Compaction of a swelling clay soil by agricultural traffic; effects upon conditions for growth of winter cereals and evidence for some recovery of structure

A swelling stagnogley soil remained unwheeled or was uniformly wheeled by a combine harvester and a tractor in two successive autumns before direct drilling winter cereals. Combine wheeling of the soil at its wettest condition caused the largest loss of soil porosity. The autumn and spring of the second growing season for the winter cereals were wetter than long term average. The smaller porosity in the wheeled soil, created lower soil redox potential and smaller oxygen flux as well as greater soil strength and larger amounts of available water, but little difference in soil temperature. The crop in the wheeled soil had fewer plants, less root and a lighter yield than in the unwheeled soil. The wheeled soil recovered some porosity and lost strength after wetting and drying during the second growing season, whereas soil freezing had very little effect. This restructuring was sufficient to reverse some of the detrimental effects of compacting the soil.     

Effect of Cloprostenol Treatment at Artificial Insemination on Sow Fertility

In two experiments, we examined the effect of administration of cloprostenol at artificial insemination on fertility of multiparous sows. Lactation length was 21 days and only sows exhibiting estrus by 7 days after weaning were included. Cloprostenol was administered by IM injection (175 microg; n=126) or supplemented in the semen dose (525 microg; n=129). Control sows (n=130) received no hormone. In either experiment, there was no effect of any treatment on subsequent litter sizes. In experiment 1, there was no effect of treatment on farrowing rate, but in experiment 2, farrowing rate was higher (p < 0.05) in sows receiving cloprostenol by injection. Taken together, these results indicate no consistent effect of cloprostenol administration by intramuscular injection or by inclusion in the semen dose on sow fertility and so its routine use is not warranted.     

DYNAMIC HELICAL COMPUTED TOMOGRAPHY OF THE PITUITARY GLAND IN HEALTHY DOGS

Dynamic helical computed tomography (CT) of the pituitary gland can be used to image the three-dimensional shape and dimensions of abnormalities within the pituitary gland. The aim of this study was to develop a protocol for dynamic helical CT of the pituitary gland in healthy dogs as a future reference study for patients with pituitary disease. Dynamic helical series of nine scans of the pituitary gland during and following contrast medium injection were performed in six healthy dogs using the following protocols: a series with 1 mm collimation and a table feed per X-ray tube rotation of 2 mm (pitch of 2) in six dogs, a series with 2 mm collimation and pitch of 2 in three dogs, and a series with 1 mm collimation and pitch of 1 in three other dogs. Multiplanar reconstructions of the images were made using a reconstruction index of 0.5. Images of all series were assessed visually for enhancement of the arteries, the neurohypophysis, and the adenohypophysis. The enhancement pattern of the neurohypophysis was distinguished adequately from that of the adenohypophysis in five dogs that were scanned with 1 mm collimation and pitch of 2, but the difference was less discernable when the other protocols were used. The carotid artery, its trifurcation, and the arterial cerebral circle were best visualized in dorsal reconstructions. Dynamic helical CT of the pituitary gland in healthy dogs can be performed with 1 mm collimation and pitch of 2, and a scan length that includes the entire pituitary region. Using this protocol, with the specific scanner used, the neurohypophysis, the adenohypophysis, and the surrounding vascular structures are adequately visualized.     

The effects of formalin, malachite green and suspended solids on the respiratory activity of rainbow trout, Salmo gairdneri Richardson

Abstract. The influence of formalin and malachite green on ventilation rate, cough rate and oxygen consumption rate of rainbow trout, Salmo gairdneri Richardson, was investigated. The effect of suspended silt on these parameters is also described. In all cases ventilation rate increased by up to 60%. Cough rate increased more dramatically by up to 300%. Some acclimation to the various treatments was observed. Rates of oxygen consumption increased markedly in all cases but particularly when the fish were exposed to silt, when an increase of 500 to 700% was noted. These data emphasize the need for stress-free husbandry when using prophylactics or disease treatments and demonstrate the high oxygen demand of fish in these conditions.     

The use of yttrium oxide and the effect of faecal collection timing for determining the apparent digestibility of minerals and trace elements in Atlantic salmon (Salmo salar, L.) feeds

The effectiveness of the external marker yttrium oxide (Y₂O₃) and sampling period for determining the apparent digestibility (AD) of minerals and trace elements within Atlantic salmon feeds were compared. Yttrium oxide was compared at inclusions of 0.01, 0.1, 1 and 10 g kg^?1 wet weight of the feeds. Samples were analysed for a range of mineral and trace elements via inductively coupled plasma optical emission spectroscopy after wet decomposition with concentrated nitric acid. Feed marked with 1 g kg^?1 provided the greatest recovery, and provided analytical values within an optimal range, and therefore, the effect of faecal sampling period on AD of mineral and trace element was then compared using the feed marked with 1 g kg^?1 Y₂O₃. Faeces were collected over three different time periods within a 24 h period: 4 × 6 h, 2 × 12 h and 1 × 24 h. Magnesium, manganese, phosphorus, iron and chromium displayed significant differences in AD relating to sampling period. An inclusion level of 1 g kg^?1 Y₂O₃ and faecal sampling over at least an 18 h period after feeding proved to be the most effective method of determining AD of mineral and trace element in Atlantic salmon feed.