Evaluation of denaturing gradient gel electrophoresis for the detection of mycobacterial species and their potential association with waterborne pathogens.

The versatility of denaturing gradient gel electrophoresis (DGGE) protocol provides enough grounds for its wide application over an array of microorganisms. This work was designed to evaluate DGGE for the detection and confirmation of mycobacteria and their association, if any, with waterborne pathogens. A total of 76 samples comprising raw untreated water, schmutzdecke, floccules and final treated water obtained from a common water source, and two water treatment works (WTW1 and WTW2), were analysed. Thirty-five species were identified from the overall samples, with 7% (5/76), 13% (10/76) and 26% (20/76) from the common raw water source, WTW1 and WTW2 respectively. The majority of the species were Cyanobacteria, with high dominance in the raw water entering WTW2. In the final treated water of WTW1 Eutreptiella braarudii was found, and that of WTW2 contained Anabaena nereformis, Anabaena torulosa and Podocarpus nerrifolius. Furthermore, one Mycobacterium species was found in the raw water of WTW1 aside from the detection of Mycobacterium avium ssp. paratuberculosis by the technique. No association between mycobacteria and the other species was observed. This implies DGGE may be employed to study the diversity of other akin mycobacterial species from various sources, and not as a direct means of elucidating microbial associations.

Optimisation of decontamination method and influence of culture media on the recovery of Mycobacterium avium subspecies paratuberculosis from spiked water sediments.

The recovery of Mycobacterium avium subspecies paratuberculosis (Map) from the environment can be a laborious process - owing to Map being fastidious, its low number, and also high numbers of other microbial populations in such settings. Protocols i.e. filtration, decontamination and modified elution were devised to recover Map from spiked water sediments. Three culture media: Herrold's Egg Yolk Media (HEYM), Middlebrook 7H10 (M-7H10) and Bactec 12B were then employed to grow the organism following its elution. In the sterile sediment samples the recovery of Map was significant between the time of exposure for each of HEYM and M-7H10, and insignificant between both media (P < 0.05). However, in the non-sterile sediment samples, the HEYM grew other background microflora including moulds at all the times of exposure whilst 4 h followed by M-7H10 culture yielded Map colonies without any background microflora. Using sterile samples only for the Bactec 12B, the recovery of Map decreased as time of exposure increased. Based on these findings, M-7H10 should be considered for the recovery of Map from the natural environment including water sediments where the recovery of diverse microbial species remains a challenge. SIGNIFICANCE OF THE STUDY: Map is a robust pathogen that abides in the environment. In water treatment operations, Map associates with floccules and other particulate matter including sediments. It is also a fastidious organism, and its detection and recovery from the water environment is a laborious process and can be misleading within the abundance of other mycobacterial species owing to their close resemblance in phylogenetic traits. In the absence of a reliable recovery method, Map continues to pose public health risks through biofilm in household water tanks, hence the need for the development of a reliable recovery protocol to monitor the presence of Map in water systems in order to curtail its public health risks.

Effects of replacing fishmeal with black soldier fly larval meal in the diets of grower-finishing guinea fowls reared under tropical conditions.

The study was conducted with the view to determine the impact of replacing fishmeal with black soldier fly larval meal (BSFLM) on growing guinea fowls. BSFLM replaced fishmeal (3% in the control diet) in the ratios of 0, 20, 40, 60, 80, and 100% to produce six dietary treatments, which were iso-caloric and iso-nitrogenous. Two hundred and forty-eight-week old guinea fowls with mean live weight of 273.2 ± 10.9 g were tagged, weighted, and randomly assigned to 24 (6 × 4) floor pens; each pen was treated as a replicate. Feed and water were provided ad libitum during the entire period, which lasted 10 weeks. Feed consumption differed among the treatment groups (P = 0.0072) with the 100% fishmeal diets recording the lowest. Daily gain was significantly (P = 0.009) higher for birds fed high BSFLM diets compared to the control (100% fishmeal diet). The inclusion of BSFLM in the diets elicited positive linear effect on weight gains of the guinea fowls (R2 = 0.91) with increasing concentration resulting in higher live weight gains. The feed conversion ratio (FCR) also differed between treatments (P < 0.05) but similar for the 100% fishmeal (control) and 100% BSFLM diets. Organ and haematopoitic integrity were equally assured regardless of levels of the protein sources fed to the birds. Generally, meats from birds fed 60 to 100% BSFLM and from hens were more acceptable. A study to evaluate the economics of utilising BSFLM in guinea fowl production is recommended.

Impact of black soldier fly larval meal on growth performance, apparent digestibility, haematological and blood chemistry indices of guinea fowl starter keets under tropical conditions.

In order to assess the impact of larval meal on guinea fowl, six iso-caloric and iso-nitrogenous diets were fed to day-old-keets ad libitum till 8 weeks of age. Water was also freely provided. The fishmeal (FM) component of the experimental diets was replaced with black soldier fly larval meal (BSFLM) in the following percentage ratios of 0-100%. Results showed that body weight gain significantly (P < 0.05) increased in all the BSFLM treatment groups compared to the control group. The final body weight of the birds at age 8 weeks differed significantly (P < 0.001). Dry matter intake varied (P < 0.001) slightly among the birds but never affected (P > 0.05) ME intake and faecal output as well as weight changes of the keets. Digestibility of dry matter and energy were not affected (P > 0.05) by the differences in diet. Organ and haematopoietic integrity were assured regardless of the protein types used as well as levels of inclusion. The results suggest that the replacement of fishmeal with BSFLM in so far as the economics of production is concerned could result in reduced feed cost for starter guinea keet judging from diets that contained 60-100% BSFLM.

Occurrence of Mycobacterium avium subsp. paratuberculosis in raw water and water treatment operations for the production of potable water.

Mycobacterium avium subsp. paratuberculosis (Map) causes Johne's disease of cattle and is implicated as a cause of Crohn's disease in humans. The organism is excreted in animal faeces and can contaminate water catchment areas. This coupled with Map's survival in the environment means that water destined for domestic use may be a source of exposure. This work was designed to determine the occurrence of Map in Lough Neagh (the largest freshwater lake in the British Isles), used as a reservoir, and in two water treatment works (WTW1 and WTW2) which abstract from the lough and which have slow sand filtration (SSF) and dissolved air flotation respectively as their principal treatment regimes. The organism was not detected in lough water samples by culture (n=70) but 29% (20/70) were positive by PCR. In the raw water to WTW1 and WTW2 no culture positives were detected but 54% (13/24) and 58% (14/24) respectively were PCR positive. In WTW1 there were no culture positives at the SSF or final water but 31% (8/26) and 45% (9/20) respectively were PCR positive. In WTW2 similar results were obtained with 26% (6/23) and 48% (11/23) in the floccules and final water respectively. At WTW2 however one culture positive was detected in the final water. This latter finding is of concern. The inability to reach definitive conclusions indicates the need for further research, particularly in the detection methods for viable Map.

Preweaning growth performance of west African shorthorn cattle and their Jersey crossbreds in Ghana.

Calf records on 621 West African Shorthorn (WASH) and 3 grades of Jersey x WASH crossbreds were analysed for the effects of the level of Jersey breeding and other factors on birth weight, 205-day weaning weight and average daily gain (ADG). Crossbred calves were significantly (P < 0.01) heavier at birth than purebred WASH and birth weights increased with increasing level of Jersey breeding. No significant differences were established for 205-day weaning weight, however ADG declined with increasing level of Jersey breeding suggesting possible problems of adaptation for calves of over 75% Jersey breeding. Age of dam effect was significant and linear (P < 0.0001) for birth weight and significant and quadratic (P < 0.01) for weaning weight and ADG, with values increasing from 3-year old dams to a peak in 7 year old dams.