Risk factors for bovine mastitis in the Central Province of Sri Lanka

A study of the risk factors associated with mastitis in Sri Lankan dairy cattle was conducted to inform risk reduction activities to improve the quality and quantity of milk production and dairy farmer income. A cross-sectional survey of randomly selected dairy farms was undertaken to investigate 12 cow and 39 herd level and management risk factors in the Central Province. The farm level prevalence of mastitis (clinical and subclinical) was 48 %, similar to what has been found elsewhere in South and Southeast Asia. Five cow level variables, three herd level variables, and eight management variables remained significant (p?相似文献   

Prion protein genotypes of sheep as determined from 3343 samples submitted from Ontario and other provinces of Canada from 2005 to 2012

This study analyzed sheep prion protein (PrP) genotypes of samples submitted from Ontario and other provinces of Canada to the Animal Health Laboratory at the University of Guelph, Guelph, Ontario, between 2005 and 2012. In Ontario, the proportion of scrapie-resistant sheep increased from 2005 to 2012 as evidenced by an increase in the ARR haplotype. When Canadian provinces (Alberta, Ontario, Quebec, and Nova Scotia) were compared from 2008 to 2012, a high proportion of scrapie-resistant sheep was found in all the provinces. The proportions of resistant sheep were lower in Alberta and Quebec than in Ontario and Nova Scotia. Alberta had higher proportions of susceptible sheep and a higher frequency of VRQ alleles, and Quebec had a higher frequency of the ARQ allele.     

A B-cell targeting virus disrupts potentially protective genomic methylation patterns in lymphoid tissue by increasing global 5-hydroxymethylcytosine levels

The mechanisms by which viruses modulate the immune system include changes in host genomic methylation. 5-hydroxymethylcytosine (5hmC) is the catalytic product of the Tet (Ten-11 translocation) family of enzymes and may serve as an intermediate of DNA demethylation. Recent reports suggest that 5hmC may confer consequences on cellular events including the pathogenesis of disease; in order to explore this possibility further we investigated both 5-methylcytosine (5mC) and 5hmC levels in healthy and diseased chicken bursas of Fabricius. We discovered that embryonic B-cells have high 5mC content while 5hmC decreases during bursa development. We propose that a high 5mC level protects from the mutagenic activity of the B-cell antibody diversifying enzyme activation induced deaminase (AID). In support of this view, AID mRNA increases significantly within the developing bursa from embryonic to post hatch stages while mRNAs that encode Tet family members 1 and 2 reduce over the same period. Moreover, our data revealed that infectious bursal disease virus (IBDV) disrupts this genomic methylation pattern causing a global increase in 5hmC levels in a mechanism that may involve increased Tet 1 and 2 mRNAs. To our knowledge this is the first time that a viral infection has been observed to cause global increases in genomic 5hmC within infected host tissues, underlining a mechanism that may involve the induction of B-cell genomic instability and cell death to facilitate viral egress.     

Fishing gear effects and ecology of the sea whip (Halipteris willemoesi (Cnidaria: Octocorallia: Pennatulacea)) in British Columbia,Canada: preliminary observations

• 1. We conducted a preliminary study of the effects of a shrimp beam trawl and prawn traps on sea whips (Halipteris willemoesi (Cnidaria: Octocorallia: Pennatulacea)) at two bays on Clio Channel, south central coast of British Columbia, Canada. Video and grabs surveys were conducted to estimate abundance and make observations on sea whips and their habitat.
• 2. No adult sea whips were caught in six beam trawls. In 600 prawn (Pandalus platyceros) trap sets at Turnour Bay, 30 sea whips were found entangled in the gear and of these 50% of the colonies were damaged. The length of broken sea whips ranged from 0.09 to 1.03 m. At Turnour Bay, the density of adults observed in video surveys ranged from 7.1 to 14.3 m^?2. Juvenile density in grab samples ranged from 53 to 123 m^?2 and a few adults were also caught. The lengths of intact adult sea whips caught in traps and grabs ranged from 0.20 to 1.98 m and juveniles from 0.3 to 0.7 cm.
• 3. Fewer adult sea whips (<0.1 m^?2) were seen in Bones Bay, where sediments were muddier (grain size <0.25 mm: 84.6 to 97.2%) relative to Turnour Bay (grain size <0.25 mm: 71.4 to 85.9%). Bottom water characteristics at the two bays were similar. Seasonal temperature range was 7.5–8.4°C, salinity 30.63–31.49 psu, and dissolved oxygen 2.76–5.97 mg L^?1. Differences in sediment characteristics and food availability may have been a factor influencing differences in abundance of sea whips between the two bays.
• 4. Further data are needed to investigate the effects of trawling and trapping on sea whips, as sample sizes were small in the present study and only two gear types were evaluated. Studies of effects of otter trawling and heavier traps, such as those used for Dungeness crab (Cancer magister), are warranted.

Copyright © 2005 John Wiley & Sons, Ltd.     

Light level thresholds for visual reaction of mackerel, Scomber scombrus L., to coloured monofilament nylon gillnet materials

A continuously swimming school of 12 dark-adapted mackerel was challenged to show visual reaction to barriers made from horizontal parallel lines (5 cm apart) of either monofilament nylon (0.40 mm diameter) gillnet material or, for comparison, the more visible twisted multifilament nylon (1.73 mm diameter). Six colours of each material were tested. The barriers were placed across the path of the approaching mackerel school while their behaviour was observed at low intensities of green light arranged to mimic undersea conditions. At very low light levels, the mackerel swam without hesitation through the barrier, whereas at higher light levels they turned or paused, indicating that they visually aware of the presence of the lines. The light level thresholds for visual reaction for the six colours of monofilament nylon were between −0.06 and −1.0 log lx, and for the same colours of twisted multifilament nylon were between −1.8 and −3.6 log lx. These findings are discussed in relation to the natural intensities of light in the sea, and the prediction of the visibility of drift and gillnet materials.     

The progeny of sex-inverted female Atlantic salmon (Salmo salar L.)

A group of Atlantic salmon juveniles received dietary 17α-methyl-testosterone (3 mg/kg of food) for 60 days after first-feeding. Many of these fish became sexually mature as males at 1.5 years of age, while they remained in freshwater. Supposed sex-inverted females among these were identified by their failure to strip manually. Milt from the excised gonads of five of these fish was used separately to fertilise mixed ova from normal adult females. The progeny of each male, when examined 8 weeks after first-feeding, all had typically female gonads (n = 50).     

Oxidation of glutathione during hydroperoxide metabolism in isolated hepatocytes of rainbow trout (Salmo gairdneri)

Freshly isolated rainbow trout hepatocytes were exposed to tert-butyl hydroperoxide (BuOOH), a substrate for glutathione peroxidase. BuOOH at a concentration approximately equimolar (1 mM) with intracellular reduced glutathione (GSH) caused a reversible increase in intracellular glutathione disulphide (GSSG) but did not compromise cell viability or damage membrane lipids. BuOOH at 10 mM caused a large irreversible increase in intracellular GSSG followed by efflux into the medium. Considerable leakage of lactate dehydrogenase and loss of highly unsaturated fatty acids, particularly docosahexaenoic acid also occurred. Dependence of hydroperoxide removal on flux through the hexose monophosphate pathway was suggested by the increased release of ¹⁴CO₂ from [1-¹⁴C] glucose from hepatocytes incubated with BuOOH.