The potential of frozen rumen fluid for ruminant feed evaluation using in vitro gas production technique

The aim of this study was to determine the potential of frozen rumen fluid (RF) for ruminant feed evaluation using in vitro gas production (IVGP) technique. This study used a factorial randomized block design with a 3 × 3 × 3 pattern, consisting three feeding regimes varying in forage to concentrate proportion, namely 20%:80% (feed A), 40%:60% (feed B), and 60%:40% (feed C), respectively; three storage time (2, 11, and 19 days); and RF from 3 breeds of indigenous cattle, namely Bali, crossbred Ongole and Madura cattle as groups. The results showed that the effects of feeding regimes, inoculum source, or storage time on total gas production, potential of gas production, rate of gas production, dry matter and organic matter degradability. Based on the results, it can be concluded that frozen RF may be used as inoculum source for feed evaluation using the IVGP technique and hence it supports the previous findings reported in the literature. Considering that the effects of different feeds, inoculum sources, and storage times gave the specific values, it is advisable that to use RF from slaughtered animals should be taken from the same breed to allow accurate comparison for feed evaluation using IVGP technique.

Spatiotemporal Dynamics of Stemphylium Leaf Blight and Potential Inoculum Sources in New York Onion Fields

Stemphylium leaf blight (SLB) caused by Stemphylium vesicarium is the dominant foliar disease affecting large-scale onion production in New York. The disease is managed by fungicides, but control failures are prevalent and recently attributed to fungicide resistance. Little is known of the relative role of inoculum sources in initiation and spread of SLB epidemics. Plate testing of 28 commercially available organic onion seedlots from 2016 and 2017 did not detect S. vesicarium. This finding suggests that although S. vesicarium has been reported as seed transmitted, this is unlikely to be a significant inoculum source in commercially available organic seed lots and even less so in fungicide-treated seed used to establish conventional fields. The spatial and spatiotemporal dynamics of SLB epidemics in six onion fields were evaluated along linear transects in 2017 and 2018. Average SLB incidence increased from 0 to 100% throughout the cropping seasons with an average final lesion length of 28.3 cm. Disease progress was typical of a polycyclic epidemic and the logistic model provided the best fit to 83.3% of the datasets. Spatial patterns were better described by the beta-binomial than binomial distribution in half of the datasets (50%) and random patterns were more frequently observed by the index of dispersion (59%). Geostatistical analyses also found a low frequency of datasets with aggregation (60%). Spatiotemporal analysis of epidemics detected that the aggregation was influenced by disease incidence. However, diseased units were not frequently associated with the previous time period according to the spatiotemporal association function of SADIE. Variable spatial patterns suggested mixed inoculum sources dependent upon location, and likely an external inoculum source at the sampling scale used in this study. A small-plot replicated trial was also conducted in each of two years to quantify the effect of S. vesicarium-infested onion residue on SLB epidemics in a field isolated from other onion fields. SLB incidence was significantly reduced in plots without residue compared to those in which residue remained on the soil surface. Burial of infested residue also significantly reduced epidemic progress in one year. The effect of infested onion residue on SLB epidemics in the subsequent onion crop suggests rotation or residue management may have a substantial effect on epidemics. However, the presence of an inoculum source external to fields in onion production regions as indicated by a lack of spatial aggregation may reduce the efficacy of in-field management techniques.

Spatiotemporal Dynamics of Stemphylium Leaf Blight and Potential Inoculum Sources in New York Onion Fields

Stemphylium leaf blight (SLB) caused by Stemphylium vesicarium is the dominant foliar disease affecting large-scale onion production in New York. The disease is managed by fungicides, but control failures are prevalent and recently attributed to fungicide resistance. Little is known of the relative role of inoculum sources in initiation and spread of SLB epidemics. The spatial and spatiotemporal dynamics of SLB epidemics in six onion fields were evaluated along linear transects in 2017 and 2018. Average SLB incidence increased from 0 to 100% throughout the cropping seasons with an average final lesion length of 28.3 cm. Disease progress was typical of a polycyclic epidemic and the logistic model provided the best fit to 83.3% of the datasets. Spatial patterns were better described by the beta-binomial than binomial distribution in half of the datasets and random patterns were more frequently observed by the index of dispersion. Geostatistical analyses of spatial pattern also found a low frequency of datasets with aggregation. Spatiotemporal analysis of epidemics detected that the aggregation was influenced by disease incidence. However, diseased units were not associated with the previous time period according to the spatiotemporal association function of SADIE. Variable spatial patterns suggested mixed inoculum sources dependent upon location, and likely an external inoculum source at the sampling scale used in this study. Plate testing of 28 commercially available organic onion seedlots from 2017 and 2018 did not detect S. vesicarium. This finding suggests that although S. vesicarium has been reported as seed transmitted, this is unlikely to be a significant inoculum source in commercially available organic seed lots and even less so in fungicide-treated seed used to establish conventional fields. A small-plot replicated trial was also conducted in each of two years to quantify the effect of S. vesicarium-infested onion residue on SLB epidemics in a field isolated from other onion fields. SLB incidence was significantly reduced in plots without residue compared to those in which residue remained on the soil surface. Burial of infested residue also significantly reduced epidemic progress in one year. The effect of infested onion residue on SLB epidemics in the subsequent onion crop suggests rotation or residue management may have a substantial effect on epidemics. However, the presence of an inoculum source external to fields in onion production regions as indicated by a lack of spatial aggregation may reduce the efficacy of in-field management techniques.

Effect of Combining Different Substrates and Inoculum Sources on Bioelectricity Generation and COD Removal in a Two-Chambered Microbial FuelCell: A Preliminary Investigation

In recent years, fuel cells have become a renewable source of energy. Among different kinds of fuel cells, microbial fuel cells, which convert organic substrates to electricity by electrogenic bacteria have attracted most attention. In this study, which is preliminary in nature, potential of electricity generation and chemical oxygen demand (COD) removal were studied in a two-chamber microbial fuel cell (MFC) reactor. Effect of type of feedstock and inoculum source on bioelectricity generation and COD removal was studied as well. Brewery wastewater and potato waste were used as substrates while anaerobic sludge and cow dung were used as inoculum sources. The substrate and inoculum sources were in 8.2:1 ratio and a phosphate buffer was added to the anode compartment to regulate the pH. The system was operated at 30 °C and a home-made membrane served as a bridge between the electrodes. A maximum voltage of 3.6 mV was generated from the brewery wastewater sludge and the maximum COD removal after 3 days was 43.7 %. It was further found that the use of animal dung as inoculum source outperformed the use of sludge as regard the bioelectricity generation but not for COD removal. Similarly, the use of the brewery waste as an organic substrate outperformed the use of potato waste as regard the bioelectricity generation but not for COD removal. All experiments yielded a measurable voltage, however, the unsteady behaviour of the voltage output made it difficult to compare substrates in terms of their viability as organic fuel. Therefore, future studies should consider conducting substrate physico-chemical analysis and genomic analysis of the inoculum sources to understand their composition.