Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes

In 1990, two selection lines of Merino sheep were established for low and high behavioural reactivity (calm and nervous temperament) at the University of Western Australia. Breeding records consistently showed that calm ewes weaned 10% to 19% more lambs than the nervous ewes. We hypothesise that calm ewes could have a higher ovulation rate than nervous ewes and/or calm ewes could have a lower rate of embryo mortality than nervous ewes. We tested these hypotheses by comparing the ovulation rate and the rate of embryo mortality between the calm and nervous lines before and after synchronisation and artificial insemination. Merino ewes from the temperament selection lines (calm, n=100; nervous, n=100) were synchronised (early breeding season) for artificial insemination (day 0) (intravaginal sponges containing fluogestone acetate and eCG immediately after sponge withdrawal). On day-17 and 11 ovarian cyclicity and corpora lutea, and on days 30 and 74 pregnancies and embryos/foetuses were determined by ultrasound. Progesterone, insulin and leptin concentrations were determined in blood plasma samples from days 5, 12 and 17. Ovarian cyclicity before and after oestrus synchronisation did not differ between the lines, but ovulation rate did (day-17: calm 1.63; nervous 1.26; P<0.01; day 11: calm 1.83; nervous 1.57; P<0.05). Ovulation rate on day 11 in nervous ewes was higher than on day-17. Loss of embryos by day 30 was high (calm: 71/150; nervous: 68/130); but nervous ewes had a lower proportion (15/47) of multiple pregnancies compared with calm ewes (30/46; P<0.01). Reproductive loss between days 30 and 74 represented 7.3% of the overall loss. Temperament did not affect concentrations of progesterone, but nervous ewes had higher insulin (32.0 pmol/l±1.17 SEM; P=0.013) and lower leptin (1.18 μg/l±0.04 SEM; P=0.002) concentrations than calm ewes (insulin: 27.8 pmol/l±1.17 SEM; leptin: 1.35 μg/l±0.04 SEM). The differences in reproductive outcomes between the calm and nervous ewes were mainly due to a higher ovulation rate in calm ewes. We suggest that reproduction in nervous ewes is compromised by factors leading up to ovulation and conception, or the uterine environment during early pregnancy, that reflect differences in energy utilisation.     

Prepartum plasma estradiol and postpartum cortisol, but not oxytocin, are associated with interindividual and breed differences in the expression of maternal behaviour in sheep

Consistent, individual differences in the expression of maternal behaviour have been described in several species including the sheep. The neuroendocrine mechanisms underlying the onset of maternal behaviour in the sheep have been described, although the relationship between hormonal events and individual differences in behaviour has yet to be determined. In this study, we examined whether the individual differences in plasma estradiol, progesterone, oxytocin and cortisol concentrations were related to observed individual and breed differences in maternal behaviours in two breeds of sheep (Scottish Blackface and Suffolk) known to differ in maternal behavioural expression. Maternal estradiol concentration increased rapidly before parturition and was higher in Blackface ewes than Suffolk ewes. Plasma progesterone declined before parturition and was higher in Suffolk than Blackface ewes. Prepartum estradiol, but not progesterone, was related to individual differences in maternal grooming of the lamb. Plasma oxytocin did not differ between breeds in late gestation. There was a tendency for oxytocin to be higher in Blackface than Suffolk ewes immediately after birth. However, there were no significant relationships between prepartum or postpartum oxytocin and any maternal behaviours. Plasma cortisol was higher in Blackface than Suffolk ewes in the last days of pregnancy but rose in both breeds over the last 24 h before parturition and did not differ at delivery. Cortisol peripartum was negatively related to individual differences in maternal affiliative behaviours. These data suggest that estradiol, and potentially cortisol, may mediate individual differences in maternal behaviour in sheep.     

From birth to colostrum: early steps leading to lamb survival

New-born lambs have limited energy reserves and need a rapid access to colostrum to maintain homeothermy and survive. In addition to energy, colostrum provides immunoglobulins which ensure passive systemic immunity. Therefore, getting early access to the udder is essential for the neonate. The results from the literature reviewed here highlight the importance of the birth site as the location where the mutual bonding between the mother and her young takes place. Attraction to birth fluids by the periparturient ewe leads to intense licking of the lamb. Grooming not only dries, cleans and stimulates the newborn it also facilitates bonding through learning of its individual odour. Ewes having twins should ideally stay on the birth site for at least six hours in order to establish a strong bond with both lambs and favour lambs survival. However, primiparous ewes or ewes having high levels of emotivity are more likely to exhibit poor maternal behaviour. In addition, difficult parturition and weather conditions have an indirect effect on the behaviour of the mother and are other major causes of lamb death. On the lamb's side, rapid access to the udder and early suckling are extremely important. Delayed lactation or insufficient colostrum yield may be fatal especially since suckling has strong rewarding properties in the establishment of a preference for the mother, which in turn increases lamb survival. Insufficient access to the udder in mothers leaving the birth site too soon after parturition, especially in twin-bearing ewes, could also partly account for the high incidence of loss of mother-young contact and subsequent death in such lambs. Strategies to improve neonatal survival should be aimed at maximising lamb vigour, colostrum production, and mutual mother-young bonding through adequate feeding in late pregnancy and selection on behaviour.     

Preventing physical interactions between parturient ewes and their neonate differentially impairs the development of maternal responsiveness and selectivity depending on maternal experience

The present study investigated whether deprivation of nursing or of any physical interaction with the lamb impairs the onset of maternal responsiveness and the establishment of selectivity in primiparous and multiparous ewes. Just after parturition, ewes could interact freely with their lamb, or could only lick their lamb but not nurse them, or could neither lick nor nurse them for the first 4 h. At 4 h, mothers were successively observed for 3 min with an alien lamb and then with their own lamb. Only 5/14 primiparous mothers accepted their own lamb following deprivation of all physical contact whereas all multiparous mothers did so (19/19). Also, deprivation of all physical contact resulted in a significantly higher proportion of multiparous mothers accepting an alien lamb (6/18) than following deprivation of nursing only (0/19) indicating an impairment in selectivity. Finally, there was no indication that preventing only nursing led to a deficit either in maternal responsiveness or selectivity, neither in primiparous nor in multiparous ewes. These findings underline the importance of perception of olfactory cues from amniotic fluids through licking and/or physical contact and interacting with the lamb for the development of maternal responsiveness and selectivity.     

Inactivation of the medial preoptic area or the bed nucleus of the stria terminalis differentially disrupts maternal behavior in sheep

The present study was designed to investigate the role of the medial preoptic area (MPOA) and the bed nucleus of the stria terminalis (BNST) in the onset and maintenance of maternal behavior in sheep. In a first experiment, the MPOA or BNST were transiently inactivated during the first 2 h postpartum in primiparous ewes with the use of the anaesthetic lidocaine. MPOA inactivation greatly impaired the display of maternal behavior whereas inactivation of BNST or of adjacent sites (septum or diagonal band of Broca) or infusion of cerebrospinal fluid did not. In a separation/reunion lamb test (S/R) performed at 2 h postpartum, ewes with MPOA inactivation exhibited little reaction after separation of their lambs and did not show any motivation to reunite with them. Ewes with BNST inactivation showed intermediate performances in the S/R test. Moreover, in control ewes that were maternal for the first 2 h postpartum, MPOA or BNST inactivation performed in the following 12 h induced deficits in the S/R test, indicating that the MPOA and to a lesser extent BNST are also involved in the maintenance of maternal behavior. A second experiment showed that, in multiparous ewes, MPOA inactivation at parturition induced less deficit in the display of maternal behavior and in the S/R test than in primiparous mothers. These findings indicate that the MPOA and, to some extent, the BNST are functionally involved in the initiation and in the maintenance of maternal behavior in sheep, but this involvement is influenced by maternal experience.     

Amniotic fluid is important for the maintenance of maternal responsiveness and the establishment of maternal selectivity in sheep

Amniotic fluid (AF) is important for the establishment of maternal behaviour in inexperienced ewes, but its role in experienced mothers remains to be studied. Here, the maintenance of post-partum maternal responsiveness and the establishment of exclusive bonding was investigated in multiparous ewes when AF was removed from the neonate or/and physical contact with the young was precluded for the first 4 h post partum. Maintenance of maternal responsiveness and establishment of exclusive bonding were measured by the proportion of mothers accepting their own lamb and alien lambs that had been either washed or not washed, and by comparing an acceptance score for each type of lamb. The acceptance score was computed by summing standardised variables of acceptance (low bleats, acceptance at udder, nursing and licking time) and subtracting standardised variables of rejection (high-pitched bleats, rejection at the udder and aggressive behaviour). Washing the neonate reduced its acceptance score, but the proportion of mothers rejecting their own lamb was reduced only when washing the neonate and prevention of physical contact for 4 h were combined (7/15 v. 0/10 in controls, P = 0.02). In addition, washing the neonate increased the acceptance score of the washed alien lamb, but not of the unwashed alien. However, washing and privation of physical contact did not increase significantly the proportion of mothers accepting an alien lamb at 4 h post partum. We conclude that AF is important in experienced ewes for the establishment of maternal responsiveness, as already found in primiparous mothers. In addition, our results indicate that AF also carries some chemosensory information facilitating exclusive bonding.     

Direct Exposure to Corticosterone During Embryonic Development Influences Behaviour in an Ovoviviparous Lizard

It is becoming increasingly clear that conditions experienced during embryonic development can be of major importance for traits subsequent to parturition or hatching. For example, in mammals, offspring from stressed mothers show a variety of changes in behavioural, morphological, and life‐history traits. The effects of maternal stress on trait development are believed to be mediated via transfer of glucocorticoids, the main hormones released during the stress response, from mother to offspring. However, also other physiological maternal responses during stress could be responsible for changes in offspring phenotype. We investigated the direct effects of corticosterone on offspring development, without other confounding factors related to increased maternal stress, by injection of corticosterone in eggs of the ovoviviparous lizard Lacerta vivipara. Corticosterone‐manipulated offspring did not show impaired development, reduced body size or body condition at parturition. However, corticosterone‐treated offspring showed altered anti‐predator behaviour, as measured by the time required to emerge from shelter after a simulated predator attack. Differential steroid exposure during development, possibly mediated by maternal stress response, may explain some of the variation in behaviour among individuals in natural populations.     

Differential effects of undernutrition during pregnancy on the behaviour of does and their kids at parturition and on the establishment of mutual recognition

We investigated whether undernutrition during the second half of pregnancy impaired the behaviour of does and their kids at parturition and early mutual recognition. Twenty-two control and 22 underfed mixed-breed, multiparous dairy goats were used, together with their respective kids (control, n = 31: nine singles, 16 twins and six triplets; underfed, n = 32: 11 singles, 18 twins and three triplets). Undernutrition involved limiting protein and energy intake at 70% of the nutritional requirements for maintenance and foetal growth from day 70 of pregnancy until birth. The behaviour of mothers and their two first-born kids was observed for 90 min from the birth of each kid. Maternal olfactory recognition of the kid was assessed at 4 h post partum by testing selective nursing behaviour. Non-olfactory recognition was assessed at 8 h in a two-choice test excluding olfactory cues. In kids, preference for the mother was assessed in a two-choice test at either 12 or 24 h post partum. Bodyweight of does and kids were lower in the underfed group up to 2 weeks post partum. At parturition, licking, maternal bleating frequency and latency to nursing did not differ between nutritional groups. Control kids were faster than underfed kids to stand, search for and reach the udder, but underfed kids bleated more and tended to spend more time at the udder. Both control and underfed does accepted their own kid and rejected the alien in the selectivity test at 4 h. In contrast, at 8 h post partum, only control goats showed a significant preference for their own kid in the non-olfactory recognition test. Both control and underfed kids showed a preference for their own mother at 12 and 24 h and undernutrition during pregnancy had little influence on the performance of kids. However, 12 h-old underfed kids tended to be less active than control kids and visited their own mothers less than control kids. There were no significant correlations between the behaviour of the mother or of the kid at parturition and their performance in the discrimination tests. Overall, undernutrition in the second half of pregnancy appears to be more detrimental for the behaviour of the mother than for the kid. Furthermore, it has more impact on the establishment of maternal non-olfactory recognition than on maternal care at parturition or the establishment of maternal selectivity.     

Consistency of temperament in bighorn ewes and correlates with behaviour and life history

Individual differences in temperament may affect how animals react to novel situations, avoid predation, invest in reproduction and behave in a variety of social contexts. Little information is available, however, about individual differences in temperament for wild animals. For bighorn sheep, Ovis canadensis, ewes captured as part of a long-term study, we compared behaviour during handling to behaviour in the field and reproductive history. We considered 'bold' ewes those that were frequently trapped during the summer, and assigned to each ewe a docility index based on her behaviour during handling. Measurements of temperament for the same individual at different captures were highly consistent. Temperament was not affected by reproductive status or age, nor was it related to body mass. Correlations between behaviour at the trap and in the field were weak and mostly nonsignificant, suggesting that temperament is domain specific rather than domain general. Bold ewes tended to start reproducing earlier and have higher weaning success than shy ewes. Variability in temperamental traits in the study population could be maintained by life-history trade-offs and by yearly changes in selective pressures. Copyright 2000 The Association for the Study of Animal Behaviour.     

Mechanisms of activation of maternal behaviour in mammals

In mammals, the activation of maternal behaviour depends on internal maternal factors related with parturition. The nature of these factors may vary between species, although oestradiol, foetus expulsion and intracerebral oxytocin are the most commonly encountered. They induce a period of specific receptivity to some sensory cues provided by the neonate. These cues (tactile, olfactory, auditory, ...) also vary between species. The interactions between the mother and her progeny during this period, known as the sensitive period, facilitate the maintenance of maternal responsiveness beyond the initial phase of activation by the factors internal to the mother. The ability of mothers to display a well-adapted maternal behaviour is also modulated by maternal experience gained at the first parturition. Furthermore, this capacity is also influenced by the nature of the interactions experienced in infancy with the own mother of the female, which can lead to a non-genomic transmission of some individual characteristics of maternal behaviour or sensitivity to stress across generations.     

Motherless mothers revisited: Rhesus maternal behavior and rearing history

Classic studies have demonstrated that isolation- and peer-rearing in infancy can result in overt deficits in maternal behavior in rhesus monkeys, although nonmother-reared monkeys may become adequate caretakers if allowed experience with infants. Maternal styles in normally-reared mothers have been reported to vary widely. In the present study, the range of maternal proficiency of nonabusive, nonrejecting nonmother-reared mothers was examined. The behavior of mother-reared, peer-reared, and isolate-reared multiparous mothers was observed and compared for the first six months following parturition. Both peer-reared and isolate-reared mothers exhibited differences in maternal behavior from mother-reared mothers. Inasmuch as variations in maternal behavior may impact on the infant, investigators should be aware of the rearing histories of females used as breeders in the laboratory.     

Maternal behaviour and lamb survival: from neuroendocrinology to practical application

Parental care promotes offspring survival and, for livestock species, this care is provided solely by the mother. Maternal behaviour in the sheep has been exceptionally well-studied compared with other species and many of the underpinning biological processes leading to the expression of maternal care are known. In this review the current state of play with regard to the biology of maternal care will be reviewed, and its application to provide practical solutions to reduce lamb mortality considered. For maternal care to be elicited at birth the ewe requires elevated circulating oestradiol in late gestation, which stimulates the expression of oxytocin receptors in both peripheral and central areas (particularly the hypothalamic and limbic areas of the brain). At birth stretching of the vaginocervical canal elicits a spinal reflex which triggers the release of oxytocin primarily from neurones within the paraventricular nucleus of the hypothalamus. Oxytocin release causes an increase in the neurotransmitters noradrenaline, acetylcholine, glutamate and γ-aminobutyric acid (GABA) in the olfactory bulb, and other brain regions important for maternal behaviour. Finally, sensory cues provided by the lamb, in particular the amniotic fluids surrounding it, lead to the expression of maternal behaviours (licking, low-pitched bleats, acceptance of the lamb at the udder and suckling). This allows the expression of the two facets of maternal behaviour in the ewe: nurturance of the young and maternal selectivity, whereby a specific olfactory memory for the ewes own lamb is formed and the expression of maternal care is restricted to this lamb. Variation in the expression of maternal care has been demonstrated in primiparous ewes compared with multiparous, in different sheep genotypes, with undernutrition, stress in pregnancy, following a difficult delivery, and may occur with variation in ewe temperament. An understanding of the importance of the timing of various events in late pregnancy and during parturition, as well as the factors that can disrupt these events, can help to design management activities to minimise risks to the successful onset of maternal behaviour. Management practices that work with the biology of the ewe will be the most successful in ensuring that maternal care is expressed, so improving the welfare of the ewe and lamb, and the profitability of the farm.     

Pen size and parity effects on maternal behaviour of Small-Tail Han sheep

The aim of this experiment was to study the effects of pen size and parity on maternal behaviour of twin-bearing Small-Tail Han ewes. A total of 24 ewes were allocated to a 2×2 design (six per pen), with parity (primiparous or multiparous) and pen size (large: 6.0×3.0 m; small: 6.0×1.5 m) as main effects at Linyi University, Shandong Province, China. Behaviour was observed from after parturition until weaning. All ewes were observed for 6 h every 5 days from 0700 to1000 h and from 1400 to 1700 h. Continuous focal animal sampling was used to quantify the duration of maternal behaviours: sucking, grooming and following as well as the frequency of udder accepting, udder refusing and low-pitched bleating. Oestradiol and cortisol concentrations in the faeces (collected in the morning every 5 days) were detected using EIA kits. All lambs were weighed 24 h after parturition and again at weaning at 35 days of age. The small pen size significantly reduced following (P<0.005), grooming (P<0.001) and suckling durations (P<0.05), as well as the frequency of udder refusals (P<0.001). However, there was a significant interaction with ewe parity, with decreased grooming and suckling in the small pen largely seen in the multiparous ewes (P<0.001). Independent of pen size, multiparous ewes accepted more sucking attempts by their lambs (P<0.05) and made more low-pitched bleats than primiparous ewes (P<0.001). Multiparous ewes had higher faecal oestradiol concentrations than primiparous ewes (P<0.001), and ewes in small pens had higher faecal cortisol levels compared with ewes in larger pens (P<0.001). As lambs increased in age, the duration of maternal grooming, following and suckling as well as frequency of udder acceptance and low-pitched bleating all declined, and the frequency of udder refusing increased (P<0.001 for all). Ewe parity, but not pen size, affected lamb weight gain during the period of observation (P<0.001). This is the first study to show that pen size, interacting with parity, can affect the expression of maternal behaviour in sheep during lactation. The study is also the first to report on the maternal behaviour of Chinese native sheep breeds (Small-Tail Han sheep), with implications for the production of sheep in China.     

Genital stimulation facilitates maternal behavior in estrous ewes

Only a small proportion of ewes at estrus have been found to respond maternally to newborn lambs, and this low maternal responsiveness may be partially attributable to the absence of the genital stimulation which occurs at parturition. Therefore, the effect of artificial genital stimulation on maternal behavior of estrous ewes was investigated. Estrus was synchronized in 33 ewes by placement and withdrawal of progestin-saturated vaginal sponges. Estrous ewes were divided into two groups, a control group and a group receiving 5 min of artificial genital stimulation, and observed following presentation of newborn lambs. Significantly more stimulated ewes licked the lamb and emitted low-pitched bleats in a 30-min test. When genital stimulation was subsequently administered to control ewes, more of them also became maternal so that the two groups were no longer significantly different. These results indicate that absence of genital stimulation is one of the factors contributing to the low maternal responsiveness of estrous ewes. They also demonstrate for the first time that artificial genital stimulation is effective in eliciting maternal behavior in nonpregnant ewes even at physiological concentrations of estradiol.     

Estradiol receptor-alpha expression in hypothalamic and limbic regions of ewes is influenced by physiological state and maternal experience

The influence of estrus, pregnancy, parturition, and maternal experience on the expression of estrogen receptor-alpha (ERalpha) was investigated in hypothalamic and limbic regions of the sheep brain, using immunocytochemistry. Four days before parturition, previous maternal experience was associated with a higher density of ERalpha-labeled neurons in the paraventricular and supraoptic nuclei, the medial preoptic area, and the medial amygdala, but not in the mediobasal hypothalamus. Furthermore, an interaction was found between physiological state and experience in the peripartum period as the effect of experience existing 4 days prepartum was not found at parturition, when densities were lowest both in primiparous and in multiparous ewes. An additional effect of physiological state was also observed between parturition and estrus, densities being significantly lower at parturition than at estrus in the SON, PVN, and MPOA, but not in the medial amygdala. These results indicate that in sheep ERalpha expression is influenced by previous physiological and/or maternal experience at specific times of the reproductive cycle. They are also congruent with the higher ability of multiparous than nulliparous ewes to show maternal behavior several days prepartum.     

Maternal-care behavior and life-history traits in house mice (Mus domesticus) artificially selected for high voluntary wheel-running activity

To test the hypothesis that selective breeding for high voluntary wheel running negatively affects maternal performance in house mice, we observed maternal behavior and compared litter size and mass, in replicate lines of selected (N=4) and control (N=4) mice from generations 20 and 21 of an artificial selection experiment. At generation 21, selected-line females ran 2.8-times more revolutions per day than females from random-bred control lines, when tested at approximately 6 weeks of age as part of the normal selection protocol. After giving birth, dams from selected and control lines exhibited similar frequencies of maternal behaviors and also spent similar amounts of time in general locomotor activity at litter ages of both 9 and 16 days. Dams from selected lines also performed equally well as controls in repeated pup-retrieval trials. At first parturition, selected-line dams averaged 2.4 g smaller in body mass as compared with dams from the control lines; however, neither litter size nor litter mass at birth (generation 20) or at weaning (generation 21) differed significantly between selected and control lines. We conclude that, at least under the husbandry conditions employed, maternal behavior and reproductive output at first parturition are genetically independent of wheel-running behavior.     

Maternally Derived Egg Hormones,Antibodies and Antimicrobial Proteins: Common and Different Pathways of Maternal Effects in Japanese Quail

Avian eggs contain a variety of maternally-derived substances that can influence the development and performance of offspring. The levels of these egg compounds vary in relation to environmental and genetic factors, but little is known about whether there are correlative links between maternal substances in the egg underlying common and different pathways of maternal effects. In the present study, we investigated genetically determined variability and mutually adjusted deposition of sex hormones (testosterone-T, androstenedione-A₄ and progesterone-P₄), antibodies (IgY) and antimicrobial proteins (lysozyme) in eggs of Japanese quail (Coturnix japonica). We used different genetic lines that were independently selected for yolk T concentrations, duration of tonic immobility and social reinstatement behaviour, since both selections for behavioural traits (fearfulness and social motivation, respectively) produced considerable correlative responses in yolk androgen levels. A higher selection potential was found for increased rather than decreased yolk T concentrations, suggesting that there is a physiological minimum in egg T levels. Line differences in yolk IgY concentrations were manifested within each selection experiment, but no consistent inter-line pattern between yolk IgY and T was revealed. On the other hand, a consistent inverse inter-line pattern was recorded between yolk IgY and P₄ in both selections for behavioural traits. In addition, selections for contrasting fearfulness and social motivation were associated with changes in albumen lysozyme concentrations and an inverse inter-line pattern between the deposition of yolk IgY and albumen lysozyme was found in lines selected for the level of social motivation. Thus, our results demonstrate genetically-driven changes in deposition of yolk T, P₄, antibodies and albumen lysozyme in the egg. This genetic variability can partially explain mutually adjusted maternal deposition of sex hormones and immune-competent molecules but the inconsistent pattern of inter-line differences across all selections indicates that there are other underlying mechanisms, which require further studies.     

The effect of farrowing environment and previous experience on the maternal behaviour of sows in indoor pens and outdoor huts

Outdoor farrowing huts facilitate a less restricted maternal behaviour in sows compared with sows kept indoors in farrowing pens. The aim of our study was to investigate whether there are behavioural differences between primiparous sows kept outdoors in farrowing huts and indoors in pens, and whether the maternal behaviour during the second parity, when all sows were kept outdoors in farrowing huts, would differ between sows that have experienced the indoor or the outdoor environment, respectively, during their first parturition. A total of 26 Yorkshire×Swedish Landrace sows were studied. Of these, 11 sows were housed outdoors in farrowing huts during both parturitions (group=OUTOUT). The other 15 sows were kept indoors in a barn with single farrowing pens during their first parturition. During their second parturition, sows were kept outdoors in farrowing huts (group=INOUT). The behaviour was video recorded from 2 h prepartum to 48 h postpartum. The sows’ responsiveness to playbacks of a piglet’s screams was tested on days 2 to 3 postpartum. Parity 1: during the last 2 h prepartum, OUTOUT sows had a higher proportion of observations in the sternal lying position (P<0.01). During parturition, OUTOUT sows changed posture more often (P<0.05) and were lying less (P<0.05) than INOUT sows. All sows in both groups responded with ‘lifting head’ towards the playback of piglet scream, whereas 100% of OUTOUT sows and only 43% of INOUT sows thereafter were ‘getting up’ (P <0.01). Parity 2: There were no behavioural differences between INOUT and OUTOUT sows. In conclusion, it is not problematic for a second parity sow with initial maternal experience from an indoor farrowing pen to be kept outdoors in farrowing huts during its following farrowing.     

Endocrine and metabolic factors involved in the effect of nutrition on the production of colostrum in female sheep

We investigated the physiological relationship between diet during pregnancy and colostrum production in ewes to test the hypothesis that for ewes that are in low body condition, with low fat reserves, the food supply will be the main source of energy for colostrum synthesis. To this end, we measured the amount of colostrum accumulated by ewes under two levels of nutrition. We also measured the circulating concentrations of metabolites and hormones associated with lactogenesis (beta-hydroxybutyrate, glucose, progesterone, prolactin, cortisol, growth hormone, leptin, insulin and insulin-like growth factor-I) Ewes were either under-fed at 70 (n = 15) or well-fed at 110% (n = 10) of their daily metabolisable energy requirement during the last two months of pregnancy. Colostrum accumulation up to parturition was 168 +/-48 g for under-fed ewes and 451 +/-103 g for well-fed ewes. After birth, under-fed ewes produced less colostrum than well-fed ewes but the difference was no longer significant. The level of nutrition also influenced the plasma concentrations of hormones and metabolites related to lactogenesis. Progesterone concentrations decreased before lambing in all animals but in under-fed ewes the fall appeared to be too small to initiate the onset of colostrum production. Beta-hydroxybutyrate concentrations were higher in under-fed than in well-fed ewes, suggesting that the under-fed ewes were mobilising more adipose tissue but they still did not meet their ME requirements for colostrum production. We concluded that, in underfed ewes, there are insufficient nutrients for adequate lactation and the hormone regime is inappropriate for good udder development and colostrum synthesis.     

Low pasture allowance until late gestation in ewes: behavioural and physiological changes in ewes and lambs from lambing to weaning

Low pasture allowance during gestation affects ewes’ BW at parturition, the bond with their lamb, lamb development, and thus also may affect their responses to weaning. The objectives were to determine if native pasture allowance from before conception until late pregnancy affects ewe–lamb behaviours at lambing, ewes’ milk yield, lambs’ BW, and the behavioural and physiological changes of ewes and lambs at weaning. From 23 days before conception until 122 days of pregnancy, 24 ewes grazed on two different native pasture allowances: high (10 to 12 kg of dry matter (DM)/100 kg of BW per day; HPA treatment; n=12) or low (5 to 8 kg of DM/100 kg of BW per day; LPA treatment; n=12). Thereafter, all ewes grazed on Festuca arundinacea and received rice bran and crude glycerine. Ewes’ body condition score (BCS) and BW were recorded during pregnancy and postpartum periods. Milk yield was determined on days 32, 41 and 54 after lambing. Lambs’ BW was recorded from birth until 72 days after lambing. Latency from parturition until the ewe licked her lamb, maternal behaviour score (a test that evaluates maternal attachment to the lamb) and latency for lamb to stand up and suckle were determined. The behaviour of the lambs and ewes was recorded before and after weaning (at 65 days). The ewes’ serum total protein, albumin and globulin concentrations were measured before and after weaning. The HPA ewes presented greater BW (P<0.005) and BCS (P<0.005) than the LPA ewes during pregnancy and postpartum (P<0.04), and had a greater milk yield than the LPA ewes (P<0.03). Treatments did not influence any behaviour at lambing, lambs’ BW, neither the ewes’ behavioural and physiological changes at weaning. HPA lambs paced and vocalized more than LPA lambs (P<0.0001). The variation of albumin concentration before and after weaning was greater in the HPA lambs than in the LPA lambs (P<0.0001). In conclusion, although ewes’ BW, BCS and milk production were affected by pasture allowance until late pregnancy, this did not affect the behaviours that lead to the establishment of the mother–young bond, nor the ewes’ behavioural responses at weaning. Lambs reared by ewes that grazed on low pasture allowance during pregnancy presented fewer behavioural changes and a lower decrease of albumin concentration after weaning. Lambs’ BW was not affected by the feeding received by their mothers.