The Effects of Incremental Doses of Aflatoxin B1 on In Vitro Ruminal Nutrient Digestibility and Fermentation Profile of a Lactating Dairy Cow Diet in a Dual-Flow Continuous Culture System.

Aflatoxin B1 (AFB1) is a mycotoxin known to impair human and animal health. It is also believed to have a deleterious effect on ruminal nutrient digestibility under in vitro batch culture systems. The objective of this study was to evaluate the effects of increasing the dose of AFB1 on ruminal dry matter and nutrient digestibility, fermentation profile, and N flows using a dual-flow continuous culture system fed a diet formulated for lactating dairy cows. Eight fermenter vessels were used in a replicated 4 × 4 Latin square design with 10 d periods (7 d adaptation and 3 d sample collection). Treatments were randomly applied to fermenters on diet DM basis: (1) 0 µg of AFB1/kg of DM (Control); (2) 50 µg of AFB1/kg of DM (AF50); (3) 100 µg of AFB1/kg of DM (AF100); and (4) 150 µg of AFB1/kg of DM (AF150). Treatments did not affect nutrient digestibility, fermentation, and N flows. Aflatoxin B1 concentration in ruminal fluid increased with dose but decreased to undetectable levels after 4 h post-dosing. In conclusion, adding incremental doses of AFB1 did not affect ruminal fermentation, digestibility of nutrients, and N flows in a dual-flow continuous culture system fed diets formulated for lactating dairy cows.

Effects of exogenous α-amylases, glucoamylases, and proteases on ruminal in vitro dry matter and starch digestibility, gas production, and volatile fatty acids of mature dent corn grain.

Two separate experiments were carried out to evaluate the effects of incremental doses of 10 exogenous endo-acting α-amylase and exo-acting glucoamylase; 1LAT (bacterial α-amylase), 2AK, 3AC, 4Cs4, 5Trga, 6Afuga, 7Fvga, and 10Tg (fungal α-amylases, glucoamylases, and α-glucosidase), 8Star and 9Syn (fungal amylase-mixtures; experiment 1) and three exogenous proteases; 11P14L, 12P7L, and 13P30L (bacterial proteases; experiment 2) on in vitro dry matter digestibility (IVDMD) and in vitro starch digestibility (IVSD) of mature dent corn grain using a batch culture system. Incremental doses of the exogenous enzymes (0, 0.25, 0.50, 0.75, and 1.00 mg/g of dried substrate) were applied directly to the substrate (0.5 g of ground corn, 4 mm) in sextuplicate (experiment 1) or quadruplicate (experiment 2) within F57 filter bags, which were incubated at 39 °C in buffered rumen fluid for 7 h. Rumen fluid was collected 2-3 h after the morning feeding from three lactating dairy cows and pooled. Cows were consuming a midlactation total mixed ration (TMR; 1.60 Mcal/kg DM and 15.4%; net energy of lactation and crude protein, respectively). Three independent runs were carried out for each experiment. Data were analyzed as a randomized complete block design using run as the blocking factor. Dose was used as a fixed factor while run was considered a random factor. Linear, quadratic, and cubic orthogonal contrasts were also tested. In experiment 1, enzymes 2AK, 3AC, and 10Tg did not increase (P > 0.10) IVDMD and IVSD, whereas 0.25 mg of enzymes 1LAT, 5Trga, and 8Star increased (P < 0.01) IVDMD by 23%, 47%, and 62% and IVSD by 35%, 41%, and 58%, respectively, compared with the control. Enzymes 4Cs4, 6Afuga, 7Fvga, and 9Syn linearly increased IVDMD and IVSD (P < 0.01). Greatest increases in IVDMD (82.9%) and IVSD (85.9%) resulted with 1 mg of 6Afuga compared to control. In experiment 2, the lowest dose of exogenous proteases 11P14L and 12P7L increased (P < 0.01) IVDMD by 98% and 87% and IVSD by 57% and 64%, respectively, whereas the highest dose of 13P30L increased (P = 0.02) IVDMD by 44.8% and IVSD by 30%, relative to the control. In conclusion, IVSD and IVDMD were increased by one α-amylase, certain glucoamylases, and all proteases tested, with the glucoamylase 6Afuga in experiment 1 and the neutral protease 12P7L in experiment 2, increasing IVDMD and IVSD to the greater extents. Future in vivo studies are required to validate these findings before these enzyme additives can be recommended for improving the digestibility of mature dent corn grain.

Meta-analysis of effects of inoculation with Lactobacillus buchneri, with or without other bacteria, on silage fermentation, aerobic stability, and performance of dairy cows.

A meta-analysis of 158 peer-reviewed articles was conducted to examine effects of inoculation with Lactobacillus buchneri (LB)-based inoculants (LBB) that did or did not include homolactic or obligate heterolactic bacteria on silage fermentation and aerobic stability. A complementary meta-analysis of 12 articles examined LBB inoculation effects on dairy cow performance. Raw mean differences between inoculant and control treatment means weighted by inverse variance were compared with a hierarchical effects model that included robust variance estimation. Meta-regression and subgrouping analysis were used to identify effects of covariates including forage type, application rate (≤104, 105, 106, or ≥ 107 cfu/g as fed), bacteria type (LB vs. LB plus other bacteria), enzyme inclusion, ensiling duration, and silo type (laboratory or farm scale). Inoculation with LBB increased acetate (62%), 1, 2 propanediol (364%) and propionate (30%) concentration and aerobic stability (73.8%) and reduced lactate concentration (7.2%), yeast counts (7-fold) and mold counts (3-fold). Feeding inoculated silage did not affect milk yield, dry matter intake, and feed efficiency in lactating dairy cows. However, forage type, inoculant composition, and dose effects on silage quality measures were evident. Inoculation with LBB increased aerobic stability of all silages except tropical grasses. Adding obligate homolactic or facultative heterolactic bacteria to LB prevented the small increase in DM losses caused by LB alone. The 105 and 106 cfu/g rates were most effective at minimizing DM losses while aerobic stability was only increased with 105, 106, and ≥ 107 cfu/g rates. Inoculation with LBB increased acetate concentration, reduced yeast counts and improved aerobic stability but did not improve dairy cow performance.

An expansin-like protein expands forage cell walls and synergistically increases hydrolysis, digestibility and fermentation of livestock feeds by fibrolytic enzymes.

Bacterial expansin-like proteins have synergistically increased cellulose hydrolysis by cellulolytic enzymes during the initial stages of biofuel production, but they have not been tested on livestock feeds. The objectives of this study were to: isolate and express an expansin-like protein (BsEXLX1), to verify its disruptive activity (expansion) on cotton fibers by immunodetection (Experiment 1), and to determine the effect of dose, pH and temperature for BsEXLX1 and cellulase to synergistically hydrolyze filter paper (FP) and carboxymethyl cellulose (CMC) under laboratory (Experiment 2) and simulated ruminal (Experiment 3) conditions. In addition, we determined the ability of BsEXLX1 to synergistically increase hydrolysis of corn and bermudagrass silages by an exogenous fibrolytic enzyme (EFE) (Experiment 4) and how different doses of BsEXLX1 and EFE affect the gas production (GP), in vitro digestibility and fermentation of a diet for dairy cows (Experiment 5). In Experiment 1, immunofluorescence-based examination of cotton microfiber treated without or with recombinant expansin-like protein expressed from Bacillus subtilis (BsEXLX1) increased the surface area by > 100% compared to the untreated control. In Experiment 2, adding BsEXLX1 (100 µg/g FP) to cellulase (0.0148 FPU) increased release of reducing sugars compared to cellulase alone by more than 40% (P < 0.01) at optimal pH (4.0) and temperature (50°C) after 24 h. In Experiment 3 and 4, adding BsEXLX1 to cellulase or EFE, synergistically increased release of reducing sugars from FP, corn and bermudagrass silages under simulated ruminal conditions (pH 6.0, 39°C). In Experiment 5, increasing the concentration of BsEXLX1 linearly increased (P < 0.01) GP from fermentation of a diet for dairy cows by up to 17.8%. Synergistic effects between BsEXLX1 and EFE increased in vitro NDF digestibility of the diet by 23.3% compared to the control. In vitro digestibility of hemicellulose and butyrate concentration were linearly increased by BsEXLX1 compared to the control. This study demonstrated that BsEXLX1 can improve the efficacy of cellulase and EFE at hydrolyzing pure substrates and dairy cow feeds, respectively.

Dermatitis de contacto por proteínas, una entidad poco conocida como enfermedad profesional. A propósito de un caso / Protein Contact Dermatitis, a Little-Known Entity as Occupational Disease. About a case

INTRODUCCIÓN: La dermatitis de contacto por proteínas es una patología infrecuente poco conocida, de curso crónico y recurrente, generalmente en contexto de patología laboral. MÉTODOS: Se informa de un caso de dermatitis de contacto por proteínas en un sujeto adulto. RESULTADOS: Paciente masculino de 42 años, sin antecedentes médicos de importancia. Trabaja en jornada completa como panadero en un supermercado desde hace 5 años. Presenta lesiones no pruriginosas de 20 días de evolución, caracterizadas por placas y pápulas eritematosas, descamativas en ambos antebrazos, que se acompañan de prurito durante el desempeño de su labor (imagen nº 1 y nº 2). Se realiza test de parche estándar que resulta positivo a níquel. El test de parche laboral da positivo a jabón triclosán, desmoldante y harina de trigo. Prick test negativo e IgE específica positiva para harina de trigo en grado moderado. Estos hallazgos son compatibles con diagnóstico de DCP. DISCUSIÓN: Es una patología sub diagnosticada por muchos dermatólogos, por lo cual es fundamental un alto índice de sospecha. Se postula que se daría por una combinación de HS tipo I y IV. Muchos trabajadores están expuestos al contacto con proteínas, siendo los más afectados aquellos que manipulan alimentos. Clínicamente se caracterizan por placas eritematosas, asociado a prurito intenso, en los sitios de contacto con la proteína. El estudio se debe hacer principalmente con pruebas de HS tipo I (prick test e IgE específica). El test de parche es negativo. El tratamiento consiste en evitar el contacto con proteínas y tratamiento tópico (corticoides tópicos o inhibidores de la calcineurina) para bajar inflamación. CONCLUSIONES: Se presenta un caso clínico de paciente con DCP, diagnosticado mediante la anamnesis y pruebas alergológicas cutáneas y no cutáneas, junto con un diagnóstico correcto y oportuno, puesto que la DCP provoca un impacto negativo importante para el trabajador con inactividad laboral prolongada y readecuación en su puesto de trabajo

INTRODUCTION: protein contact dermatitis is a chronic and recurrent, uncommon condition, usually in context of occupational pathology. METHODS: A case of protein contact dermatitis is reported in an adult subject. RESULTS: Male patient 42 years, with no significant medical records. He works full time as a baker in a supermarket since 5 years. He has nonpruritic lesions of 20 days of evolution, characterized by erythematous plaques and papules, scaly on both forearms, accompanied by itching during the course of their job (picture No. 1 and No. 2). Standard patch test is positive to nickel. Patch test positive to triclosan soap, mold release and wheat flour. Negative Prick test and positive specific IgE to wheat flour in moderate degree. These findings are consistent with a diagnosis of protein contact dermatitis. DISCUSSION: By many dermatologists it is a underdiagnosed pathology, so a high rate of suspicion is crucial. It is postulated that it would arise by a HS combination of type I and IV. Many workers are exposed to contact with proteins; food handlers are the most affected workers. Clinically are characterized by erythematous plaques associated with intense itching at the areas in contact with the protein. The study should be done primarily with type I HS tests (prick test and specific IgE). The patch test is negative. The treatment involves avoiding the contact with protein and topical treatment (topical corticosteroids or calcineurin inhibitors) in order to lower inflammation. CONCLUSIONS: clinical case of a patient with protein contact dermatitis is presented, diagnosed by anamnesis and skin and non-skin allergological tests, emphasizing the importance of an accurate and proper diagnosis. The PCD causes a significant negative impact for the worker with prolonged inactivity and adjustments in the workplace