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 …

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 …

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 …

Amputation Of Vibrissae In Show Dogs, Thomas E. Mcgill

International Journal for the Study of Animal Problems

No abstract provided.

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.