Exploration of early social behaviors and social styles in relation to individual characteristics in suckling piglets.

Social behavior is a key component of pig welfare on farms, but little is known on the development of social behaviors in piglets. This study aimed to explore social behaviors and identify early social styles in suckling piglets. Social behaviors of 68 piglets from 12 litters were scored continuously for 8 h per day at 21 and 42 days of age, and were included in a Hierarchical Clustering on Principal Components analysis to identify clusters of pigs with similar social styles. Social nosing represented 78% of all social interactions given. Three social styles were identified: low-solicited inactive animals (inactive), active animals (active), and highly-solicited avoiders (avoiders). Belonging to a cluster was independent of age, but was influenced by sex, with females being more represented in the 'inactive' cluster, and males in the 'active' cluster, whereas both sexes were equally represented in the 'avoider' cluster. Stability of piglets' allocation to specific clusters over age was high in the 'inactive' (59%) and 'active' (65%) clusters, but low in the 'avoider' cluster (7%). Haptoglobin and growth rate were higher in 'active' than 'inactive' pigs, and intermediate in 'avoiders'. Our findings suggest the existence of transient social styles in piglets, likely reflective of sexual dimorphism or health status.

Effect of cow-calf contact on cow motivation to reunite with their calf.

Early cow-calf separation prevents much of cows' natural maternal behaviour. Early separation is thought to prevent the development of a cow-calf bond. To assess this bond, we measured motivation of dairy cows to reunite with their calf. To vary the degree of bonding, some cows were allowed continued contact with their calf and others were separated from their calf soon after birth, following standard practice on most farms. Among cows allowed continued contact, some were able to suckle their calf and others were prevented from suckling (by covering the cow's udder with an udder net). Cows were habituated to the weighted-gate apparatus before calving by daily training with the (un-weighted) gate. After calving, cow willingness to use the gate was assessed by determining if she would push open the gate to access to her own calf. Testing occurred once daily, with weight on the gate gradually increased. After passing through the gate, the dam's calf-directed behaviour was recorded. Suckled cows pushed a greater maximum weight (45.8 ± 7.8 kg) than separated cows (21.6 ± 6.7 kg) and non-suckled cows (24.3 ± 4.5 kg), with no differences between separated and non-suckled cows. Once reunited, latency to make nose contact and duration of licking did not differ between treatments. We conclude that motivation for calf contact is greater for cows that are suckled.

Perinatal Docosahexaenoic Acid Supplementation Improves Cognition and Alters Brain Functional Organization in Piglets.

Epidemiologic studies associate maternal docosahexaenoic acid (DHA)/DHA-containing seafood intake with enhanced cognitive development; although, it should be noted that interventional trials show inconsistent findings. We examined perinatal DHA supplementation on cognitive performance, brain anatomical and functional organization, and the brain monoamine neurotransmitter status of offspring using a piglet model. Sows were fed a control (CON) or a diet containing DHA (DHA) from late gestation throughout lactation. Piglets underwent an open field test (OFT), an object recognition test (ORT), and magnetic resonance imaging (MRI) to acquire anatomical, diffusion tensor imaging (DTI), and resting-state functional MRI (rs-fMRI) at weaning. Piglets from DHA-fed sows spent 95% more time sniffing the walls than CON in OFT and exhibited an elevated interest in the novel object in ORT, while CON piglets demonstrated no preference. Maternal DHA supplementation increased fiber length and tended to increase fractional anisotropy in the hippocampus of offspring than CON. DHA piglets exhibited increased functional connectivity in the cerebellar, visual, and default mode network and decreased activity in executive control and sensorimotor network compared to CON. The brain monoamine neurotransmitter levels did not differ in healthy offspring. Perinatal DHA supplementation may increase exploratory behaviors, improve recognition memory, enhance fiber tract integrity, and alter brain functional organization in offspring at weaning.

Neonatal Suckling, Oxytocin, and Early Infant Attachment to the Mother.

The neuropeptide oxytocin (OT) promotes maternal care and social affiliation in adults but its importance in infant attachment still remains unknown. True animal models of infant attachment are extremely rare, and the sheep (in complement to non-human primates) is one of the few that provides the opportunity to investigate its neuroendocrinological basis. In the lamb, access to the udder has strong rewarding properties for the establishment of a preferential relationship with the mother. Therefore, the present study explored the possible involvement of OT through its release during close social contacts with the mother. The first experiment revealed that lambs having free access to the udder from birth onward developed, by 12 h of age, a clear preference for their mothers over another maternal ewe. Delaying access to the udder for six, four or even only 2 h starting at birth, by covering the ewe's udder, resulted in the lack of such a preference without affecting general activity. These effects persisted in most cases at 24 h but by 72 h of age a bond with the mother was clearly expressed. Experiment two showed that social interactions with the mother were followed by a release of OT in the plasma when lambs had the possibility to suckle. Non-nutritive interactions were without effects. Preliminary data on two subjects suggested that OT might also increase in the cerebrospinal fluid after suckling. Finally, in the third experiment, oral administration of a non-peptide OT receptor antagonist (L-368-899, Merck) over the first 4 h after birth led to decreased exploration of the mother's body compared to lambs receiving saline, and impaired the expression of a preference for the mother at 24 h. The effects were no longer observed at 48 h. Our findings demonstrate that both delayed access to the mother's udder and OT receptor antagonist alter the onset of mother preference in newborn lambs. This suggests that central OT facilitates the development of filial attachment through its release during suckling.

Positive or negative emotion induced by feeding success or failure can affect behaviors, heart rate and immunity of suckling calves.

This study investigated behavioral and physiological responses of suckling calves to either positive or negative situations. Twelve healthy female suckling Holstein calves at approximately 30 days of age were randomly selected and allocated to two groups: a) a positive situation (POS) group that received a feed reward and b) a negative situation (NEG) group that experienced food frustration. Behavior, heart rate (HR), and immune parameters were measured during the emotion-inducing periods and analyzed via ANOVA. The results indicated that the POS calves showed significantly increased locomotive play but decreased self-grooming, head shaking, and tongue-rolling behaviors as compared to the NEG counterparts (p < .05). The NEG calves had the highest HR (p < .01) after negative emotion induction. Salivary cortisol (S-CORT) level significantly increased following both positive and negative emotional induction (p < .05). In humoral immunity, serum concentrations of IgA were not significantly affected by either the positive or negative situation (p > .05), but the salivary SIgA level of the POS calves was higher than that of the NEG group (p < .01). Serum IL-2 and IL-3 levels in the POS calves were significantly higher than those of the NEG group (p < .01). However, the serum TNF-α level in the POS group was significantly lower than in the NEG group (p < .05). The results suggest that hunger satiation or food frustration may induce different behavioral and physiological responses in suckling calves, presenting an interesting set of reactions appropriate in response to the emotional situations elicited by this short-term stimulus.

Postpartum oestrous cycling resumption of yak cows following different calf weaning strategies under range conditions.

Early weaning can improve body condition and reproductive performance of cows. The objectives of this study were to examine and compare oestrous cycling resumption, behaviour and blood parameters of yak cows following four different strategies of calf weaning. Twenty-six yak cows (4-8 years) and their calves (94.3 ± 2.4 days) were studied in which calves were: weaned naturally with free access to their mothers (NW; n = 13); weaned abruptly and separated permanently from their mothers (PW; n = 5); separated temporarily from their mothers for 15 days (TW; n = 5); and fitted with nose plates for 15 days, but allowed free access to their mothers (NP; n = 3). Yak cows with sucking calves (NW) spent more time grazing in the cold season (from d 39 to 84). Based on serum progesterone concentrations, none of nine NW yak cows resumed oestrous cycling during the study, while seven of nine yak cows with weaned calves resumed cycling (3/3 for PW; 2/3 for TW; and 2/3 for NP yaks). We concluded that early weaning improved postpartum reproductive performance of yak cows on the Qinghai-Tibetan plateau and that abrupt and permanent weaning was an appropriate strategy.

Interactions between fawns and does of farmed fallow deer Dama dama in the postnatal period.

The aim of the present study was to describe the suckling behavior of the offspring of farmed European fallow deer Dama dama in the postnatal period. Video surveillance footage from the first 18 days postpartum was analyzed in detail to reveal that the duration of interactions between the mother and the offspring changed with the fawns' age. The duration of mother-offspring interactions was longest between postpartum days 12 and 18. The frequency of interactions at different times of the day varied in the analyzed periods. The results of the study could be used to increase the welfare of farmed deer.

Prenatal transportation stress alters temperament and serum cortisol concentrations in suckling Brahman calves.

This experiment examined the relationship between prenatal stress and subsequent calf temperament through weaning. The prenatal stressor used was repeated transportation of pregnant Brahman cows for 2 h at 60 ± 5, 80 ± 5, 100 ± 5, 120 ± 5, and 140 ± 5 d of gestation. Prenatally stressed calves ( = 41) were compared with controls ( = 44; dams did not undergo transportation during pregnancy) from 2 wk of age until weaning (average age at weaning = 174.8 ± 1.3 d). Temperament was defined by pen score (PS; 1 = calm and 5 = excitable), exit velocity (EV; m/sec), and temperament score (TS; (PS + EV)/2) and was recorded for each calf on d -168, -140, -112, -84, -56, -28, and 0 relative to weaning (d 0 = weaning). Cortisol concentrations were determined in serum samples obtained on d -168, -140, -28, and 0 relative to weaning. Birth weight and weaning weight were not different between treatment groups ( > 0.1). Pen score was greater ( = 0.03) in prenatally stressed calves (2.84 ± 0.21) relative to controls (2.31 ± 0.21). Exit velocity was greater ( < 0.01) in prenatally stressed calves (2.1 ± 0.14 m/sec) than in controls (1.61 ± 0.14 m/sec). Exit velocity was affected by a treatment × calf sex interaction ( = 0.04) and was greater in prenatally stressed females. Exit velocity was also affected by day ( < 0.0001). Temperament score was greater ( = 0.01) in prenatally stressed calves (2.45 ± 0.16) than in controls (1.95 ± 0.16). Temperament score was affected by day ( < 0.01). Basal cortisol concentrations were greater ( = 0.04) in prenatally stressed calves (15.87 ± 1.04 ng/mL) than in controls (13.42 ± 1.03 ng/mL). Basal cortisol concentrations were greater ( < 0.01) in females (16.61 ± 1.06 ng/mL) than in males (12.68 ± 1.02 ng/mL). Cortisol concentrations were positively correlated ( < 0.01) with PS ( = 0.55, < 0.01), EV ( = 0.4, < 0.01), and TS ( = 0.55, < 0.01). Overall, suckling Brahman calves that were prenatally stressed were more temperamental and had greater circulating serum concentrations of cortisol than control calves.

Tear staining in pigs: a potential tool for welfare assessment on commercial farms.

Tear staining or chromodacryorrhea refers to a dark stain below the inner corner of the eye, caused by porphyrin-pigmented secretion from the Harderian gland. It has been shown to be a consistent indicator of stress in rats and to correlate with social stress and a barren environment in pigs. The current study was, to our knowledge, the first to test it on commercial pig farms as a potential welfare indicator. The study was carried out on three commercial farms in Finland, in connection to a larger study on the effects of different types of manipulable objects on tail and ear biting and other behavioural parameters. Farm A was a fattening farm, on which 768 growing-finishing pigs were studied in 73 pens. Farm B had a fattening unit, in which 656 growing-finishing pigs were studied in 44 pens, and a farrowing unit, in which 29 sows and their litters totalling 303 piglets were studied in 29 pens. Farm C was a piglet-producing farm, on which 167 breeder gilts were studied in 24 pens. Data collection included individual-level scoring of tear staining; scoring of tail and ear damage in the growing-finishing pigs and breeder gilts; a novel object test for the piglets; and a novel person test for the growing-finishing pigs on Farm B and the breeder gilts on Farm C. On Farm A, tear staining was found to correlate with tail damage scores (n=768, rs=0.14, P<0.001) and ear damage scores (n=768, rs=0.16, P<0.001). In the growing-finishing pigs on Farm B, tear staining of the left eye correlated with tail damage (n=656, rs=0.12, P<0.01) and that of the right eye correlated with ear damage (n=656, rs=0.10, P<0.01). On Farm A, tear-staining sores were lower in the treatment with three different types of manipulable objects as compared with controls (mean scores 3.3 and 3.9, respectively, n=31, F29=4.2, P<0.05). In the suckling piglets on Farm B, tear staining correlated with the latency to approach a novel object (n=29, rp=0.41, P<0.05). Although correlations with tail and ear damage were low, it was concluded that tear staining has promising potential as a new, additional welfare indicator for commercial pig farming. Further research is needed on the mechanisms of tear staining.

Early-life object exposure with a habituated mother reduces fear reactions in foals.

Fear reactions in horses are a major cause of horse-human accidents, and identification of effective pathways for reduction in fearfulness can help decreasing the frequency of accidents. For a young mammal, the mother is one of the most salient aspects of its environment, and she can have a strong influence on her offspring's behaviour. This study investigated whether fearfulness in foals can be reduced through weekly exposure to usually frightening objects with a habituated mother during the first 8 weeks of life. Prior to foaling, mares (N = 22) were habituated to five initially fear-eliciting situations, including exposure to novel stationary and moving objects. At birth, the foals were randomly assigned to either a Demonstration group (N = 11) or a Control group (N = 11). Demonstration mares demonstrated habituation towards the objects to their foals once per week in weeks 1-8 post-partum. Control mares were inside the empty test arena with their foals for the same amount of time. The foals were tested at 8 weeks and 5 months of age in four standardised fear tests. Demonstration foals showed significantly reduced fear responses (behaviour and heart rate) and increased exploratory behaviour at both 8 weeks and 5 months of age. The effect was likely achieved through a combination of maternal transmission and individual learning. It is concluded that fearfulness in foals may be reduced through exposure to frightening objects together with their habituated mother during the first 8 weeks of life.

Caracterización del metabolismo óseo mineral en pacientes con enfermedad renal crónica en hemodiálisis en el Servicio de Salud Metropolitano Sur, Santiago de Chile / Bone mineral metabolism in patients with chronic kidney disease on dialysis in Southern Metropolitan Santiago

Background: Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) is a condition of dialysis patients associated with both morbidity and mortality. Management is based on clinical guidelines with goals that are hard to comply with. Aim: To describe and compare biochemical variables associated with this disorder in two different time periods. Material and Methods: Revision of medical records of 814 patients (49% females) dialyzed during 2009 and 1018 patients (48% females), dialyzed during 2012 in Southern Metropolitan Santiago. Information about serum calcium, phosphorus, parathyroid hormone (PTH) and albumin was retrieved. Results: Median PTH values in 2009 and 2012 were 222.5 and 353.5 pg/ml respectively (p < 0.05). The figures for serum calcium corrected by albumin were 9.0 and 8.5 mg/dl respectively (p < 0.05). The figures for phosphorus were 4.7 and 5.0 mg/dl respectively (p < 0.05). The Calcium x Phosphorus product was 41.4 and 42.5 mg²/dl² (p < 0.05). Of note, the proportion patients with serum calcium below recommended levels (< 8.4 mg/dl) increased from 16% to 40% from 2009 to 2012. The proportion of patients with biochemical variables within recommended ranges was lower in 2012 than in 2009. Conclusions: There was a low proportion of patients with bone metabolism parameters within ranges recommended by clinical guidelines. These parameters were worst in 2012.

Allosuckling in reindeer (Rangifer tarandus): milk-theft, mismothering or kin selection?

Allosuckling, the suckling of offspring from females other than their own mother, has been reported in a number of mammalian species, including reindeer. The causes and function of this behaviour are still being investigated. We monitored 25 doe-calf pairs of semi-domestic reindeer Rangifer tarandus over 10 weeks to test three allosuckling/allonursing hypotheses: (1) milk theft, calves opportunistically allosuckle; (2) mismothering, misdirected maternal care; and (3) kin-selected allonursing. A calf soliciting an allosuckling bout was categorized as non-filial (NF), and a calf soliciting a suckling bout from its mother was categorized as filial (F). We recorded 9757 solicitations, of which 5176 were successful F bouts and 1389 were successful NF bouts. The rejection rates were greater for NF than F calves. The proportions of antiparallel positions adopted were greater for F than NF calves. The odds of an allobout were lower for calves arriving 1st, 3rd, 4th, 5th or 6th than for those arriving 2nd, but the odds did not vary with position adopted and relatedness. Our results provided support to the milk-theft hypothesis, whereas limited support for the mismothering hypothesis was found. Our results did not support the hypothesized kin selection function of allosuckling in reindeer. This article is part of a Special Issue entitled: insert SI title.

Relationships of neonatal plasma oxytocin with the behavioral characteristics of cattle introduced into a novel environment.

To examine the influence of postnatal oxytocin (OXT) on behavioral development, we examined individual variations in basal OXT and suckling-induced changes in OXT, and their relationship with emotional traits during development. Blood OXT were measured in 20 Holstein heifer calves at 1 (wk1), 2 (wk2), and 6 weeks of age (wk6). The relationships of OXT variables with principal component scores in the open-field tests at wk2 and 2 months and the number of flinch, step and kick responses during first artificial insemination and machine milking were analyzed. The basal OXT showed individual variability and significantly correlated (wk1 vs. wk2: r = 0.753, P < 0.001; wk1 vs. wk6: r = 0.499, P < 0.05; wk2 vs. wk6: r = 0.476, P < 0.05). The personality traits reflecting a response in the form of escape from novel environments in the open-field test at wk2 were inversely correlated with basal OXT at wk1 (rs = -0.640, P < 0.01) and wk2 (rs = -0.447, P < 0.05). However, none of the behavioral variables after 2 months correlated with OXT. These findings suggest that, postnatal OXT might be related to behavioral characteristics in novel environments only during the early stages of life.

Behavioural response of grazing lambs to changes associated with feeding and separation from their mothers at weaning.

This study aimed to determine which behaviours were provoked in lambs in response to the separation from their dams or to the changes associated with feeding and separation from adults at weaning. Fourteen lambs were separated from their dams at 24-36 h after birth and artificially reared (AR) in presence of four adult ewes, while another 13 lambs remained with their dams from birth (DR). At 75 days of age on average (day 0) DR lambs were separated from their dams and AR lambs no longer received sheep's milk and were separated from adults. Behaviours were recorded every 10 min (6h per day) from day -3 to day 4. We observed an increase (p<0.05) in pacing behaviour, as well as in the frequency in which lambs were observed vocalizing, walking and staying under shade, and a decrease (p<0.05) in the frequency of grazing in the DR group in comparison to AR at weaning, but there were no differences in body weight gain from day -4 to day 5 after weaning. Additionally, we observed a decrease in the frequency in which lambs were observed standing and grazing (p<0.05), and an increase in vocalizing and staying under shade (p<0.05) in group AR at weaning in comparison to the previous days. Therefore, it was concluded that although some specific behaviours as pacing or vocalizing were clearly related with the separation from the mother at weaning, the change of food and separation from adults must be also considered as an important stressor in grazing lambs at weaning. In addition, the provision of shade when grazing is also important for lambs at the time of weaning.

Piglet behavior as a measure of vitality and its influence on piglet survival and growth during lactation.

The aim of the study was to develop a vitality scoring method, based on piglet behavior and relate it to piglet growth and survival. From 21 sows (Sus scrofa), 287 piglets were used. After farrowing (d 0), piglets were weighed and tested for 4 behavioral parameters in a circular enclosure (55 cm diam.): movement capacity (M), udder stimulation (U), number of completed circles around the enclosure (NCC), and screaming (Sc). Piglets were weighed again on d 1, 2, 3, and 17. Piglet rectal temperature (RT) was recorded on d 0, 1, 2, and 3. Farrowing information of the sow was also recorded. Multiple regression analyses for survival and BW gain at weaning as dependent variables were performed. Piglet BW gain at weaning was influenced by BW at birth (P < 0.001), sow parity (P = 0.024), total number of piglets born alive per sow (P < 0.001), and sum of U and NCC parameters (UN; P = 0.023). Piglet survival during lactation was influenced by BW at birth (P = 0.015), UNCC parameter (P = 0.026), and RT on d 3 (P = 0.085). The sum of U and NCC parameters, in combination with BW at birth and information of the sow, might be useful to predict piglet growth survival during lactation, thus becoming a useful tool to improve piglet management during the first days of lactation. In conclusion, UNCC parameter seems to be an easy and useful way to assess piglet vitality for both scientific and commercial purposes.

Lateralized suckling in domestic horses (Equus caballus).

Brain lateralization enables preferential processing of certain stimuli and more effective utilization of these stimuli in either the left or the right cerebral hemisphere. Horses show both motor and sensory lateralization patterns. Our aim was to determine whether a lateralized response could be detected in foals during the naturally side-biased behaviour, suckling. The foals' preferred suckling side could be the effect of either visual or motor lateralization. In the case of a visual lateralized response, foals are expected to suck more often from the mother's right side, so potential danger can be detected by the better adapted right hemisphere (i.e. left eye). Motor lateralization can be identified when a foal will suck predominantly from one side, either left or right. We found no population trend in the preferred suckling side, but we detected significant differences amongst individual foals. One-third (35.4 %) of 79 foals showed a strong, either right or left side preference which increased with age. The mothers did not influence the foals' suckling side preferences either by side-biased rejection or termination of suckling. According to our findings, a general pattern of sucking with the left eye open for better danger detection and recognition is unlikely in foals up to 7 months old. Foals of this age are probably young or fully focused on suckling and rely on their mothers' vigilance. Individual side preferences amongst foals are suggested to be based on motor lateralization.

Fostering in mice induces cardiovascular and metabolic dysfunction in adulthood.

Cross-fostering is widely used in developmental programming studies to determine the relative contribution of the in utero and suckling periods in establishing the adult offspring phenotype in response to an environmental challenge. We have investigated whether the process of fostering per se influences cardiovascular and metabolic function in adult offspring of C57BL/6J mice in comparison with animals suckled by their biological dams. Cross-fostered (CF) mice demonstrated juvenile onset hyperphagia and significantly higher body weight (from weaning to 12 weeks: male control (CON) vs. CF: P < 0.01, female CON vs. CF: P < 0.001; RM ANOVA) accompanied by increased abdominal adiposity in males only (white adipose tissue mass (mg): CON 280.5 ± 13.4 [mean ± SEM] (n = 7) vs. CF, 549.8 ± 99.3 (n = 8), P < 0.01). Both male and female CF mice demonstrated significantly enhanced glucose tolerance. A marked increase in systolic blood pressure (SBP) was observed in male CF mice (SBP (mmHg), day: CON 100.5 ± 1.4 (n = 6) vs. CF 114.3 ± 0.7 (n = 6), P < 0.001; night: CON 108.0 ± 2.0 (n = 6) vs. CF 123.2 ± 1.1 (n = 6), P < 0.001). Endothelium-dependent relaxation was enhanced in male CF mice, and renal noradrenaline was increased in female CF mice. Concentration of serum triglycerides, cholesterol, insulin and leptin were increased in CF vs. CON. The process of cross-fostering profoundly affects cardiovascular and metabolic phenotype in mice. The findings have implications for the inclusion of appropriate controls in the design of future studies and in the interpretation of previous cross-fostering studies in mice.

Cardiovascular, endocrine and behavioural responses to suckling and permanent separation in goats.

BACKGROUND: Suckling can be a peaceful or vulnerable event for goats and kids, whereas, separation is suggested as stressful. The aim of this study was to investigate physiology and behaviour in these two different situations in dairy goats. METHODS: Four studies were performed with seven goats kept with their first-born kid in individual boxes. The goats were videotaped and heart rate and arterial blood pressure were recorded every minute by telemetry from parturition until 24 hours after separation. One to two days after parturition, Study 1 was performed with analyses of heart rate and blood pressure around a suckling. In Study 2, performed 3-5 days after parturition, blood sampling was done before, during and after suckling. Study 3 was performed 4-6 days post partum, with blood sampling before and after a permanent goat and kid separation. In addition, vocalisations were recorded after separation. Blood samples were obtained from a jugular vein catheter and analysed for plasma cortisol, ß-endorphin, oxytocin, and vasopressin concentrations. Study 4 was performed during the first (N1) and second nights (N2) after parturition and the nights after Study 2 (N3) and 3 (N4). Heart rate, blood pressure and time spent lying down were recorded. RESULTS: The kids suckled 2 ± 0.2 times per hour and each suckling bout lasted 43 ± 15 s. In Study 1, heart rate and blood pressure did not change significantly during undisturbed suckling. In Study 2, plasma cortisol (P ≤ 0.05 during suckling and P ≤ 0.01 five minutes after suckling) and ß-endorphin (P ≤ 0.05) concentrations increased during suckling, but oxytocin and vasopressin concentrations did not change. In Study 3, the goats and kids vocalised intensively during the first 20 minutes after separation, but the physiological variables were not affected. In Study 4, heart rate and arterial blood pressure declined gradually after parturition and were lowest during N4 (P ≤ 0.05) when the goats spent longer time lying down than during earlier nights (P ≤ 0.01 during N1 and N3 and P ≤ 0.05 during N2). CONCLUSIONS: Suckling elevated plasma cortisol and ß-endorphin concentrations in the goats. The intensive vocalisation in the goats after separation, earlier suggested to indicate stress, was not accompanied by cardiovascular or endocrine responses.

Maternal dietary restriction during lactation influences postnatal growth and behavior in the offspring of mice.

It is well known that maternal nutritional status is important to the development of mammalian offspring. We examined the effect of maternal food restriction during lactation on offspring in mice. From 1 to 21 days after parturition, control dams (CDs) were fed with the standard amounts of daily food consumption, whereas dietary restricted dams (RDs) received 70% of daily food consumption. Although the mean body weight of RDs was not significantly different from that of the CDs, body weight of the offspring from RD (RD offspring) was significantly lower than that of the offspring from CD (CD offspring). The difference was detectable until 10 weeks of age. Body lengths and brain weights of RD offspring at postnatal day 22 were lower than those of the CD offspring. Plasma concentrations of leptin in RD offspring decreased significantly. But plasma concentrations of growth hormone and thyroxin were not different between the two groups. In the open field tests, total distance was significantly decreased in RD offspring compared with CD offspring. In the hole-board test, head dip latency was increased and the number of dips was decreased significantly in RD offspring. In the elevated plus maze test, total distance and risk assessment were significantly decreased in the RD offspring. There was no difference between the two groups in the rota-rod and wire-hang tests. These results suggest that maternal dietary restriction during lactation can affect the growth, locomotor activity and anxiety behavior of offspring, but not motor or neuromuscular function.

Lactational programming? Mother's milk energy predicts infant behavior and temperament in rhesus macaques (Macaca mulatta).

There are many aspects of "mothering" that may provide information to the mammalian infant about environmental conditions during critical periods of development. One essential element of mothering involves the quantity and quality of milk that mothers provide for their infants, but little is known about the consequences of variation in milk production. Mother's milk may affect infant behavior by contributing to brain development and to the development of behavioral dispositions. Here we present the first evidence for any mammal that natural variation in available milk energy (AME) from the mother is associated with later variation in infant behavior and temperament in rhesus macaques (Macaca mulatta, N=59). In the early postnatal period, heavier mothers with more reproductive experience produced greater AME, which is the product of milk energy density (kcal/g) and milk yield (g). Moreover, infants whose mothers produced greater AME in the early postnatal period showed higher activity levels and greater confidence in a stressful setting later in infancy. Our results suggest that the milk energy available soon after birth may be a nutritional cue that calibrates the infant's behavior to environmental or maternal conditions. These data provide new insight into potential mechanisms for the development of behavior and temperament and illuminate new directions for investigating maternal effects, nutritional programming, and developmental plasticity.