Sampling potato tubers to determine peel loss

A simple marker was fabricated for the purpose of rapidly labeling tubers that are to be used for determining the amount of peel loss. The effect of tuber size and shape on quantity of peel removed, and its significance to continuous in-plant monitoring of peel loss, is discussed. A standardized peel removal testing procedure for plant use is described.     

Double-dip caustic peeling of potatoes II: Studies on commercialization

A study of “double-dip” caustic peeling of potatoes was made at two commercial potato processing plants. The “double-dip” system uses two caustic dips, each followed by a holding period at ambient temperature. The peel is then removed using rubber-tipped scrubbers. Four hundred and fiftyfour g of pure caustic peeled about 90 to 180 kg of potatoes. Good quality peel was attained with a 10 to 14% peel loss. The equipment in both plants performed with little mechanical difficulty. Quick changes in dip-time and holding-time were used to compensate for changes in the condition of raw material without causing excessive variations in caustic-use or peel-removal. Problems encountered and solutions applied to each are described in detail.     

Effects of pruning time and resting period on total non-structural carbohydrates,regrowth and yield of tea (Camellia sinensis L.)

Summary

An experiment was conducted at Kipkebe Estate, Sotik, Kenya, with the aim of establishing the effects of pruning time and resting period on total non-structural carbohydrate (TNC) reserves, regrowth and yield of tea. In this experiment, tea bushes were freely left unplucked for 45 and 90.d before pruning. Control treatments were continuously plucked until pruning. Results showed that TNC was significantly (P≤0.05) increased at pruning time. October pruning significantly increased leaf, stem, and root TNC. A longer resting period of 90.d significantly increased leaf and root TNC to 294 and 230.gkg^–1, respectively. Generally, TNC declined after pruning and thereafter increased. Root TNC significantly correlated with regrowth period, diebacks and yield. Generally, the best resting period for increased TNC, regrowth and yield, is between 45 and 90.d. The best pruning time is October, if drought stress can be avoided.     

Stable isotope evaluation of population‐ and individual‐level diet variability in a large,oligotrophic lake with non‐native lake trout

Non‐native piscivores can alter food web dynamics; therefore, evaluating interspecific relationships is vital for conservation and management of ecosystems with introduced fishes. Priest Lake, Idaho, supports a number of introduced species, including lake trout Salvelinus namaycush, brook trout S. fontinalis and opossum shrimp Mysis diluviana. In this study, we used stable isotopes (δ¹³C and δ¹⁵N) to describe the food web structure of Priest Lake and to test hypotheses about apparent patterns in lake trout growth. We found that isotopic niches of species using pelagic‐origin carbon did not overlap with those using more littoral‐origin carbon. Species using more littoral‐origin carbon, such as brook trout and westslope cutthroat trout Oncorhynchus clarki lewisi, exhibited a high degree of isotopic niche overlap and high intrapopulation variability in resource use. Although we hypothesised that lake trout would experience an ontogenetic diet shift, no such patterns were apparent in isotopic signatures. Lake trout growth rates were not associated with patterns in δ¹⁵N, indicating that variation in adult body composition may not be related to adult diet. Understanding trophic relationships at both the individual and species levels provides a more complete understanding of food webs altered by non‐native species.     

cBSA-147 for the preparation of bacterial biofilms in a microchannel reactor

Whole cells are attractive biocatalysts, particularly if the reaction requires cofactors or involves multiple transformations. Immobilization of the catalyst is often a prerequisite for continuous processes. The highly cationic chemically modified plasma protein bovine serum albumin (cBSA-147) has been applied for the electrostatically mediated immobilization of the planktonic bacterium E. coli BL21 star (DE3), and the resulting biofilms were superior to those formed on poly-L-lysine coated surfaces. The biocatalyst was immobilized in a capillary column (inside diameter of 530?μm and L=30?m) and evaluated in the enantioselective reduction of ethyl acetoacetate to R-(-)ethyl hydroxybutyrate. In continuous operation in the microreactor format, the productivity of the cells was about 30% higher than that determined in a bench-scale fermentation system. This increase is attributed to the improved mass transfer over short geometrical dimensions. The similarity in the results indicates that studies on a biofilm-coated microreactor can be used for the accelerated collection of data for process optimization.     

Forensic DNA profiling of tropical timber species in Peninsular Malaysia

Illegal logging poses a significant threat to the sustainability of tropical forest ecosystems. By using Neobalanocarpus heimii (Dipterocarpaceae) as an example, the study assessed the feasibility of using short tandem repeats (STRs) as a tool to identify the source of illegally logged timber. Thirty natural populations of N. heimii were profiled using 12 STRs to develop the DNA profiling databases. As the cluster analysis divided the 30 populations into three genetic clusters, corresponding to three subregions within Peninsular Malaysia. The DNA databases were characterised at the levels of population, subregion and Peninsular Malaysia. Independence tests within and among loci were violated in all the databases due to significant levels of population differentiation and inbreeding. Thus, the effects of population substructure and inbreeding should be incorporated into the calculation of random match probability. The random match probabilities estimated using subpopulation and subpopulation-cum-inbreeding models were biased in favour of the defendant, whereas the random match probabilities estimated using product rule were biased in favour of the prosecutor. The conservativeness tests showed that the subregion and Peninsular Malaysia databases were conservative, and these databases should be able to provide legal evidence for court proceedings against illegal loggers in Peninsular Malaysia.     

Characteristics of the smallholder free-range pig production system in western Kenya

Free-range pig farming is common amongst the small-scale farmers in western Kenya. In order to determine the characteristics of this type of production system, a cross-sectional questionnaire survey on farm characteristics and management was collected from 182 farmers in Busia District. The mean farm size was one acre, while the mean number of pigs per farm was 3.6. Pigs were mainly kept as a source of income (98%) and majority were of cross breed variety (64%). The production systems included farrow to weaner (12%), porker to finisher (36%), and mixed (46%). Sixty five percent (65%) of the pigs were tethered and housing was not provided in 61% of the farms. Most of the feeds were sourced locally. Lack of castration and delayed weaning of pigs was observed on 49% and 30% of the farms, respectively. The main production constraints included pig diseases (81%) and high cost or lack of feed (81%). Haematopinus suis infestations and worm infections were considered to be the most important diseases by 71% and 55% of the farmers, respectively. Farmers had moderate knowledge on parasitic disease diagnosis with 31% and 62% not having a history of either deworming or spraying pigs with acaricides, respectively. Marketing constraints were common amongst the farmers and included poor prices and inadequate market information. In conclusion, the production system was characterized as low-input with an income objective. Future research and development approaches should focus on the integration of free-range farmers into the country’s market chains through access to extension services.     

Effects of a dietary organic acids blend and oxytetracycline on the growth,nutrient utilization and total cultivable gut microbiota of the red hybrid tilapia,Oreochromis sp., and resistance to Streptococcus agalactiae

A 20‐week feeding trial was conducted to measure growth, nutrient utilization and faecal/gut bacterial counts in triplicate groups of red hybrid tilapia, Oreochromis sp., when fed diets supplemented with 0.5% organic acids blend (OAB), 1.0% OAB, 0.5% oxytetracycline (OTC) or a control diet (no additives). At the end of the feeding trial, tilapia were challenged with Streptococcus agalactiae for 22 days. Fish fed the OTC diet had significantly higher (P < 0.05) growth than the control treatment, while growth between fish fed the OTC or OAB diets was not significantly different (P > 0.05). Phosphorus, dry matter and ash digestibility were significantly higher in the 1.0% OAB diet than the control diet. Fish fed the OAB diets had significantly lower colony‐forming units of adherent gut bacteria compared to the control or OTC treatments while those fed the 1.0% OAB diet had the lowest total faecal bacterial counts. Tilapia fed the 0.5% OTC or OAB diet had significantly higher resistance to S. agalactiae than those fed the control diet. This study indicates that dietary organic acids can potentially replace OTC as a growth promoter and antimicrobial in tilapia feeds.     

Reproduction,larviculture and early development of the Bluebanded goby,Lythrypnus dalli,an emerging model organism for studies in evolutionary developmental biology and sexual plasticity

The Bluebanded goby, Lythrypnus dalli, is a popular ornamental aquarium species and a key organism for the study of several fundamental biological questions, most notably reversible sex change in adults. To maximize the tractability of this species as an emerging model system, it is essential to have an optimized propagation system and a detailed developmental staging scheme. One limitation to the larviculture of L. dalli is the relatively small size of the larvae, which makes the transition from yolk to feeding challenging. We developed a protocol and successfully reared three generations of L. dalli in the laboratory. The protocol contains several key innovations for the rearing of diminutive fish larvae, including tank design and co‐culturing of microalgae (Isochrysis galbana) with copepods (Parvocalanus sp.) in the larval rearing tanks. In addition, we describe the embryonic and larval development of L. dalli under controlled conditions and in comparison with the model organism Danio rerio. We found that at 21°C L. dalli larvae hatch in 4 days, reach flexion in 18–25 days and are sexually mature by 3 months. Overall, the embryonic development of L. dalli is remarkably similar to D. rerio with several striking differences, including the position and shape of the blastomere, size of the neuromasts and corresponding cupula, and relative timing of pigmentation and brain subdivision. The ability to rear this species in captivity is a valuable tool that could be utilized for a variety of similarly diminutive species and to address a greater breadth and depth of biological questions.     

Effects of Dietary Probiotics on the Growth and Feeding Efficiency of Red Hybrid Tilapia,Oreochromis sp., and Subsequent Resistance to Streptococcus agalactiae

An eight-week trial was performed to evaluate three commercial/prototype probiotics supplemented in red hybrid tilapia, Oreochromis sp. diets. Triplicate groups of tilapia were measured for growth performance, feeding efficiencies, and whole-body composition. After the feeding trial, duplicate groups of tilapia were assessed for their resistance to Streptococcus agalactiae over 23 days. Six diets were supplemented with 0.1% or 0.3% PB₁ consisting of Bacillus subtilis, 0.1% or 0.3% PB₂ consisting of B. licheniformis or 0.1% MPB consisting of Bacillus sp. and Pediococcus sp. Probiotics had no effect (p > 0.05) on growth or feeding efficiencies, although whole-body crude protein was significantly higher in the PB₁ 0.3% treatment. Tilapia in the probiotic treatments had a higher resistance to S. agalactiae and, with the exception of the PB₂ 0.1% diet, were all significantly higher than the control treatment. Although the tested probiotics were not growth promoters, dietary B. subtilis was the most effective prophylactic against pathogenic bacteria.