Behavior Of Pups Research Articles

Diving behavior and swimming style of nursing bearded seal pups

Seals are born on land or ice and must acquire the diving and swimming skills required to forage and avoid predators during their early lives. While diving behavior, including swim speed and swimming style (e.g. prolonged gliding and stroke-and-glide swimming), of adult seals is well documented, knowledge regarding the diving behavior of pups is still limited to records of dive depth and duration measured by simple time-depth recorders. In the present study, we attached multi- sensor data loggers to 6 bearded seal Erignathus barbatus pups weighing between 33 kg (newborn) and 104 kg (close to weaning). The mean swim speed and the mean distance covered by a stroke cycle was lowest (0.5 m s -1 and 0.3 m, respectively) in the smallest pup and highest (0.9 m s -1 and 0.6 m) in the largest pup. The largest pup showed substantial periods (17% of transit time) of prolonged gliding, as adult seals commonly do. However, the 3 medium-sized pups glided only during <5% of the transit time, and the 2 smallest pups did not glide. Stroke-and-glide swimming was not observed in any pups. The stroke cycle frequency of the smallest pup was highly variable, while that of the largest pup was relatively stable. These results suggest that the swimming performance of the pups developed during the short nursing period.

Home seeking behavior in rat pups: Attachment vs. kin selection, oxytocin vs. vasopressin

We are interested in the rat as an animal model for infant–mother attachment. In the first experiment we tried to distinguish between a preference for familiar animals (attachment theory) and a preference for genetically related animals (kin selection theory) with the use of an early cross-fostering procedure. Genetic relationships did not influence preferences in cross-fostered pups on postnatal day17, only familiarity did. Subsequently we investigated if peptides known to influence affiliative behaviors were also effective in the present paradigm. Injection of oxytocin into the cisterna magna did not yield significant effects on preference, while vasopressin and desglycinamide-[Arg8]vasopressin reduced the preference in a dose dependent manner. The effect of vasopressin was completely blocked by pretreatment with the vasopressin V 1A receptor antagonist d(CH 2) 5Tyr(Me) 2,Arg 8-vasopressin. We discuss the explanatory power of attachment theory and kin selection theory with regard to preference experiments in rats and the usefulness of the rat as an animal model for infant–mother attachment.

Prenatal chlorpyrifos exposure alters motor behavior and ultrasonic vocalization in cd-1 mouse pups

BackgroundChlorpyrifos (CPF) is a non-persistent organophosphate (OP) largely used as pesticide. Studies from animal models indicate that CPF is a developmental neurotoxicant able to target immature central nervous system at dose levels well below the threshold of systemic toxicity. So far, few data are available on the potential short- and long-term adverse effects in children deriving from low-level exposures during prenatal life and infancy.MethodsLate gestational exposure [gestational day (GD) 14–17] to CPF at the dose of 6 mg/kg was evaluated in CD-1 mice during early development, by assessment of somatic and sensorimotor maturation [reflex-battery on postnatal days (PNDs) 3, 6, 9, 12 and 15] and ultrasound emission after isolation from the mother and siblings (PNDs 4, 7 and 10). Pups' motor skills were assessed in a spontaneous activity test on PND 12. Maternal behavior of lactating dams in the home cage and in response to presentation of a pup previously removed from the nest was scored on PND 4, to verify potential alterations in maternal care directly induced by CPF administration.ResultsAs for the effects on the offspring, results indicated that on PND 10, CPF significantly decreased number and duration of ultrasonic calls while increasing latency to emit the first call after isolation. Prenatal CPF also reduced motor behavior on PND 12, while a tendency to hyporeflexia was observed in CPF pups by means of reflex-battery scoring. Dams administered during gestation with CPF showed baseline levels of maternal care comparable to those of controls, but higher levels of both pup-directed (licking) and explorative (wall rearing) responses.ConclusionOverall our results are consistent with previous epidemiological data on OP neurobehavioral toxicity, and also indicate ultrasonic vocalization as an early marker of CPF exposure during development in rodent studies, with potential translational value to human infants.

Behavioural and Neurochemical Consequences of Early Weaning in Rodents

Among all mammalian species, pups are highly dependent on their mother not only for nutrition, but also for physical interaction. Therefore, disruption of the mother-pup interaction changes the physiology and behaviour of pups. We review how maternal separation in the early developmental period brings about changes in the behaviour and neuronal systems of the offspring of rats and mice. Early weaning in mice results in adulthood a persistent increase in anxiety-like and aggressive behaviour. The early-weaned mice also show higher hypothalamic-pituitary-adrenal activity in response to novelty stress. Neurochemically, the early-weaned male mice, but not female mice, show precocious myelination in the amygdala, decreased brain-derived neurotrophic factor protein levels in the hippocampus and prefrontal cortex, and reduced bromodeoxyuridine immunoreactivity in the dentate gyrus. Because higher corticosterone levels are persistently observed up to 48 h when the mice are weaned on postnatal day 14, the exposure of the developing brain to higher corticosterone levels may be one of the effects of early weaning. These results suggest that deprivation of the mother-infant interaction during the late lactating period results in behavioural and neurochemical changes in adulthood and that these stress responses are sexually dimorphic (i.e. the male is more vulnerable to early weaning stress).

Ontogeny of Circadian Organization in the Rat

The mammalian circadian system is orchestrated by a master pacemaker in the brain, but many peripheral tissues also contain independent or quasi-independent circadian oscillators. The adaptive significance of clocks in these structures must lie, in large part, in the phase relationships between the constituent oscillators and their micro- and macroenvironments. To examine the relationship between postnatal development, which is dependent on endogenous programs and maternal/environmental influences, and the phase of circadian oscillators, the authors assessed the circadian phase of pineal, liver, lung, adrenal, and thyroid tissues cultured from Period 1-luciferase (Per1-luc ) rat pups of various postnatal ages. The liver, thyroid, and pineal were rhythmic at birth, but the phases of their Per1-luc expression rhythms shifted remarkably during development. To determine if the timing of the phase shift in each tissue could be the result of changing environmental conditions, the behavior of pups and their mothers was monitored. The circadian phase of the liver shifted from the day to night around postnatal day (P) 22 as the pups nursed less during the light and instead ate solid food during the dark. Furthermore, the phase of Per1-luc expression in liver cultures from nursing neonates could be shifted experimentally from the day to the night by allowing pups access to the dam only during the dark. Peak Per1-luc expression also shifted from midday to early night in thyroid cultures at about P20, concurrent with the shift in eating times. The phase of Per1-luc expression in the pineal gland shifted from day to night coincident with its sympathetic innervation at around P5. Per1-luc expression was rhythmic in adrenal cultures and peaked around the time of lights-off throughout development; however, the amplitude of the rhythm increased at P25. Lung cultures were completely arrhythmic until P12 when the pups began to leave the nest. Taken together, the data suggest that the molecular machinery that generates circadian oscillations matures at different rates in different tissues and that the phase of at least some peripheral organs is malleable and may shift as the organ's function changes during development.

Neonatal handling and the maternal odor preference in rat pups: Involvement of monoamines and cyclic AMP response element-binding protein pathway in the olfactory bulb

Early-life environmental events, such as the handling procedure, can induce long-lasting alterations upon several behavioral and neuroendocrine systems. However, the changes within the pups that could be causally related to the effects in adulthood are still poorly understood. In the present study, we analyzed the effects of neonatal handling on behavioral (maternal odor preference) and biochemical (cyclic AMP response element-binding protein (CREB) phosphorylation, noradrenaline (NA), and serotonin (5-HT) levels in the olfactory bulb (OB)) parameters in 7-day-old male and female rat pups. Repeated handling (RH) abolished preference for the maternal odor in female pups compared with nonhandled (NH) and the single-handled (SH) ones, while in RH males the preference was not different than NH and SH groups. In both male and female pups, RH decreased NA activity in the OB, but 5-HT activity increased only in males. Since preference for the maternal odor involves the synergic action of NA and 5-HT in the OB, the maintenance of the behavior in RH males could be related to the increased 5-HT activity, in spite of reduction in the NA activity in the OB. RH did not alter CREB phosphorylation in the OB of both male and females compared with NH pups. The repeated handling procedure can affect the behavior of rat pups in response to the maternal odor and biochemical parameters related to the olfactory learning mechanism. Sex differences were already detected in 7-day-old pups. Although the responsiveness of the hypothalamic–pituitary–adrenal axis to stressors is reduced in the neonatal period, environmental interventions may impact behavioral and biochemical mechanisms relevant to the animal at that early age.

Grueneberg ganglion neurons respond to cool ambient temperatures

The Grueneberg ganglion (GG) - a neuronal cell cluster of unknown function localized to the vestibule of the anterior nasal cavity - is considered as a chemosensory compartment based on the expression of olfactory receptors and the olfactory marker protein. Axonal projection of GG neurons to so-called 'necklace glomeruli' in the olfactory bulb of the brain, which are thought to be important for suckling behaviour in rodent pups, has led to the hypothesis that the GG might be involved in mother/child interactions. To survey potential activation of GG neurons in living animals during the course of mother/child interactions, expression of the activity-dependent gene c-Fos in the GG of neonatal mouse pups was monitored in the presence and absence of the dam. It was found that GG neurons were only activated in the absence of the mother. Moreover, GG activation was independent from olfactory cues as revealed by naris occlusion. Searching for stimuli eliciting GG activity in pups separated from the dam, cool ambient temperatures were found to induce strong c-Fos expression in GG neurons whereas warmer temperatures did not. These coolness-induced responses were only observed in a distinct subset of GG neurons characterized by the expression of the olfactory receptor V2r83. Finally, GG responsiveness to coolness was remarkably reduced in older stages. In summary, these findings suggest that the GG of neonatal mice is activated by cool ambient temperatures to which they are exposed in the absence of their dam, indicating that the GG might function as a thermosensor.

Pup development and maternal behavior in captive Key Largo woodrats (Neotoma floridana smalli)

This study describes the first systematic observations of maternal behavior and pup development of captive Key Largo woodrats (Neotoma floridana smalli) during the first 30 days of life. Data were collected on six litters of pups born to four dams between December 2006 and July 2007. Gestations for the six litters averaged 38 days and all dams exhibited adequate maternal care postpartum. Key Largo woodrat maternal and pup behavior was generally consistent with behavior observed in other woodrat species. We observed greater pup independence from the dam and a marked change in social interactions between days 13-22. No sex differences in pup development or maternal care were observed. Activity budgets were consistent across dams and across days within the observation period. Although dams spent much of their time inactive with pups attached to their teats, the average percent of intervals with at least one pup observed attached decreased steadily during the 30-day observation period. Attachment of pups to the dams' teats did not interfere with dams' ability to forage. Feeding with pups attached and feeding following active detachment of pups were both common. Dams were observed to actively detach pups by performing a circular turning motion. This information has application for the future management of this endangered species in captivity and in the wild. Zoo Biol 27:394-405, 2008. (c) 2008 Wiley-Liss, Inc.

Effects of Genetic Background, Gender, and Early Environmental Factors on Isolation-Induced Ultrasonic Calling in Mouse Pups: An Embryo-Transfer Study

Infant rodents emit ultrasonic vocalizations when isolated from dam and littermates. Due to the context of their occurrence and the well described bidirectional modulation by substances known for their capability to influence emotionality, it was postulated that such calls reflect a negative affective state akin anxiety. Comparative studies observed pronounced differences in calling behavior between strains, which were paralleled by differences in maternal care. Therefore, it was recently hypothesized that early environmental factors may have strong impact on call production. Here, the relative contributions of genetic background, gender, and early environmental factors on calling behavior in C57BL/6JOlaHsd and C57BL/6NCrl were studied by using an embryo-transfer procedure. The results show that these sub-strains differ in the amount of calling and specific call features, like call frequency and amplitude. The embryo-transfer procedure indicated that the observed differences in the amount of ultrasonic calling are dependent on the dyadic interaction between mother and pup. Conversely, call features were primarily dependent on the genotype of the pup. Thus, call frequency and frequency modulation were solely dependent on the pup, i.e. its genotype and gender. However, there was one exception, namely call amplitude, which was solely dependent on the genotype of the mother, i.e. on early environmental factors. Furthermore, it was shown that particularly changes in call amplitude might be of high functional relevance, since a sub-strain dependent preference towards pups emitting calls with high amplitudes was observed. In total, it can be concluded that both genomic and nongenomic factors can tune calling behavior in mouse pups.

Neonatal PCP Is More Potent than Ketamine at Modifying Preweaning Behaviors of Sprague-Dawley Rats

Treatment with N-methyl-D-aspartate (NMDA) receptor antagonists, such as ketamine (KET) or phencyclidine (PCP), can trigger apoptotic neurodegeneration in neonatal rodents; however, little is known about the behavioral alterations resulting from such treatment. Here, rats were sc treated with saline; 10 mg/kg PCP on postnatal days (PNDs) 7, 9, and 11; 20 mg/kg KET (six injections every 2 h on PND 7); or a regimen of ketamine and 250 mg/kg L-carnitine (KLC) both administered on PND 7 with additional 250 mg/kg doses of L-carnitine given on PNDs 8-11. Postinjection, the home cage behavior of each pup was categorized on PNDs 7-11. Slant board and forelimb hang behaviors were examined on PNDs 8-11 and 12-16, respectively. The initial KET or KLC injections on PND 7 elevated abnormal home cage activity (i.e., paresis and paddling); however, KLC pup behavior returned to normal by the fourth injection, indicating the protective effects of L-carnitine against NMDA antagonist toxicity. PCP treatment caused substantial abnormal home cage activity on each injection day (PNDs 7, 9, and 11). Latencies to turn on the slant board were significantly longer on PND 8 for KET- and PCP-treated pups and PND 10 for PCP-treated pups. On PND 12, the forelimb hang time of PCP-treated pups was significantly shorter. Body weight was decreased on PNDs 8-18 in PCP-treated pups and PNDs 8-10 in KET-treated pups. These data indicate that developmental NMDA antagonist treatment causes short-term behavioral alterations which appear related to motor coordination and may be cerebellar in nature. Furthermore, single PCP injections appear more potent at altering behavior than multiple injections of KET.

Differences in diving and swimming behavior of pup and juvenile Steller sea lions (Eumetopias jubatus) in Alaska

Reduced juvenile survival caused by prey depletion is one hypothesis for the decline in the western Alaska population of Steller sea lions ( Eumetopias jubatus (Schreber, 1776)). To understand the exposure of young sea lions to these depletions, the swimming and diving behavior of pups, juveniles, and subadults was evaluated relative to prey behavior. Pups made shorter and shallower dives (13 m, 0.9 min) than juveniles or subadults, as expected based on physiological limitations, but juveniles and subadults dived to similar depths and durations (29 m, 1.7 min and 38 m, 2.0 min, respectively). Activity patterns of juveniles and subadults reflected diurnal prey migrations, while pup activity did not. Longitudinal trends in pup dive behavior reflected both physiological and behavioral development, while juvenile dive behaviors reflected seasonal changes in prey availability. Results suggest that adult females must continue to provide nutritional support to pups during winter because of the limited diving ability of these young animals. For this reason, the flexible lactation strategies that allow for longer nursing periods during periods of low prey availability and reduce female fecundity may improve juvenile survival.

Variation in pup vocalisations and mother‐pup behaviour between harp seal whelping patches: effects of climate or geography

Harp seals breed in pack‐ice, a substrate which can vary substantially between whelping patches depending on differing environmental and oceanographic conditions. This study demonstrates clear site differences in pup vocalizations and mother pup behaviour between Northeast (Greenland Sea) and Northwest (Canadian Front) Atlantic harp seal populations. Classification trees showed a distinctive split between Front and Greenland Sea pup vocalisations. No clear sex differentiation in vocalizations was present for pups at the Front; 42% (n = 12) of male and 38% (n = 13) of female calls could be attributed to a given individual. In the Greenland Sea, 55% (n = 42) of female vocalisations were attributed to individuals compared with only 8% for males (n = 47). In addition behavioural observations of mother pup pairs were conducted (Front, n = 58; Greenland Sea, n = 78). Greenland Sea pups were found to nurse more, and were more alert than Front pups. Female attendance patterns also differed between sites: females ...

Frequency of maternal licking and grooming correlates negatively with vulnerability to cocaine and alcohol use in rats

Because licking and grooming behavior of dams with pups can influence some behaviors of pups when they are adults, we tested if licking and grooming scores in a maternal separation protocol correlated with cocaine or ethanol self-administration in the pups as adults. The protocol produced litters that were separated from dams for 0 (MS0), 15 (MS15) or 180 (MS180) min, and a nonhandled (NH) group as well. Self-administration of both drugs as shown in earlier studies was lowest in the MS15 group, highest in the NH group and intermediate in the other groups. Licking and grooming scores correlated negatively with drug intake and suggests that maternal care of pups can influence drug use in pups when they are adults.

Rats selectively bred for low levels of 50 kHz ultrasonic vocalizations exhibit alterations in early social motivation

In rats, the rates of 50 kHz ultrasonic vocalizations (USVs) can be used as a selective breeding phenotype and variations in this phenotype can be an indicator of affective states. The 50 kHz USV is elicited by rewarding stimuli (e.g., food, sexual behavior) and therefore can express a positive affective state. Conversely, the 22 kHz USV is elicited by aversive stimuli (e.g., presence of a predator, social defeat) indicating a negative affective state. In the present study, we tested the effect of selectively breeding for 50 kHz USVs on a variety of maternal social/emotional behaviors in young rat pups (PND 10-12). These measures consisted of an assessment of isolation calls and conditioned odor preference paradigm. Results indicate that animals selected for low levels of 50 kHz USVs show the greatest alterations in social behaviors compared to the control animals. The low line animals had an increase in isolation calls tested during place preference conditioning and a decrease in 50 kHz ultrasonic calls in all conditions. These same low line animals failed to show a typical preference for a maternally-associated odor during the place preference test. The different social behaviors of the high line animals did not consistently vary from those of the control group. These results have important implications for the study of genetic and epigenetic mechanisms underlying emotional states, and possibly contribute to the research underlying the emotional changes in developmental disorders such as autistic spectrum disorder by providing a novel animal model that displays communication deficits that are interdependent with significant social behavioral impairments.

Learning behavior in rat offspring after in utero and lactational exposure to either TCDD or PCB126

We studied and compared the possible effects of in utero and lactational exposure to 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) or 3, 3', 4, 4', 5-pentachlorobiphenyl (PCB126) on learning behavior in offspring. Pregnant Long-Evans Hooded rats were administered either TCDD (50, 200, or 800 ng/kg) or PCB126 (500, 2,000 or 8,000 ng/kg) on gestational day 15. A procedure of schedule-controlled operant behavior was applied to examine learning behavior in the male and female offspring at 11 weeks of age for 30 days. Three indices, namely, response rates in a fixed ratio (FR) and in a differential reinforcement of low rates (DRL), and reward rate in the DRL component in multiple FR 20 DRL 20 s (mult-FR 20 DRL 20-s) test sessions, were used for the evaluation of learning behavior. Toxic effects on learning behavior in male and female pups following in utero and lactational exposure to TCDD or PCB126 were observed mainly in the FR learning component. However, no linear dose-dependent effects of either of the two compounds were observed for the above three indices. The response rates of animals in the low-dose TCDD and PCB126 groups decreased and those in medium-dose TCDD and PCB126 groups appeared to induce hyperactive behavior. The high dose of PCB126 appeared to have a distinct toxicity from that of TCDD in terms of the acquisition of learning behavior. Toxicities of PCB126 and TCDD in learning behavior might be similar to each other and the current toxic equivalency factor (TEF) of 0.1 for PCB126 can be considered to be appropriate for this endpoint.

Changing supply and demand by cross-fostering: effects on the behaviour of pups and mothers in guinea pigs, Cavia aperea f. porcellus, and cavies, Cavia aperea

The regulation of parental supply and offspring demand was modelled for altricial birds. The situation might differ for precocial species, where offspring can also feed themselves. We investigated the effect of supply and demand on mother–offspring interaction in precocials by cross-fostering pups between the domestic guinea pig and its ancestor, the cavy. The two are closely related, yet guinea pigs are heavier and produce more milk than cavies. We thus created a low-supply situation for pups raised by cavy mothers and a high-supply situation for pups raised by guinea pigs. Females nursing cavy pups confront low demand; those nursing guinea pig pups confront high demand. Pups in a high-supply situation showed more sucking attempts than pups in a low-supply situation, indicating a positive effect of supply on demand. High-demand pups showed more sucking attempts than low-demand pups. Mothers with high-demand pups nursed more frequently and spent more time nursing than mothers with low-demand pups. Milk production remained unaffected and timing of weaning was only slightly adjusted to the kind of pup fostered. Weaning was marked by decreasing of sucking attempts and maternal responsiveness and by increasing aggression. Mothers apparently received information about pup demand, but maternal state seemed to induce the weaning process largely independent of pup demands. The effect of supply on demand differed from predictions of current models. Differences in parent–offspring interaction in altricials and precocials deserve more research attention.

Effect of perinatal iron deficiency on myelination and associated behaviors in rat pups

Iron deficiency in early development has been associated with irreversible alterations in brain myelination, but whether these neural changes are mirrored in altered behaviors in rats is not known. The goals were to determine if dietary induced gestational and lactational iron deficiency alters brain myelination and behaviors dependent on that system. Pregnant rats were randomly assigned to control (CN) or iron-deficient (ID) groups by providing iron-sufficient (40 ppm Fe) or iron-deficient (2–6 ppm Fe) diets from gestational day 5 through to weaning of pups. Thereafter, all offspring were fed the iron-sufficient diet. The myelination of subcortical white matter and the fimbria of hippocampus was measured by 2′,3′-cyclic nucleotide 3′-phosphohydrolase (CNPase, marker of oligodendrocyte) density at 25 days of age. Specific behavioral assessments were performed at multiple time points after birth. By contrast, ID rats had significantly lower density of CNPase in the subcortical white matter but the density of CNPase in fimbria of hippocampus was comparable to CN rats. Moreover, ID rats showed significant behavioral impairments in surface righting reflex, negative geotaxis reflex, vibrissae-evoked forelimb placing test and novel object recognition task. In conclusion, perinatal iron deficiency can significantly alter behavioral outcomes which may be due to delayed myelination in specific brain regions.

Testing German shepherd puppies to assess their chances of certification

Behavioral activity of 7-week-old German shepherd puppies was tested and the activities analyzed if they could be used for predicting police efficiency of the individual. In total 206 individuals sired by 42 sires and 44 dams were used. The activities were divided into 10 tasks in which reactions and behavior of pups were scored from 0 to 5 points. All pups were tested separately from other conspecifics. Probability that the puppy will pass the certification was tested by a logistic regression. Of the 206 puppies, 148 passed the certification while 58 failed. Some tested behavioral variables were moderately to highly correlated with one another. Therefore we applied a factor analysis. Three factors were retained accounting for 100% of the shared variance. After inspection of the rotated factor pattern matrix and its confidence intervals, it appeared that variables “Independent movement and interactions with the tester”, “Negotiating obstacles”, “Entering a room”, “Behavior toward a person”, and “Behavior in new environments” loaded on Factor 1 (“Factor for movement”), while variables “Response to distracting stimuli caused by a shovel”, “Response to a distracting noise while left alone in a room”, and “Response to loud distracting stimuli” on Factor 2 (“Factor for responding to noise”) and variables “Retrieval” and “Tug of war” on Factor 3 (“Factor for attitude to predation”). In the final logistic regression model, the probability that the puppy will pass the certification depended on the higher weight at the time of testing ( χ ( 1 ) 2 = 12.00 , P = 0.0005), on the “Factor for attitude to predation” ( χ ( 1 ) 2 = 11.63 , P = 0.0007), on the “Factor for responding to noise”, where the higher the score, the weaker was the response ( χ ( 1 ) 2 = 5.16 , P = 0.0232), and on the “Factor for movement” showing an increasing probability with decreasing score ( χ ( 1 ) 2 = 5.25 , P = 0.0219). The tests in our study seem to be a good base which might enable selection for suitable dogs as early as 7 weeks of age. The puppies having high probability to pass certification in adulthood were heavy individuals willing to chase, catch, and fetch a tennis ball, and follow a rag drawn away from them, while weakly responding to a distracting noise in various situations and showing low activity while negotiating obstacles and moving and interacting with the tester. To conclude, contrary to skeptical assumptions expressed by various authors, the specific puppy tests for police dogs provide a reliable tool for predicting future service ability of a puppy. Differences in methodology are likely to contribute to a lack of consensus among various studies.

P.1.d.010 Interaction between dopaminergic and food derived opioid regulation of mother dependent behaviour of albino rat pups

P.1.d.010 Interaction between dopaminergic and food derived opioid regulation of mother dependent behaviour of albino rat pups

Social deficits in BTBR T + tf/J mice are unchanged by cross-fostering with C57BL/6J mothers

Inbred strains of mice are useful model systems for studying the interactions of genetic and environmental contributions during neurodevelopmental stages. We recently reported an inbred strain, BTBR T+tf/J (BTBR), which, as compared to the commonly used C57BL/6J (B6) strain, displays lower social interactions as juveniles, lower social approach in adult ages, and higher levels of repetitive self-grooming throughout developmental stages. The present study investigated whether the early postnatal maternal environment contributes substantially to the unusually low expression of social behaviors and high self-grooming in BTBR as compared to B6. Within 24h of birth, entire litters of pups were cross-fostered to either a dam of the same strain or a dam of the opposite strain. Control litters were left with their own mothers. Offspring were tested for juvenile play at postnatal day 21±1, for sociability at 8 weeks of age in an automated three-chambered social approach test, and for self-grooming at 9–11 weeks of age. Results indicate that deficits in play behaviors in juvenile BTBR pups were not rescued by a B6 maternal environment. Similarly, a BTBR maternal environment did not induce play deficits in B6 pups. Cross-fostering had no effect on sociability scores in adults. The high self-grooming in BTBR and low self-grooming in B6 were not affected by maternal environment. These findings favor a genetic interpretation of the unusual social behaviors and self-grooming traits of BTBR, and support the use of the BTBR inbred strain as a mouse model to study genetic mechanism of autism.