Physiological and proteomic evidences that domestication process differentially modulates the immune status of juvenile Eurasian perch (Perca fluviatilis) under chronic confinement stress

The current study aimed to evaluate the influence of domestication process on the stress response and subsequent immune modulation in Eurasian perch juveniles (Perca fluviatilis) submitted to chronic confinement. Briefly, F1 and F4 generations were confined into small-size tanks and sampled 7 and 55 days after stocking. Cortisol and glucose levels as well as lysozyme activity and immunoglobulin level were evaluated in the serum. Spleen Somatic Index and spleen ROS production were also measured. A proteomic analysis was performed on serum sampled on day 7. Finally, both generations were genetically characterized using a microsatellite approach. Globally, results revealed that chronic confinement did not elicit a typical stress response but resulted in a prolonged immune stimulation. Proteomic results suggested that domestication process influenced the immune status of perch submitted to chronic confinement as the F1 confined fish displayed lower abundance of C3 complement component, transferrin and Apolipoprotein E. Microsatellite data showed a strong genetic drift as well as reduced genetic diversity, allelic number and heterozygosity along with domestication process. The present work is the first to report that fish under domestication can develop an immune response, assessed by a combined approach, following recurrent challenges imposed by captive environment despite a reduced genetic variation.     

Changes in behaviour, cortisol and lymphocyte types during isolation and group confinement of sheep

This experiment compared changes in complex behaviour patterns, adrenal corticosteroid secretion and the numbers of various types of lymphocytes in sheep that were subjected to the stress of confinement. Grazing Merino ewes (n=80 in five replicated experiments) were confined either in groups of four per pen or in total isolation from other sheep. The percentage of CD4+ lymphocytes increased while the percentage of CD8+ lymphocytes decreased over the experimental period. This result was more pronounced in isolated sheep than in grouped sheep. The increase in CD4:CD8 was greater for isolated sheep than for grouped sheep and greater for 2 week sheep than for 3 week sheep. The percentage of CD5+ cells also increased, less so in isolated than in grouped animals. Interpreting these changes as a recovery of immune competence following introduction of a stressor, it is apparent that isolation impaired immune system recovery more severely than group confinement. Physiological and behavioural adaptation over the period were characterized by a decline in the adrenocortical response, resumption of the normal pattern of flocking behaviour and a reduction in motor activity during the test. These findings add to the evidence pointing to the possible correspondence between critical features of the psychoneural, neuroendocrine and immune systems.     

Effects of 10-day confinement on the immune system and psychological aspects in humans.

We investigated the changes in percentages of leukocyte subpopulations, natural killer (NK) cells, CD69-expressing lymphocytes, and psychological aspects in 10 subjects who participated in a 10-day confinement study. Suppression of lymphocyte proliferative reaction and changes in leukocyte distribution are known to occur in space. These responses are similar to those induced by psychological stress. Ground-based confinement studies are suitable for validating the effects of stress arising only due to confinement. Two groups, consisting of five male subjects (ages 20-27 yr, mean 22.8 yr) each, participated in a 10-day confinement study. Blood samples were taken once before, three times during, and once after the confinement and activated with an anti-CD2 agonistic antibody cocktail. The percentages of leukocyte subpopulations, NK (CD45(+)CD56+) cells, and activated lymphocytes (CD45(+)CD69+) were measured by flow cytometric assay. The face scale test was used to measure psychological aspects. The percentage of CD69+ lymphocytes decreased during the period of confinement. This was mostly caused by changes in the ratio between NK and non-NK lymphocytes. The face scale showed that the subjects' moods improved toward the postconfinement period. Consistent with the face scale, the percentages of innate immune cells, such as NK cells and granulocytes, increased during the postconfinement period. We concluded that the changes in the distribution of immune cells caused by stress plays an important role in suppression of proliferative reactivity. The observed physiological reactions were specific to the confined environment, and the stress caused by confinement plays a role in the immune changes observed in space.     

Bone Mass and Bone Quality Are Altered by Hypoactivity in the Chicken

Disuse induces a rapid bone loss in adults; sedentarity is now recognized as a risk factor for osteoporosis. Hypoactivity or confinement also decrease bone mass in adults but their effects are largely unknown and only few animal models have been described. We have used 10 chickens of the rapidly growing strain 857K bred in a large enclosure (FREE group); 10 others were confined in small cages with little space to move around (HYPO group). They were sacrificed at 53 days and femurs and tibias were evaluated by texture analysis, dual energy X-ray densitometry, microcomputed tomography (microCT) and histomorphometry. Hypoactivity had no effect on the length and diameter of the bones. Bone mineral density (BMD), microCT (trabecular bone volume and trabecular microarchitecture) and texture analysis were always found significantly reduced in the animals of the HYPO group. BMD was reduced at both femur and tibia diaphysises; BMD of the metaphysis was significantly reduced in the femur but not in the tibia. An increase in osteoid volume and surfaces was noted in the HYPO group. However, there was no alteration of the mineral phase as the osteoid thickness did not differ from control animals. Bone loss was much more pronounced at the lower femur metaphysis than at the upper metaphysis of the tibia. At the tibia, only microarchitectural changes of trabecular bone could be evidenced. The confined chicken represents a new method for the study of hypodynamia since these animals do not have surgical lesions.     

Does domestication process affect stress response in juvenile Eurasian perch Perca fluviatilis?

The objective was to evaluate the impact of domestication process on the physiological stress response of cultured Eurasian perch confronted to a chronic stress situation. Briefly, F1 and F4 juveniles were submitted to chronic confinement and investigated on days 5, 15 and 30. Capture and 15min-anesthesia were imposed on fish to assess the effect of preceding confinement on acute stress response. On day 30, the fish were finally challenged with Aeromonas hydrophila and sampled after 5 and 10 days for immune parameter measurements. Cortisol and glucose levels were not affected by confinement but increased significantly after acute stressor exposure. Moreover, cortisol rise following capture and anesthesia was higher in F1 confined-fish, suggesting that they have previously been affected by chronic confinement. A higher HSP70 level was also observed on day 30 in F1 confined-juveniles. During bacterial challenge, regardless of confinement level, F4 juveniles displayed higher lysozyme activity and agglutination response than F1 which may indicate a higher immune capacity in domesticated fish. In conclusion, chronic confinement stressor induced few physiological responses but may increase the responsiveness to other aquacultural stressors. Domestication process also seems to improve chronic stress resistance, growth as well as the immune status of the fish.     

The effect of confinement on motivation to exercise in young dairy calves

The objective of this research was to determine if confinement of 8-day-old calves for varying lengths of time is associated with an increase in motivation to perform locomotor behaviors. Holstein heifer and bull calves (N=48) were used in a factorial arrangement with two crossed factors. Factor A was housing with two levels (individual confinement versus group pens) and factor B was hours in confinement with four levels (6, 12, 24, and 48h). Individual confinement was in 1.06mx1.06m pens, while group pens had a 3.68mx6.09m outside run and a 3.68mx6.09m covered area that also contained a 3.68mx2.44m area bedded with wood shavings. The calves were placed on treatment when they were 8+/-2 days of age.At the end of the treatments, a blood sample was taken for plasma cortisol determination and lymphocyte counts and the calves were open-field tested for 5min.Walk, trot, distance traveled and behaviors performed while standing during the open-field test were higher in the calves kept in group pens (P=0.0003, 0.01, 0.04 and 0.04), but were not influenced by hours in treatment. Calves confined for 48h had greater incidences of kicking and falling (P=0.014 and 0.025). Lymphocyte count (P=0.029) was lower in the calves confined for 12h, but there was not a trend across hours in confinement that indicated a consistent effect. Housing or hours in treatment did not affect canter, buck, buck-kick, rear, stumble, vocalization and cortisol concentrations. The interaction between hours in treatment and housing was not significant for any of the variables tested.This study suggests that 2 days may not have been enough time for the effects of close confinement to influence motivation in young calves, or that calves averaging 8 days of age may be too young to display increased motivation for locomotor activity. Confinement of such young calves actually inhibits locomotor activity in open-field tests.     

Effects of confinement stress of variable duration on the growth and microincrement deposition in the otoliths of Oreochromis niloticus(Cichlidae)

The effects of chronic confinement stress (1, 5 and 10 days) and of periodic blood sampling on somatic growth and the structure and growth of otoliths was studied in Oreochromis niloticus . During the study, the plasma concentrations of cortisol were measured at various times during the application of stress: they were significantly higher in confined fish than in control fish (mean ±  s . d . 3·40 ± 0·47 v . 1·26 ± 0·62 ng ml⁻¹, P  < 0·05) up to 5 days after the start of a 10 day stress period. The somatic growth (standard length, L _S, and mass) was affected by the confinement and by the sampling (from 16·21 ± 1·07 to 14·64 ± 1·15 cm for L _S, and from 173·31 ± 33·14 to 110·50 ± 29·48 g for mass). But the confinement masked the effect of the sampling on somatic growth. Tetracycline was injected at the start of the experiment to mark the otoliths, and showed that the short and long duration confinements led to a clear check in the pattern of primary increments in the otoliths. The number of primary increments deposited during the resting periods that followed each period of confinement was always less than the number of days that these periods lasted. No relation was found between the duration of confinement and the structure of the resulting checks. These results suggest that there is a disruption in the laying down of primary increments during periods of confinement resulting in an underestimation of their number compared to the actual number of days of growth. These results call into question the use of otolith primary increments as a means of estimating the age of Nile tilapia that have experienced periods of stress.     

Dietary Korean mistletoe enhances cellular non-specific immune responses and survival of Japanese eel (Anguilla japonica)

The present study was performed to investigate the immunostimulatory effects of Korean mistletoe extract (KM-110; Viscum album Coloratum) on the non-specific immune response and protection against Aeromonas hydrophila infection in Japanese eel (Anguilla japonica). Eels were fed under 4 regimes, 0%, 0.1%, 0.5% and 1.0% KM-110 mixed diet. On day 14 after feeding, 15 fish from each group were injected i.p. with live A. hydrophila (3 x 10(6)CFU) and the remaining unchallenged fish from each group were used to study the innate immune response. On 14 days post-infection, the total survival rates were 26.6% in control, and 33.3%, 66.6% and 80% in 0.1%, 0.5% and 1% KM-110-treated groups, respectively. The maximum lysozyme activity was observed in the 1% KM-110-treated group. There was no significant difference of lysozyme activity between 0.1% and 0.5% KM-110 group. Superoxide anion (O(2)(-)) production was significantly (p<0.05) augmented in the 0.5% and 1% KM-110 groups compared to the control and 0.1% KM-110 group. No significant difference of (O(2)(-) production was found between 0.5% and 1% KM-110 group. Likewise, there was a significant increase in phagocytic activity in the 0.5% KM-110 group compared with the 0.1% group (p<0.05), but no significant difference between the 0.5% and the 1% KM-110 group indicating that 0.5% KM-110 concentration is suitable for stimulating maximum phagocytic activity resulting in a high amount of ROI production. Considering the present results, KM-110 could be utilized as a promising immunostimulating substance for a diet in aquaculture.     

Root-shoot signalling in sunflower plants with confined root systems

Sunflower plants were grown hydroponically under controlled conditions with the root systems confined in small containers. Root confinement inhibited the growth of sunflower plants as indicated by reduction in both leaf and cotyledon area and root and shoot fresh weight. This effect was more pronounced in shoots. Root confinement favored the accumulation of potassium in the roots and shoots, and the exudation of potassium and water in excised roots. Xylem sap from root confined plants inhibited cotyledon expansion as revealed by bioassay with decapited sunflower seedlings. In addition decapited control plants incubated in ABA solution also showed cotyledon growth reduction. Xylem sap ABA analysis indicated a 7-times higher concentration in root confined than control plants. Our results suggest the synthesis of a chemical signal in the roots of plants subjected to mechanical stress which can be responsible for the inhibition of plant growth.     

Inhibition of spawning and associated suppression of sex steroid levels during confinement in the substrate-spawning Tilapia zillii

Substrate-spawning Tilapia zillii failed to spawn in crowded holding tanks but exhibited a marked tendency to spawn soon after transfer to individually partitioned aquaria. Confined conditions suppressed the levels of serum 17 β -oestradiol (E₂) and testosterone (T) in females, which remained low throughout the period of confinement. Levels of both steroids rose significantly following transfer of fish to individual aquaria and were maintained at consistently higher levels than those of fish which remained confined. Proportions of stage 3 (late perinucleolar) oocytes were significantly lower ( P <0.001) in individual fish 21–30 days after transfer, coincident with significantly higher ( P <0.01) proportions of stage 6 or 7 oocytes (late vitellogenic or maturing oocytes). However, no significant differences ( P ≥0.05) were detected between individual or confined groups of fish in the relative proportions of stage 2 (early perinucleolar), stage 4 (cortical alveolar) or stage 5 (early vitellogenic) oocytes. Atresia increased as the period of confinement increased. Following return of individual fish to confined conditions, blood steroids fell rapidly to levels seen in fish that had remained confined throughout. It is suggested that the reduced sex steroid levels detected during confinement were insufficient to allow developing oocytes to complete oocyte growth and maturation. The detection of significantly lower proportions of stage 3 and significantly higher proportions of stage 6/7 oocytes soon after transfer suggest that fish were preparing one batch of oocytes for spawning (stage 6/7 oocytes) whilst recruiting from a pool of previtellogenic oocytes (stage 3) for the ensuing spawning cycle.     

The response to capture and confinement stress of plasma cortisol, plasma sex steroids and vitellogenic oocytes in the marine teleost, red gurnard

Reproductively active female red gurnard Chelidonichthys kumu were captured on long-lines, and placed in confinement tanks for 24, 48, 72 and 96 h to examine the effect of capture and confinement on reproductive parameters (experiment I). Plasma cortisol at the time of capture was elevated to levels typical of stressed fish in other species (53–125 ng ml⁻¹). Final plasma cortisol levels in red gurnard confined for any length of time were not significantly different from one another (ranging from 17 to 43 ng ml⁻¹), indicating that fish were chronically stressed when held in captivity for up to 96 h after capture. When initial and final plasma cortisol levels were compared within confinement groups, cortisol decreased significantly after 24 and 96 h of confinement indicating that some acclimation to captivity may have occurred. In contrast, plasma 17β-estradiol (E₂) and testosterone (T) levels decreased significantly to levels comparable to those in post-spawned fish, after any period of confinement, and remained low throughout the experiment. Another group of fish was captured and confined in the same manner as experiment I but subjected to repeated blood sampling every 24 h, until 96 h post-capture. In these fish, plasma cortisol levels decreased significantly from 127 ng ml⁻¹ after 24 h confinement and thereafter showed no change (25–45 ng ml⁻¹). Plasma E₂ decreased significantly after 72 h of confinement while plasma T showed no change from levels at capture. Increased amounts of follicular atresia were found in vitellogenic oocytes of fish confined for longer periods of time in experiment I, indicating that capture and confinement stress affect reproduction negatively in captive wild fish.     

The influence of social interaction on the acclimation of rainbow trout, Oncorhynchus mykiss (Walbaum) to chronic stress

To establish the time required for fish to acclimate to experimental conditions, comprising holding within a spatially restrictive environment, rainbow trout were transferred from rearing tanks (1500 1) to smaller volume holding tanks (50 1). The fish were maintained singly, in pairs, in groups of five fish, and in groups of 10 fish, and selected indices of physiological stress were monitored at intervals following the onset of confinement. In all cases transfer and confinement provoked a stress response in the fish, indicated by significantly elevated plasma cortisol levels, and significantly reduced numbers of circulating lymphocytes. Recovery of these parameters to levels similar to unstressed control fish, was most rapid among the fish confined singly, requiring 2 to 4 weeks, although weight gain, indicative of feeding, was apparent within 1 to 2 weeks. Acclimation of the fish confined as pairs was severely confounded by the development of hierarchical relationships between the fish. This resulted in some individuals displaying rapid acclimation and growth, in contrast to other fish within the groups which failed to acclimate, exhibited signs of chronic stress, and ultimately succumbed to bacterial infections. Similar, though less severe, evidence of social stress was observed among the fish confined as groups of five. A decline in the coefficient of variance for weight within the fish confined as groups of 10 suggested an absence of growth inhibition due to social interaction among these fish. The implications of these results for experimental design are discussed.     

A note on the effect of isolation during testing and length of previous confinement on locomotor behaviour during open-field test in dairy calves

This study investigated firstly if confined calves perform more locomotor behaviour when open-field tested in pairs than when tested individually, and secondly if length of confinement affects the build-up of motivation to perform locomotor behaviour. In the first experiment,14 calves were open-field tested on two successive days either individually or as a pair. Calves walked more and performed more locomotor play when tested in pairs, suggesting that it may be appropriate to avoid isolation when aiming to measure the effects of confinement on locomotor behaviour. In the second experiment, in each of three successive weeks, 24 calves had access to an exercise arena for 45 min daily on three successive days either: (i) the first 3 days, (ii) the third, fourth and fifth day, or (iii) the fourth, fifth and sixth day. On the seventh day the calves were released into the arena for 10 min (open-field test). All calves received all three treatments in a Latin square design. Calves performed more locomotor play, and they trotted more after 3 days without access to the arena than after 1 or 0 days, suggesting that in calves the motivation to perform locomotor play and trotting increases with length of confinement.     

甘露寡糖对异育银鲫生长性能、免疫及HSP70基因表达的影响

为探讨甘露寡糖(MOS)对异育银鲫生长、免疫、肠道组织结构及抗病力的影响,试验选取360尾异育银鲫[初均重(16.19±0.03)g],随机分成5组、每组3个重复,在日粮中添加不同浓度甘露寡糖(0、60、120、240、480 mg/kg),连续投喂80d,并于第80天时进行嗜水气单胞菌感染,测定异育银鲫生长、免疫、肠道结构等指标及异育银鲫抗嗜水气单胞菌感染的能力。试验结果表明,无论投喂50d,还是80d,甘露寡糖对鱼体的生长指标(特定生长率、增重率、蛋白质效率、饵料系数)均没有显著影响(P>0.05);投喂50d,与对照组比,甘露寡糖能显著提高血清球蛋白浓度(P<0.05);投喂80d后,与对照组比,240、480 mg/kg甘露寡糖组能显著提高碱性磷酸酶活性,甘露寡糖组能显著提高血清球蛋白浓度(P<0.05),480 mg/kg甘露寡糖组能显著提高血清总抗氧化能力,120、240 mg/kg甘露寡糖组能显著提高肠褶皱襞长(P<0.05),对皱襞间质宽、黏膜下层宽没有显著影响(P>0.05),肌层宽随着MOS的添加有增加趋势(P>0.05);嗜水气单胞菌感染后,与对照组比,240、480 mg/kg甘露寡糖组成活率提高了22.6%,免疫保护率达45.4%。日粮中添加甘露寡糖组对鱼体肝脏HSP70基因表达没有显著影响(P>0.05)。因此,添加240、480 mg/kg甘露寡糖能提高鱼体的免疫能力,增强鱼体抗病原菌感染能力。     

DNA Damage and Radiosensitivity in Blood Cells from Subjects Undergoing 45 Days of Isolation and Confinement: An Explorative Study

The effect of confined and isolated experience on astronauts’ health is an important factor to consider for future space exploration missions. The more confined and isolated humans are, the more likely they are to develop negative behavioral or cognitive conditions such as a mood decline, sleep disorder, depression, fatigue and/or physiological problems associated with chronic stress. Molecular mediators of chronic stress, such as cytokines, stress hormones or reactive oxygen species (ROS) are known to induce cellular damage including damage to the DNA. In view of the growing evidence of chronic stress-induced DNA damage, we conducted an explorative study and measured DNA strand breaks in 20 healthy adults. The participants were grouped into five teams (missions). Each team was composed of four participants, who spent 45 days in isolation and confinement in NASA’s Human Exploration Research Analog (HERA). Endogenous DNA integrity, ex-vivo radiation-induced DNA damage and the rates of DNA repair were assessed every week. Our results show a high inter-individual variability as well as differences between the missions, which cannot be explained by inter-individual variability alone. The ages and sex of the participants did not appear to influence the results.     

Ameliorative effect of nanoencapsulated flavonoid against chlorpyrifos‐induced hepatic oxidative damage and immunotoxicity in Wistar rats

The theme of the present work is to evaluate the protective effect of nanoencapsulated quercetin (NEQ) against chlorpyrifos (CPF)‐induced hepatic damage and immune alterations in animals. Nanoparticles (NP) drug encapsulation was prepared. Forty male Wistar rats were divided into eight groups. Two groups served as control and CPF (13.5 mg/kg) treatment for 28 days. Other three groups were free quercetin (QC), NP and NEQ treated with 3 mg/kg respectively for 15 days; whereas remaining three groups received treatment of CPF and QC, NP, NEQ, respectively, for 15 days. The results show that significantly altered oxidative stress in the liver tissue and liver enzyme parameters in blood and immune responses in CPF‐treated rats compared to controls. Administration of NEQ attenuated biochemical and immunological parameters. The liver histopathological analysis confirmed pathological improvement. Hence, use of NEQ appeared to be beneficial to a great extent in attenuating and restoring hepatic oxidative damage and immune alteration sustained by pesticide exposure.     

Mechanical Stress Impairs Mitosis Progression in Multi-Cellular Tumor Spheroids

Growing solid tumors are subjected to mechanical stress that influences their growth rate and development. However, little is known about its effects on tumor cell biology. To explore this issue, we investigated the impact of mechanical confinement on cell proliferation in MultiCellular Tumor Spheroids (MCTS), a 3D culture model that recapitulates the microenvironment, proliferative gradient, and cell-cell interactions of a tumor. Dedicated polydimethylsiloxane (PDMS) microdevices were designed to spatially restrict MCTS growth. In this confined environment, spheroids are likely to experience mechanical stress as indicated by their modified cell morphology and density and by their relaxation upon removal from the microdevice. We show that the proliferation gradient within mechanically confined spheroids is different in comparison to MCTS grown in suspension. Furthermore, we demonstrate that a population of cells within the body of mechanically confined MCTS is arrested at mitosis. Cell morphology analysis reveals that this mitotic arrest is not caused by impaired cell rounding, but rather that confinement negatively affects bipolar spindle assembly. All together these results suggest that mechanical stress induced by progressive confinement of growing spheroids could impair mitotic progression. This study paves the way to future research to better understand the tumor cell response to mechanical cues similar to those encountered during in vivo tumor development.     

The effect of elevated reproductive effort onhumoral immune function in collared flycatcher females

In order to test whether high reproductive investments impair immune function in naturally breeding collared flycatchers, we performed a brood manipulation experiment and simultaneously induced an immune response by challenging birds with a non-pathogenic antigen – sheep red blood cells (SRBC). Females rearing experimentally enlarged number of nestlings showed significantly lower level of specific anti-SRBC antibodies than control females attending unaltered broods, but only in one of the two study years. The haemoconcentration of leukocytes did not differ between the two groups in both study years. The significant difference in immunological responsiveness between control and enlarged group coincided with differences in survival probability to the next breeding season: females attending enlarged broods showed lower probability of survival than control females, but there was no relationship between the level of immune response and survival probability. Our results indicate that reproduction may indeed trade for resources with immune functions at least in terms of specific antibody production. However, as in the other studies on reproductive costs, these costs seem not always to be pronounced.     

Thie expression of an intraspecific aggressive reaction in the face of a stressor agent alters the immune response in rats.

The repercussion on the immune response of the expression of intraspecific aggressiveness in the face of a stressor agent was investigated in rats. Ninety-day-old animals were divided into three groups: the control group (only immunological measurements were performed), the foot-shock (FS) (animals individually receiving FS), and the intraspecific aggressive response (IAR) group (animals receiving FS and presenting IAR). For immunological measurements, blood samples were collected promptly at 7 and 15 days after FS or IAR. The FS reduced the total leukocyte amount presented. However, aggressiveness triggered not only reduction of the leukocytes, but also lymphocyte decrease and neutrophil increase. Moreover, an elevation in total leukocytes associated with an increase in the humoral immune response was also observed one week after IAR. In this study, the expression of intraspecific aggressiveness in the face of a stressor seemed to activate the immune system and to potentiate the antigen specific humoral response.     

Delayed puberty in gilts in total confinement

Two hundred fourteen crossbred gilts, born in January through March and June through July of two different years, were raised in total confinement until 100 to 120 days of age and then moved to an outside dirt lot (non-confined) or to a single pen in a confinement, finishing building (confined). Beginning at 150 days of age, estrus was checked daily with a boar to determine percentage of gilts that attained puberty and age at first estrus, and weekly blood samples were collected and analyzed for progesterone by radioimmunoassay to determine age at first ovulation. In the Jan.-Mar. born gilts, 75.4% of the non-confined gilts and 37.4% of the confined gilts attained puberty by 270 days of age (P<.001). Although differences were not significant in the gilts born in June-July, more non-confined gilts (62.6%) than confined gilts (50.9%) attained puberty. Of the 121 gilts that ovulated, only 1 non-confined and 3 confined gilts did not exhibit estrus. Average age at first estrus or at first ovulation were similar for confined and non-confined gilts. Adrenal gland weights at 250 to 270 days of age were similar also for confined and non-confined gilts. Based on the results of this study, we conclude that total confinement housing can reduce, by as much as 50%, the proportion of gilts that attain puberty by 8 to 9 months of age and that time of year may influence the extent of delayed puberty.