Article

Phenol-hypochlorite reaction for determination of ammonia

Analytical Chemistry (Impact Factor: 5.83). 04/2002; 39(8). DOI: 10.1021/ac60252a045
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    ABSTRACT: tRumen cannulation is the reference method for collection of representative samples ofrumen digesta. However, it is not always viable, which obliges to depend on less invasivetechniques, such as stomach tubing. The aim of this work was to study if the differencesin fermentation parameters and rumen microbial populations observed between species(sheep and goats), diets (forage and forage plus concentrate) and sampling times (pre-and post-feeding) are consistent when collecting the samples through stomach tube orrumen cannula, in an attempt to validate the use of the former as an alternative to the lat-ter. Four sheep and four goats, fitted with ruminal cannula, were fed either forage (F diet;alfalfa hay) or forage plus concentrate (1:1; FC diet), in two 15-day periods. At the end ofeach period (days 14 and 15), samples of rumen digesta were taken by stomach tube andrumen cannula, before and 4 h after morning feeding, for determination of ruminal fermen-tation parameters (pH, and lactate, ammonia and total VFA concentrations). The three mainrumen microbial groups (bacteria, protozoa and methanogenic archaea) and two fibrolyticbacteria (Ruminococcus flavefaciens and Fibrobacter succinogenes) were quantified by real-time PCR and, additionally, PCR-DGGE analysis of the bacterial community on the rumendigesta samples collected post-feeding was carried out. Overall, sampling through ruminalcannula and stomach tube gave similar results regarding fermentation parameters whencomparing species, diets and sampling times. Despite samples for microbiology assays con-tained liquid plus solid fractions when collected through rumen cannula and mostly liquidwhen collected through stomach tube, both techniques showed certain consistency in theeffects of treatments on the rumen microbiota (e.g., both revealed no differences between species in total bacteria, archaea and R. flavefaciens concentrations, and higher protozoanumbers in goats than in sheep). However, there was also some discrepancy regardingmicroorganism concentrations, particularly concerning sampling times (e.g., differencesbetween pre- and post-feeding samplings were only observed in rumen cannula samplesfor total bacteria and methanogenic archaea, and in stomach tube samples for R. flavefa-ciens concentrations). Therefore, this study supports that non-invasive stomach tubing is afeasible alternative to surgical rumen cannulation in sheep and goats to examine ruminalfermentation. Nonetheless, caution should be taken when using this technique to assessthe structure and composition of the rumen microbial community.
    Animal Feed Science and Technology 09/2014; 198:57-66. · 2.09 Impact Factor
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    Soil Science Society of America Journal 01/2012; 76(2):505. · 2.00 Impact Factor
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    ABSTRACT: Smallholder farmers in western Kenya who plant maize (Zea mays L.) intercropped with beans (Phaseolus vulgaris L.) face many challenges associated with nutrient-poor soils and weather-related crop failures. In regions where temperatures are favorable, crops are grown twice per year during long and short rainy seasons and in other regions, once per year during one long growing Original Research Article Odhiambo et al.; IJPSS, 5(3): 127-142, 2015; Article no.IJPSS.2015.067 128 season. Growing crops two times per year necessitates frequent land preparation using inversion-type tillage. Little is known about the impact of current tillage-intensive crop management on annual soil organic matter (SOM) recovery. The aim of this study was to assess changes to soil carbon (C), nitrogen (N) and crop performance in typical maize-bean production during long rainy season (LR), short rainy season (SR) and a fallow period (FP) in areas where crops are grown one time (Trans-Nzoia) and two times per year (Bungoma). The two locations were sampled three times per year for a period of three years. Soils were analyzed for potentially mineralizable nitrogen (PMN), ammonium (NH 4), nitrate (NO 3), water filled pore space (WFPS), nitrous oxide (N 2 O), methane (CH 4) and carbon dioxide (CO 2). Results demonstrated significantly greater PMN, NH 4 N 2 O and CO 2 during SR in Bungoma compared with LR and FP suggesting high C and N mineralization caused by warmer temperatures and high frequency of tillage. Soils in Trans-Nzoia also showed elevated NH 4 , NO 3 and N 2 O during the same period but the magnitude of these changes was much lower compared with Bungoma. Mineralization negatively impacted annual SOM renewal and crop production as further demonstrated by low soil total C and N and cumulative crop yields in Bungoma. Planting edible cover crops, reducing tillage and using manure should become a necessity to support sustainable crop production. Particular attention should concentrate on designing appropriate management strategies for SR season in Bungoma.
    12/2014; 5(3):127-142.