The role of unregulated chicken marketing practices on the frequency of Newcastle disease outbreaks in Kenya.

In developing countries, chicken trade is characterized by complex chains comprising of many actors with limited biosecurity. This increases the spread of chicken diseases like Newcastle disease (ND). In Kenya, there is lack of uniformity in practices used in live bird markets, leading to increased disease outbreaks. This study aimed at assessing the effects of the chicken marketing practices on the frequency of ND outbreaks. A Poisson regression (PRM) was used on data collected from 336 traders selected using multi-stage sampling in Kakamega, Machakos, and Nairobi. Results highlight the low access of trainings and credit by traders. From the PRM results, breed composition, market channel, transportation, origin of birds, mixing of birds, slaughter of birds, disposal of waste, and housing as well as trader attributes like ND awareness, licensing, gender, and age had significant effects on the frequency of ND outbreaks. The study recommends that County governments collaborate with development partners to develop innovative ways of disseminating information on ND. The County governments should invest in market infrastructure such as slaughter facilities, special shelters and waste disposal equipment. There is also need for enforcement of biosecurity and hygiene measures through regular market inspections.

Endogenous beta-glucosidase and beta-galactosidase activities from selected probiotic micro-organisms and their role in isoflavone biotransformation in soymilk.

AIM: To compare endogenous beta-glucosidases and beta-galactosidases for hydrolysis of the predominant isoflavone glycosides into isoflavone aglycones in order to improve biological activity of soymilk. METHODS AND RESULTS: beta-glucosidase and beta-galactosidase activities of probiotic organisms including Lactobacillus acidophilus ATCC 4461, Lactobacillus casei 2607 and Bifidobacterium animalis ssp. lactis Bb12 in soymilk were evaluated and correlated with the increase in concentration of isoflavone aglycones during fermentation. The concentrations of isoflavone compounds in soymilk were monitored using a Varian model high-performance liquid chromatography (HPLC) with an amperometric electrochemical detector. In all micro-organisms, beta-glucosidase activity was found greater than that of beta-galactosidase. There was an increase in the aglycone concentration with incubation time because of the apparent hydrolytic action on isoflavone glycosides. Aglycone concentration in the soymilk with L. acidophilus 4461, L. casei 2607 and B. animalis ssp. lactis Bb12, increased by 5.37-, 5.52- and 6.10-fold, respectively, after 15 h of fermentation at 37 degrees C. The maximum hydrolytic potential was also observed at 15 h of fermentation for the three micro-organims coinciding with peak activities of the two enzymes. CONCLUSIONS: beta-glucosidase activity was more than 15 times higher than beta-galactosidase activity in soymilk for each of the micro-organisms during fermentation. beta-glucosidase played a greater role in isoflavone glycoside hydrolysis. SIGNIFICANCE AND IMPACT OF THE STUDY: Screening for beta-glucosidase and beta-galactosidase activities among probiotics in soymilk is important for the improvement of biological activity of soymilk and in the selection of micro-organisms for use in the growing industry of functional foods and beverages.

A comparison of changes in the transformation of isoflavones in soymilk using varying concentrations of exogenous and probiotic-derived endogenous beta-glucosidases.

AIMS: To compare endogenous and exogenous beta-glucosidases for the hydrolysis of the predominant isoflavone glucosides in soymilk in order to improve the biological activity. METHODS AND RESULTS: beta-glucosidase activity of probiotic organisms, including Bifidobacterium animalis ssp. lactis Bb12, Lactobacillus acidophilus ATCC 4461 and Lactobacillus casei 2607 in soymilk, was evaluated and was related to the increase in the concentration of isoflavone aglycones during fermentation. The concentrations of isoflavone compounds in soymilk were monitored using a Varian model HPLC with an Amperometric electrochemical detector. The aglycone composition, also known as aglycone equivalent ratio, has been considered to be important for the delivery of health benefits of isoflavones, and was monitored during the fermentation of soymilk. Comparison of the hydrolytic effectiveness of both exogenous and endogenous enzyme during 4-h incubation in soymilk was conducted using the Otieno-Shah (O-S) index. Results showed that exogenous enzyme exhibited faster rate of isoflavone glucoside hydrolysis than that by endogenous enzyme. Highest O-S indices were obtained after 4, 3 and 2 h of incubation with enzyme solution having beta-glucosidase activity of 0.288 U ml(-1), 0.359 U ml(-1) and 0.575 U ml(-1), resulting into aglycone concentration increments of 5.87-, 6.07- and 5.94-fold, respectively. Conversely, aglycone concentration in the soymilk with B. animalis ssp. lactis Bb12, L. casei 2607 and L. acidophilus 4461 increased by 3.43-, 2.72- and 3.03-fold, respectively, after 4 h of fermentation at 37 degrees C. In addition, the O-S index of endogenous enzyme was much lower than that of the exogenous enzyme over the same 4-h incubation period. Optimum aglycone equivalent ratios coincided with highest O-S indices and highest aglycone concentrations in soymilk hydrolysed with exogenous enzyme. The same correlation of O-S indices and highest aglycone concentrations occurred for endogenous enzyme during the 24 h of fermentation. CONCLUSIONS: Obtaining highest aglycone concentration and optimum aglycone equivalent ratio could provide a critical beginning point in clinical trials for the realization of unique health benefits of soy isoflavones. SIGNIFICANCE AND IMPACT OF THE STUDY: Screening for beta-glucosidase activities of probiotics in soymilk and comparing their hydrolytic potentials with that of exogenous beta-glucosidase could find wide applications in the development of different aglycone-rich functional soy beverages.

Regulation of transpirational water loss in Quercus suber trees in a Mediterranean-type ecosystem.

Sap flux density in branches, leaf transpiration, stomatal conductance and leaf water potentials were measured in 16-year-old Quercus suber L. trees growing in a plantation in southern Portugal to understand how evergreen Mediterranean trees regulate water loss during summer drought. Leaf specific hydraulic conductance and leaf gas exchange were monitored during the progressive summer drought to establish how changes along the hydraulic pathway influence shoot responses. As soil water became limiting, leaf water potential, stomatal conductance and leaf transpiration declined significantly. Predawn leaf water potential reflected soil water potential measured at 1-m depth in the rhizospheres of most trees. The lowest predawn leaf water potential recorded during this period was -1.8 MPa. Mean maximum stomatal conductance declined from 300 to 50 mmol m(-2) s(-1), reducing transpiration from 6 to 2 mmol m(-2) s(-1). Changes in leaf gas exchange were attributed to reduced soil water availability, increased resistances along the hydraulic pathway and, hence, reduced leaf water supply. There was a strong coupling between changes in soil water content and stomatal conductance as well as between stomatal conductance and leaf specific hydraulic conductance. Despite significant seasonal differences among trees in predawn leaf water potential, stomatal conductance, leaf transpiration and leaf specific hydraulic conductance, there were no differences in midday leaf water potentials. The strong regulation of changes in leaf water potential in Q. suber both diurnally and seasonally is achieved through stomatal closure, which is sensitive to changes in both liquid and vapor phase conductance. This sensitivity allows for optimization of carbon and water resource use without compromising the root-shoot hydraulic link.

Isoflavone phytoestrogen degradation in fermented soymilk with selected beta-glucosidase producing L. acidophilus strains during storage at different temperatures.

Soymilk fermented with 3 selected Lactobacillus acidophilus strains were stored at various temperatures (-80 degrees C, 4 degrees C, 25 degrees C and 37 degrees C) for 8 weeks and the concentration of isoflavones determined weekly using RP-HPLC. The decreasing concentration of isoflavones in soymilk during storage due to degradation was found to fit the first order kinetics model. Isoflavone aglycones as well as isoflavone glucosides largely appeared to be stable during storage (P<0.01). Interestingly, the aglycone forms showed much smaller degradation as compared to glucoside forms at all the storage temperatures studied. Of the isoflavone aglycones, daidzein was found to be the most stable followed by genistein, while glycitein was least stable. Isoflavone aglycones such as glycitein, daidzein and genistein showed smaller degradation constants in fermented soymilk at lower storage temperatures (-80 degrees C and 4 degrees C) and higher degradation constants at higher storage temperatures (25 degrees C and 37 degrees C) with each strain. In contrast, glucosides glycitin and daidzin showed higher degradation at lower storage temperatures (-80 degrees C and 4 degrees C) and lower degradation at higher storage temperatures (25 degrees C and 37 degrees C). Storage temperature was therefore found to be very important in regulating the rate of degradation soy isoflavones in fermented soymilk.

Physiological and morphological responses to water stress in two Acacia species from contrasting habitats.

Container-grown seedlings of Acacia tortilis Forsk. Hayne and A. xanthophloea Benth. were watered either every other day (well watered) or every 7 days (water-stressed) for 1 year in a greenhouse. Total plant dry mass (T(dm)), carbon allocation and water relations were measured monthly. Differences in leaf area (LA) accounted for differences in T(dm) between the species, and between well-watered and water-stressed plants. Reduction in LA as a result of water stress was attributed to reduced leaf initiation, leaf growth rate and leaf size. When subjected to prolonged water stress, Acacia xanthophloea wilted more rapidly than A. tortilis and, unlike A. tortilis, lost both leaves and branches. These differences between species were attributed to differences in the allocation of carbon between leaves and roots and in the ability to adjust osmotically. Rapid recovery in A. xanthophloea following the prolonged water-stress treatment was attributed to high cell wall elasticity. Previous exposure to water stress contributed to water-stress resistance and improved recovery after stress.