Milk Fever Control Principles: A Review

Three main preventive principles against milk fever were evaluated in this literature review, and the efficacy of each principle was estimated from the results of controlled investigations. Oral calcium drenching around calving apparently has a mean efficacy of 50%–60% in terms of milk fever prevention as well as prevention of milk fever relapse after intravenous treatment with calcium solutions. However, some drenches have been shown to cause lesions in the forestomacs. When using the DCAD (dietary cation-anion difference) principle, feeding rations with a negative DCAD (measured as (Na + K) – (Cl + S)) significantly reduce the milk fever incidence. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a mean RR between 0.19 and 0.35 when rations with a negative versus positive DCAD are compared. The main drawback from the DCAD principle is a palatability problem. The principle of feeding rations low in calcium is highly efficient in milk fever prevention provided the calcium intake in the dry period is kept below 20 g per day. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a very low mean RR (between 0 and 0.20) (daily calcium intake below versus above 20 g/d). The main problem in implementing the low-Ca principle is difficulties in formulating rations sufficiently low in calcium when using commonly available feeds. The use of large doses of vitamin D metabolites and analogues for milk fever prevention is controversial. Due to toxicity problems and an almost total lack of recent studies on the subject this principle is not described in detail. A few management related issues were discussed briefly, and the following conclusions were made: It is important to supply the periparturient cow with sufficient magnesium to fulfil its needs, and to prevent the dry cows from being too fat. Available information on the influence of carbohydrate intake, and on the effect of the length of the dry period and prepartum milking, is at present insufficient to include these factors in control programmes.     

Tactile stimulation and teat-seeking behaviour in newly born lambs

Behavioural effects of tactile stimulation were investigated in newly-born lambs, which had, or had not, been suckled. A smooth or woolly, warm or cold stimulus which covered one side of the face elicited in unsuckled lambs a forceful response resembling its teat-seeking approach to the dam: vigorous forward and upward head movements, munching and sucking. Smaller amounts of tactile stimulation applied at discrete facial sites showed that most head movements occurred in response to touch on the upper surfaces of the face and most oral activity in response to touch on the muzzle. The response to touch was less in lambs which had been suckled, even when age was kept constant. Results are discussed in terms of the natural situation and of the response to touch in the 40–80 day foetus.     

Risk of Infection with Leishmania spp. in the Canine Population in the Netherlands

The dog is the main reservoir of Leishmania infantum, the causative agent of visceral leishmaniasis (VL) in humans in Southern Europe. In order to identify the risk of dogs from a Leishmania non-endemic area traveling to a Leishmania -endemic area becoming infected and the risk of transmitting infection to humans in non-endemic areas an investigation was performed, in which the results of a questionnaire were combined with the results of a serologic survey.     

Freshwater acidification: effects on the early life stages of fish

Summary Over the last 20–30 years there has been a very extensive international research effort into freshwater acidification and the decline or loss of soft-water fisheries. The research includes many laboratory studies on physiology and survival of fish under the conditions caused by acidification. The causes of acidification have become increasingly well understood and accepted. In many countries, industrial and environmental management strategies are being implemented with the eventual aim of halting or reversing acidification in vulnerable areas. Attention has shifted away from research into the effects of acidification on fish, and the number of new papers on this subject is declining. Now appears a good time to review this research.As is often the case in research of this kind, it is difficult to compare work from different laboratories. Especially in earlier work, experimental conditions may not be fully relevant to the field (e.g. in the choice of ambient calcium concentration), experimental media may be inadequately specified (e.g. trace metal concentrations) and analytical techniques may be open to question (e.g. pH measurement). This may explain, in part, why agreement is lacking on many aspects of the physiological effects on the early life stages of fish, as well as the adult stages to some extent. If research is to continue in this field, then adoption of standard soft, acid water media would be of significant benefit. Nethertheless, some very general conclusions on fish early life stages can be reached.There is some evidence of impaired gametogenesis and spawning, but in this area there is still a need for systematic research. After fertilization, the chorionic membranes afford protection from the effects of low pH and especially the accompanying toxic trace metals, notably aluminium. Indeed, dissolved aluminium can ameliorate acid toxicity at this stage in development, possibly by helping to decrease membrane permeability and reduce H⁺ uptake. The main hazard seems to be impaired development (perhaps related to a decline in pH of the perivitelline fluid), often leading to a lack of ability to escape from the chorionic membranes on hatching.After hatching, vulnerability increases. Dissolved aluminium, and other trace metals associated with acidification, become more important. Some studies indicate continuing protection from low pH afforded by low concentrations of aluminium. The causes of death can still only be inferred: much attention has concentrated on mineral uptake and balance, and there is anecdotal evidence of respiratory impairment, although not as unequivocal as it is for postlarval fish. Comparison with the physiological effects on postlarval fish is not necessarily helpful. There seems to be at least one important difference. Unlike postlarvel fish, larvae do not find aluminium at around pH 5.5 (when respiratory effects are probably most important) the most hazardous combination; rather, the greatest danger to larvae seems to be when very low pH (<5.0) and trace metals (including aluminium) combine in some kind of joint toxic effect.There is a great increase in vulnerability once dependence on the yolk has come to an end. This period coincides with the movement from the incubation site in the substratum into the open water, where the relevant water chemistry is likely to fluctuate between greater extremes. However, it is earlier, during autumn rainstorms and spring snowmelt, that pH and concentrations of protective calcium ions usually reach their lowest and metals like aluminium their highest values. In waters where acidification is most likely to occur, the early life stages of many freshwater fish species will be close to their survival threshold and only a slight decline in water quality might result in the loss of a complete year class, which would affect recruitment and eventual population status.With gradual acceptance of the causes and effects of freshwater acidification, the research effort in relation to fish is declining or shifting towards attempts to re-establish fisheries in vulnerable areas. As outlined above, only very general conclusions can be reached on individual life stages, and the relative susceptibilities compared. However, in many respects the sequence of events in the loss of fisheries is not fully understood, and information is lacking on how events at significant stages of the life cycle affect subsequent survival, development and recruitment. Plenty of work is still required.     

The diabetic rat kidney mediates inosituria and selective urinary partitioning of D-chiro-inositol

Diabetic nephropathy is a serious complication of diabetes mellitus with a pressing need for effective metabolic markers to detect renal impairment. Of potential significance are the inositol compounds, myo-inositol (MI), and the less abundant stereoisomer, D-chiro-inositol (DCI), which are excreted at increased levels in the urine in diabetes mellitus, a phenomenon known as inosituria. There is also a selective urinary excretion of DCI compared to MI. As the biological origins of altered inositol metabolism in diabetes mellitus are unknown, the aim of this study was to determine whether the diabetic kidney was directly responsible. Kidneys isolated from four-week streptozotocin-induced diabetic rats were characterized by a 3-fold reduction in glomerular filtration rate (GFR) compared to matched non-diabetic kidneys. When perfused with fixed quantities of MI (50 µM) and DCI (5 µM) under normoglycemic conditions (5 mM glucose), GFR-normalized urinary excretion of MI was increased by 1.7-fold in diabetic vs. non-diabetic kidneys. By comparison, GFR-normalized urinary excretion of DCI was increased by 4-fold. Perfusion conditions replicating hyperglycemia (20 mM glucose) potentiated DCI but not MI urinary excretion in both non-diabetic and diabetic kidneys. Overall, there was a 2.4-fold increase in DCI urinary excretion compared to MI in diabetic kidneys that was independent of glucose ambience. This increased urinary excretion of DCI and MI in diabetic kidneys occurred despite increased renal expression of the inositol transporters, sodium myo-inositol transporter subtype 1 and 2 (SMIT1 and SMIT2). These findings show that the diabetic kidney primarily mediates inosituria and altered urinary partitioning of MI and DCI. Urinary inositol levels might therefore serve as an indicator of impaired renal function in diabetes mellitus with wider implications for monitoring chronic kidney disease.     

Reactivity to acetylcholine developed by artificial membranes containing a protein from Electrophorus electricus: the effect of uranyl ions

A special hydrophobic protein fraction from the electroplax of $\text{Electrophorus}\text{electricus}$, when incorporated into artifical lipid membranes, induces a reactivity to acetylcholine. Uranyl ions increase 10–20 times the conductivity of such membranes, produce discrete current jumps, and strongly potentiate the effect of acetylcholine. The response to acetylcholine was studied in media containing KCl,NaCl, Choline-Cl and Na-Propionate in the presence or absence of uranyl ions. control membranes made of lipids or containing a non-cholinergic protein from the same tissue showed no reactivity to acetylcholine and had only a slight increase in conductance at very high concentrations of uranyl ions.