Veterinary Physiology Commons^™

Differential Stress Responses In Fish From Areas Of High- And Low-Predation Pressure, Culum Brown, Carolyn Gardner, Victoria Braithwaite

Aquaculture Collection

We subjected fish from regions of high and low levels of predation pressure in four independent streams to a mild stressor and recorded their opercular beat rates. Fish from low-predation areas showed higher maximum, minimum and mean opercular beat frequencies than fish from high-predation regions. The change in opercular beat frequency (scope) was also significantly greater in fish from low- than in fish from high-predation regions. Under normal activity levels, however, low predation fish showed a reduced opercular beat frequency, which may be indicative of reduced activity levels or metabolic rate. Opercular beat frequency was negatively correlated with standard length …

Do Fishes Have Nociceptors? Evidence For The Evolution Of A Vertebrate Sensory System, Lynne U. Sneddon, Victoria A. Braithwaite, Michael J. Gentle

Veterinary Science and Medicine Collection

Nociception is the detection of a noxious tissue-damaging stimulus and is sometimes accompanied by a reflex response such as withdrawal. Pain perception, as distinct from nociception, has been demonstrated in birds and mammals but has not been systematically studied in lower vertebrates. We assessed whether a fish possessed cutaneous nociceptors capable of detecting noxious stimuli and whether its behavior was sufficiently adversely affected by the administration of a noxious stimulus. Electrophysiological recordings from trigeminal nerves identified polymodal nociceptors on the head of the trout with physiological properties similar to those described in higher vertebrates. These receptors responded to mechanical pressure, …

Trigeminal Somatosensory Innervation Of The Head Of A Teleost Fish With Particular Reference To Nociception, Lynne U. Sneddon

Veterinary Science and Medicine Collection

Trigeminal somatosensory receptors have not been characterised in teleost fish and studies in elasmobranchs have failed to identify nociceptors. The present study examined the trigeminal nerve of a teleost fish, the rainbow trout (Oncorhynchus mykiss) to determine what types of somatosensory receptors were present on the head of the trout specifically searching for nociceptors. Single unit recordings were made from receptive fields on the head of the fish innervated by the trigeminal nerve. Each receptive field was tested for sensitivity to mechanical, thermal and chemical stimulation. Five different receptor types were found: fast adapting receptors responding to mechanical stimulation; slowly …

Effects Of Methylxanthines On Newborn Rat Respiration, Craig Gatto

Masters Theses

Methylxanthines (MX), such as theophylline, are commonly used in the treatment of recurrent apnea due to their stimulant effects on the respiratory center. Structure-activity studies have demonstrated that substitution of alkyl groups on the 3-position of the xanthine nucleus results in increased bronchodilator potency, while substitution on the 1-position is important for adenosine antagonism and CNS stimulation. Three different alkylxanthines were studied to determine the structural requirements for respiratory stimulation. Respiratory rates and volumes were determined in 4- to 7-day-old rats using a volume displacement body plethysmograph. Measurements were made before and at 5 minute intervals after subcutaneous (s.c.) injection …

Survival Of Lambs, R W. Kelly, David Lindsay

Journal of the Department of Agriculture, Western Australia, Series 4

Between one in every five or six lambs that are born each year in Western Australia die at or about the time of birth. This represents a loss approaching two million lambs and is arguably out single greatest wastage in sheep production. The deaths have an immediate impact on lambing performance and therefore lamb sales, and ultimately effects on such areas as selection of breeding replacement stock, the proportion of ewes and weathers that can be run in a self-replacing flock and the amount of wool produced and its uality.

This article summarises information on what influences lamb survival, and …

The Effects Of Xanthine And Adenosine Analogs On Rat Pup Diaphragmatic Contractility, Liam C. Farrell

Masters Theses

Methylxanthines are commonly used in the treatment of respiratory disorders such as asthma, apnea of prematurity and Cheyne-Stokes respiration. Recently, certain methylxanthines have been found to potentiate the contraction of the diaphragm and increase contraction strength of the fatigued diaphragm. The mechanism of action of the methylxanthines is unknown. Three theories have been proposed but each has its supportive and negative points. One theory is that methylxanthines inhibit cyclic AMP phosphodiesterase (PDE) which facilitates contraction by increasing cyclic AMP levels in the cell. Another theory is that methylxanthines antagonize adenosine, thus blocking the adenosine-induced inhibition of contraction. The third theory …

Ovulation Rate Of Ewes : Role Of Energy And Protein, E Teleni, J. B. Rowe

Journal of the Department of Agriculture, Western Australia, Series 4

Western Australia's sheep farmers are familiar with the low ovulation rate of Merino ewes and how this limits the lambing performance of ewe flocks.

One way in which ovulation rate and therefore lambing percentage may be increased is to feed seed of sweet lupin (Lupinus augustifolius) to ewes at mating. However, Department of Agriculture research has found that these increases do not show up consistently, and that there is considerable variability between farms.

If improved nutrition is to be a useful way to increasing ovulation rate, the mechanism by which nutrition affects ovulation rate must first be understood. This article …

Pregnancy Diagnosis Using Ultrasound, M A C Johns

Journal of the Department of Agriculture, Western Australia, Series 4

Few Western Australian ewe flocks are diagnosed for pregnancy despite the precence of high numbers of barren ewes. Surveys of farm flocks in the early 1970s recorded that between 14 and 29 per cent of ewes failed to lamb each year.

Techniques for diagnosing pregnant ewes have been available for many years, but ultrasonic devices and computer technology have made it possible for skilled operators to determine whether ewes are pregnant and more importantly, whether they have one, two or more foetuses.

Once the number of pregnant ewes is known farmers can use labour more efficiently. They can minimise the …

Reproductive Wastage In Sheep, R W. Kelly

Journal of the Department of Agriculture, Western Australia, Series 4

The average lambing performance of Western Australia's ewe flock fluctuates between 60 and 70 per cent. Although this level of performance and variation between years is important for the sheep industry, individual farmers are more concerned about performance of their own flocks.

Figure shows the range in lambing performances that exist between farms in this State in 1983-84. The seriously poor performance of many flocks is apparentm - 28 percent of farms had less than 60 per cent lambing. By contrast, 24 farms had performances better than 100 per cent. The reasons for the large differences between farms ( and …

Some Factors Influencing The Availability Of Colostrum To Piglets, D. Fraser

Physiology Collection

Five experiments, involving the hand milking of 53 farrowing sows, examined aspects of colostrum yield during and soon after farrowing. The initial and abundant yield of colostrum from a teat (averaging 6 to 10 g/min) declined after several minutes of continuous milking. Thereafter, most colostrum was released in discrete ejections, possibly caused by discrete releases of oxytocin. Colostrum ejections varied greatly in their yield and duration, and were sometimes associated with the birth of a piglet, sounds of other sows nursing, or other factors.

Teats varied greatly in their yield. During the initial minutes of milking, the most anterior teats …

Protecting Off-Shears Sheep In Adverse Weather, T M. Ellis

Journal of the Department of Agriculture, Western Australia, Series 4

In January 2982 in the Narrogin-Darkan area of Western Australia, about 14,500 sheep up to 40 days off-shears died after a 48-hour period of heavy soaking rain that followed a thunderstorm three days previously. An estimated 100,000 sheep died throughout the South-West at the time.

P. G. Buckman - at the time Department of Agriculture District Veterinary Officer, Narrogin - surveyed 17 properties in the area. He found that losses in unshedded sheep 0 to 40 days off-shears ranged from 0 to 84 per cent of sheep on the property with an overall average of 27.9 per cent. Rainfall in …

Amputation Of Vibrissae In Show Dogs, Thomas E. Mcgill

Veterinary Science and Medicine Collection

Dogs of many different breeds competing in the show-ring are routinely subjected to amputation of the vibrissae, organs that are commonly and incorrectly called "whiskers." This procedure is thought to give the animal's head a cleaner look, which in turn supposedly increases its chances of winning. There are several tricks involved in "whisker trimming" since the animals can retract each vibrissae at least one-quarter inch. Furthermore, they often object strenuously to the operation.

Diagnosing Pregnancy In Sheep : The 'Scanopreg', R H. Wroth, M. J. Mccallum

Journal of the Department of Agriculture, Western Australia, Series 4

The "Scanopreg", an ultrasonic machine for diagnosing pregnancy in sheep, is effective as early as eight to nine weeks of pregnancy, and could therefore be a useful management tool.

Pigs May Need More Protein, N W. Godfrey

Journal of the Department of Agriculture, Western Australia, Series 4

Results of trials indicate that meatmeal based rations of 18 to 20 per cent protein may improve carcase quality and give better returns.

Treflan And The Oxygen Consumption Of Green Sunfish (Lepomis Cyanellus), Barbara Jo Warner

Masters Theses

Oxygen consumption rates of 51 green sunfish (Lepomis cyanellus, Rafinesque) were monitored over five hours exposure to Treflan E.C. concentrations of 0, 0.32, 0.56, 1.0, and 2.0 ppm. There was a great variation in the responses of the fish at each concentration; and Student's t-tests revealed no significant differences. However, graphs of the mean hourly oxygen consumption rates showed certain trends. During the fifth hour of exposure, there appears to be an acclimation to the Treflan at concentrations of 0.32 and 0.56 ppm; but no such acclimation at the higher concentrations of 1.0 and 2.0 ppm. Hourly oxygen …

The Effects Of Crowding On The Diurnal Ascorbic Acid Levels Of Albino Rats, Mary Jo Barr

Masters Theses

The adrenal physiology of the albino rat was studied through the measurement of adrenal ascorbic acid levels. A cyclic phenomenon was observed which follows the diel periodicity of the animal. Ascorbic acid values were found to be characteristically higher in males than in females. A similar difference was also seen in populations divided into young animals (body weight less than 175 grams) and old animals (body weight greater than 175 grams). Crowding, induced by manipulating the area of cage space per gram of body weight, was observed to be a definite stressor and caused the adrenal ascorbic acid levels to …

The Effects Of Acute Stress On Adrenal Ascorbic Acid Levels, Robert Joseph Collier

Masters Theses

The diurnal rhythm of adrenal ascorbic acid (DAR) displays an inverse relationship to the diurnal rhythm of circulating levels of plasma corticosteroids. Alloxan monohydrate, 175 mg/kg body weight was given subcutaneously to albino rats to determine the effect of the diabetic state on the DAR. A total of 200 female albino rats were divided into two study groups. Study Group I was composed of 150 animals divided into populations of 15, each including 3 controls. Study Group II was composed of populations of 5, each group containing all controls or all alloxinated rats. The populations of 15 were sacrificed at …

Sheep Fertility In Western Australia, R J. Lightfoot

Journal of the Department of Agriculture, Western Australia, Series 4

Why do one-quarter of the ewes that are joined in W.A. fail to lamb? Sheep and Wool Adviser Dr. R. J. Lightfoot analyses the eight stages in sheep reproduction, explaining the causes and possible prevention of infertility at each stage.

Pasture Legume Varieties And Ewe Fertility, T Marshall, H. E. Fels, H. G. Neil, R. C. Rossiter

Journal of the Department of Agriculture, Western Australia, Series 4

ALTHOUGH it was first thought that all varieties of subterranean clover would cause ewe infertility, research in the last 10 to 15 years has shown that varieties differ in potency.

The relative level of potency has also been shown to remain consistent for any one variety under normal conditions.

Prevent Worms In Cattle, G C De Chaneet

Journal of the Department of Agriculture, Western Australia, Series 4

PARASITIC gastro enteritis, caused by roundworms, is a common cause of economic loss in calves, yearlings and occasionally cows in south-western Australia. Losses could be prevented if stock owners realised the full effects of these parasites, and understood the causes of worm infestation.

High Pre-Mating Liveweights Improve The Lambing Performance Of Merino Ewes, R J. Suiter

Journal of the Department of Agriculture, Western Australia, Series 4

Analysis of lambing trials with Merino ewes has shown a highly significant association between pre-mating liveweight and lambing performance.

With May-June lambing ewes there was a 2.9 per cent, lambing increase for every extra 10 lb. liveweight; for July-August- September lambing ewes there was a 6.9 per cent, increase for every 10 lb. liveweight increase.

With the May-June lambing there was a critical weight below which twinning was negligible.

Maintaining Ewe Bodyweight For A Late Mating, T Marshall

Journal of the Department of Agriculture, Western Australia, Series 4

DEPARTMENT OF AGRICULTURE experiments have indicated that the bodyweight of ewes at mating can have a large bearing on lambing performance.

It appears that for every 10 lb. increase in pre-mating bodyweight, an increase of some 3 to 6 per cent, lambs born could be expected, depending on the lambing time.

Later Mating Improves Lambing Results, R J. Suiter

Journal of the Department of Agriculture, Western Australia, Series 4

Ovulation studies in Western Australia have indicated that increased lambing percentages in crossbred and Merino ewes could be expected from mating in February-April rather than December- January.

Such increases have been demonstrated in time of lambing trials with crossbred ewes, but had not been seen in Merino flocks until recently.

This report summarises the results of time of lambing trials with Merinos carried out at the Merredin and Wongan Hills Research Stations between 1963 and 1969.

Causes Of Low Lambing Percentages, Department Of Agriculture, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

West Australian Merino flocks average about 70 per cent, lambs marked each year. Reasons for this low percentage are that as many as 30 per cent, of ewes do not lamb, twinning rates are low and from 10 to 25 per cent, of lambs born die.

Among the research projects by the Department of Agriculture's Sheep and Wool Branch have been a number directed at the various stages of reproduction in the ewe. These have given some important leads on the causes of low lambing percentages.

If you have marked less than 60 per cent, lambs in the past several …

Two Causes Of Reduced Profit From Pigs, G A L Ward

Journal of the Department of Agriculture, Western Australia, Series 4

LOSS of condition in a pig affects profits more severely than slow rate of growth.

Two common symptoms, scouring and itching, cause weight loss and are followed by a period of reduced weight gain.

Shed Lambing In The Esperance Environment, T Marshall, F. F. Dixon

Journal of the Department of Agriculture, Western Australia, Series 4

Neonatal lamb mortality is often high in Western Australia and losses as high as 33 per cent, have been recorded on private properties in the Esperance area. Surveys by Western Australian Department of Agriculture officers have indicated that more than threequarters of such lamb deaths occur after birth. About half these deaths result from the combined effects of weather and mismothering.

Work in Victoria has indicated that lamb mortality may be reduced by intensive lambing systems such as shedding and this trial was established to see if shedding could reduce lamb mortality in the Esperance environment.

Pendulous Crop Of Turkeys, M E. Bacon

Journal of the Department of Agriculture, Western Australia, Series 4

THE condition known as pendulous crop occurs occasionally in a mild form in fowls, but the most commonly reported cases concern the classical symptoms that occur from time to time in turkeys.

The condition is also referred to as baggy crop, dropped crop, hanging crop and sour crop, and causes mortality, poor development and emaciation within turkey flocks in some areas.

A Guide To Good Lamb Marking, H E. Fels

Journal of the Department of Agriculture, Western Australia, Series 4

LAMB marking is the most severe of the various ordeals that sheep are called upon to endure.

It is a series of surgical operations, each involving a risk of infection, and some involving risks of severe haemorrhage.

Growth rate is reduced to the same extent by rubber rings as by the knife.

Reproductive Wastage And The Sheep Shortage In Western Australia, Department Of Agriculture, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

WESTERN AUSTRALIA has an acute shortage of sheep.

It is estimated that about seven million extra sheep are needed to stock existing pastures fully; meanwhile the carrying capacity of the State's pastures is increasing at the rate of three million sheep a year.

The Abnormal Coxofemoral Articulation In The German Shepherd Dog, Griselda Hanlon

Journal of the Minnesota Academy of Science

A common abnormality among dogs of the coxofemoral articulation, known as developmental hip dysplasia, is discussed with special reference to its occurrence in the German Shepherd breed. Some observations made from serial radiographic studies of the maturation of normal and abnormal coxofemorol articulation of 200 experimental German Shepherd dogs are presented, and a method of measuring the ilio-acetabular angle is described. Further evaluation will be made of the angle as an early predictor in the course of developmental hip dysplasia.