Lina Maria Peñuela Sierra

Background and Aim: The widespread use of antibiotic growth promoters (AGPs) in poultry production has been implicated in altering gut microbiota and promoting the excretion of multidrug-resistant (MDR) bacteria into the environment. Salmonella enterica serovar Infantis (Salmonella Infantis [S.I]), a prevalent zoonotic pathogen, has demonstrated increasing resistance in poultry systems. This study aimed to evaluate the efficacy of natural control microorganisms (NCM), Bacillus subtilis and Lactobacillus plantarum, in reducing the abundance of MDR S.I in fresh chicken litter from birds raised with or without AGP supplementation. It also examined how physicochemical properties and microbial dynamics influence pathogen persistence. Materials and Methods: Microcosms were constructed using litter from broilers raised under two dietary regimes (with and without avilamycin). Treatments included combinations of AGP, S.I, and NCM. Bacterial enumeration was performed using selective media, and whole-genome sequencing of S.I was conducted to characterize antimicrobial resistance and virulence genes. Physicochemical parameters (pH, humidity, temperature, and ammonia) were measured and correlated with microbial loads. Antagonistic activity of NCM strains was assessed using agar diffusion assays. Results: Genome analysis revealed that S.I carried multiple resistance genes (e.g., blaCTX-M-65, tet(A), and sul1) and efflux systems conferring MDR. In vitro assays showed strong antagonism by L. plantarum and moderate activity by B. subtilis. In microcosms, S.I counts significantly decreased in the presence of both AGP and NCM, indicating synergistic inhibition. Conversely, in the absence of AGP, NCM had a limited effect. Statistical analyses showed strong correlations between microbial groups and physicochemical variables, particularly during later production stages. Conclusion: The application of B. subtilis and L. plantarum in chicken litter significantly reduced S.I colonization under AGP supplementation, suggesting their potential as biocontrol agents. These findings support the development of integrated litter management strategies to mitigate zoonotic and resistant pathogen dissemination, particularly in AGP-using systems. However, the effectiveness of such interventions may vary across farms due to differences in microbial ecology and environmental conditions. Keywords: antimicrobial resistance, Bacillus subtilis, competitive exclusion, food safety, Lactobacillus plantarum, poultry litter, Salmonella Infantis.

This study assessed the impact of a mixture of garlic (Allium sativum) and oregano (Origanum vulgare) essential oils (EOGOs) on in vitro dry matter digestibility (IVDMD) and in vivo apparent nutrient digestibility. Different EOGO inclusion levels were evaluated to assess the dose response and potential effects of the mixture. Three EOGO inclusion levels (0.5, 0.75, and 1 mL/kg of incubated dry matter) were evaluated in vitro, while four treatments (0.5, 0.75, and 1 mL/day of EOGO and a control group) were tested in vivo on 12 West African sheep. A randomized controlled trial was conducted using a 4 × 4 design. Blood parameters (glucose, blood urea nitrogen, and β-hydroxybutyrate) were measured to observe the effect of EOGO on the metabolism. The results showed that the inclusion of EOGO significantly enhanced IVDMD at low levels (p < 0.052) compared with the highest levels in treatments containing 0.5 and 0.75 mL/kg of EOGO dry matter. A higher intake of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) (p < 0.05) was observed in the in vivo diets with the inclusion of EOGO. In terms of in vivo apparent digestibility, significant differences were found among treatments in the digestibility coefficients of DM, CP, and NDF. EOGO inclusion increased the digestibility of DM. CP digestibility displayed a cubic effect (p < 0.038), with the lowest values of digestibility observed at 1 mL EOGO inclusion. Additionally, NDF digestibility showed a cubic effect (p < 0.012), with the highest value obtained at 0.75 mL of EOGO inclusion. The inclusion levels above 0.75 mL EOGO showed a cubic effect, which indicates that higher concentrations of EOGO may not be beneficial for the digestibility of CP and NDF. Although no significant difference was observed in total digestible nutrients, a linear trend was observed (p < 0.059). EOGO improved the intake of DM, CP, and NDF. EOGO supplementation improved the digestibility of DM and NDF, with optimal levels observed at 0.5 mL/day. No significant effects were observed in the blood parameters. These results suggest that EOGO has the potential as an additive in ruminal nutrition to improve food digestibility and serve as an alternative to antibiotic additives. The use of EOGO potentially improves fiber digestion and may reduce the use of antibiotics in livestock production. Garlic (A. sativum) and oregano (O. vulgare) essential oils effectively modulated fiber digestibility at 0.75 mL/day. Garlic (A. sativum) and oregano (O. vulgare) essential oils have the potential to improve digestibility at low inclusion levels and serve as an alternative to antibiotic additives. The effectiveness of essential oils is greater in a mixture and at lower doses.

The objective of this study was to evaluate the effect of dehydrated orange by-product on the productive parameters, carcass yield, and meat quality of rabbits in the fattening stage. Four diets with increasing levels of orange by-products (0%, 10%, 20%, and 30%) were evaluated, each with six replicates of two 32-day-old crossbred rabbits that were randomly allocated. The experimental period was from 32 to 70 days of age of the rabbits. A higher weight gain (p < 0.05) was achieved for observed with 20% substitution, along with a better feed conversion, without any effects on carcass yield and meat quality parameters. The treatment with 30% citrus pulp showed no differences (p > 0.05) in the parameters evaluated. Based on our results, dehydrated orange by-product can replace up to 30% of the commercial feed concentrate without affecting performance, yield, and carcass quality in rabbits feeding since 32 to 72 days of age.

A inclusão de aditivos na alimentação de frangos de corte tem sido uma estratégia para reduzir os custos de produção, sendo o ponto central das pesquisas na avicultura, uma vez que a alimentação equivale a 70% do custo total de produção. O objetivo desta revisão é apresentar uma atualização sobre os benefícios do uso de proteases adicionadas à dieta de frangos de corte e como elas são oportunidades para melhorar variáveis produtivas como desempenho das aves, digestibilidade de nutrientes da ração e parâmetros hismorfométricos intestinais. Além disso, foi destacado que sua inclusão pode aumentar a energia metabolizável aparente e diminuição da proteína que chega ao cólon, que podem gerar síndromes inflamatórias intestinais e levar à diarreia, além de servir de substrato para o crescimento de bactérias patogênicas. Alguns estudos de viabilidade econômica mostraram que, quando manejadas dietas hipoproteicas com adição de protease, se pode ter melhor rentabilidade do que dietas comerciais totalmente balanceadas. Por isso, novas pesquisas devem ser realizadas.

Background and Aim: The use of antibiotics as growth promoters in the feed of poultry, has contributed to an increase in the antimicrobial resistance of foodborne pathogens worldwide. Hence, the development of new effective alternatives to antibiotics that do not hinder productivity is imperative. For this, the aim of the present study was to determine whether oregano essential oil (OEO) extracted from Lippia origanoides is a suitable alternative to growth-promoting antibiotics (GPAs) for improving the performance, egg quality, and intestinal morphometry of ISA Brown laying hens. Materials and Methods: A total of ninety-six 70-week-old ISA Brown laying hens were randomly assigned to four treatment groups with four replicates per treatment and six hens per replicate. The treatments consisted of four different diets that were formulated according to the nutritional requirements of the genetic line and the production phase with and without the addition of GPA and OEO: NC, which did not contain OEO or GPA; GPA, which included 50 ppm zinc bacitracin as a GPA; 80OEO, which included 80 ppm OEO and no GPA; and 150OEO, which included 150 ppm OEO and no GPA. Results: All of the OEO and GPA treatment groups had a better feed conversion ratio than the NC group. However, the addition of 150 ppm OEO to the diet improved the percentage egg production and egg mass, as well as the external and internal quality of the egg compared with the other treatments. In addition, both the 80OEO and 150OEO treatments improved the yolk color, shell thickness, and shell color, as well as parameters related to the intestinal morphometry compared with the NC group. Conclusion: The findings of this study indicate that 150 ppm OEO can be used as a substitute for GPA to improve the performance, egg quality, and parameters related to the intestinal morphometry of ISA Brown laying hens.

In tropical dry forest conditions, small ruminant production is an alternative for small farmers. Even so, the quality of the forages does not meet the nutritional requirements of the animals. However, the high biodiversity of trees that exist in the region offers a supplementation alternative especially during the dry season. The objective of this research work was to evaluate the quality and the profile effect of fatty acids in Colombian creole lamb meat supplemented with tree species from the tropical dry forest. A total of 35 lambs were used which were randomly distributed in 5 treatments as follows: T1: Botriochloa pertusa; T2: Botriochloa pertusa + 300 g/day of Leucaena leucocephala; T3: Botriochloa pertusa + 300 g/day of Gliricidia sepium; T4: Botriochloa pertusa + 300 g/day of Guazuma ulmifolia and T5 (BpSs): Botriochloa pertusa + 300 g/day of Senna spectabilis. The experimental units were brought to a final slaughter weight of ±32 kg and the pH, color, and fatty acid composition of the carcasses were evaluated at 24 hours. The meat quality parameters did not present significant differences (P>0.05) in the different supplements and obtained acceptable parameters for their consumption.It was evidenced that the proportions of saturated fatty acids (C 16: 0, C 18: 0, total SFA) in lambs supplemented with Senna spectabilis and Gliricidia sepium were lower (P<0.05). It is concluded that under the conditions of the study the supplementations with Senna spectabilis and Gliricidia sepium can induce a favorable change in the fatty acid content of lamb meat.

This study was conducted to evaluate the effects of including two types of crude glycerin (CG) in feed on plasma parameters, quantitative and qualitative carcass characteristics, and the fatty acid profile of the Longissimus dorsi pig muscle. Sixty-three commercial line pigs were used, with an average weight of 30.53 ± 1.59 to 59.55 ± 4.27 kg in the growing phase and 60.35 ± 2.25 to 89.91 ± 5.23 kg in the finishing phase. The pigs’ diet included two sources of CG (vegetable and mixed) at four inclusion levels (3%, 6%, 9% and 12%). One CG was derived from soybean oil (VCG) and the other from 80% animal fat + 20% soybean oil (MCG). The control diet contained 0% glycerin. Blood samples were collected at the beginning, middle and final phases of the trial. In addition, at the end of the finishing phase, the animals were fasted for 12 h and then sacrificed to measure the quantitative and qualitative carcass characteristics and the fatty acid profile of the Longissimus dorsi. The results indicate that in both phases there was a quadratic effect on plasma triglycerides. There was no effect on carcass parameters. A quadratic behaviour for pH24 h was obtained, with the lowest value attained at 1.05% CG inclusion. There was an interaction between the type of glycerin and the inclusion level in the diets for polyunsaturated fatty acids. VCG and MCG can be used at up to 12% inclusion because they cause no negative effects on carcass characteristics and pig meat quality.

Clostridium perfringens tipo A é uma bactéria Gram-positiva anaeróbia que habita a biota intestinal nativa do intestino grosso de aves, causando uma enterotoxemia necrótica, especialmente em sistemas intensivos de frangos de corte com mais de 4 semanas de idade, potencialmente zoonótica e causadora de altas perdas econômicas devido à morbimortalidade e diminuição nos parâmetros de produção. O objetivo desta revisão foi analisar os problemas gerados pela presença de Clostridium perfringens em sistemas de produção de aves para engorda, com base nos fatores predisponentes de crescimento bacteriano, patogenicidade e tratamentos alternativos e controle da doença. Sua importância no campo avícola nos levou a investigar alternativas para prevenir e controlar a doença causada pelo Clostridium perfringens em aves, além de reduzir a proliferação e as perdas econômicas.

This study was carried out to evaluate the inclusion of two rice co-products in pig feed during the starter phase in terms of the nutritional value and digestibility of the co-products, and the effect on plasma parameters, growth performance and economic viability. In Experiment I, a digestibility assay was performed using 30 barrows (14.4 ± 2.4 kg body weight), which were distributed in a completely randomised design. The co-products studied were broken rice (BR) and hominy rice 3/4 (HR) to replace the reference diet (300 g/kg). The estimated digestible energy (DE) and metabolisable energy (ME) were 3,476 and 3,360 kcal/kg for BR and 3,487 and 3,362 kcal/kg for HR, respectively. In Experiment II, 108 pigs (15.5 ± 1.0 to 30.1 ± 1.3 kg body weight) were used, distributed in a randomised block design with a factorial analysis scheme (2 × 4), using two types of rice and four inclusion levels (160, 320, 480, and 640 g/kg), with six replicates and two pigs per experimental unit. Additionally, a control diet was used with no inclusion of the co-product. The daily weight gain increased and the feed:gain (F:G) ratio decreased as HR content of feed increased. An effect of both types of rice on plasma glucose concentration was obtained, in which the pigs fed with BR showed the highest values. The cost of diet per kilogram of body weight gain increased as BR levels in the diet increased. It was observed that inclusion levels of 480 and 640 g/kg of BR differed from the control diet, showing the highest costs. HR and BR can be used in pig feed in the starter phase at up to 640 g/kg without impairing performance.

Los residuos orgánicos como alternativa para la alimentación en porcinos