EVALUATION OF POTENTIAL SUBSTRATES TO MONITOR RESPIRATORY NITRATE REDUCTASE ACTIVITY IN SOILS

Different inorganic ions were tested for their ability to replace nitrate as the terminal oxidant for bacterial respiration in anaerobic soils. Chlorate, bromate. selenate. tellurite and ferric ions were all unsuitable substitutes, lodate reduction in soils was similar to nitrate reduction because it required anaerobic conditions, was increased by glucose amendment and decreased by phenylmercuric acetate. Amendment of soils with iodate and measurement of iodide production can be used to measure nitrate reductase activity in a soil and so give a qualitative indication, and possibly a quantitative estimate, of the denitrification capacity of soils.     

Classification of Bacteroides nodosus by agglutination tests

One thousand two hundred and sixty seven isolates of Bacteroides nodosus from 292 sheep in 58 flocks were examined. Of these, 1260 could be classified by slide agglutination into 8 serogroups designated A to H. Up to 6 serogroups were detected in individual flocks, with up to 4 serogroups being detected in a single foot. Of the 292 sheep examined, 38 (13%) carried mixed serogroup infections. Determination of the range of serological types infecting a flock frequently required the examination of a number of isolates from each of a number of sheep. Cross-tube agglutination tests carried out on 44 isolates and their antiserums indicated that members of some serogroups could be divisible into subgroups or serotypes. These results suggested that 16 or more serotypes of B. nodosus might exist. The nature of the antigens responsible for both slide and tube agglutination reactions needs to be determined.     

Sheep productivity in the Ethiopian Highlands on a diet supplemented with urea-molasses block and/or noug cake

A feeding experiment was carried out in which adult ewes of the Ethiopian Highland Menz breed grazed on meadow pasture were supplemented with urea-molasses block and/or noug cake. There was low consumption of urea-molasses block (67 gd-1) and its contribution to total nitrogen requirement was minimal. Dietary treatment had no significant effect on liveweight changes of ewes, their reproductive performance and performance of the lambs. When there was liver fluke infection, ewes and their lambs which were supplemented with urea-molasses block and/or noug cake had better survival compared to those which did not get any supplements (35% mortality vs 55%). The rumen ammonia-N concentration was significantly lower in the control sheep (11 mg/100 ml) and those that received only urea-molasses (14 mg/100 ml) and highest in sheep receiving the urea-molasses block and noug cake (26 mg/100 ml). The volatile fatty acid proportions were not significantly affected by the diets. Low level of urea-molasses block consumption seemed to be a main factor limiting the usefulness of the urea-molasses block and it is recommended that factors likely to enhance its consumption be investigated.     

Use of a flexed dorsoplantar radiographic view of the talocrural joint to evaluate lameness in two dogs.

A flexed dorsoplantar radiographic view of the talocrural joint was a useful additional view to diagnose abnormalities of the lateral trochlear ridge of the talus of 2 dogs. This view outlined the subchondral bone of both trochlear ridges of the talus and the apposing cochlea tibiae of the distal portion of the tibia. The tarsus was flexed at the level of the talocrural joint, and an x-ray beam was centered on the joint. With this additional view, fractures of the lateral trochlear ridge were readily diagnosed. This view would help to demonstrate osteochondral lesions of the lateral trochlear ridge.