BW gain, ADG, DMI, and G:F during the first 17 d, but BW gain (P=0.10) and ADG (P=0.10) tended to decrease for FA from d 17 to 34 and from d 1 to 34 without affecting (P≥0.16) DMI and G:F in ewe lambs. Serum concentrations of glucose, cholesterol, triglyceride, total protein, and urea were not affected (P>0.05) by FA at d 1, 17, and 34 of the feeding period. Carcass characteristics were not affected (P>0.05) by FA. Stomach percentage tended (P=0.08) to decrease and leg yields increased (P=0.02) for FA. Other noncarcass components and wholesale cut yields were not affected (P>0.10) by FA. In conclusion, FA supplementation did not improve productive performance, metabolic status, and carcass characteristics of ewe lambs receiving a feedlot finishing diet.

No abstract

Agave leaves are considered a by-product of alcoholic beverage production (tequila, mezcal and bacanora) because they are discarded during the production process, despite accounting for approximately 50% of the total plant weight. These by-products constitute a potential source of Agave extracts rich in bioactive compounds, such as saponins, phenolic compounds and terpenes, and possess different biological effects, as demonstrated by in vitro and in vivo tests (e.g. antimicrobial, antifungal, antioxidant, anti-inflammatory, antihypertensive, immunomodulatory, antiparasitic and anticancer activity). Despite their positive results in biological assays, Agave extracts have not been widely evaluated in food systems and pharmaceutical areas, and these fields represent a potential route to improve the usage of Agave plants as food additives and agents for treating medical diseases. © 2017 Society of Chemical Industry.

Forty Dorper × Pelibuey ram lambs initially weighing 31.7 ± 2.30 kg were stratified by BW and randomly assigned to treatments under a completely randomized design with a 2 × 2 factorial arrangement of treatments to evaluate effects of zilpaterol hydrochloride (ZH; 0 or 10 mg/lamb daily) and soybean oil (SBO; 0 or 6%) on feedlot performance, carcass characteristics, and wholesale cut yield of ram lambs under heat stress conditions. After a 34-d feeding period, all lambs were harvested. Climatic conditions were of moderate heat stress (average temperature 35.7°C) for lambs during the study. Interactions ZH × SBO were not observed (P ≥ 0.11) for any of the variables evaluated. During the first 17 d of experiment, ZH increased (P ≤ 0.05) BW, ADG, and G:F without affecting feed intake (P = 0.40), but from d 18 to 34 and the entire 34-d feeding period, feedlot performance was not affected (P = 0.18) by ZH. Also, ZH decreased KPH, dressing percent, LM area, LM pH at 24 h postmortem, and leg perimeter (P ≤ 0.04). Renal fat (P = 0.03) decreased with ZH while other noncarcass components were not affected (P ≥ 0.06) by ZH supplementation. Leg yield (P = 0.01) and plain loin (P = 0.04) decreased with ZH and yields of other wholesale cuts were not affected (P ≥ 0.10) by ZH. Feedlot performance (P ≥ 0.20) and wholesale cut yield (P ≥ 0.21) were not affected by SBO. Additionally, dressing percentage decreased (P < 0.01) with SBO while other carcass characteristics (P ≥ 0.12) were not affected by SBO. In conclusion, inclusion of both ZH and SBO in feedlot finishing diets did not improve feedlot performance, carcass characteristics, or wholesale cut yield of hair-breed ram lambs under moderate heat stress. Feedlot performance responded only to ZH and only during the first 17 d of the feeding period. In addition, some carcass characteristics of economic importance, such as dressing, LM area, and leg yield, were improved by ZH.

In the first part of this study, samples were collected from farms, cheese processing plants (CPPs), and retail markets located in various geographical areas of Sonora, Mexico, over a 12-month period during the summer of 2004 and winter of 2005. Four (all Queso Fresco [QF] from retail markets) of 349 total samples tested positive for Listeria monocytogenes (Lm). Of these four positive samples, three were collected in the northern region and one in the southern region of Sonora. Additionally, two were collected during the winter months, and two were collected during the summer months. For the second part of the study, a total of 39 samples from a farm, a CPP, and retail markets were collected and processed according to a combination of the Norma Oficial Mexicana NOM-143-SSA1-1995.10 method (NOM) and the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual method, and 27 samples from these same locations were collected and processed according to the U.S. Department of Agriculture Food Safety and Inspection Service method (USDA-FSIS). The NOM-FDA method recovered the pathogen from 6 (15%) of 39 samples (one cheese and five product contact surfaces), while the USDA-FSIS method recovered the pathogen from 5 (18.5%) of 27 samples (all product contact surfaces). In addition, the 40 isolates recovered from the 15 total samples that tested positive for Lm grouped into five distinct pulsotypes that were ca. 60% related, as determined by pulsed-field gel electrophoresis analysis. The results of this study confirmed a 3.4% prevalence of Lm in QF collected from retail markets located in Sonora and no appreciable difference in the effectiveness of either the NOM-FDA or USDA-FSIS method to recover the pathogen from cheese or environmental samples.