Effects of variations in the environment, length of journey and type of trailer on the mortality and morbidity of pigs being transported to slaughter.

The month, average air temperature, relative humidity, number of pigs of each sex per trailer load, journey time, type of trailer and bedding, and waiting time at the processing plant were recorded from 16,323 trailers transporting 2,730,754 pigs to a packing plant in the USA during a year, together with the numbers of pigs that were dead on arrival, injured or unable to walk. The percentage of pigs dead on arrival increased at temperatures above 20 degrees C, and the percentage of pigs unable to walk increased at temperatures of 5 degrees C or below. The journey time and waiting time at the processing plant influenced the percentages of dead and injured pigs and pigs unable to walk.

A glucocorticoid receptor agonist improves post-weaning growth performance in segregated early-weaned pigs.

While beneficial for sow reproductive efficiency and biosecurity, segregated early weaning (SEW) leads to a systemic immune response that adversely affects the digestive physiology and post-weaning growth of pigs. Two experiments were conducted to evaluate the effects of a glucocorticoid receptor agonist (GA) on growth performance, measures of immune function and intestinal integrity of SEW pigs. In both experiments, pigs were fed corn-soybean meal-based starter diets. In the first experiment, 48 pigs (initial BW 4.8 ± 0.7 kg) were weaned at 21 ± 1 days and randomly assigned to three GA treatment groups: 0, 0.2 and 0.6 mg GA/kg of BW injected intramuscularly. Treatments were administered one day before weaning. Pigs in the 0 mg GA group received sterile saline in place of GA. Body weight was measured daily from one day before to 7 days post-weaning, and then weekly until 28 days post-weaning. Piglets treated with 0.2 mg GA had a higher BW than piglets in other treatment groups during the 28-day course of the study (P <0.02). To further explore the mechanisms behind this result, a second experiment was performed in which a total of 18 gilts (BW 5.6 ± 0.85 kg) were randomly assigned into three treatment groups: suckling plus saline (UWS), weaned treated with GA (WGA; 0.2 mg GA/kg BW) and weaned plus saline (CON). Treatments were administered one day before and 3 days post-weaning. The WGA and CON groups were weaned at 23 ± 2 days, while the UWS group remained with sow for the duration of the study. Body weight was measured daily and blood plasma was collected at 0, 1, 4 and 5 days post-weaning. All gilts were euthanized 5 days after weaning and jejunum samples were collected for mucosal scrapings, histomorphological analysis and gene expression analysis. Plasma levels of interleukin-1ß (IL-1ß) and haptoglobin were lower in WGA pigs compared with CON (P <0.02), while plasma total antioxidant capacity was higher in WGA pigs compared with both CON and UWS groups (P <0.01). Relative to CON, GA downregulated IL-18 gene expression in the jejunum, as assessed by both tissue homogenate and mucosal scrapings, but it upregulated claudin-IV gene expression only in the tissue homogenate (P <0.01). These results suggest that GA treatment improves the growth performance of SEW pigs in part by mitigating the negative effects of systemic inflammation. However, the effect of GA on barrier integrity requires further investigation.

Immunophysiological responses of horses to a 12-hour rest during 24 hours of road transport.

Thirty-eight mature horses were assigned to one of two equal groups to evaluate two treatments consisting of either 24 hours of continuous road transport (24T) or two 12-hour periods of transport separated by off-loading, resting and feeding the horses for 12 hours (12/12T). A subset of six horses from each group served as controls for the other group. The horses were loaded into a commercial straight-deck trailer and travelled loose in one of two standard-sized compartments. After the journeys the horses were put back into their paddocks for a 24-hour recovery period. Venous blood samples were collected before loading, after unloading and after the 24-hour recovery period. Transport significantly increased the horses' cortisol concentrations, neutrophil counts and neutrophil:lymphocyte (nl) ratios, and decreased the numbers of all the lymphocyte subpopulation cell types. Collectively, no significant differences were observed between the two treatments in the horses' cortisol concentrations, total leucocyte counts, neutrophil and lymphocyte counts, nl ratios, and the cd8a+ and cd21+ lymphocyte subpopulations, but there were differences in the numbers of cd3+, cd4+, and cd8b+ subpopulations. The inclusion of a 12-hour rest-stop interrupted the transport-related decline in the lymphocyte subpopulations and allowed them to recover towards their resting levels.

A natural interomone 2-methyl-2-butenal stimulates feed intake and weight gain in weaned pigs.

A novel approach to potentially improve pig growth and welfare is to supplement environments with biologically meaningful odors that are deficient. The post-weaning environment lacks maternal odors that may contribute to the often-observed post-weaning lag in growth and health challenges. A recently reported rabbit maternal pheromone (2-methyl-2-butenal (2M2B)) may act as an interomone in the pig. The objective of this study was to determine if providing a maternal pheromone/interomone during transport and the post-weaning environment may enhance pig performance. A total of 40 replicated pens were used in a factorial arrangement of two transport olfactory experiences (Control v. 2M2B), two nursery olfactory experiences (Control v. 2M2B) and two sexes (barrow v. gilt). Pig body weight, average daily gain (ADG), average daily feed intake (ADFI) and gain : feed ratio (G : F) were measured and calculated over a 28-day post-weaning period. Pig sex and application of 2M2B during transport had no effect on pig performance. However, pigs that had 2M2B applied to their feeder at weaning had 15% greater feed intake (0.74 v. 0.64±0.03 kg/day, P<0.01) and 12% greater ADG (0.27 v. 0.24 kg/day, P<0.05) than control pigs. G : F ratio was not different between treatments. The interomone 2M2B is a novel, safe molecule that can improve pig post-weaning performance. This report highlights a new area of study and a natural class of compounds that can improve pig performance and potentially improve pig welfare.

Adrenocorticotropin stimulates natural killer cell activity.

Central release of CRH has recently been implicated in modulating natural killer cell (NK) activity independent of its role in activation of the hypothalamic-pituitary-adrenal axis. In the present study, NK- and interleukin-2 (IL-2)-activated NK cytotoxicity against K-562 target cells was examined in porcine lymphocytes cultured in vitro with ACTH or pig lymphocytes after iv or im ACTH administration. Physiological concentrations of porcine ACTH (10(-8)-10(-11) M) added to the culture medium had no direct influence on NK- or IL-2-stimulated NK cytotoxicity. In a second experiment four unrestrained pigs with indwelling catheters given an iv bolus of vehicle or ACTH (1 IU/kg BW) at 0800 h showed significantly elevated cortisol levels for 3 h after ACTH. Although serum cortisol had returned to baseline by 4 h after ACTH treatment, NK- and IL-2-stimulated NK cytotoxicity was dramatically elevated (P less than 0.01) compared to that in saline-injected controls. NK cytotoxicity in control pigs followed a diurnal pattern, with low morning and high evening cytotoxicity. Exogenous ACTH, given by bolus in the morning, prevented the normal morning decline in NK cytotoxicity. Because of this unexpected dramatic increase in NK- and IL-2-stimulated NK cytotoxicity in animals given ACTH, the experiment was replicated in two subsequent studies using 16 pigs (8 controls and 8 experimental) in each. Pigs were injected im with either ACTH (1 IU/kg BW) or an equivalent volume of saline at 0600 h. Two hours later, blood was collected by venipuncture to determine NK cytotoxicity and measure the cortisol response. As was observed in the previous study, NK- and IL-2-stimulated NK cytotoxicity was significantly greater (P less than 0.01) than that in saline-injected controls. In the final experiment pigs were given either ACTH (1 IU/kg BW) or an equivalent volume of saline at 1800 h. Two hours later, blood was collected by venipuncture to determine NK cytotoxicity and cortisol response. ACTH administered in the evening increased NK cytotoxicity, but the effect was only marginally significant and far less dramatic than in previous studies. Because ACTH had little effect on NK- and IL-2-stimulated NK activity in vitro, we hypothesize that the stimulatory effect of exogenous ACTH is mediated through an indirect mechanism, possibly through the suppression of central CRH as a result of elevated cortisol. This effect is more pronounced when the stimulatory dose of ACTH is given at a time in the circadian cycle when NK cytotoxicity is normally low.

Consequences of restraint stress on natural killer cell activity, behavior, and hormone levels in rhesus macaques (Macaca mulatta).

Three experiments were performed to determine the effect of stress on the neuroendocrine-immune system in nonhuman primates. In Experiment 1 the diurnal variation in cell and hormone levels was determined. The percentages of neutrophils, monocytes, and eosinophils fluctuated throughout the 24-hr period, while white blood cell (WBC), neutrophil-to-lymphocyte ratio (N:L), hemoglobin (Hgb), natural killer cell cytotoxicity (NK activity) and beta-endorphin levels did not. Experiment 2 investigated the effects of ketamine and restraint on behavior. Scratching was increased in control monkeys and animals receiving ketamine, whereas passivity was increased in chair-restrained animals. In Experiment 3, eight adult male rhesus monkeys were restrained in primate chairs at 0600h. Behavior was filmed for 3 hr and blood samples were collected at 0700, 0800, and 0900. Whole blood was analyzed for total WBC and percentage of each leukocyte type. NK activity was also measured. Plasma levels of cortisol and beta-endorphin were determined and behavior was quantitated from video-records. WBC and the percentage of neutrophils increased during the restraint period, while the percent lymphocytes and monocytes decreased. NK activity also decreased over time after restraint whereas plasma cortisol and beta-endorphin levels increased significantly. Although after the 3 hr of restraint stress, changes were found in hormone levels, behavior, and NK activity, there were no significant correlations between the parameters measured. Thus, our results indicate that there is not a common neuroendocrine response or single neuroendocrine mediator that results in predictable behavioral changes and immune suppression following stress.

Effects of diverse developmental environments on neuronal morphology in domestic pigs (Sus scrofa).

Potential effects of environmental rearing conditions on the brains of farm animals have not been examined experimentally, with the exception of one report for pig somatosensory cortex. The goal of the present experiment was to determine whether different developmental environments in use in agricultural production units affect neuronal morphology in the pig cerebral cortex. Littermate female pigs (gilts) were cross-fostered at birth and reared in either an indoor (n = 6) or outdoor (n = 6) production unit for 8 weeks. Additional littermates (n = 6) were sacrificed at 3 days of age to provide a developmental reference point. Brains were fixed by perfusion and stained by the Golgi-Cox method. The primary somatosensory, auditory and visual cortices were sectioned at 170 microns, and layer IV stellate neurons (n = 492) were digitized and 3-dimensionally reconstructed. Measurements of dendritic length, membrane surface area, total number of segments, number of 1st- through 7th-order dendrites, spine density, soma area, and soma form factor were taken. In auditory cortex neurons, outdoor pigs compared to indoor pigs had (a) significantly more primary dendrites, (b) significantly greater spine density, and (c) trends of increases both in number of 2nd- and 3rd-order dendrites and in total dendritic length. In visual cortex neurons, indoor pigs had significantly more 7th-order dendrites, whereas in all three cortical areas, the indoor animals had more 5th-order dendrites. Multiple morphological differences occurred in stellate cell populations between the three sensory areas of the Week 8 pigs. Also, within different cortical areas, dendritic morphology changed substantially from 3 days to 8 weeks of age. Further investigations are needed to determine which environmental factors are critical in producing the observed changes in brain morphology and whether other brain effects may be produced by varying developmental environments.

Olfactory cues and pig agonistic behavior: evidence for a submissive pheromone.

One hundred and two prepubertal pigs were used in two experiments to determine if adrenocorticotropin hormone (ACTH)-induced increase in submissive behavior could be mediated by odorous signals. In experiment one, urine was collected from pigs treated with either 0, 1 or 10 IU/kg ACTH. Urine from pigs given 1.0 IU/kg ACTH caused a trend for a rise in submissive behavior. Level of plasma cortisol from donor pigs correlated well (r = .92) with duration of submissive behavior in the tested pigs. In experiment two, urine from ACTH-treated pigs increased submissive behavior when sprayed in the air during late fight. Thus, ACTH-induced submissiveness may be mediated by a pheromone. These results fit the hypothesis that, in addition to visual cues, an olfactory cue (perhaps adrenal in origin) is released towards the end of a fight to signal submission. Aerosolizing urine from ACTH-treated pigs may have interfered with this pheromonal signal.

Sensory systems and nipple attachment behavior in neonatal pigs.

The influence of piglet sensory systems and the role of odors from the sow's ventrum on piglet nipple attachment were investigated. In Experiment 1, four sows had their ventrum washed with organic solvents and four were unwashed control sows. Piglets were given one of four treatments shortly after birth: nares that were mechanically blocked (B), a lidocaine flush of the olfactory system (LFO), a saline flush of the olfactory system (SFO) or nontreated controls (C). Time to attach to a nipple, up to a maximum of 600 sec, was recorded. On unwashed sows, nipple attachment was affected (p less than 0.01) by piglet treatment. Piglets have B or LFO treatments took longer to attach to a nipple than SFO or C piglets. Piglets of all treatments took longer to attach to washed sows than to unwashed controls. Seven unwashed sows and their litters were used in Experiment 2. Piglets were tested after birth with one of the following treatments: an olfactory system flushed with lidocaine, lidocaine on nose (LN), lidocaine applied to the tongue (LT) or nontreated controls. All lidocaine-treated piglets took more time to attach than C piglets. Nipple attachment latencies were intermediate for LN or LT piglets. In Experiment 3, three unwashed sows and their litters were used. Treatments were: lidocaine applied to both the nose and the tongue (LNT), an olfactory system flushed with lidocaine or nontreated controls. LFO piglets had an increased latency to attachment compared to controls while LNT piglets were intermediate in latency to attach. Piglet olfaction, gustation and tactile sensory modalities as well as odors on the sow's ventrum influenced nipple attachment.(ABSTRACT TRUNCATED AT 250 WORDS)

The antiaggressive effect of lithium is abolished by area postrema lesion.

Lithium (Li) suppresses intraspecific aggression in rats and other mammals. However, antiaggressive doses of Li have been shown to produce signs of illness and to serve as an unconditioned stimulus for conditioned taste aversions (CTA). Therefore, it is possible that the antiaggressive effects of Li result from Li-induced malaise. Malaise and CTA's produced by some drugs and toxins are mediated by chemoreceptors in the area postrema. In this paper we report [1] that thermal lesion of the area postrema abolishes Li's ability to condition taste aversions and [2] that area postrema lesion abolishes the antiaggressive effect of Li as measured by attack latency in a shock-induced aggression test. Taken together, these findings suggest that some or all of Li's antiaggressive action in rats may result from malaise attributable to Li's action on the area postrema.

Intracerebroventricular porcine corticotropin-releasing hormone and cortisol effects on pig immune measures and behavior.

The effects of intracerebroventricular (icv) administration of porcine corticotropin-releasing hormone (pCRH) and cortisol on the immune system and behavior were examined in domestic pigs. In Experiment 1, 50 micrograms of pCRH in 200 microliters of saline or 200 microliters of vehicle was administered i.c.v. at 0600 h. Blood samples were obtained at 0600 (prior to injection), 0700, and 0800 h. Plasma cortisol concentrations were higher at 1 and 2 h after pCRH than after saline. Generally, pCRH failed to effect NK cytotoxicity or lymphocyte proliferation in response to phytohemagluttin (PHA). However, 1 h postinjection, pigs administered pCRH i.c.v. had marginally lower NK activity than control pigs. Pigs injected with pCRH had substantially lower neutrophil chemotaxis (CHTX) than the control pigs at 1 and 2 h postinjection. As blood cortisol concentration increased, neutrophil CHTX decreased. Pigs injected i.c.v. with pCRH had higher neutrophil numbers and neutrophil:lymphocyte ratios than control pigs. Percentage of lymphocytes was higher among control than treated pigs. Central pCRH increased overall activity, particularly walking, standing, licking, rooting, and increased activity-related sequences (e.g., sit, walk and stand, walk), but reduced complex oral/nasal sequences (e.g., root, lick). In Experiment 2, pigs were injected i.c.v. with 10 micrograms of cortisol in 200 microliters of saline or with vehicle at 0600 h. Administration of cortisol failed to effect NK cytotoxicity, lymphocyte proliferation, CHTX, or leukocyte distribution. Pigs given cortisol had no apparent change in behavior. These data indicate leukocyte distribution and specific neutrophil function in pigs were significantly modulated by stress-related hormones of the hypothalamic-pituitary-adrenal axis and complexity of behavioral sequences (pigs repeating certain behavioral sequences) associated with increased activity was reduced. Oral/nasal stereotypies (as seen among confined sows) were not elevated among pigs given i.c.v. pCRH. CRH given by i.c.v. administration may serve as a better model for acute rather than chronic stress.

Effects of in vitro adrenocorticotrophic hormone, cortisol and human recombinant interleukin-2 on porcine neutrophil migration and luminol-dependent chemiluminescence.

Experiments were performed on isolated neutrophils tested in vitro to investigate the role of adrenocorticotrophic hormone (ACTH), cortisol and recombinant human interleukin-2 (rhIL-2) in modulating porcine polymorphonuclear (PMN) leukocyte function. Elevated levels of cortisol, similar to that observed during stressful experiences, caused a decrease in PMN chemokinesis (P < 0.02), chemotaxis (P < 0.001) and luminol-dependent chemiluminescence. ACTH at concentrations reflective of high stress conditions reduced PMN chemotaxis (P < 0.02) and chemokinesis (P < 0.01). In vitro rhIL-2 reversed (P < 0.05) the cortisol-induced and ACTH-induced suppression of PMN chemokinesis. These data indicate that specific neutrophil functions in pigs may be impaired by stress-related hormones of the pituitary-adrenal axis and that IL-2 may reverse some endocrine-induced suppression in chemokinesis.

Influence of resources on pig aggression and dominance.

Relationships between presence of feed and water and aggressive behaviour and correlations between dominance and use of these resources were investigated in 64 five to eight week old pigs (Sus scrofa ). Pens of four randomly-selected pigs were established. Social dominance order was obtained largely within the first four hours but aggressive behaviour reached zero 19.4 hours after regrouping four pigs. Whether feed or water were present, pigs fought at similar levels. Pigs who were more aggressive did spend more time drinking water when resources were limited. Pigs that headed the aggressive dominance order did not gain preferred access to resources when they were in limited supply nor when they were abundant.

Techniques for evaluation and quantification of pig reproductive, ingestive, and social behaviors.

A literature survey was conducted to find papers that reported pig behavior during the period 1987 to June 1990. A total of 171 papers reporting measures of pig behavior was identified. Investigators used either descriptions of behavior or they quantified behavior. Behavior was quantified by recording frequency, durations, sequences, or bouts of behavior. Sexual behavior was often recorded as an all-or-none event (e.g., they were bred or not). Feeding behavior was studied by either weighing feeders often or by operant techniques. Operant feeding devices were commonly used to study pig feeding and drinking behaviors. Social behavior was studied either as interactions among established groups or when pigs fought after grouping. In either case, behavioral frequencies or durations were often reported. A large number of papers documented studies of maternal-neonatal interactions, teat orders, and animal care issues. Only a few studies reported mechanisms controlling pig behavior. Because few studies investigated behavior-genetics or physiological mechanisms controlling pig behavior, these areas of investigation hold great opportunity for future improvements in pork production.

Agonistic behavior in food animals: review of research and techniques.

One type of social behavior--agonistic behavior--is commonly observed among food animals. Agonistic behaviors are those behaviors which cause, threaten to cause or seek to reduce physical damage. Agonistic behavior is comprised of threats, aggression and submission. While any one of these divisions of agonistic behavior may be observed alone, they usually are found, in sequence, from the start to the end of an interaction. Food animals may show interspecific or intraspecific agonistic behaviors. Interspecific agonistic behavior has not been extensively studied but it is agriculturally important because farm workers may become injured or killed by aggressive food animals. Types of intraspecific agonistic behavior are: when animals are brought together, intermale fighting, resource defense, inter-gender fighting and aberrant aggression. Common pitfalls in research on agonistic behavior among food animals include too few replicates to detect a biological difference, the assumptions of the analysis are not met, only aggression and not submission or other agonistic behavior components are measured, incomplete description of the behaviors are reported and a complete, quantitive ethogram did not form the basis for selecting behavioral measures.

Deletion of supplemental minerals and vitamins during the late finishing period does not affect pig weight gain and feed intake.

Two studies were conducted to determine the effects of eliminating the supplemental vitamin and minerals during the last 30 d of finishing on pig performance. The first study was conducted in a controlled university environment and the second under field conditions. Deletion of vitamin and mineral supplements for the last 30 d of finishing had no effects on pig performance or general health of pigs in either the university or the field trial. Besides lowering feed costs, deletion of dietary supplements may reduce the environmental impact of late finishing diets.

A quantitative ethogram of aggressive and submissive behaviors in recently regrouped pigs.

Twenty prepubertal Yorkshire X Hampshire pigs were mixed in groups of four. Their behaviors were recorded on video tape for 48 h, and a detailed behavioral analysis was performed. Aggressive interactions of 10 unique pairs of pigs were observed. Twenty-five distinct behavioral categories were identified in the total data set, which contained 1,846 behaviors. On average, an interacting pair showed 92 behavioral elements (range: 10 to 307). Eighty-one percent of the behaviors observed consisted of bites and pushes given and received. Bites were targeted mainly at the ears (55%), face (17%) and neck (23%). Most bites to the rump and turning the body 180 degrees occurred during the last third of the fight. Pigs that eventually won fights showed higher incidences of ear bites and lower incidences than expected of head-under-head pushing and body-turning. Pigs that lost fights showed higher frequencies of head-under-head pushing and body-turning. Losers also showed a lower frequency of rump biting. Overall, many of the behaviors performed by the losing pigs were followed by the loser receiving an ear bite. Body-turning was a sign of submission and was always preceded by, and often followed, ear-biting. Once a pig showed body-turning, it generally avoided further face-to-face interaction. Behaviors exhibited as signs of submission were found in each of the 10 pairs observed.

Immune status of PIC Camborough-15 sows, 25% Meishan sows, and their offspring kept indoors and outdoors.

Newer genetic lines of pigs are being used in indoor and outdoor production systems. The objectives of Exp. 1 were to describe the effects of the maternal sow line genotype, environment (indoor vs outdoor), and the genotype x environment interactions on blood hemoglobin (Hb), immunoglobulin G (IgG) concentrations, white blood cell (WBC) numbers, lymphocyte transformation/blastogenesis (LTA), natural killer (NK) cell activity, neutrophil chemotaxis, cortisol concentrations, and leukocyte differentials. Studies were performed using two genotypes: PIC Experimental-94 (Exp-94, an experimental line containing 25% Meishan) and PIC Camborough-15 (C-15). The Exp-94 sows had lower LTA at 0.2 microg/mL mitogen than the C-15 sows, whereas Exp-94 sows had higher NK cytotoxicity than the C-15 sows. When indoors, the two genotypes showed similar neutrophil chemotaxis. When outdoors, the C-15 genotype had higher (P < .01) neutrophil chemotaxis than the Exp-94 sows. The other immune measures were statistically similar for the two genotypes for each environment and for the genotype x environment interaction of sows. Experiment 2 sought to determine the effects of genotype on the immune system of nursery-age offspring of the experimental lines. Each sow line was bred to a common PIC 405 boar line. The Exp-94 x 405 pigs had elevated WBC numbers than C-15 x 405 pigs. The social status of the Exp-94 x 405 or the C-15 x 405 pigs showed no effect on any of the immune measures studied. The other immune measures were statistically similar for the two lines of pigs. The Exp-94 line had marginally increased NK activity but reduced lymphocyte blastogenesis and neutrophil chemotaxis compared with the C-15 line.

Reduction of pig agonistic behavior by androstenone.

One hundred twenty-four prepuberal crossbred pigs were used in a series of behavioral bioassays to determine the minimum dose of androstenone (5 alpha-androst-16-en-3-one) that would reduce the level of agonistic behavior among dyads of newly regrouped pigs. Randomly selected females and castrated males were used in 21-h videotaped observation periods. In Exp. 1, isopropyl alcohol was tested against no aerosol to determine if the vehicle (isopropyl alcohol) influenced agonistic behavior. Level of submissive and aggressive behaviors were similar (P greater than .10) between treatments. In Exp. 2, vehicle or androstenone in vehicle was sprayed on the snout and head of both pigs at the start of the encounter. Four bioassays were performed with four levels (.05, .5, 5 and 50 micrograms/pig) of androstenone dissolved in isopropyl alcohol. Sprayed isopropyl alcohol served as a control. At concentrations of .5 and 5 micrograms/pig, androstenone reduced aggressive behavior (P less than .05). Androstenone had no consistent effect on submissive behavior. In Exp. 3, androstenone was sprayed on pigs at the start of the encounter and again at 30, 60 and 90 min after pairs of pigs were mixed. Repeated application of this androgen resulted in levels of agonistic behavior similar to those recorded when nothing was applied (P greater than .10). A single application of as little as .5 micrograms androstenone per pig reduced aggressive behavior among prepuberal pigs and, therefore, may be a way of reducing fighting among newly regrouped prepuberal pigs.

Local and general anesthetic effects on behavior and performance of two- and seven-week-old castrated and uncastrated piglets.

Four experiments were conducted to examine the effects of general and local anesthetics given prior to castration on piglet behavior and weight gain. The first experiment showed that use of general anesthesia by xylazine, ketamine hydrochloride and glyceryl guaiacolate for 2-wk-old piglets resulted in the death of 28% of the piglets and, for those that survived, suppressed nursing behavior. In the second experiment, using 2-wk-old piglets, local anesthesia by lidocaine hydrochloride prevented the slight (30 min) castration-induced nursing behavior suppression. In the third and fourth studies, using 7-wk-old pigs, local or general anesthetic did not overcome castration-induced changes in behavior. Castration affected behavior of 7-wk-old pigs for 6 to 8 h. None of the treatments in any of the studies influenced weight gain. We conclude that castration is painful for 2-wk-old and 7-wk-old pigs. The 2-wk-old pig seems behaviorally less affected by castration than does the 7-wk-old pig. Local anesthetic prevented pain-induced behavior changes for 2-wk-old, but not for 7-wk-old, pigs. At present, the FDA does not permit use of these anesthetics in meat-producing animals.