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Biomedical subjects

J Rushen

Publications and source records attributed to J Rushen.

11 recordsLinked to original sources
PubMed1991

Stereotypic behavior and heart rate in pigs.

Heart rate responses to feeding of both loose-housed and tethered sows, some of which engaged in persistent behavioral stereotypies, were recorded telemetrically in order to determine if stereotypic behavior occurs in response to, and serves to reduce increased sympathetic nervous activity. Heart rates rose in response to feeding (after which stereotypic behavior is most common) and this was greater for tethered sows. This response was partly blocked by a beta-adrenoreceptor antagonist (carazolol), but not by naloxone, although the latter tended to lead to overall increases in heart rate. Thus long-term tethering of sows leads to greater sympathetic nervous responses to feeding. No consistent relationships were found between heart rate and the performance of stereotypic behavior. In Experiment 1, using sows tethered for 6-8 months, neither basal heart rates nor heart rates following naloxone or carazolol differed between high- and low-stereotyping sows. In Experiment 2, using sows tethered for 1-2 months, high-stereotyping sows had lower basal heart rates than low-stereotyping sows. Marked reductions in heart rate caused by a beta-adrenoreceptor blocker did not lead to any change in stereotypic behavior, and preventing stereotypic behavior led to a reduction not an increase in heart rates. The results suggest that stereotypies are performed in situations where heart rate is high, but they provide no evidence that stereotypies reduce this heart rate.

Adrenergic beta-Antagonists↗
PubMed1991

Stress-induced hypoalgesia and opioid inhibition of pigs' responses to restraint.

Pigs' responses to physical restraint were examined in order to detect a stress-induced increase in endogenous opioid activity. Tail-flick latencies in response to a source of thermal energy were used to assess the sensitivity of pigs to pain. Restraining pigs for 15 min with a nose snare resulted in a temporary increase in tail-flick latencies that was apparent after 5 min, absent after 30 min and was blocked by naloxone. Tail-flick latencies were unaffected by IV ACTH injections and were not related to plasma cortisol concentrations. Naloxone increased the pigs' vocalization during the restraint and prolonged the elevation of plasma cortisol levels that followed the restraint. The cortisol response to naloxone was larger than when the animals were not restrained. The results indicate a transient, opioid-based hypoalgesia following restraint stress that is not a result of ACTH or cortisol secretion. Endogenous opioids inhibit the pigs' behavioral and pituitary-adrenocortical responses to the restraint stress.

Adrenocorticotropic Hormone↗
PubMed1990

Stereotypic behavior, endogenous opioids, and postfeeding hypoalgesia in pigs.

Tethered sows, some of which performed marked behavioral stereotypies after feeding, were injected IM with 1 mg/kg of naloxone 30 min before feeding (with 2 saline control days). Tail-flick latencies on a pain-sensitivity test were recorded before and after feeding. On control days, tail-flick latencies after feeding were longer than those before feeding, and this effect was abolished by naloxone pretreatment. Thus, there is an opioid-based hypoalgesia after feeding. However, sows with marked behavioral stereotypies had shorter tail-flick latencies after feeding. Thus, we have no evidence that performance of behavioral stereotypies results in increased opioid activity. Naloxone reduced the time spent in behavioral stereotypies by approximately 30% but this may be due to a reduction in time spent active. Naloxone increased the frequency and reduced the mean duration of bouts of chain manipulating, operating the drinker and rooting. We suggest that endogenous opioids are involved in the positive feedback that maintains the persistence of behavior and inhibits switching between different activities.

Animals↗
PubMed1989

Nutritive and nonnutritive sucking and the temporal organization of the suckling behavior of domestic piglets.

Detailed video recordings of the suckling behavior of one piglet from each of four litters were analyzed to determine how the components of piglet suckling behavior are organized in relation to the time of milk ejection and the temporal pattern of grunting by the sow. Early in the suckling episode, most piglets massaged the udder with their snouts, and then changed gradually to sucking the teats with slow mouth movements (1-2/sec). The piglets then had a distinct phase of sucking with rapid mouth movements (4-5/sec) which began suddenly and lasted about 5 to 15 sec. The weight gains of piglets removed at different times showed that piglets consumed milk during the fast sucking but not during the preceding slow sucking, regardless of how much slow sucking had occurred. Three of the four sows showed a characteristic increase in rate of grunting about 20 to 25 sec before fast sucking began. The piglets' change from massaging to slow sucking often coincided with the increase in grunt rate, but the timing of the transition varied greatly. This suggests that the change in grunting is one but not the only cue used by the piglets to time their suckling behavior. During the slow, nonnutritive sucking, mouth movements were highly variable in duration, with occasional short bursts of rapid mouth movements. This contrasted with the more uniform duration of fast sucking movements. Evidently, in piglets, nutritive and nonnutritive sucking differ in both rate and temporal patterning.

Animals↗
PubMed1987

Electro-immobilisation of sheep may not reduce the aversiveness of a painful treatment.

Sheep were repeatedly chased down a race and were then either subjected to the noise of a shearing handpiece or had wool shaved off. An increase in the time that had to be spent pushing the sheep down the race indicated that the latter treatment was aversive. Similar results were obtained when the sheep were subjected to the same two treatments while electro-immobilised. This throws doubt on the analgesic effectiveness of electro-immobilisation.

Animals↗
PubMed1987

Aggressive behavior.

This article considers the major fighting-related activities of the most common food animals. Instead of being seen as a largely pathologic phenomenon born solely of frustration and pain, aggressive behavior is now regarded as a natural part of an animal's behavioral equipment for survival and reproduction. There is a need, spurred by consideration for both productivity and animal well-being, to understand the fundamentals of the aggressive behavior of domestic species so that one can accommodate for this behavior in systems of livestock management.

Aggression↗
PubMed1986

Some problems with the physiological concept of "stress".

Stress has become a central concept in discussion of animal welfare, partly because it has been seen to have a precise physiological definition. However, stress is a term in ordinary language with a variety of connotations, not all of which can be related to activity of the pituitary adrenal axis. There is good evidence against the idea that the rise in plasma corticosteroids that occurs in response to some treatment can be used to assess the degree of suffering or distress experienced by an animal. The rise may simply reflect demands on the learning abilities of the animals. Veterinarians should be careful in their use of the term, and in their interpretation of such physiological data, in the context of animal welfare.

Adrenal Cortex Hormones↗
PubMed1986

Effect of electroimmobilisation on ovine plasma concentrations of beta-endorphin/beta-lipotrophin, cortisol and prolactin.

The effect of electroimmobilisation on the plasma concentrations of beta-endorphin/beta-lipotrophin (beta-EP/beta-LPH), cortisol and prolactin (PRL) has been assessed in sheep. Serial blood samples were collected from control and electroimmobilised animals during the first and fourth of a series of four repeated treatments over two days. After electroimmobilisation the mean (+/- SEM) plasma concentrations of beta-EP/beta-LPH increased significantly from 132 +/- 19 pg ml-1 to 545 +/- 111 pg ml-1; the plasma concentrations of cortisol also increased significantly from 22.3 +/- 3.5 ng ml-1 to 108.0 +/- 12.9 ng ml-1. There was no significant change in plasma PRL concentrations after electroimmobilisation and also no significant difference between the plasma concentrations of PRL in the control and electroimmobilised animals. There was no significant difference between the effects of the first and fourth exposure to electroimmobilisation on the plasma concentrations of beta-EP/beta-LPH, cortisol and PRL. These results suggest that the endocrine response to electroimmobilisation may be specific to the pituitary-adrenal axis.

Animals↗