Identifying and monitoring pain in farm animals: a review.

One important objective for animal welfare is to maintain animals free from pain, injury or disease. Therefore, detecting and evaluating the intensity of animal pain is crucial. As animals cannot directly communicate their feelings, it is necessary to identify sensitive and specific indicators that can be easily used. The aim of the present paper is to review relevant indicators to assess pain in several farm species. The term pain is used for mammals, birds and fish, even though the abilities of the various species to experience the emotional component of pain may be different. Numerous behavioural changes are associated with pain and many of them could be used on farms to assess the degree of pain being experienced by an animal. Pain, as a stressor, is associated with variations in the hypothalamic-pituitary-adrenal axis as well as in the sympathetic and immune systems that can be used to identify the presence of pain rapidly after it started. However, most of these measures need sophisticated equipment for their assessment. Therefore, they are mainly adapted to experimental situations. Injuries and other lesional indicators give information on the sources of pain and are convenient to use in all types of situations. Histopathological analyses can identify sources of pain in experimental studies. When pronounced and/or long lasting, the pain-induced behavioural and physiological changes can decrease production performance. Some indicators are very specific and sensitive to pain, whereas others are more generally related to stressful situations. The latter can be used to indicate that animals are suffering from something, which may be pain. Overall, this literature review shows that several indicators exist to assess pain in mammals, a few in birds and very few in fish. Even if in some cases, a single indicator, usually a behavioural indicator, may be sufficient to detect pain, combining various types of indicators increases sensitivity and specificity of pain assessment. Research is needed to build and validate new indicators and to develop systems of pain assessment adapted to each type of situation and each species.

Minimising pain in farm animals: the 3S approach - 'Suppress, Substitute, Soothe'.

Recently, the French National Institute for Agricultural Research appointed an expert committee to review the issue of pain in food-producing farm animals. To minimise pain, the authors developed a '3S' approach accounting for 'Suppress, Substitute and Soothe' by analogy with the '3Rs' approach of 'Reduction, Refinement and Replacement' applied in the context of animal experimentation. Thus, when addressing the matter of pain, the following steps and solutions could be assessed, in the light of their feasibility (technical constraints, logistics and regulations), acceptability (societal and financial aspects) and availability. The first solution is to suppress any source of pain that brings no obvious advantage to the animals or the producers, as well as sources of pain for which potential benefits are largely exceeded by the negative effects. For instance, tail docking of cattle has recently been eliminated. Genetic selection on the basis of resistance criteria (as e.g. for lameness in cattle and poultry) or reduction of undesirable traits (e.g. boar taint in pigs) may also reduce painful conditions or procedures. The second solution is to substitute a technique causing pain by another less-painful method. For example, if dehorning cattle is unavoidable, it is preferable to perform it at a very young age, cauterising the horn bud. Animal management and constraint systems should be designed to reduce the risk for injury and bruising. Lastly, in situations where pain is known to be present, because of animal management procedures such as dehorning or castration, or because of pathology, for example lameness, systemic or local pharmacological treatments should be used to soothe pain. These treatments should take into account the duration of pain, which, in the case of some management procedures or diseases, may persist for longer periods. The administration of pain medication may require the intervention of veterinarians, but exemptions exist where breeders are allowed to use local anaesthesia (e.g. castration and dehorning in Switzerland). Extension of such exemptions, national or European legislation on pain management, or the introduction of animal welfare codes by retailers into their meat products may help further developments. In addition, veterinarians and farmers should be given the necessary tools and information to take into account animal pain in their management decisions.

New VMD2 gene mutations identified in patients affected by Best vitelliform macular dystrophy.

PURPOSE: The mutations responsible for Best vitelliform macular dystrophy (BVMD) are found in a gene called VMD2. The VMD2 gene encodes a transmembrane protein named bestrophin-1 (hBest1) which is a Ca(2+)-sensitive chloride channel. This study was performed to identify disease-specific mutations in 27 patients with BVMD. Because this disease is characterised by an alteration in Cl(-) channel function, patch clamp analysis was used to test the hypothesis that one of the VMD2 mutated variants causes the disease. METHODS: Direct sequencing analysis of the 11 VMD2 exons was performed to detect new abnormal sequences. The mutant of hBest1 was expressed in HEK-293 cells and the associated Cl(-) current was examined using whole-cell patch clamp analysis. RESULTS: Six new VMD2 mutations were identified, located exclusively in exons four, six and eight. One of these mutations (Q293H) was particularly severe. Patch clamp analysis of human embryonic kidney cells expressing the Q293H mutant showed that this mutant channel is non-functional. Furthermore, the Q293H mutant inhibited the function of wild-type bestrophin-1 channels in a dominant negative manner. CONCLUSIONS: This study provides further support for the idea that mutations in VMD2 are a necessary factor for Best disease. However, because variable expressivity of VMD2 was observed in a family with the Q293H mutation, it is also clear that a disease-linked mutation in VMD2 is not sufficient to produce BVMD. The finding that the Q293H mutant does not form functional channels in the membrane could be explained either by disruption of channel conductance or gating mechanisms or by improper trafficking of the protein to the plasma membrane.

Do beef cattle react consistently to different handling situations?

Beef cattle responses to handling depend partly on the genetic characteristics of the animals. However, the various methods used in order to assess these responses differ to a great extent. The purpose of this work is to study the relationship between two different situations extensively used to evaluate cattle reactions to handling. Moreover, the genetic variability of cattle responses to these two handling situations was investigated. Behavioural reactions of 245 Limousine heifers, from 10 sires, were evaluated both in a docility test and in a crush test. In the docility test, a human tried to lead and then to maintain the animal in the corner of a pen during 30 consecutive seconds, with a maximum duration of the test of 3.5min. A docility score summarised the animal's behavioural reactions to the test. The crush test procedure consisted of social isolation of the animal in a crush, with the head maintained in a head gate (5min), then exposure to a stationary human (30s), and finally stroking on the forehead (30s). An agitation index for each part of this test was computed from PCA analyses based on agitation behaviours. Sire effect was significant for every part of both tests (P<0.05). Heifers' behavioural responses to the docility test were significantly correlated with their responses to the crush test, when the animals were in isolation (r=0.29; P<0.001), when the human stood motionless in front of the animals (r=0.37; P<0.001), and when the human stroked them (r=0.28; P<0.001). Sires' behavioural reactions to the docility test (computed from their daughters' scores) were correlated with their reactions to the crush test only when the human was present, both when motionless (r=0.88; P<0.001) and when stroking the heifer (r=0.81; P<0.05). No relationship appeared between sires' behavioural reactions to the docility test and their responses to restraint in the crush when the human was absent (P=0.17). Furthermore, the crush test did not reveal the animals which presented aggressive reactions to handling in the docility test. The results exposed in this paper pointed out the existence of a general reactivity of beef cattle to handling, whether the animals are restrained or not, which appears influenced by the sire. Such reactivity is suggested to be mainly a consequence of the animals reactions to humans. The human environment needs to be precisely defined in the handling test procedures before using them as a selection criteria.

Reducing veal calves' reactivity to people by providing additional human contact.

We studied the importance of the stockperson's behavior on veal calf behavior using 22 veal calves housed in individual crates. Eleven calves received minimal contact from the stockperson, and the other 11 calves were stroked and allowed to suck the stockperson's fingers after each meal during the entire fattening period (21 wk). The effects of this additional contact with the stockperson on the calves' responses to people was studied, when in their home environment (crate) or outside their home environment (singly in a novel arena). When tested in their home environment, the calves receiving additional contact withdrew less from the approach of humans (familiar or unfamiliar) (P < .05) compared with control calves. When tested outside the home environment with a human (familiar or unfamiliar) standing motionless, calves that had received additional contact interacted more frequently and for a longer time with the humans and defecated less often compared with control calves (P < .05). In conclusion, being stroked and sucking the stockperson's fingers seemed to be experienced as positive by the calf, because they reduced withdrawal from and increased approaches to familiar and unfamiliar humans in familiar and unfamiliar environments. Such a lower reactivity to people could improve ease of handling, animal performance, and animal welfare.

The impact of gentle contacts on ease of handling, welfare, and growth of calves and on quality of veal meat.

It has been demonstrated previously that regularly stroking and letting calves suck fingers leads to less avoidance and more approach behavior of the calves toward people. To examine whether these positive contacts affect the welfare and productivity of calves and the quality of veal meat we used 22 veal calves housed in individual crates. Half of them received minimal contact with the stockperson (controls), and the other half were given additional gentle contacts around meals, by stroking the calves and allowing them to suck the stockperson's fingers, during the entire fattening period (21 wk). Welfare was assessed through behavioral reactivity (reactions to handling, to surprise stimuli, and to novelty), neuroendocrine responses to stress (cortisol in response to an ACTH challenge, catecholamine-synthesizing enzymes), and health (number of medical treatments, abomasal lesions). Calf productivity was assessed through growth rates and meat quality through glycolytic potential (an estimator of resting glycogen level in muscle), pH, and color. Calves that received gentle contacts were less agitated (P < .01) and tended to defecate less (P = .08) when handled in a cart on wheels than the control calves, but no treatment effects were found in reactivity to novelty and surprise stimuli, responses to ACTH, and catecholamine synthetic potential. Calves given gentle contacts had fewer abomasal lesions than controls (0/11 vs 4/11, P = .05). The glycolytic potential of the semimembranosus muscle was higher in calves that received gentle contacts than in controls (172.6 vs 154.1 micromol/g, P < .05), but no treatment effects were observed on meat pH, meat color, or growth rates. It is concluded that gentling veal calves reduces their reactions to handling. Gentle contacts reduce the reaction to transport shown by differences in glycolytic potential. In addition, the reduction in reactions to handling and the decreased incidence of abomasal lesions can contribute to an improvement of the calves' welfare.

Hand-feeding and gentling influence early-weaned lambs' attachment responses to their stockperson.

Artificially reared herbivores are highly dependent on the stockperson at an early age in order to learn to drink from an artificial milk provider. This period of training may be a determinant for the animals' subsequent responses toward humans. However, long-term responses may also depend on the human contact (e.g., visual, physical interactions, gentling, and handling) provided to the young lambs after this training period. We examined whether different levels of subsequent contact (no visual and physical contact, stroking, and feeding reward) affect long-term attachment responses of lambs to the caretaker that provided the subsequent contact, after a common initial training period for artificial feeding provided by another person. Ewe lambs (n = 45) were artificially reared from multinippled buckets in groups of three. All the lambs were trained by a stockperson (S1) to suck from the bucket (4.4 +/- .3 sessions of 3 min per animal for the first 2 d of life). Subsequently, 15 lambs received no further human contact (T0). Fifteen other lambs received only stroking from a second stockperson (S2) for 6 min three times a day during the first 4 wk (T1). The remaining 15 lambs (T2) were stroked and bottle-fed by S2 during the same posttraining period as for T1. Tests were performed at 4, 6 (just before weaning), 9, and 13 wk of age in an unfamiliar arena marked in a grid pattern. The test procedure included three successive parts: 1) isolation for 1 min; 2) S2 presence for 2 min; and 3) isolation for 1 min. The T0 lambs spent a similar amount of time in the grid square close to S2 regardless of whether he was present. The T1 and T2 lambs spent more time close to S2 than T0 (P < .01), and T2 spent more time close than T1 (P < .05). In the presence of S2, T2 vocalized less (P < .01) than T0, and T1 did not differ from either T2 or T0. The T2 lambs also crossed fewer squares than T0. When S2 left the arena, T2 vocalized more (P < .01) than T0 and more (P < .05) than T1, and T1 had a tendency to vocalize more (P = .08) than T0. Differences persisted with increasing age. Human contact, especially stroking and feeding, during the 4 wk following initial training strongly and durably influenced the lambs' response not only to the appearance but also to the disappearance of a familiar stockperson. This last result supports the idea that lambs could form a social bond with their stockperson.

The social environment influences the behavioural responses of beef cattle to handling.

In cattle, a gregarious species, the social group influences individual stress responses to fear-eliciting situations. As handling can be stressful for farm animals, it can be hypothesised that social partners modify individual responses to handling. The present experiment investigated the effect of the presence or absence of social partners on behavioural reactions of beef calves in a handling test. At the age of 10 months, 38 calves from two breeds (Salers and Limousine) were individually subjected to the docility test, once while in visual contact with four familiar peers, and once in the absence of peers, following a crossover design. The docility test procedure included physical separation from peers (30 s; period 1), exposition to a stationary human (30 s; period 2), and handling by human (30 s-2.5 min, according to the success in handling; period 3). In absence of human (period 1), calves in visual contact with their peers spent more time motionless than when peers were totally absent (P<0.001). The social environment also influenced the duration of handling (period 3); the human required more time to successfully handle calves when peers were present (P<0.05). In conclusion, the presence of peers affects individual calves' reactions to the docility test.

Presence of cues from stressed conspecifics increases reactivity to aversive events in cattle: evidence for the existence of alarm substances in urine.

In gregarious species like cattle, the presence of partners often affects fear-related reactions. The first experiment investigated whether behavioral and physiological responses to stress depend on the emotional state of the partner. Aubrac heifers were presented with food in a novel environment. Compared to heifers in the presence of a companion that had been previously habituated to the environment without receiving shocks, those in the presence of a companion animal that had previously received electric shocks in that environment had a stronger increase of cortisol response (11.2+/-1.1 vs. 7.4+/-0.9 ng/mL), showed a significantly longer latency to feed (60.1+/-12.3 vs. 17.8+/-5.9 s), and fed more slowly (54.5+/-11.4 vs. 110+/-7.3 s). After repeated exposure to the test conditions, when heifers of both treatments fed rapidly after entrance, response to an unexpected air blast from the feeding bucket was measured. Heifers in the presence of a stressed companion showed an increased latency to feed again compared to those with a nonstressed companion (44.5+/-5.1 vs. 22.8+/-4.3 s). Stressed companions urinated during tests; therefore the second experiment investigated whether heifers respond differently to urine collected from stressed and nonstressed conspecifics. In a first test, heifers were presented with food on a grid in a bucket in a novel environment. They had a longer latency to feed when the bucket contained urine from stressed rather than from nonstressed conspecifics underneath the grid (128.1+/-9.6 vs. 108.2+/-4.9 s). In a second test, heifers were presented with a novel object in a familiar environment. Heifers showed a longer latency to explore the object when it had been sprayed with urine from stressed compared to urine from nonstressed conspecifics (215.2+/-45.0 vs. 25.8+/-8.6 s). The results show that heifers perceive the state of increased stress of conspecifics and become more fearful as a result. They further show that this perception is at least partly mediated by olfactory cues in the urine.

Discrimination between shepherds by lambs reared under artificial conditions.

We studied the ability of 32 lambs reared artificially in groups of four to discriminate between their shepherd and an unknown shepherd. Half of the lambs were bottle fed in isolation by one shepherd during the first 3 wk. The other half was fed alternately by three shepherds. Lambs had no visual contact with humans for the next 3 wk. Lambs were weaned at 6 wk of age and reared together with the minimum human contact necessary for rearing management. Lambs were tested at 3, 6, and 14 wk of age, investigating the effect of the rearing conditions on the response to isolation and to reunion with the known or an unknown shepherd. During tests, lambs were observed 1) in isolation for 1 min, 2) in the presence of a shepherd who entered and squatted at one end of the pen for 1 min, trying to touch the lambs if they approached, 3) again in isolation for 1 min. Early rearing management (one vs three shepherds) had no significant effect on any criteria studied. Lambs vocalized and moved less when in the presence of the shepherd than when isolated. They vocalized less, moved less, approached more quickly, and interacted more with the known than with an unknown shepherd. The difference persisted after 3 wk spent without visual human contact. However, no difference was evident at 14 wk of age. The effect of shepherd knowledge is clearly demonstrated by this experiment after an intensive early period of contact.

Behavioral, cardiac and cortisol responses to brief peer separation and reunion in cattle.

Behavioral, cardiac, and adrenal responses of heifers to short-term isolation and to subsequent reunion with familiar or nonfamiliar conspecifics were measured. Two groups of heifers were studied according to their different social reactivity: Aubrac heifers (n = 12) reared under suckler conditions and Friesian heifers (n = 12) reared under dairy management. Because these two groups could also react differently to human beings, testing social isolation was realized by removing pen mates without handling the subject. Moreover, heifers were tested in confinement to avoid an alteration of the cardiac response to isolation by an excessive motor activity. Although physical restraint can influence the reactions, this effect is assumed to be weak because heifers had been exposed to the experimental procedures, including confinement for 3 days before isolation test, in addition to brief periods of physical restraint occurring regularly according to rearing practices. Results show that social separation induced struggling and large increases in vocalization, heart rate, and plasma cortisol concentrations in all heifers. Except for vocalization, these effects were more severe in Aubrac than in Friesian heifers. For all heifers, isolation-induced distress was positively correlated with the duration of social contacts they engaged with the pen mates prior to separation. Behavioral responses, i.e., struggling and vocalization, decreased when conspecifics were brought back, independently of their familiarity to the subject. In contrast, the heart rate decline induced by the entrance of conspecifics was more pronounced in response to reintroduction of pen mates. These findings indicate that social isolation is a severe psychological stress in cattle and that the mere sight of conspecifics reduces behavioral distress regardless of peer identity. The isolation-induced distress depends on the genetic and rearing backgrounds of the heifers without allowing to differentiate their respective effects.

Providing social contacts and objects for nibbling moderates reactivity and oral behaviors in veal calves.

The aim of this work was to assess the role of social and physical enrichment in the adaptation of veal calves to their environment. We compared calves housed in individual stalls that varied in the extent of contacts they allowed between neighbors (16 calves: open partitions; 16 calves: solid partitions; 32 calves: solid and extended partitions preventing all contact). All but 16 out of the 32 isolated calves were provided with a piece of tire and a chain, objects they could easily nibble. We assessed time budget, behavioral reactions to a water throw, neuroendocrine responses to stress (ACTH challenge and catecholamine synthesis), health, and growth. Calves kept in isolation displayed more startled reactions (16 isolated calves vs 5 non-isolated calves were startled by the throw, P < .05). Calves without objects spent more time nibbling at the feeding grille (5 vs 3% time, P < .01), licking their lips and tongue-rolling (7 vs 4% time, P < .05). Social contacts and the provision of objects had no incidence on neuroendocrine measurements and growth. Contacts with neighbors resulted in a slight but nonsignificant rise in disease. Depriving calves of social contacts increases behavioral reactivity, probably because there are no peer animals through which reactions can be moderated, and the lack of adequate objects to nibble promotes self-directed activities.

Individual differences in docility in Limousin cattle.

Docility tests were performed over 3 yr on 906 Limousin heifers sired by 34 males. The heifers were tested individually when they were 10 to 11 mo old in a pen with a handler who had 2 min to lead the animal to a corner, keep it there for 30 consecutive seconds, and then to stroke it. Behaviours of the animals were recorded and scores calculated. The first score (docility score) was a continuous variable combining the greatest possible information. The second score (docility criterion) was a categorical trait with four classes. Tests were performed by seven different handlers. The effects of handler, year, birth period, dam parity, birth region, husbandry system, and sire were estimated. Handlers, birth period, husbandry system, and sire had significant effects. In particular, animals that were managed indoors were more docile than those reared out-of-doors at least part of the time. Heritability estimates of the docility score (.22) and docility criterion (.18) seem sufficient to select for docility traits.

Evaluating housing systems for veal calves.

Limitations of space, diet, and social environment can impair the welfare of veal calves reared in intensive farms compared with those calves allowed to pasture with their dams. In intensive farms most of the animals are housed in tether stalls or in crates. Stalls that greatly restrict the behavior of calves are not an adequate housing system. If the crates are small enough to prevent calves from lying in a comfortable position, they also impair the welfare of calves and lower their growth rate and disease resistance. Social contacts are limited in crates with solid partitions, but even if this social isolation seems unnecessary, it does not have the long-term effects on social and maternal behavior previously described. Because mortality rate is lower in crates than in group pens, and considering the time a calf spends grooming itself and lying with its legs stretched, large crates with open partitions are an acceptable alternative to group housing. However, improving group pens by providing adequate floors and automated feeding systems should make that type of housing better than crates. Other types of veal production such as the rearing of the calves by their dams could also be promoted. Other factors interact with housing system to affect the welfare status of veal calves. Milk-only diets should be avoided, and it is necessary to provide calves with adequate roughage as a way to enrich their environment. Friesian calves adapt better to veal calf operations than do Salers calves, and this difference between breeds must be considered when designing housing systems. The age of veal calves at slaughter should be considered to avoid maintaining calves in a preruminant physiological state beyond the point of the naturally occurring transition.

Decrease in cow-calf attachment after weaning.

Experiments were undertaken to measure attraction of suckler calves to their dams after separation for abrupt weaning. On days 0, 2, 7 and 20 after weaning in experiment 1 and on days 1, 9, 16, 24 and 35 after weaning in experiment 2, calves were observed in a pen where they could stay either near the dam or near another familiar cow or calf. On days 0, 2, 7, 20 and 35, calves and their dams were reunited for 2 min. Calves showed a preference for the dam to another cow up to day 24 and to a calf up to day 9 only. From day 20, cows rejected their calves at suckling. It is concluded that the calves remained attracted by their dams for at least three weeks after weaning while the cows already rejected them. In addition, attraction between calves increased after weaning.

[Value of cerebral mapping in the study of amblyopia]. / Intérêt de la cartographie cérébrale dans l'étude de l'amblyopie.

The Alpha attenuation response to a visual stimulation was studied by quantified electroencephalogram for three posterior electrodes 01, 02, Pz, in twenty-five patients presenting either functional, deprived or cured amblyopia. A sample group allows the comparison of differences of visual attenuation responses with or without penalisation on the normal eye. The decreased percentage of cerebral activity during visual stimulations, in the Alpha band of cerebral frequencies represents the visual reactivity. Cerebral activity was checked during different sequences and visual reactivity was calculated. It demonstrates that the stimulation of the amblyopic eye shows a visual Alpha attenuation response only slightly more significant than the one obtained by stimulation of the healthy or normalised eye, or the stimulation of both eyes at the same time. But there is no change of visual Alpha attenuation when a +15 diopters penalisation is used as an optical correction for the normal eye. These findings allow us to disregard either deficient visual acuity or monocular stimulation as a cause of this phenomenon and seems to suggest a cortical neutralization as its origin. This technique could possibly objectify the therapeutic improvements during the treatment. These facts are in accordance with the neurophysiological studies of Hubel and Wiesel.

Cortisol responses to physical and pharmacological stimuli in heifers.

The aim of this study was to assess bovine plasma cortisol response to blood sampling, to 5-min isolation in a novel arena and to dexamethasone blockade and ACTH stimulation. Twelve 10-month old heifers of the Friesian and Salers breeds were used. Blood collection, carried out via a jugular cannula or caudal venipuncture, had no significant effect on cortisol level. This level increased by about 20 ng/ml 10 min after the heifers were isolated in the novel arena, and it returned to the initial value within 70 min. Cortisol response at 10 min was a good indicator of overall response and was also related to the animal remaining motionless in the arena. The cortisol level declined 14 hrs after dexamethasone injection. Intramuscular or intravenous administration of ACTH resulted in a large increase (maximum: 44 ng/ml above the initial level), and high levels were maintained from 30 to 180 min following injection. The cortisol level at 30 min seemed to be a reliable indicator of mean response to ACTH.

[Mother-young relations and prolactin response to mammary stimulation in the cow: influence of milking and free or fettered suckling]. / Relations mère-jeune et réponse prolactinique à la stimulation mammaire chez la vache: influences de la traite et de l'allaitement libre ou entravé.

Maternal behaviour and PRL response to mammary stimulation have been studied in three groups of 20 Friesian cows each, held according to three different systems of management. In the 1st group (group AL), the cows suckled 3 alien calves and were all kept in one pen after a fostering period of two weeks. In the second group (group AE), the cows suckled 3 alien calves twice a day when tethered. In this group, the fostering procedure was limited to 18 h. In the 3rd group (group T), the cows were separated from their calves just after birth and then milked twice a day. On day 45 after calving, mother-young relationships were observed in the three groups for one day, the animals all being kept with familiar or alien calves on this occasion. Then, on day 112 postpartum, the PRL response to suckling (groups AL and AE) or to milking (group T) was studied in 4 cows of each group. Group AL cows were maternal and selective. They preferentially suckled their foster calves rather than alien ones and suckling was carried out in parallel-inverse position. Group AE cows were also maternal but the relationships were not selective and suckling in parallel-inverse position was less frequent. Finally, most milked cows did not allow the calves to suck. A comparison of PRL response to mammary stimulation showed that the response of milked cows (group T) to milking was low whereas suckling by an alien calf in group AL did not lead to a PRL response; the presence of the 3 foster calves was needed to induce this response. These results indicate that breeding conditions after calving influence mother-young relationships and suggest that maternal behaviour is a modulating factor of PRL response to suckling.

Attraction and repulsion by amniotic fluids and their olfactory control in the ewe around parturition.

The reaction of ewes towards amniotic fluids was studied in intact multiparous ewes in various physiological states (oestrus, luteal phase, mid-pregnancy and around parturition), using a test of preference for food associated or not with the presence of amniotic fluids in the food. Fluids were collected on alien newborn lambs. Results indicate that ewes are strongly repelled by amniotic fluid at all of the times tested except for a short period around parturition. Immediately before expulsion of the foetus ewes become strongly attracted by amniotic fluids. This attraction persists just after parturition, but fades within 4 hours in most animals. This attraction-repulsion behavior appears to rely heavily on olfactory cues. Ewes made anosmic with zinc sulphate do not show repulsion or attraction towards amniotic fluids at any of the physiological states studied. These results are discussed in the light of our knowledge about the factors controlling the onset of maternal behavior in the ewe (hormones and genital stimulation).