RESUMEN
Light enables vision and exerts widespread effects on physiology and behavior, including regulating circadian rhythms, sleep, hormone synthesis, affective state, and cognitive processes. Appropriate lighting in animal facilities may support welfare and ensure that animals enter experiments in an appropriate physiological and behavioral state. Furthermore, proper consideration of light during experimentation is important both when it is explicitly employed as an independent variable and as a general feature of the environment. This Consensus View discusses metrics to use for the quantification of light appropriate for nonhuman mammals and their application to improve animal welfare and the quality of animal research. It provides methods for measuring these metrics, practical guidance for their implementation in husbandry and experimentation, and quantitative guidance on appropriate light exposure for laboratory mammals. The guidance provided has the potential to improve data quality and contribute to reduction and refinement, helping to ensure more ethical animal use.
Asunto(s)
Experimentación Animal , Animales de Laboratorio , Animales , Reproducibilidad de los Resultados , Ritmo Circadiano/fisiología , MamíferosRESUMEN
Heat supplementation during surgery is a common practice; however, thermal support is not commonly used during anesthesia induction. Mice lose body temperature quickly, and air movement can exacerbate this, potentially putting mice at a thermal deficit before surgery. Whether the method of warming during induction affects overall heat loss during anesthesia is unknown. We hypothesized that the method of heating would affect body temperature (Tb) during anesthesia induction, maintenance, recovery, and once placed back on the rack. Mice (C57BL/6NHsd-6M/6F [C57BL/6]; Hsd:Athymic Nude-Foxn1nu [Nude]; N = 24;12M/12F) were assigned to a treatment in a factorial design: thermal chamber (TC; ambient temperature [Ta] = 28.8°C); heating pad (HP; induction chamber placed on an electric heating pad;Ta = 28.4°C); and control (Ctrl; Ta = 21.6°C). During induction, one mouse at a time was anesthetized with isoflurane over a 3min period and then maintained under anesthesia for 10min on a hot water heating pad (33 °C). Then isoflurane was stopped and time to ambulation was recorded. Tb and activity were tracked in the home cage on the rack before and after anesthesia. During induction, Ctrl mice lost significantly more heat (-2.8 °C) than did TC (+0.2 °C) and HP mice (+0.1 °C) but TC and HP were not different. During anesthesia maintenance, Ctrl mice regained 1 °C, but their Tb was still lower than that of the treated groups. Nude mice consistently had a lower Tb than C57BL/6 mice, regardless of treatment or anesthesia phase. C57BL/6 Ctrl mice took longer to ambulate than either HP or TC mice, but the method of heating did not differentially affect Nude mice. In general, C57BL/6 as compared with Nude and females as compared with males were comparatively more active and had higher Tb during certain times of day, regardless of the heating methods. Overall, our findings support the provision of heat during anesthesia induction, regardless of method, to reduce overall Tb loss during a short anesthesia event.
Asunto(s)
Temperatura Corporal , Ratones Endogámicos C57BL , Ratones Desnudos , Animales , Masculino , Ratones , Femenino , Isoflurano , Calefacción/métodos , Calor/efectos adversos , Anestesia/veterinariaRESUMEN
Light is a key factor influencing the welfare of laboratory rodents, but little is known about their optimal lighting condition. It i common knowledge that rats prefer dim light, so bright light is mitigated with red-tinted shelters or cages, which alter both the color and intensity of light. Because both aspects are altered, the contribution of each feature to rodent preference is unknown. Further, it is unknown if this preference is influenced by previous experience. We hypothesized that rats would prefer lower light intensity and that their preferences would be influenced by their housing environment. Breeder pairs of rats were randomly separated into four treatments groups: red 200 lux, red 25 lux, clear 200 lux, and clear 25 lux. The breeders' offspring were tested three times in an apparatus that offered access to each environment, and their preferences were analyzed. Generally, the rats preferred the lower-lux environments and showed no color preference. However, the rats from the clear, 200 lux cages, preferred clear caging and only showed a preference for 25 lux conditions during the second and third preference tests. These results suggest that the light intensity, more than color, should be considered when designing rodent housing and testing facilities.
RESUMEN
As experienced authors, statisticians, editors, and scientists, we present the following comments to highlight some usages or omissions that are common in research manuscripts. Consideration of these comments will improve practices of data analysis and reporting.
Asunto(s)
Modelos Animales , Proyectos de Investigación , AnimalesRESUMEN
Enrichment is important for animal welfare and data quality. Provision of enrichment opportunities varies between species and enrichment category. However, data benchmarking these differences does not exist. Our objective was to characterize enrichment provision and associated factors across species in the US and Canada. Personnel who work with research animals (n = 1098) in the US and Canada voluntarily responded to online promotions and completed a survey about enrichment used for the species they worked with most, their control of and wish for more enrichment, stress or pain in the animals they worked the most with, and demographics. All participants (except those working with rats) received the same questionnaire regardless of species to allow objectivity, as the effects of many enrichment items on some species have not yet been determined. The questionnaire asked about enrichments that were beneficial to at least one species. The provision of enrichment was allocated into 2 outcome variables: diversity and frequency per enrichment category. Results showed a significant interaction between enrichment category and species. Generally, physical, nutritional, and sensory enrichments were provided less often than social enrichment. In addition, nonhuman primates received more diverse and more frequent enrichment than did other species (twice as much as rats and mice). Enrichment was provided less frequently by personnel who wished they could do more than the status quo. Both enrichment frequency and diversity were higher in respondents from Canada, those who had more control over provision, and those who had been in the field longer. While our results cannot be used to determine the quality of enrichment provided to various species, they do provide information on current enrichment practices in the US and Canada and identify differences in implementation by species and enrichment category. The data also indicate provision of enrichment is influenced by factors such as country and individual control over enrichment. This information can also be used to identify areas for greater enrichment efforts for some species (for example, rats and mice) and categories, with the ultimate goal of improving animal welfare.
Asunto(s)
Benchmarking , Animales , Ratas , Ratones , CanadáRESUMEN
An accurate understanding of boar temperature preferences may allow the swine industry to design and utilize environmental control systems in boar facilities more precisely. Therefore, the study objective was to determine the temperature preferences of sexually mature Duroc, Landrace, and Yorkshire boars. Eighteen, 8.57 ± 0.10-mo-old boars (N = 6 Duroc, 6 Landrace, and 6 Yorkshire; 186.25 ± 2.25 kg) were individually tested in thermal apparatuses (12.20 m × 1.52 m × 1.86 m) that allowed free choice of their preferred temperature within a 8.92 to 27.92 ºC range. For analyses, the apparatuses were divided into five thermal zones (3.71 m2/thermal zone) with temperature recorded 1.17 m above the floor in the middle of each zone. Target temperatures for thermal zones 1 to 5 were 10, 15, 20, 25, and 30 ºC, respectively. All boars were given a 24-h acclimation phase followed by a 24-h testing phase within the thermal apparatuses. Daily feed allotments (3.63 kg/d) were provided to each boar and all boars were allowed to consume all feed prior to entering the thermal apparatus. Water was provided ad libitum within the thermal apparatuses with 1 waterer per thermal zone. During testing, boars were video recorded continuously to evaluate behavior (inactive, active, or other), posture (lying, standing, or other), and thermal zone the boar occupied. All parameters were recorded in 15 min intervals using instantaneous scan sampling. Data were analyzed using GLM in JMP 15. For the analyses, only time spent lying or inactive were used because they were observed most frequently (lying 80.02%, inactive 77.64%) and were deemed to be associated with comfort based on previous research. Percent time spent active (19.73%) or standing (15.87%) were associated with latrine or drinking activity and were too low to accurately analyze as an indicator of thermal preference. Breed did not affect temperature preference (P > 0.05). A cubic regression model determined that boars spent the majority of their time inactive at 25.50 ºC (P < 0.01) and lying (both sternal and lateral) at 25.90 ºC (P < 0.01). These data suggest that boar thermal preferences did not differ by breed and that boars prefer temperatures at the upper end of current guidelines (10.00 to 25.00 ºC).
RESUMEN
Current understanding of how odors impact intra-sex social behavior is based on those that increase intermale aggression. Yet, odors are often promoted to reduce fighting among male laboratory mice. It has been shown that a cage of male mice contains many proteins used for identification purposes. However, it is unknown if these proteins relate to social behavior or if they are uniformly produced across strains. This study aimed to compare proteomes from used nesting material and three sources (sweat, saliva, and urine) from three strains and compare levels of known protein odors with rates of social behavior. Used nesting material samples from each cage were analyzed using LC-MS/MS. Sweat, saliva, and urine samples from each cage's dominant and subordinate mouse were also analyzed. Proteomes were assessed using principal component analyses and compared to behavior by calculating correlation coefficients between PC scores and behavior proportions. Twenty-one proteins from nesting material either correlated with affiliative behavior or negatively correlated with aggression. Notably, proteins from the major urinary protein family, odorant binding protein family, and secretoglobin family displayed at least one of these patterns, making them candidates for future work. These findings provide preliminary information about how proteins can influence male mouse behavior. SIGNIFICANCE: Research on how olfactory signals influence same sex social behavior is primarily limited to those that promote intermale aggression. However, exploring how olfaction modulates a more diverse behavioral repertoire will improve our foundational understanding of this sensory modality. In this proteome analysis we identified a short list of protein signals that correspond to lower rates of aggression and higher rates of socio-positive behavior. While this study is only correlational, it sets a foundation for future work that can identify protein signals that directly influence social behavior and potentially identify new murine pheromones.
Asunto(s)
Proteoma , Saliva , Animales , Cromatografía Liquida , Masculino , Ratones , Conducta Social , Espectrometría de Masas en TándemRESUMEN
Alzheimer's disease affects an array of activities in patients' daily lives but measures other than memory are rarely evaluated in animal models. Home cage behavior, however, may provide an opportunity to back translate a variety of measures seen in human disease progression to animal models, providing external and face validity. The aim of this study was to evaluate if home cage measures could indicate disease in the rTg4510 mouse model. We hypothesized that sleep, nesting, and smell discrimination would be altered in mutant mice. Thirty-two transgenic mice were used in a Latin square design of four genotypes x both sexes x two diets. Half the mice received a doxycycline diet to suppress tauopathy and evaluate tau severity on various measures. At 8-, 12-, and 16-weeks old, 24 h activity/sleep patterns, nest complexity, and odor discrimination were measured. After 16-weeks, tau concentration in the brain was quantified. Mutant mice had increased tau concentration in brain tissue, but it was reduced by the doxycycline diet. However, only nest complexity was different between mutant mice and controls. Overall, tauopathy in rTg4510 mice does seem to affect these commonly observed symptoms in human patients. However, while running this study, a report showed that the rTg4510 mutant phenotype is not caused by the mutation itself, but confounding factors from transgene insertion. Combined with report findings and our data, the rTg4510 model may not be an ideal model for all aspects of human Alzheimer's disease.
Asunto(s)
Enfermedad de Alzheimer , Tauopatías , Enfermedad de Alzheimer/genética , Animales , Encéfalo/metabolismo , Modelos Animales de Enfermedad , Doxiciclina , Femenino , Humanos , Masculino , Ratones , Ratones Transgénicos , Tauopatías/genética , Proteínas tau/genética , Proteínas tau/metabolismoRESUMEN
Excessive sound, vibration, and light are detrimental to rodent welfare, yet these parameters are rarely recorded in vivaria. Whether housing environments exceed the suggested thresholds and which specific factors may alter these parameters is generally unknown. The goal of this study was to determine how environmental factors may alter sound, vibration, and light at the room and cage levels. Measurements were made using an ultrasonic microphone, accelerometer, and light sensor. Measurement sites were 1) in open air at a central location in 64 rooms located in 9 buildings, and 2) inside an empty mouse or rat cage containing chow, water, and bedding and located on an animal transfer station (n = 51) or housing rack (n = 102). Information collected for each transfer station and rack measurement included the year of manufacture, the species on the rack, and the number of cages on the rack. For each location, a baseline measurement was taken with the transfer station turned off, followed by another measurement after the transfer station was turned on. In general, many factors influenced ambient sound, vibration, and light, indicating that values are not uniform across rodent rooms in the same institution or across cages in a single room. Sound peaks capable of startling rodents were measured in association with hallway ultrasonic motion sensors and during cage change. Vibration and light intensity were generally low when cages were located on the rack. In contrast, active transfer stations had more vibration and light intensity, reaching levels that were potentially stressful for rodents. These data reflect the ambient sound, vibration, and light that rodents experience during normal facility operations. These patterns may extend to other locations, but given the variability in all parameters, the data highlight the need for institutions to conduct their own monitoring.
Asunto(s)
Vivienda para Animales , Vibración , Ratones , Ratas , Animales , Roedores , SonidoRESUMEN
Home cage aggression causes poor welfare in male laboratory mice and reduces data quality. One of the few proven strategies to reduce aggression involves preserving used nesting material at cage change. Volatile organic compounds from the nesting material and several body fluids not only correlate with less home cage aggression, but with more affiliative allo-grooming behavior. To date, these compounds have not been tested for a direct influence on male mouse social behavior. This study aimed to determine if 4 previously identified volatile compounds impact home cage interactions. A factorial design was used with cages equally split between C57BL/6N and SJL male mice (N = 40). Treatments were randomly assigned across cages and administered by spraying one compound solution on each cage's nesting material. Treatments were refreshed after day 3 and during cage change on day 7. Home cage social behavior was observed throughout the study week and immediately after cage change. Several hours after cage change, feces were collected from individual mice to measure corticosterone metabolites as an index of social stress. Wound severity was also assessed after euthanasia. Measures were analyzed with mixed models. Compound treatments did not impact most study measures. For behavior, SJL mice performed more aggression and submission, and C57BL/6N mice performed more allo-grooming. Wound severity was highest in the posterior region of both strains, and the middle back region of C57BL/6N mice. Posterior wounding also increased with more observed aggression. Corticosterone metabolites were higher in C57BL/6N mice and in mice treated with 3,4-dimethyl-1,2-cyclopentanedione with more wounding. These data confirm previous strain patterns in social behavior and further validates wound assessment as a measure of escalated aggression. The lack of observed treatment effects could be due to limitations in the compound administration procedure and/or the previous correlation study, which is further discussed.
Asunto(s)
Líquidos Corporales , Corticosterona , Animales , Masculino , Ratones , Agresión , Conducta Animal , Vivienda para Animales , Ratones Endogámicos C57BL , Comportamiento de Nidificación , Conducta Social , SudorRESUMEN
BACKGROUND: Although thermal indices have been proposed for swine, none to our knowledge differentiate by reproductive stage or predict thermal comfort using behavioral and physiological data. The study objective was to develop a behavior and physiology-based decision support tool to predict thermal comfort and stress in multiparous (3.28 ± 0.81) non-pregnant (n = 11), mid-gestation (n = 13), and late-gestation (n = 12) sows. RESULTS: Regression analyses were performed using PROC MIXED in SAS 9.4 to determine the optimal environmental indicator [dry bulb temperature (TDB) and dew point] of heat stress (HS) in non-pregnant, mid-gestation, and late-gestation sows with respiration rate (RR) and body temperature (TB) successively used as the dependent variable in a cubic function. A linear relationship was observed for skin temperature (TS) indicating that TDB rather than the sow HS response impacted TS and so TS was excluded from further analyses. Reproductive stage was significant for all analyses (P < 0.05). Heat stress thresholds for each reproductive stage were calculated using the inflections points of RR for mild HS and TB for moderate and severe HS. Mild HS inflection points differed for non-pregnant, mid-gestation, and late gestation sows and occurred at 25.5, 25.1, and 24.0 °C, respectively. Moderate HS inflection points differed for non-pregnant, mid-gestation, and late gestation sows and occurred at 28.1, 27.8, and 25.5 °C, respectively. Severe HS inflection points were similar for non-pregnant and mid-gestation sows (32.9 °C) but differed for late-gestation sows (30.8 °C). These data were integrated with previously collected behavioral thermal preference data to estimate the TDB that non-pregnant, mid-gestation, and late-gestation sows found to be cool (TDB < TDB preference range), comfortable (TDB = TDB preference range), and warm (TDB preference range < TDB < mild HS). CONCLUSIONS: The results of this study provide valuable information about thermal comfort and thermal stress thresholds in sows at three reproductive stages. The development of a behavior and physiology-based decision support tool to predict thermal comfort and stress in non-pregnant, mid-gestation, and late-gestation sows is expected to provide swine producers with a more accurate means of managing sow environments.
RESUMEN
Characterizing the sow physiological response to an increased heat load is essential for effective heat stress mitigation. The study objective was to characterize the effects of a 400-min heating episode on sow heart rate variability (HRV) at different reproductive stages. HRV is a commonly used noninvasive proxy measure of autonomic function. Twenty-seven sows were enrolled in the study according to their gestation stage at time of selection: 1) nonpregnant (NP; n = 7), 2) mid-gestation (MID; 57.3 ± 11.8 d gestation; n = 11), and 3) late-gestation (LATE; 98.8 ± 4.9 d gestation; n = 8). The HRV data utilized in the study were collected from each pig as the dry bulb temperature in the room increased incrementally from 19.84 ± 2.15 °C to 35.54 ± 0.43 °C (range: 17.1-37.5 °C) over a 400-min period. After data collection, one 5-min set of continuous heart rate data were identified per pig for each of nine temperature intervals (19-20.99, 21-22.99, 23-24.99, 25-26.99, 27-28.99, 29-30.99, 31-32.99, 33-34.99, and 35-36.99 °C). Mean inter-beat interval length (RR), standard deviation of r-r intervals (SDNN), root mean square of successive differences (RMSSD), high frequency spectral power (HF), sample entropy (SampEn), short-term detrended fluctuation analysis (DFAα1), and three measures (%REC, DET, LMEAN) derived from recurrence quantification analysis were calculated for each data set. All data were analyzed using the PROC GLIMMIX procedure in SAS 9.4. Overall, LATE sows exhibited lower RR than NP sows (P < 0.01). The standard deviation of r-r intervals and RMSSD differed between each group (P < 0.01), with LATE sows exhibiting the lowest SDNN and RMSSD and NP sows exhibiting the greatest SDNN and RMSSD. Late-gestation sows exhibited lower HF than both MID and NP sows (P < 0.0001), greater DFA values than NP sows (P = 0.05), and greater DET compared to MID sows (P = 0.001). Late-gestation also sows exhibited greater %REC and LMEAN compared to MID (P < 0.01) and NP sows (all P < 0.01). In conclusion, LATE sows exhibited indicators of greater autonomic stress throughout the heating period compared to MID and NP sows. However, temperature by treatment interactions were not detected as dry bulb increased. Future studies are needed to fully elucidate the effect of gestational stage and increasing dry bulb temperature on sow HRV.
Pregnant pigs may be at a higher risk of poor physiological outcomes due to heat exposure compared to mature female pigs that are not pregnant. The purpose of this study was to evaluate the stress response of pregnant pigs to increasing environmental temperatures using heart rate variability, a noninvasive measure commonly used to evaluate the physiological stress response. Our findings show that pregnant pigs, particularly those who are closer to giving birth, exhibit greater evidence of physiological stress compared to pigs who are not pregnant. However, we did not find evidence that increasing environmental temperature throughout the experimental period was a primary reason for the increased stress exhibited by pregnant pigs. It is possible that the physiological changes that normally occur during pregnancy may have masked the physiological stress response typically associated with increased heat exposure.
Asunto(s)
Respuesta al Choque Térmico , Reproducción , Animales , Femenino , Frecuencia Cardíaca , Embarazo , Porcinos , TemperaturaRESUMEN
Although nesting material is beneficial to the welfare of laboratory mice, provision of appropriate amounts may impair visualization of the mice. In anticipation of our academic research institution transitioning to providing 6 grams of nesting material to all mice, we conducted a 2-step prospective epidemiologic study to 1) evaluate whether 0, 2, or 6 grams of nesting material alters the ability to identify sick or dead mice, and 2) evaluate the number and severity of health concerns identified in the presence of 6 grams of crinkle paper nesting material at cage-side health check as compared with cage change. Animal Treatment Reports (ATRs) and death incidences were collected across a variety of research and breeding uses. This information was used to determine if nesting material prevented prompt identification of mice in need of veterinary attention. The clinical health condition category (CHCC) was determined based on the severity of the animal's health condition on initial veterinary exam. Additional assessment determined if the identification of the animal's condition was a success (early-stage or mild illness when first identified) or a failure (late-stage or endstage illness when first identified). Mice that died spontaneously were also assessed with regard to which observation activity was being performed at the time of the animal's identification (daily health check or cage change) and location of the mouse in relation to the nest. The results showed that nesting material did not cause a significant increase in the severity of CHCCs at the time reported for veterinary evaluation. Successful identification of health concerns occurred significantly more often than failures. Death rates were similar between all nesting groups, and dead mice were more likely to be located outside of the nest. In summary, nesting material did not hinder the ability to identify mice in need of veterinary care during routine cage-side health checks and did not critically affect the ability to identify mice that died spontaneously. These results indicate that mice can receive appropriate amounts of crinkle paper nesting material without lowering the ability of staff to recognize mice in need of veterinary attention.
Asunto(s)
Vivienda para Animales , Comportamiento de Nidificación , Animales , Ratones , Estudios ProspectivosRESUMEN
Housing pigs within their thermal comfort zone positively impacts productivity and performance. However, fundamental information on behavioral thermoregulatory responses of individual and group-housed pigs is meager. As a gregarious species, pigs prefer to be near one another, touching and often huddling. As pigs huddle together, they decrease their heat loss to the environment by decreasing exposed surface area and increasing mass. Additionally, pigs gain weight rapidly as they age. As an individual grows, their ability to withstand lower temperatures increases. We hypothesized that group size would alter pig thermal preference and that thermal preference would change based upon body weight. Thirty-six groups of pigs (n = 2 pigs/group) were tested in a factorial design based on group size (1, 2, or 4) and weight category (small: 5.20 ± 1.15 kg; medium: 8.79 ± 1.30 kg; and large: 13.95 ± 1.26 kg) in both sexes. Treatment groups were placed inside a chamber with a controlled thermal gradient (4.6 m × 0.9 m × 0.9 m; L × W × H) that ranged in temperature from 18 to 30 °C. Pigs habituated to the gradient for 24 h. The following 24 h testing period was continuously video recorded and each pig's location during inactivity (~70% daily budget) within the thermal apparatus was recorded every 10 min via instantaneous scan sampling. Data were analyzed using a GLM and log10 + 0.001 transformed for normality. Tukey tests and Bonferroni-corrected custom tests were used for post hoc comparisons. Peak temperature preference was determined by the maximum amount of time spent at a specific temperature. Both group size (p = 0.001) and weight category (p < 0.001) influenced the thermal location choice of pigs. Individual pigs preferred 30.31 °C, which differed from a group of 2 (20.0 °C: p = 0.003) and 4 pigs (20.0 °C: p < 0.001). The peak temperature preference of the small pigs (30.2 °C) differed from the large pigs (20.0 °C: p < 0.001) but did not differ from the medium-sized pigs (28.4 °C: p > 0.05). Overall, heavier pigs and larger groups preferred cooler temperatures.
RESUMEN
Aggression among group housed male mice continues to challenge laboratory animal researchers because mitigation strategies are generally applied at the cage level without a good understanding of how it affects the dominance hierarchy. Aggression within a group is typically displayed by the dominant mouse targeting lower ranking subordinates; thus, the strategies for preventing aggression may be more successful if applied specifically to the dominant mouse. Unfortunately, dominance rank is often not assessed because of time intensive observations or tests. Several correlates of dominance status have been identified, but none have been directly compared to home cage behavior in standard housing. This study assessed the convergent validity of three dominance correlates (urinary darcin, tube test score, preputial gland to body length ratio) with wound severity and rankings based on home cage behavior, using factor analysis. Discriminant validity with open field measures was assessed to determine if tube test scores are independent of anxiety. Cages were equally split between SJL and albino C57BL/6 strains and group sizes of 3 or 5 (N = 24). Home cage behavior was observed during the first week, and dominance measures were recorded over the second. After controlling for strain and group size, darcin and preputial ratio had strong loadings on the same factor, which was a significant predictor of home cage ranking showing strong convergent validity. Tube test scores were not significantly impacted by open field data, showing discriminant validity. Social network analysis revealed that despotic power structures were prevalent, aggressors were typically more active and rested away from cage mates, and the amount of social investigation and aggression performed by an individual were highly correlated. Data from this study show that darcin and preputial ratio are representative of home cage aggression and provide further insight into individual behavior patterns in group housed male mice.
RESUMEN
Gestating sows may be more susceptible to increasing dry bulb temperatures (TDB) due to greater metabolic heat production and increased body mass, especially as gestation advances. However, there are few studies on the thermoregulatory and physiological responses of sows at differing gestation stages exposed to gradually increasing temperatures. The study objective was to determine the thermoregulatory and physiological responses of nonpregnant (n = 12; parity 3.27 ± 0.86), mid-gestation (59.7 ± 9.6 d pregnant, n = 12; parity 3.25 ± 0.83), and late-gestation (99.0 ± 4.8 d pregnant, n = 12; parity 3.33 ± 0.75) sows exposed to increasing TDB. Prior to the experiment (5.0 ± 0.7 d), jugular catheters were placed in all sows. During the experiment, the TDB was increased incrementally by 2.45 ± 0.43 °C every 60 min from 19.84 ± 2.15 to 35.54 ± 0.43 °C over 400 min, and relative humidity was recorded at 40.49 ± 18.57%. Respiration rate (RR), heart rate (HR), skin temperature, and vaginal temperature were measured, and blood samples were obtained via the jugular catheter every 20 min. Data were analyzed using PROC MIXED in SAS 9.4. RR increased at a lower TDB (P < 0.01) in late-gestation sows compared with mid-gestation and nonpregnant sows, but no differences were detected between mid-gestation and nonpregnant sows. Overall, late-gestation sows had greater RR (P < 0.01; 23 ± 2 breaths per min [brpm]) compared with mid-gestation (16 ± 2 brpm) and nonpregnant (15 ± 2 brpm) sows. Late-gestation sows had an overall greater HR (P < 0.01; 84 ± 5 beats per min [bpm]) than mid-gestation (76 ± 5 bpm) and nonpregnant (69 ± 5 bpm) sows. Late-gestation sows had overall reduced bicarbonate and total carbon dioxide levels (P = 0.02; 23.89 ± 1.97 and 25.41 ± 2.07 mmol/L, respectively) compared with mid-gestation (27.03 ± 1.97 and 28.58 ± 2.07 mmol/L, respectively) and nonpregnant (26.08 ± 1.97 and 27.58 ± 2.07 mmol/L, respectively) sows. Moreover, late-gestation sows had overall greater nitric oxide levels (P < 0.01; 248.82 ± 34.54 µM) compared with mid-gestation (110.47 ± 34.54 µM) and nonpregnant (41.55 ± 34.54 µM) sows. In summary, late-gestation sows appear to be more sensitive to increasing TDB as indicated by thermoregulatory and physiological responses when compared with mid-gestation or nonpregnant sows. The results from this study provide valuable information regarding thermoregulatory thresholds of sows at differing gestation stages.
Asunto(s)
Regulación de la Temperatura Corporal , Lactancia , Alimentación Animal/análisis , Animales , Dieta , Femenino , Paridad , Embarazo , Porcinos , TemperaturaRESUMEN
The metabolic heat production of modern pigs has increased by an average of 16%, compared with sows of 30 years ago. Therefore, it is likely that temperature recommendations require updating to meet the needs of modern pigs. The objective of this study was to evaluate whether different reproductive stages of sows altered thermal preference and if current recommendations required updating. Twenty multiparous sows (3.4 ± 1.2 parity) in different reproductive stages (nonpregnant: n = 7; mid-gestation: 58.5 ± 5.68 d, n = 6; and late-gestation: 104.7 ± 2.8 d, n = 7) were tested. Thermal preference was individually tested, and sows could freely choose a temperature, using a thermal gradient between 10.4 and 30.5 °C. Sows were given 24 h to acclimate to the thermal apparatus. Before testing began, sows were given daily feed allotment and returned to the apparatus. Video from the 24-h test period was used to record sow behavior (time spent inactive), posture (upright and sternal and lateral lying), and location using instantaneous scan samples every 15 min. Data were analyzed using PROC MIXED procedure in SAS 9.4. A cubic regression model was used to calculate the sow's most preferred temperature based on the location, or temperature, in which they spent the most time. The preference range was calculated using peak temperature preference ±SE for each sow. The reproductive stage altered where sows spent their time within the thermal gradient (P < 0.01). Late-gestation sows preferred cooler temperatures (14.0 °C) than mid-gestation (14.8 °C; P < 0.01) and nonpregnant sows (14.8 °C; P < 0.01). In summary, sow thermal preferences were within the lower half of the current recommended range (10 to 25 °C). This indicates that temperatures at the higher end of the recommended range could be uncomfortable to sows and that the thermal comfort zone of sows may be narrower than recommendations indicate.
Asunto(s)
Lactancia , Reproducción , Animales , Femenino , Paridad , Embarazo , Porcinos , TemperaturaRESUMEN
Excessive home cage aggression often results in severe injury and subsequent premature euthanasia of male laboratory mice. Aggression can be reduced by transferring used nesting material during cage cleaning, which is thought to contain aggression appeasing odors from the plantar sweat glands. However, neither the composition of plantar sweat nor the deposits on used nesting material have been evaluated. The aims of this study were to (1) identify and quantify volatile compounds deposited in the nest site and (2) determine if nest and sweat compounds correlate with social behavior. Home cage aggression and affiliative behavior were evaluated in 3 strains: SJL, C57BL/6N, and A/J. Individual social rank was assessed via the tube test, because ranking may influence compound levels. Sweat and urine from the dominant and subordinate mouse in each cage, plus cage level nest samples were analyzed for volatile compound content using gas chromatography-mass spectrometry. Behavior data and odors from the nest, sweat, and urine were statistically analyzed with separate principal component analyses (PCA). Significant components, from each sample analysis, and strain were run in mixed models to test if odors were associated with behavior. Aggressive and affiliative behaviors were primarily impacted by strain. However, compound PCs were also impacted by strain, showing that strain accounts for any relationship between odors and behavior. C57BL/6N cages displayed the most allo-grooming behavior and had high scores on sweat PC1. SJL cages displayed the most aggression, with high scores on urine PC2 and low scores on nest PC1. These data show that certain compounds in nesting material, urine, and sweat display strain specific patterns which match strain specific behavior patterns. These results provide preliminary information about the connection between home cage compounds and behavior. Salient compounds will be candidates for future controlled studies to determine their direct effect on mouse social behavior.
Asunto(s)
Vivienda para Animales , Ratones , Agresión , Animales , Conducta Animal , Masculino , Ratones/fisiología , Ratones/orina , Ratones Endogámicos C57BL , Comportamiento de Nidificación , Odorantes/análisis , Conducta Social , Sudor/químicaRESUMEN
The practical application of statistical power is becoming an increasingly important part of experimental design, data analysis, and reporting. Power is essential to estimating sample size as part of planning studies and obtaining ethical approval for them. Furthermore, power is essential for publishing and interpreting negative results. In this manuscript, we review what power is, how it can be calculated, and reporting recommendations if a null result is found. Power can be thought of as reflecting the signal to noise ratio of an experiment. The conventional wisdom that statistical power is driven by sample size (which increases the signal in the data), while true, is a misleading oversimplification. Relatively little discussion covers the use of experimental designs which control and reduce noise. Even small improvements in experimental design can achieve high power at much lower sample sizes than (for instance) a simple t test. Failure to report experimental design or the proposed statistical test on animal care and use protocols creates a dilemma for IACUCs, because it is unknown whether sample size has been correctly calculated. Traditional power calculations, which are primarily provided for animal number justifications, are only available for simple, yet low powered, experimental designs, such as paired t tests. Thus, in most controlled experimental studies, the only analyses for which power can be calculated are those that inheriently have low statistical power; these analyses should not be used because they require more animals than necessary. We provide suggestions for more powerful experimental designs (such as randomized block and factorial designs) that increase power, and we describe methods to easily calculate sample size for these designs that are suitable for IACUC number justifications. Finally we also provide recommendations for reporting negative results, so that readers and reviewers can determine whether an experiment had sufficient power. The use of more sophisticated designs in animal experiments will inevitably improve power, reproducibility, and reduce animal use.
Asunto(s)
Experimentación Animal , Proyectos de Investigación , Tamaño de la Muestra , Animales , Humanos , Resultados Negativos , Reproducibilidad de los ResultadosRESUMEN
Aggression in male mice often leads to injury and death, making social housing difficult. We tested whether (1) small group size, (2) early age of allocation to a group decreases aggression and 3) manipulation increases aggression in male mice. A 14wk study was performed to assess the following conditions in male CD-1/ICR mice: group size (1, 2, or 3), age at grouping (5 or 7wks), and manipulation (daily scruffing or minimal weekly handling). Wounds, body weights, food consumption, nest scores, sucrose consumption, fecal corticosterone and blood for hematology were collected. At the end of the study, mice were euthanized and pelted to assess wounding with the pelt aggression lesion scale (PALS). No signs of acute or chronic stress were observed in any of the groups. Trio housed mice showed less bite wounds than pair housed mice. In general, mice in larger groups ate less but weighed more. Individually housed mice, however, had high nest scores, low body weights, and increased sucrose and food consumption. These results suggest that even when nesting material is provided, individual mice may be experiencing thermal stress. Based on this data, CD-1 mice can successfully be housed for up to 14wks and groups of 3 may be the best for reducing even minor levels of aggression (i.e. wounding).