Aggression during sexual encounters between hormone-treated gonadectomized pigs in the presence or absence of boar pheromones

Aggressive and sexual behaviour was studied in 5-min paired encounters between castrated prepubertal boars (N = 14) and normal (N = 2) or bulbectomized (N = 2) oestrogen-treated ovariectomized gilts. The boars were made sexually active by treatment with 17β-oestradiol + 5α-dihydrotestosterone. Half of the boars were sprayed on the snout with a solution containing a mixture of the boar pheromones 3α-androstenol and 5α-androstenone immediately before testing, and the remainder were treated with the vehicle solution. Aggression was almost always initiated by the gilts, and neither bulbectomy nor pheromone treatment of the boars reduced its occurrence. The results suggest that the display of aggression by gilts towards boars of similar body size is unlikely to be suppressed by the steroidal pheromones present in boar saliva.     

Short-term effects of residence on the testosterone responses to fighting in alpha male guinea pigs

The short-term effects on testosterone (T) levels of (a) taking blood samples, (h) fighting in one's own home cage, and (c) fighting in another male's home cage were examined in eight alpha male guinea pigs, each living together with two females and two subordinate males in their home cages for 4 months. Every male was given two 5-minute agonistic encounters, one in his home cage and one in another male's home cage. After the encounter, intruder males were returned to their home cages. Three blood samples were taken 10 minutes before and 5 and 45 minutes after the agonistic encounters (sampling times were designated as 0, 20, and 60 minutes, respectively). One week before the agonistic encounters were conducted, blood samples were taken from each male on the same time schedule (0, 20, and 60 minutes). The main findings were as follows: (1) the animals showed an increase in T-levels after an agonistic encounter in their home cages and a decline in T-levels after an agonistic encounter in the home cages of other alpha males' irrespective of being the winner or the loser and the degree of escalation during the encounter; (2) the smaller the differences in T-titers between both opponents 10 minutes before the encounter, the more escalated the agonistic encounter.     

Automaintenance in guinea pigs: effects of feeding regimen and omission training

Behavior maintained by stimulus-reinforcer pairings was examined. Guinea pigs maintained at 85 per cent of free-feeding weights reliably contacted a retractable lever presented before delivery of a single piece of guinea-pig chow or a 45-milligram guinea-pig pellet. When animals were given free access to one food and received the second food preceded by the lever, contact responses persisted. Such responses seldom occurred when a single food was freely available and was also delivered after lever presentation. Introduction of an omission training (negative automaintenance) procedure, in which lever contacts resulted in lever retraction and prevented food delivery, strongly reduced lever contacts. Observation indicated that mouthing the food cup, instead of the lever, became the prominent behavior during the prefood stimulus under the omission training procedure.     

琥珀酰明胶容量治疗对脑死亡后血清TNF—α、IL－1β、IL－6水平的影响

为了观察脑死亡后不同液体容量治疗对血清肿瘤坏死因子－α（TNF—α）、白细胞介素－1β（IL-1β）和白细胞介素－6（IL－6）等炎症介质水平改变的影响,选用巴马小型猪15只,随机分为3组各5只,即对照组（C组）、4％改良琥珀酰明胶组（MFG组）及乳酸林格氏液组（RL组）。C组不建立脑死亡模型,给与乳酸林格氏液30ml·kg^-1·d^-1～40ml·kg^-1·d^-1。MGF组和RL组为脑死亡组,采用颅内加压法建立脑死亡模型,MFG组给与4％改良琥珀酰明胶溶液30ml·kg^-1·d^-1,RL组给与乳酸林格氏液30-40ml·kg^-1·d^-1。分别于麻醉后及首次判定脑死亡后3、16、12、18和24h留取血样,检测血清中TNF-α、IL-1β、IL--6水平。结果发现MGF组较RL组血压和心率平稳;RL组TNF--α、IL-1β和IL-6水平自脑死亡后3h点开始逐渐升高;MFG组TNF--α、IL--1β和IL-6水平脑死亡后3h点开始亦升高,但升高幅度均较RL组低;三组间自脑死亡后3h点开始,组间比较差异有统计学意义。提示脑死亡后血清炎症介质TNF—α、IL-1β和IL--6释放增加,琥珀酰明胶可抑制脑死亡后TNF--α、IL--6、IL-1β等炎症介质的释放,减轻炎症反应,改善机体状况。